characterization and control of selenium releases … · characterization and control of selenium...
TRANSCRIPT
ii
CHARACTERIZATION AND CONTROL OF SELENIUM RELEASES FROM MINING IN THE IDAHO PHOSPHATE REGION
A Thesis
Presented in Partial Fulfillment of the Requirements for the
Degree of Master of Science
with a
Major in Environmental Science
in the
College of Graduate Studies
University of Idaho
by
Melanie M. Bond
14 February, 2000
Major Professor: Greg Möller, Ph.D.
iii
AUTHORIZATION TO SUBMIT THESIS
This thesis of Melanie M. Bond, submitted for the degree of Master of Science with a
major in Environmental Science and titled “Characterization and Control of Selenium
Releases from Mining in the Idaho Phosphate Region,” has been reviewed in final
form, as indicated by the signatures and dates given below. Permission is now
granted to submit final copies to the College of Graduate Studies for approval.
Major Professor Date Gregory Möller, Ph. D.
Committee Members Date Donald Crawford, Ph. D.
Date Keith Prisbrey, Ph. D.
Date Phil Druker
Department Administrator Date Margrit von Braun, Ph. D.
Dean, College of Letters and Science Date Kurt Olsson, Ph. D.
Final Approval and Acceptance by the College of Graduate Studies
Date Jean’ne M. Shreeve, Ph. D.
iv
ABSTRACT
In August of 1997, the J. R. Simplot Company partnered with the University of
Idaho to investigate selenium releases from its Smoky Canyon phosphate mine in
Idaho. Site sampling provided collection of water from up- and down-gradient of
mine-affected areas as well as collection of mine overburden samples for
characterization.
Analyses of the water revealed that concentrations of selenium in a french
drain which underlies the overburden piles vary from below detection limits at the
inlet to near 0.0086 mM (680 µg/L) at the outlet. Analyses conducted on the
overburden indicated that sulfide minerals comprise about 0.2 volume percent of
siltstone, the majority component in the samples. Thin-section microprobe analysis
of the siltstones showed that selenium is substituting for approximately 1.28% of the
sulfur in the pyrite lattice (by weight). The oxidation of these reactive sulfides is
believed to be the major source of the selenium in the surface water.
Several water and soil treatments were then investigated for effectiveness in
the reduction of selenium concentrations in the surface waters as well as in the
temporary immobilization of selenium in the overburden itself. Water treatment was
ineffective due to storage aging of the water samples in which selenite (SeO32-)
oxidized to the less treatable selenate (SeO42-). Saturated soil paste studies with
amendments showed a significant reduction in the amount of selenium leached for
most amendments. Application of potato waste was the most effective, followed by
use of granular iron. Field studies with selected amendments are currently
underway.
v
ACKNOWLEDGMENTS
Recognition must certainly be given to Dr. Gregory Möller and Tamara
Shokes for their guidance and showing me the ropes, and to the staff of the U of I
Analytical Sciences Laboratory for taking such great care of my samples. I would
also like to thank the J. R. Simplot Company for making this research possible in the
first place. I am grateful to Dr. Prisbrey, Dr. Crawford and Mr. Druker for their careful
critique of this thesis; without their help it would not have gone together quite as
smoothly as it has. And finally, although certainly not the least of my thanks goes to
my family - Mom, Dick, Kirstin, Anna, Dad, Meri, and everyone else that believed I
could reach this goal, thank you!
vi
TABLE OF CONTENTS
AUTHORIZATION TO SUBMIT THESIS ...............................................................................................II
ABSTRACT .......................................................................................................................................... IV
ACKNOWLEDGMENTS........................................................................................................................ V
TABLE OF CONTENTS ....................................................................................................................... VI
LIST OF FIGURES ............................................................................................................................... IX
LIST OF TABLES................................................................................................................................. XI
1.0 PURPOSE AND OBJECTIVES........................................................................................................1
2.0 SELENIUM .......................................................................................................................................3
2.1 Chemistry, production, and uses .................................................................................................3
2.2 Nutrient and toxicant ....................................................................................................................4
2.3 Environmental sources and releases...........................................................................................6
2.4 Overview of treatment approaches..............................................................................................8
3.0 MATERIALS AND METHODS .......................................................................................................13
3.1 Sampling of site .........................................................................................................................13
3.2 Laboratory and analytical equipment.........................................................................................15
3.3 Analytical methods for water and soils ......................................................................................16
3.3.1 Water...................................................................................................................................16
3.3.2 Soil.......................................................................................................................................20
3.4 Characterization methods ..........................................................................................................22
3.5 Water and soil treatment methods.............................................................................................24
3.5.1 Water...................................................................................................................................24
3.5.2 Soil.......................................................................................................................................25
4.0 CHARACTERIZATION STUDY......................................................................................................28
4.1 Water analyses ..........................................................................................................................28
4.2 Solid matrix ................................................................................................................................34
4.2.1 Soil screens.........................................................................................................................34
vii
4.2.2 Neutron activation ...............................................................................................................37
4.2.3 Microprobe analysis ............................................................................................................38
4.2.4 Sequential extraction...........................................................................................................40
4.2.5 Organo-selenium extraction ................................................................................................41
4.2.6 Overburden leachate studies ..............................................................................................41
4.2.7 Correlation analysis.............................................................................................................44
4.3 Significant findings .....................................................................................................................45
5.0 TREATABILITY STUDIES .............................................................................................................47
5.1 Identification of target elements .................................................................................................47
5.2 Water treatment .........................................................................................................................48
5.2.1 Selenium .............................................................................................................................49
5.2.2 Other constituents of potential concern...............................................................................51
5.3 Soil treatment .............................................................................................................................54
5.3.1 Selenium .............................................................................................................................54
5.3.2 Other constituents of potential concern...............................................................................59
5.4 Significant findings .....................................................................................................................67
6.0 CONCLUSIONS .............................................................................................................................69
A. APPENDIX OF CHARACTERIZATION DATA PRESENTED IN MASS UNITS ............................71
A.1 Water .........................................................................................................................................71
A.1.1 Chloride...............................................................................................................................71
A.1.2 Sulfate .................................................................................................................................71
A.1.3 Nitrogen, Nitrate-Nitrite: ......................................................................................................71
A.1.4 Phosphorous:......................................................................................................................71
A.1.5 Anions .................................................................................................................................72
A.1.6 Dissolved Multi-element Screen .........................................................................................72
A.1.7 Total Recoverable Multi-element Screen:...........................................................................73
A.1.8 Selenium .............................................................................................................................73
A.2 Solid Matrix ................................................................................................................................74
viii
A.2.1 Phosphorous and Potassium..............................................................................................74
A.2.2 Sulfate-Sulfur ......................................................................................................................74
A.2.3 Soil Nitrogen - Ammonium and Nitrate ...............................................................................74
A.2.4 Soil Boron ...........................................................................................................................74
A.2.5 Trace Micro-element Screen ..............................................................................................75
A.2.6 Selenium .............................................................................................................................75
A.2.7 Neutron Activation Analysis ................................................................................................76
A.2.8 Sequential Extraction ..........................................................................................................76
A.2.9 Methylene Chloride Organo-Selenium Extraction ..............................................................76
A.2.10 Agitation Leach................................................................................................................76
B. APPENDIX OF TABULATED TREATMENT DATA .......................................................................80
B.1 Water .........................................................................................................................................80
B.1.1 Maximum Contaminant Levels ...........................................................................................80
B.1.2 Water Treatments ...............................................................................................................80
B.2 Solid Matrix ................................................................................................................................85
B.2.1 Chemical Armoring .............................................................................................................85
B.2.2 Saturated Paste ..................................................................................................................85
REFERENCES .....................................................................................................................................92
ix
LIST OF FIGURES
Figure 1. United States Geological Survey (USGS) topographic map of the western US phosphate resource area. Encircled area approximates the study area of concern.....................................................................................................2
Figure 2. Thermodynamic stability of selenium in water at 10°C, ionic strength 0.017 and [Se]=8.61µM (HSC Chemistry© for Windows). Solid lines indicate areas of solid phase stability, dashed lines indicate aqueous phase stability, and dotted lines indicate water stability limits. ........................................7
Figure 3. Thermal polyaspartate (tpA) subunit structure. ...................................12
Figure 4. Map showing sample locations along the Pole Canyon overburden pile and creek. Adapted from Montgomery-Watson, 1998 (69)..........................14
Figure 5. Element map derived from microprobe analysis of Pole Canyon overburden samples (66). ...................................................................................39
Figure 6. Effects of various water treatments on the concentration of selenium in Pole Creek outlet water. Error bars represent sample standard deviation (S.D.) for n=3 runs...............................................................................50
Figure 7. Effects of various water treatments on the concentration of cadmium in Pole Creek outlet water. Error bars represent sample S.D., n=3....51
Figure 8. Effects of various water treatments on the concentration of copper in Pole Creek outlet water. Error bars represent sample S.D., n=3. ..................52
Figure 9. Effects of various water treatments on the concentration of nickel in Pole Creek outlet water. Error bars represent sample S.D., n=3. ......................53
Figure 10. Effects of various water treatments on the concentration of zinc in Pole Creek outlet water. Error bars represent sample S.D., n=3. ......................54
Figure 11. Amount of soluble/exchangeable selenite leached from soil after three consecutive leach periods; water/24 hrs, 2nd water/24hrs, and phosphate/24 hrs. ...............................................................................................56
Figure 12. Effects of amendments on amount of selenium leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3......................................................................................................................57
Figure 13. Effects of amendments on amount of selenium leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3......................................................................................................................58
x
Figure 14. Effects of amendments on amount of cadmium leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3......................................................................................................................60
Figure 15. Effects of amendments on amount of cadmium leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3......................................................................................................................60
Figure 16. Effects of amendments on amount of copper leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3......................................................................................................................61
Figure 17. Effects of amendments on amount of copper leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3......................................................................................................................62
Figure 18. Effects of amendments on amount of nickel leached from overburden saturated paste after 14 days. Error bars represent samples S.D., n=3.............................................................................................................63
Figure 19. Effects of amendments on amount of nickel leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3......................................................................................................................64
Figure 20. Effects of amendments on amount of zinc leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3......................................................................................................................64
Figure 21. Effects of amendments on amount of zinc leached from overburden saturated paste after 28 days. Error bars represent sample S.D. ...65
Figure 22. Effects of amendments on amount of manganese leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3......................................................................................................................66
Figure 23. Effects of amendments on amount of manganese leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3......................................................................................................................67
xi
LIST OF TABLES
Table 1. Results of selenium analysis on Pole Canyon french drain water. Strikethrough indicates result ≤ estimated detection limit (EDL). ........................29
Table 2. Results of anion screen performed on Pole Canyon overburden french drain water. ..............................................................................................29
Table 3. Results of dissolved multi-element screen performed on Pole Canyon overburden french drain water...............................................................31
Table 4. Results of the total recoverable multi-element screen performed on the Pole Canyon overburden french drain water.................................................32
Table 5. Results of screen for domestic livestock water performed on Pole Canyon overburden french drain water...............................................................33
Table 6. Results of general soil screen performed on the -3/8 in. soil fraction of Pole Canyon overburden samples. .................................................................35
Table 7. Results of total soil microelement screen of samples from the Pole Canyon overburden dump. .................................................................................36
Table 8. Results of selenium analysis on acid digested Pole Canyon overburden samples. ..........................................................................................37
Table 9. Results of nuclear activation analysis performed on dried and ground Pole Canyon overburden samples..........................................................38
Table 10. Composition of selected minerals (weight percent) by microprobe analysis of thin sections of Pole Canyon overburden. ........................................38
Table 11. Results of the sequential extraction procedure performed on unweathered Pole Canyon overburden samples. ...............................................40
Table 12. Comparison of results of organo-selenium extraction and neutron activation analysis of Pole Canyon overburden. .................................................41
Table 13. Results of agitation leach of Pole Canyon overburden samples with Pole Creek water as leachate. ............................................................................42
Table 14. Results of agitation leach of Pole Canyon overburden with 18 MΩ-cm water as leachate. .........................................................................................43
Table 15. Determination of constituents of potential concern in the Pole Canyon french drain outlet water. After Montgomery-Watson, 1998 (69). .........48
1
1.0 PURPOSE AND OBJECTIVES
In the fall of 1996, livestock in the areas down gradient of regional phosphate
mining overburden dumps in southeastern Idaho (Figure 1) were showing signs of
selenium toxicosis (selenosis). Evidence of selenosis in the affected horses
included hair loss, hoof disorders and the most severe cases resulted in the animals
being euthanized. Post-mortem analysis confirmed chronic selenosis. Analysis of
the forages and surface water in the livestock pastures indicated higher than
recommended levels of dietary selenium. Further examination suggested that
drainage from phosphate mining waste rock dumps may have been the source of
the selenium.
This prompted action under the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA) by the United States Forest
Service against one of the companies mining in southeastern Idaho. Concurrently,
study of the source, extent, cycling, and possible control methods for the selenium
releases in the phosphate lease area began, involving five mining companies and
the state and federal land managers.
In August 1997, the J. R. Simplot Company, which operates phosphate
leases in the area, partnered with the University of Idaho to characterize selenium
releases at the Smoky Canyon Mine and examine control strategies. This
partnership provided the opportunity for the research contained in this thesis. This
research pursues two main objectives: first, to characterize the selenium release and
second, to examine potential control approaches.
2
Characterization of the selenium release employed various water, soil, and
geochemical tests as compared to what is known of the composition of the
Phosphoria Formation and its members. Primary research focused on
characterization of soil and water samples from mining overburden piles at the
Smoky Canyon Mine. It included aqueous metals screens, domestic water screens,
overburden leachate tests, neutron activation analysis, and thin section microprobe
analysis of the overburden. Appendices A and B contain the research data
presented in mass units as is more commonly used in regulatory science.
Identification of a control approach applicable to the Smoky Canyon Mine was
the second objective of this work. The second chapter provides a summary of
treatment approaches for selenium-affected waters and soil and the fifth chapter
contains the further analysis of those experiments deemed applicable to the site.
Figure 1. United States Geological Survey (USGS) topographic map of the western US phosphate resource area. Encircled area approximates the study area of concern.
3
2.0 SELENIUM
2.1 CHEMISTRY, PRODUCTION, AND USES
Selenium is a metalloid found in group VIB of the periodic table, as are sulfur
and tellurium. It commonly occurs with tellurium and acts as a sulfur analog in
nature. The atomic weight of selenium is 78.96 g/mole. It has five naturally
occurring cold isotopes and two beta particle emitting radioactive isotopes, 75Se and
79Se (1). It has four oxidation states in nature: -2, 0, +4, and +6, of which the +4 and
+6 will form the oxyanions selenite (SeO32-) and selenate (SeO4
2-) in aqueous
solution. When found in its elemental form, it is a red amorphous or black crystalline
solid (2). In the precipitation of elemental selenium from solution, the red form
precipitates first and then transforms into the black crystalline form with aging or the
application of heat (3).
Selenium substitutes for sulfur in minerals such as pyrite, chalcopyrite, and
bornite, but few deposits contain high enough concentrations for economic mining of
selenium alone. Therefore, the most common method for obtaining selenium is from
the refining of anode slimes, a product from the electrowinning of copper. One other
source of selenium is from the leaching of flue dusts from sulfide ore smelter
operations (4). According to the USGS Mineral Industry Survey: Selenium and
Tellurium (5), worldwide production of selenium reached over 2100 metric tons.
Selenium has uses in glass manufacturing, electronics, agriculture, metal
alloy production, and in chemical and pigment production. Demand for selenium
4
may increase in the future due to the possibility of using selenium to replace lead in
plumbing brass and other lead alloys (5).
2.2 NUTRIENT AND TOXICANT
Selenium is found not only in products used in everyday life, but it is also
recognized as a micronutrient required by fish, birds, and mammals (including
humans) to maintain good health (6). Plants will uptake selenium and make it
available to foraging animals, but no nutritional requirement for selenium in plants
has been determined. All animals require approximately 0.1 mg of selenium/ kg
food in their diet to maintain levels of the enzyme glutathione peroxidase
(SeGSHpx), which assists in the conversion of free radicals into other harmless
products. Deficiencies in selenium can inhibit growth, limit reproductive capability,
reduce appetite, and possibly lead to death (6).
Conversely, too much selenium in the diet of animals (3-15 mg Se/kg food)
can cause chronic or acute selenosis and death. Horses are especially susceptible
to selenosis. Evidence of chronic selenosis includes necrotic hoof (and nail)
disorders, hair loss, tender joints, stillbirths, and malformation of offspring. Effects of
acute selenosis vary greatly by dose, bioavailability of the selenium form, and animal
species affected. The most bioavailable form of selenium is selenite (SeO32-), which
is given a bioavailability of 100%. Plant products generally provide 80% bioavailable
selenium, and animal foodstuffs are generally below 25% (6).
Based on the narrow range between beneficial concentrations of selenium
and concentrations causing toxic effects, the United States Environmental Protection
Agency (EPA) has designated selenium as a priority pollutant. As of 1987, the
5
drinking water maximum contaminant level (MCL) is 10 µg/L and water-quality based
criteria for protection of aquatic life is 5 µg/L for chronic exposure (7, 8). Waters
containing more than 1000 µg/L are considered toxic waste by the EPA (9).
The EPA is currently updating water quality criteria and on December 10,
1998 promulgated a Notice of National Recommended Water Quality Criteria in the
Federal Register. Recommended chronic criteria are at 5.0 µg/L and acute criteria
are given as an equation relating the fraction selenite to fraction selenate present:
These regulations apply to all states that do not have regulations meeting federal
water quality standards (8).
While there is evidence to support having MCLs of lower values, there are
numerous problems with accurate detection of total selenium at low levels in water
and wastewater (10). In a blind round-robin study recently conducted by the
University of Idaho, seven different analytical laboratories were sent seven
duplicates of seven industrial and natural water samples for analysis of total
selenium in water. Results of the study indicated large variation in minimum and
maximum reported concentrations, distinct differences in laboratory precision, and
routine reporting of numerical results below statistical limits of quantitation. These
results suggest caution in the interpretation of selenium data without specific
knowledge of the statistical significance of the data.
)83.12/()9.185/(1
selenateselenite ffAcute
+=
6
2.3 ENVIRONMENTAL SOURCES AND RELEASES
Geologically, the highest concentrations of selenium are generally found in
copper and copper-lead-zinc sulfide deposits, but smaller concentrations of selenium
are found in the sedimentary uranium and phosphatic vanadium deposits of the
western U.S. (4). Siltstones and shales are common sedimentary rocks that host
selenium. Examples of these siltstones can be seen in members of the Phosphoria
Formation of Idaho, Wyoming, Montana, Utah, and Nevada (11, 12) (Figure 1). The
Meade Peak member of the Phosphoria Formation is being mined for phosphate
rock in the study area and is thought to be the source of selenium.
Exposure of selenium hosting sulfide minerals to air and water causes
oxidation and results in acid rock drainage, an oxidation catalyzed by aerobic
microbes such as Thiobacillus ferrooxidans. This oxidation often results in the
release of heavy metals and the production of sulfuric acid, which is generally the
main concern associated with acid rock drainage (13). Sulfur oxidizes to form
oxyanions such as sulfate (SO42-), and selenium behaves in a similar way, producing
selenite (SeO32-) and selenate (SeO4
2-) anions. Kinetically favored selenate is the
most common in oxidized waters, but neutral to acidic environments will favor the
selenite and biselenite forms (Figure 2). Selenate is much more mobile in an
aqueous environment and is much harder to treat than selenite (2).
Studies conducted by the USGS National Research Program discuss the
correlation of source rocks in California to the selenium toxicosis observed in birds of
7
the Kesterson National Wildlife Refuge in the San Joaquin Valley (14, 15).
Agricultural practices in the San Joaquin Valley area have concentrated selenium
released from cretaceous marine shales of the Coast Ranges. The practice of
storing agricultural drainage water in areas such as the Kesterson NWR
concentrates the salts when evaporation outpaces the influx of water. This results in
high levels of selenium in the water, sediments, and biota, which in turn
bioaccumulate in aquatic birds feeding in the affected areas. Bioaccumulation in the
aquatic birds led to deformities and death of embryos and hatchlings reaching 64%
14121086420
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
-0.6
-0.8
-1.0
Se - H2O System Pourbaix Diagram
pH
Eh (Volts)
Se
H2Se0
HSe-
H2SeO30
HSeO3-
HSeO4-
SeO32-
SeO42-
Figure 2. Thermodynamic stability of selenium in water at 10°°°°C, ionic strength 0.017 and [Se]=8.61µM (HSC Chemistry© for Windows). Solid lines indicate areas of solid phase stability, dashed lines indicate aqueous phase stability, and dotted lines indicate water stability limits.
8
of the population. Elevated levels of selenium are also observed in the local fish
(15).
Based on the USGS studies, areas of similar geology and hydrology that
have human-influenced selenium problems include Tulare, California; Green River,
Utah; Kendrick, Wyoming; Sun River, Montana; and Stillwater, Nevada (15).
Selenium source rocks of similar composition occur in parts of Arizona, New Mexico,
Texas, Oregon, and Idaho.
2.4 OVERVIEW OF TREATMENT APPROACHES
Many recent articles, books, and patents discuss the treatment of soil and
water for selenium contamination. Those treatments include co-precipitation,
chemical reduction, ion exchange, adsorption, membrane filtration, microbial
reduction, and physical segregation methods. The most common treatment
approaches for immobilizing or removing selenium oxyanions from water and soil
involve co-precipitation and/or chemical reduction.
Iron co-precipitation is by far the most successful and widely used method of
contaminant removal from water and soils. Iron(II) salts, such as ferrous chloride,
can be added to a near neutral solution containing oxyanions (such as selenium)
and the resulting ferric oxyhydroxide precipitate incorporates the oxyanions into its
lattice (16, 17). In addition to entrapment of these oxyanions into the lattice, the
oxidation of ferrous ions to ferric ions may have the capability of reducing some of
the selenium to its elemental form (18). The resulting FeOOH and Fe2(SeO3)3
precipitates are largely insoluble and to some extent can control selenium solubility
9
in soils. In addition to iron salts, chemicals such as polymeric dithiocarbamates will
also complex and co-precipitate with selenium oxyanions (19).
A similar technology to the addition of iron salts is chemical reduction through
the addition of a zero-valent metal (20, 21, 22). The oxidation of the metal in an
aqueous acidic to neutral solution is the driving force behind this method. Zero-
valent iron is unstable in water, and its oxidation will cause the release of electrons
with the production of the more stable Fe2+ and Fe3+. Half-reactions for this process
are
Oxidation:
Fe ⇔ Fe2+ + 2e-
Fe2+ ⇔ Fe3+ + e-
Reduction:
O2(g) + 8H+ + 8e- ⇔ 4H2O
2H+ + 2e- ⇔ H2(g)
The electrons produced in this reaction are responsible for the reduction of aqueous
metal ions as well as the hydronium ion (23).
Marchant’s (21) work showed that the direct reduction of selenium oxyanions
to elemental selenium (or selenide) through the use of zero-valent iron must be done
under acidic conditions. This acidic medium prevents the formation of iron oxy-
hydroxides while the redox couple of ferrous-ferric iron reduces the selenium
species. Work by Baldwin et al. (22) and Murphy (18) demonstrated that allowing
the production of hydroxyl ions from the corrosion of the iron can cause the selenium
oxyanions to co-precipitate with ferrous oxy-hydroxides.
10
Ion exchange and adsorption are two more processes that can also
effectively remove selenium oxyanions from water. Ion exchange is a chemical
process involving the reversible exchange of ions between a liquid and a solid (24).
A strong base resin removes selenium oxyanions, but there is competition between
selenium oxyanions and sulfate ions if they are present. This makes the application
of ion exchange to wastewater difficult (25). Most applications of ion exchange are
in the preparation of water samples for analysis in the determination of species
present (26, 27). However, recent developments in ion exchange processes, which
are cheaper and more selective for selenium species, may increase the likelihood of
the development of a commercially viable process (28, 29, 30).
Currently, physical and chemical adsorption are the two most common
adsorption methods for treatment of wastewater. Physical adsorption occurs when
the van der Waals forces between the solute and adsorbent are greater than the
forces between the solute and solvent. This is a reversible process. Chemical
adsorption involves a reaction between the adsorbent and the solute, and this
process is usually irreversible (24).
Physical adsorption of the selenium oxyanions onto surfaces of alumina or a
combination of lanthanum oxide and alumina effectively removes selenium
oxyanions from water. Regeneration of the adsorbent causes no apparent loss of
sorptive capacity (31, 32). The non-reversible adsorption of selenium oxyanions
utilizing amorphous iron oxyhydroxides, manganese dioxide, retorted oil shale, and
zeolites treated with cations of hexadecyltrimethylammonium (HDTMA) also appears
effective (33, 34, 35).
11
In the last decade, a large number of membrane systems have been
developed, especially in commercial processes that use nanofiltration. Traditional
reverse osmosis (RO) methods are too expensive for use in the treatment of
industrial and agricultural wastewater due to pretreatment and energy costs (36).
Compared to RO, nanofiltration membranes require little or no pretreatment of
wastewater prior to treatment and have much lower pressure requirements for water
to pass through them (37, 38). Nanofiltration is a proven method for removing
selenium oxyanions as well as sulfate, bromate, arsenic oxyanions, and nitrates
from water (39, 40, 41, 42, 43, 44).
Microbial approaches to treatment have also been studied more carefully in
the last decade (45). Microbial processes in a passive remediation scheme that is
low in operating costs may have long-term applicability for mine drainage treatment.
The use of bacteria of the genus Clostridium in bioreactors for the remediation of
selenium contaminated waters is one proven treatment approach (46, 47). Other
studies utilizing bacterial approaches to selenium stabilization and removal include
microbial culturing in sediments, algal-bacterial bioreactors, and slow-sand filtration
systems (48, 49, 50, 51).
Organic soil amendments for the stimulation of natural microbial activity in
soils such as irrigated farmland are a newer approach to remediation (52). Studies
indicate that the wetting-drying cycle combined with an added carbon source for
microbes significantly decreases the amount of selenium oxyanions leaching from
soil.
12
A specific organic amendment that we examined in this study is thermal
polyaspartate (tpA), a compound marketed to the agricultural industry by Donlar
Corporation as Amisorb®. Thermal polyaspartate is a low toxicity, biodegradable co-
polymer of MW 10,000-25,000 (Figure 3) which has uses in oil production water
treatment, pharmaceuticals, and the agricultural industry (53). The main uses of tpA
are corrosion inhibition and nutrient absorption enhancement. The compound can
be used by microbes as a food source (70% BOD degradation in 28 days), and it
has chelating properties which allow it to bind with positively charged ions when its
acid groups are displaced. TpA chelated with ferric iron has demonstrated the ability
to remove dissolved selenium from solution (54).
The final control method is physical segregation. These methods prevent
water or air from moving through contaminated soils, thus preventing the initial
mobilization of the contaminant. Methods include installation of drainage fields,
impermeable capping of dumps, and solidification of contaminated materials to
prevent penetration and flow of water. Segregation is not examined in this study.
α=0.3 β=0.7
NH
OH
O
OOHO
ONH
n n
Figure 3. Thermal polyaspartate (tpA) subunit structure.
13
3.0 MATERIALS AND METHODS
3.1 SAMPLING OF SITE
Prior to sampling, the materials to be used for the collection and storage of
the water and soils were washed and rinsed with deionized water to prevent cross
contamination. The wash consisted of soaking and scrubbing all materials with hot
Micro® detergent solution and triple rinsing with deionized water. A final rinse was
made with 18 MΩ-cm distilled water. A 2.5 gallon cubitainer of deionized rinse water
and a bottle of micro solution were prepared for quick clean-up of equipment
between sampling sites in order to reduce chances of cross contamination.
Four 2.5 gallon water samples were collected from the Pole Canyon
overburden dump, two at the inlet end (PCW1a, b) of the french drain and two at the
outlet end (PCW2a, b; See Figure 4). Samples were collected by allowing the creek
water to flow into the cubitainers, which were then sealed with plastic under the
valves to prevent leakage. Conductance, pH, and temperature measurements were
made on site, and the water was packed into coolers for same-day transportation to
the University of Idaho. Upon arrival at the University of Idaho Analytical Sciences
Laboratory, the samples were then stored at 4°C.
Five soil samples in five-gallon buckets were taken from the overburden piles
in Pole Canyon. Two samples were collected at the upstream (upper) end of the
piles at a depth of approximately 6 inches (PCO-01, PCO-02). A third sample was
taken from the downstream (lower) end above the French drain which had slumped
in the spring of 1997 (PCO-03). Prior to the slump, this sample site had been at a
Figure 4. Map showing sample locations along the Pole Canyon overburden pile and creek. Adapted from Montgomery-Watson, 1998 (69).
15
depth of approximately 20 feet within the pile. It is therefore considered our
‘unweathered’ overburden sample. The fourth site was on an upper bench at the
downstream end of the pile where topsoil application required excavation to about a
one foot depth to reach overburden (PCO-04). A fifth sample was a channel sample
taken from the central area on the top of the overburden pile (PC-CH). All of these
samples were stored refrigerated and sent to the University by air transport two days
after collection, upon arrival at the University the soil samples were stored at 4°C.
3.2 LABORATORY AND ANALYTICAL EQUIPMENT
All analyses were performed by the University of Idaho Analytical Sciences
Laboratory (ASL), a US EPA Drinking Water Program certified facility operating in
compliance with Good Laboratory Practice standards (55). Quality control for the
analyses involved the periodic analysis of laboratory performance check solutions at
known concentrations to verify the equipment calibration. Equipment calibration
solutions covered the anticipated range of concentrations of the samples submitted
for analysis. Standard reference water containing trace metals was used for quality
control checks (Analytical Products Group, Inc.) and equipment manufacturer
recommended statistical performance limits were followed for batch data quality
acceptance criteria. All standards used in the analyses are traceable to the US
National Institute of Standards and Technology.
Analytical instruments used by the ASL for this study included: Leeman 2000
inductively coupled argon plasma spectrophotometer (ICP), Perkin Elmer P-40 ICP,
Dionex DX-100 Ion Chromatograph, YSI model 31Conductivity Bridge, Orion model
525A pH-Eh multimeter, Milton Roy Spectronic 301, Alpkem Rapid Flow Analyzer,
16
HF Scientific Turbidimeter DRT 100B, Branson Sonifier 450, and a Zymark
TurboVap evaporator.
The following chemicals were reagent grade or better and used as received.
Chemicals used included anhydrous ferric chloride (Fisher Scientific), activated
neutral alumina (Fisher Scientific), activated carbon (J. T. Baker Inc.), colloidal iron
(micropowder iron, 1-3 µm, grade S-3700, ISP Technologies, Inc.) and industrial
mixed mesh scrap iron (100% passing 8 US Sieve; Master Builders, Inc.).
Industrial grade thermal poly-Aspartate (tpA), Amisorb® Nutrient Absorption
Enhancer™ (Amilar International Inc.), food grade potato starch (AVEBE Veendam,
the Netherlands), and potato processing waste (J. R. Simplot Company) were also
used in some trials.
3.3 ANALYTICAL METHODS FOR WATER AND SOILS
The following analytical methods are standard operating procedures followed
by the ASL for aqueous and soil sample analysis. A brief explanation of the sources
of the methods is also provided.
3.3.1 WATER
All aqueous methods except selenium determination were developed by the
EPA and can be found in EPA Methods for Chemical Analysis of Water and Wastes
(56). Selenium determination by hydride generation ICP, a method developed by
the ASL, is modeled after research conducted at the University of California, Davis
(57).
17
Acidity (pH) – Electrometric determination of acidity by EPA method 150.1.
This method involves the electrometric determination of the pH of a water sample
using a glass electrode with AgCl reference electrode filling solution.
Alkalinity – Titrimetric determination of alkalinity by EPA method 310.1. This
method involves the titration of a known aliquot of sample with 0.01N sulfuric acid.
Upon reaching a pH of 4.5, the alkalinity of the sample is determined by calculations
and is reported in mg CaCO3/L. Alkalinity is a function of carbonate, bicarbonate,
and hydroxide content of the sample.
Anions – Determination of anion concentration in water by EPA method
300.0. A Dionex DX-100 Ion Chromatograph is used to determine concentrations of
bromide, chloride, fluoride, nitrate, nitrite, ortho-phosphate, sulfate, sulfite, and
oxalate in water samples.
Chloride – Argentometric determination of chloride in water by EPA method
325.3. Acidified samples are titrated with silver nitrate in the presence of potassium
chromate indicator. The combined appearance of a red silver chromate precipitate
and a change of solution color from bright yellow to reddish brown indicates the
endpoint. Anions and cations at concentrations normally found in surface waters do
not interfere.
Conductance – Measures of the electrical resistance of a solution by EPA
method 120.1 using a YSI Conductivity Bridge, model 31. The measurement probe
is placed within the sample of interest and the range and sensitivity of the instrument
is manually adjusted so the conductance can be read directly from the instrument
dial.
18
Dissolved multi-element screen – Sequential multi-element determination
of trace elements in solution using EPA method 200.7. A Leeman 2000 ICP is used
to measure wavelengths of target elements after acidification of the sample with
nitric acid so that the pH ≤ 2.
Filterable residue – A method for determining the amount of solids in an
aliquot of water that will pass through a glass fiber filter (EPA 160.1). After vacuum
filtration, the filtrate is evaporated in a watchglass at 180°C. The watchglass and
dried residue (>4 mg/L) are weighed to determine the total filterable residue in the
water.
Hardness– A titrimetric method for determining the hardness of samples
using EPA method 130.2. Dilution of samples over 25 mg/L CaCO3 is
recommended. Disodium ethylenediamine tetraacetate (Na2EDTA) is titrated into
the sample which also contains Eriochrome Black T indicator. When the endpoint is
reached, the indicator changes from red to blue. A calculation based on the amount
of Na2EDTA titrated reveals hardness.
Nitrate-nitrite nitrogen – A colorimetric method for determining the nitrate-
nitrite nitrogen in water samples using EPA 353.2. Filtered aqueous samples pass
through a tube containing copper and cadmium, which reduces all nitrates to nitrite.
Sulfanilamide and N-(1-naphthyl)-ethylenediamine dihydrochloride is added to form
an azo dye and the concentration is read colorimetrically by an Alpkem Rapid Flow
Analyzer. Addition of EDTA can eliminate interference from iron, copper, or other
metals.
19
Phosphorous – The photometric determination of total phosphorous in water
by the EPA 365.4 method. Samples are digested with persulfate and sulfuric acid to
convert all phosphorous into ortho-phosphate. Ammonium molybdate and antimony
tartrate are added to form an antimony-phospho-molybdate complex. This complex
is reduced to an intensely blue-colored complex by addition of ascorbic acid. The
color is proportional to the phosphate concentration and is read by a Milton Roy
Spectronic 301.
Total selenium – Selenium in water measured by hydride generation ICP
(HG-ICP). Samples are digested with nitric acid and then boiled in perchloric and
sulfuric acids to convert all species to selenate. Selenate is reduced to selenite by
hydrochloric acid and then is further reduced to hydrogen selenide by sodium
borohydride, which is read by a Perkin Elmer P-40 ICP.
Selenite-selenium – Determination of selenite in samples through direct
injection of undigested water. Selenite is the only species present that can be
reduced and detected as hydrogen selenide by HG-ICP.
Sulfate – Turbidimetric determination of sulfate concentration by EPA method
375.4. Dilution to not more than 25 µg SO42-/mL is recommended. Barium sulfate
crystals are precipitated from mixing sulfate ions in an acetic acid medium with
barium chloride (BaCl2). The resulting turbidity is determined by an HF Scientific
Turbidimeter DRT 100B and compared to a curve prepared from standard sulfate
solutions.
Total Recoverable Multi-element Screen – Utilizes EPA method 200.7 after
acid digestion of unfiltered samples. Analysis is performed on an unfiltered sample
20
following a vigorous digestion using concentrated trace metal grade nitric acid and
1:1 HCl. Digestion is followed by analysis on a Leeman 2000 ICP
spectrophotometer for all the intended species.
3.3.2 SOIL
Soil analysis methods were developed by the Analytical Sciences Laboratory
through research of U.S. Department of Agriculture literature; methods provided in
Methods of Soil Analysis, 1st edition edited by C.A. Black (58), 2nd edition edited by
A.L. Page (59); and other sources. A full list of sources can be obtained from the UI
ASL.
Acidity – Soil pH measurement is performed on a saturated soil paste that
has been allowed to come to equilibrium. The reading is taken in the soil
suspension, not on the extract.
Alkalinity – This procedure is used to determine the amount of carbonate,
bicarbonate, and chloride in a soil. The extract of a saturated soil paste is titrated to
determine carbonate and bicarbonate, chloride is determined by ion
chromatography.
Boron – Air-dried and ground soil is placed into a plastic zip-lock bag in
which the soil is mixed with CaCl2 and then brought to the boiling point.
Determination of the presence of boron is done by spectrophotometry. The limited
availability of boron-free glassware has caused the development of this alternative
method.
Cation exchange capacity (CEC) – One normal (1N) ammonium acetate at
a pH 8.2 is used to leach the soil and saturate the exchange sites with ammonium
21
ion. The excess ammonium is removed with alcohol and then acidified sodium
chloride is used to displace the bound ammonium. This displaced ammonium is
measured to determine the CEC.
Soil electrical conductivity (SEC) – A saturated soil paste extract is used to
determine the conductivity attributable to the major soil anions CO32-, HCO3
-, Cl-,
SO42-, and NO3
-. A conductivity meter reads the conductivity in Ohms.
Nitrogen – nitrate and ammonium – Five grams of air-dried and ground soil
is mixed with 2M KCl, and the extract is analyzed by automated colorimeter and/or
ion selective electrode.
Organic carbon – Potassium dichromate is mixed into a soil sample.
Sulfuric acid is then added to the sample while external heat is applied. A ferroin
indicator is added and the mixture is titrated with FeSO4 until the endpoint is
reached. A quantitative calculation based on FeSO4 consumed determines the
amount of organic carbon in the sample.
Percent C H N – Total carbon, hydrogen, and nitrogen is analyzed by
combustion. The method of detection for carbon and hydrogen is infrared
adsorption and for nitrogen is thermal conductivity.
Phosphorous and potassium – Plant available phosphorous and potassium
in a soil is determined in two steps. Potassium on exchange sites is replaced by the
sodium ion in a 0.5 M sodium bicarbonate solution and potassium in the extract is
read by AA or ICP. Phosphorous is determined using a single reagent containing
sulfuric acid, ammonium molybdate, ascorbic acid and antimony potassium tartrate.
An ammonium molybdiphosphate complex is formed that is reduced by ascorbic
22
acid and color-stabilized by antimony. Concentration of the complex is read on a
spectrophotometer.
Selenium – Total selenium is measured by ICP using hydride generation.
The sample is initially digested by heating with nitric acid and boiling with a mixture
of sulfuric and perchloric acids. This digestion converts all selenium species to
selenate, Se(VI). The selenate is then reduced to selenite, Se(IV), with hydrochloric
acid and heat. Selenite is then reduced by acidic sodium borohydride to hydrogen
selenide, Se(-II), which is measured by HG-ICP.
Sulfate-sulfur – Sulfate-sulfur in saturated soil paste extract is determined by
ion chromatography. To do this procedure 10g of air-dried and ground soil is
needed.
Trace micro-element screen – A representative 1g dry weight sample of soil
is digested in nitric acid and hydrogen peroxide at 150°C. The digestate is then
refluxed at 150°C with hydrochloric acid, filtered if necessary, and analyzed for
target elements by ICP.
3.4 CHARACTERIZATION METHODS
In addition to the standard analyses described above, additional
characterizations of the overburden were carried out for this research. The methods
used for additional characterization included a modified Toxicity Characteristic Leach
of overburden, microprobe analysis of overburden thin sections, neutron activation
analysis, sequential extraction, and extraction of organo-selenium compounds.
Agitation leach – This procedure is a modification of EPA method
1311/6010, known as the Toxicity Characteristic Leaching Procedure (TCLP). Fifty
23
grams of a sample were placed into a 1L polyethylene bottle and the leachable
elements were extracted by rotary agitation in 18 MΩ-cm water for 18 ± 2 hrs. The
mixture was then filtered under pressure through a glass fiber filter and a dissolved
multi-element screen, selenium, and sulfate analyses were run on the filtrate.
Procedure was then repeated with Pole Creek inlet water as leach solution.
Microprobe analysis – Polished thin sections of representative overburden
samples were analyzed by electron microprobe at the University of Hawaii. A 20 nA,
15 kV electron beam was used, and intensities were converted to concentrations via
a PAP correction scheme. Spot analyses of two microns in size were conducted
repeatedly on the samples in order to create element maps.
Neutron activation analysis – One air dried and ground sample from each
sample location was analyzed for 75Se and 65Zn using the TRIGA III reactor at
Washington State University. This reactor irradiates the soil samples, and then the
γ-ray spectra are recorded using an ND6700 Ge(Li) γ-ray spectrometer.
Organo-selenium extraction – Three runs were made in duplicate. Each
run consisted of extracting 20 g of a representative soil sample with methylene
chloride in a 150 mL beaker. Enough methylene chloride was used so that the
sonifier probe could extend at least a centimeter below the surface of the methylene
chloride without touching the soil. The sonicator was run at full pulsed output for 3
minutes. Following sonication the liquid was vacuum filtered and collected for
evaporation and recovery of organo-selenium compounds.
Each sample was washed in this way three times. The three wash liquids
were combined in a TurboVap container and evaporated to a volume of 0.5 mL.
24
This liquid was transferred to a container usable for selenium analysis and the
TurboVap containers were washed with 10 mL of methylene chloride. The washes
were also transferred to the selenium analysis tubes. Evaporation to dryness using
nitrogen evaporation left a yellow film in the tubes, which were submitted for
selenium analysis by HG-ICP.
Sequential extraction – The determination of selenium species in the
overburden followed the sequential extraction outlined by Martens and Suarez (60).
Air-dried, ground, 5 g samples were processed by three extraction and oxidation
steps, each followed by centrifuging and decanting. Water soluble selenium species
were first extracted with 25 mL of 18 MΩ-cm water. Twenty-five milliliters of 0.1 M
phosphate buffer (pH 7.00) extracted the selenium adsorbed to the soil, followed by
the oxidation of insoluble selenium forms with 25 mL of 0.1 M persulfate. Samples
were analyzed for selenite-selenium and total selenium.
3.5 WATER AND SOIL TREATMENT METHODS
3.5.1 WATER
Co-precipitation – Four treatment runs were performed in triplicate. For
each run, 100 mL of the PCW2a water was mixed in 200 mL Erlenmeyer flasks with
the corresponding concentration of ferric (Fe3+) chloride and agitated on an orbiting
shaker for 24 hrs. Samples were treated with 5, 10, and 25 mg/L Fe3+. An
additional run with Fe3+ was conducted at 10 mg/L plus an equimolar concentration
of thermal polyaspartate (tpA), a product which we call ferric tpA. At the conclusion
25
of the 24 hrs, 10 mL of solution were filtered through a 0.2 micron syringe filter,
acidified, and submitted for total metals and selenium analysis.
Reduction – Three treatment runs were performed in triplicate. For these
runs, 100 mL of the PCW2a water was treated with colloidal iron (c-Fe) at
concentrations of 0.1%, 1.0% and 10% by weight and agitated on an orbiting shaker
for 24 hrs. At the conclusion of 24 hrs, 10 mL of the solution were filtered through a
0.2 micron syringe filter, acidified, and submitted for total selenium analysis.
Adsorption – Four treatment runs were performed in triplicate. For each run,
100 mL of the PCW2a water was mixed with 1 or 10 mg/L of either neutral activated
alumina or activated carbon and agitated on an orbiting shaker for 24 hrs. At the
conclusion, 10 mL of the solution were filtered with a 0.2 micron syringe filter,
acidified, and submitted for selenium analysis.
3.5.2 SOIL
Chemical armoring of soil – Eight treatment runs were performed in
duplicate. For each of the runs 5 grams of PCO-03 overburden soil and 25 mL of
soil amendment enriched water were mixed and then shaken lightly for one hour.
The mixtures were centrifuged and the liquid portion of each was decanted. To the
remaining soil, 25 mL of 18 MΩ-cm water was added and the mixture was then
shaken lightly for 24 hours. Following shaking, they were again centrifuged, and 10
mL of the liquid were decanted and submitted for selenite analysis.
The remaining liquid was mixed back into the soil and allowed to sit
undisturbed for an additional 48 hours after which it was again centrifuged and 10
mL were decanted and submitted for selenite analysis. Added to the remaining soil
26
was 25 mL of a 0.1M phosphate buffer to enhance extraction of selenite. The
solution was mixed into the soil and gently shaken for 24 hours. The mixture was
then centrifuged and 10 mL were decanted and submitted for selenite analysis.
Amendments tested included 5.0% tpA (w/w), 0.5% tpA (w/w), 0.05% tpA (w/w),
1000 mg/L Fe3+, 100 mg/L Fe3+, 10 mg/L Fe3+, 1.0% ferric tpA (w/w), and 18 MΩ-cm
water as a control.
Saturated paste with amendments – Ten treatment runs and one control
run were performed in triplicate for two periods of time, 14 days and 28 days. For
each run, 12.5 g of each soil (PCO-01, -02, -03, -04) were measured into a saturated
paste cup and mixed with 30 mL of 18MΩ-cm water. Dry amendments were added
to the soil prior to addition of the water, wet amendments were added to the water
prior to addition to the soil.
Dry amendments were measured at 1.0% by weight, wet amendments were
measured at 1.0% by volume, with the exception of potato waste amendment at
5.0% (by wet weight). Approximately 10,000 cells/mL suspension of a 50:50 mixed
inoculum of Desulfovibrio desulfuricans and Desulfatomaculum orientis provided by
Dr. Frank Rosenzweig of the Department of Biological Sciences was used to
inoculate some pastes. Pastes were sealed under nitrogen and two layers of
parafilm and placed into an incubator at 25° C for either 14 days or 28 days. At the
conclusion of the run, pastes were mixed and filtered. Filtrate was analyzed for
selenium, dissolved multi-elements, and sulfate if there was enough filtrate left.
Amendments tested included sulfate reducing bacteria inoculum (SRB), c-Fe, mb-
Fe, mb-Fe plus SRB, potato starch, potato starch plus SRB, ferric ion chelated
27
thermal polyaspartate (ferric tpA), ferric tpA plus SRB, potato processing waste, and
potato processing waste plus SRB.
28
4.0 CHARACTERIZATION STUDY
Analyses conducted on the water and overburden samples from Smoky
Canyon give insight into the nature and extent of the selenium releases from Idaho’s
regional phosphate mines. Data from these water and soil analyses allow us to
draw conclusions as to what the source of the selenium in the study area is and thus
aid in development of a control strategy for the selenium releases. Results of water
analyses are unique to this sampling period and will vary with precipitation and
drainage conditions.
Laboratory results below detection limits are indicated as a lined-out
(strikethrough) numerical detection limit. Percentage increase/decrease calculations
use these detection limits as needed. The concentration data is reported in units of
molarity (M, moles/liter) unless otherwise noted.
4.1 WATER ANALYSES
Analyses of Pole Canyon overburden drainage include selenium, anions,
dissolved elements, and total recoverable elements. Since Pole Creek drains into
grazing and agricultural lands, a domestic/livestock water screen for samples from
both the inlet and outlet of the overburden drain was also appropriate.
This analysis involved water collected from two sample locations and
preserved with three preservation techniques as recommended in 40 CFR § 136
(61). The water from in the inlet of the overburden piles was designated as PCW1
and the outlet water as PCW2. Preservation methods included filtered (F), filtered
and acidified (FP), and acidified (P). If a sample was not filtered or acidified it is
29
designated with -N, and all preservation methods included continuous refrigeration
at 4°C.
Selenium analysis (Table 1) shows an increase from non-detection levels at
the creek inlet of the overburden french drain, PCW1, to 8.61 µM (680 µg/L) at the
creek outlet below the overburden pile, PCW2. Selenium has a seven times greater
increase than any other ion or metal in the study. This illustrates that the selenium
problems in this particular area are influenced by the overburden piles, and it is not
found as a naturally occurring dissolved background species in this drainage.
The anion screen (Table 2) shows large increases in fluoride, chloride, nitrate,
and sulfate, although the levels of fluoride, chloride, and nitrate in the outlet water
Table 1. Results of selenium analysis on Pole Canyon french drain water. Strikethrough indicates result ≤≤≤≤ estimated detection limit (EDL).
PCW1-P PCW2-P % change units EDL
Se 0.00890 8.61 97000% µM 0.0089
Table 2. Results of anion screen performed on Pole Canyon overburden french drain water.
PCW1-Nb PCW2-Nb % change units EDL
Fluoride 2.60 9.50 260% µM 2.6
Chloride 45.1 102 125% µM 1.4
Nitrite 1.10 1.10 0% µM 1.1
Bromide 1.30 1.30 0% µM 1.3
Nitrate 0.800 12.7 1480% µM 0.80
o-Phosphate 0.500 0.500 0% µM 0.50
Sulfate 187 2920 1460% µM 1.0
Oxalate 1.10 1.10 0% µM 1.1
Sulfite 62.5 62.5 0% µM 63
30
are not considered higher than normal. Fluoride is a constituent of the phosphoria
(fluorapatite – Ca5(PO4)3F) mined in the study area, and sulfate can substitute into
the lattice where phosphate is found (62). It is likely that weathering of the
fluorapatite is the cause of the increase in fluoride in the outlet water and a source of
some of the sulfate.
Sulfate is also an indicator of sulfide oxidation (acid rock drainage), a possible
source for selenium oxyanions in the waters. However, an increase in sulfate this
large cannot solely be a result of sulfide oxidation and is likely a result of both
weathering of fluorapatite and oxidation of sulfides. It is also interesting that no
phosphorous species are detected in the outlet water even though the overburden
contains large amounts of low-grade ore (12%-17% P2O5). This may be related to
the presence of iron in the overburden, which can form stable iron phosphate
precipitates from solution at near neutral to acidic pH (63, 64, 65).
The dissolved multi-element screen (DMS) and total recoverable multi-
element screen (TMS) were conducted on the Pole Creek waters to assist in
identifying the major components of the system. The DMS results show that calcium
and magnesium are present in large concentrations and moderately increase
between the inlet and outlet of the drain (Table 3). Calcium is a component of
fluorapatite, and both calcium and magnesium are components of limestone. Their
presence is most likely a result of both the weathering of the fluorapatite and the
dissolution of limestone in acid neutralization reactions.
31
Dissolved zinc (33x), nickel (16x), and cadmium (5x) all show an increase in
concentration at the outlet. All three of these elements are commonly found as
sulfides and may be present in the overburden. Sphalerite (ZnS) has been
positively identified in this overburden (66). The release of these metals is
consistent with pyrite oxidation. Concentrations of elements such as barium,
beryllium, iron, and manganese decrease from inlet to outlet. It is interesting that the
iron concentrations decrease since the most common reactive sulfide in these
deposits is normally pyrite, FeS2. Again, this may be due to the presence of
phosphate ions in solution, which form stable compounds with ferrous and ferric
ions.
Table 3. Results of dissolved multi-element screen performed on Pole Canyon overburden french drain water.
PCW1-FP PCW2-FP % change units EDL
Al 3.30 3.30 0% µM 3.3
Ba 0.420 0.310 -28% µM 0.0040
Be 0.230 0.0100 -95% µM 0.010
Cd 0.0200 0.120 465% µM 0.020
Ca 1500 4490 200% µM 0.25
Cr 0.0800 0.0800 0% µM 0.080
Co 0.140 0.140 0% µM 0.14
Cu 0.130 0.220 67% µM 0.13
Fe 0.570 0.0700 -88% µM 0.070
Mg 658 1150 75% µM 0.19
Mn 0.510 0.360 -29% µM 0.020
Mo 0.280 0.500 78% µM 0.28
Ni 0.120 2.04 1610% µM 0.12
K 15.6 30.7 97% µM 16
Na 174 222 28% µM 5.2
V 0.290 0.290 0% µM 0.29
Zn 0.210 7.34 3330% µM 0.040
32
The TMS shows similar results as the DMS, with calcium and magnesium
comprising the majority of the cations present in the outlet water (Table 4). Zinc,
nickel, and cadmium show increases again, but the increase in zinc is much greater
than that measured in the DMS. This indicates the possible presence of zinc in the
colloidal material in the water. There is no decrease in concentration for any
element.
The domestic livestock water screen, like the previous tests, indicates that
chloride slightly increases and sulfate shows a large increase within the drain (Table
5). At over 3 mM, sulfate is the dominant oxyanion in the dissolved solids of the exit
water. There is also a 0.7 unit reduction in pH over the length of the drain. The
Table 4. Results of the total recoverable multi-element screen performed on the Pole Canyon overburden french drain water.
PCW1-Nb PCW2-Nb % change Units EDL
Ba 0.230 2.30 869% µM 0.030
Be 0.100 0.100 33% µM 0.040
Cd 0.0300 0.100 367% µM 0.030
Ca 1450 4740 228% µM 0.77
Cr 0.250 0.400 69% µM 0.25
Co 0.290 0.300 18% µM 0.19
Cu 0.550 1.20 123% µM 0.55
Fe 0.210 0.210 0% µM 0.21
Mg 617 1230 100% µM 0.080
Mn 0.160 0.300 56% µM 0.040
Mo 0.420 1.00 150% µM 0.42
Ni 0.340 2.90 750% µM 0.34
K 40.9 81.8 100% µM 41
Na 187 265 42% µM 24
V 0.550 0.550 0% µM 0.55
Zn 0.0800 10.2 13300% µM 0.050
33
combination of a decrease in pH and the large increase in sulfate also supports the
hypothesis that pyrite oxidation is occurring in the overburden. The nitrogen as
nitrate/nitrite levels are again normal to low for natural waters, and phosphorous
concentrations again show a decrease in the drain and are considered low for
natural waters.
Results in Table 5 also show that total dissolved solids increase by 230%
throughout the length of the drain, of which dissolved CaSO4 accounts for 78% of
the increase. The pH drop may be an effect of acid rock drainage production. The
alkalinity increase is most probably due to increases in dissolved bicarbonates from
dissolution reactions involving limestone. Conductance increases throughout the
drain, reflecting the increase in type and concentration of dissolved ions. Total
hardness increases and the concentration in excess of alkalinity is due to the
presence of non-carbonate/bicarbonate ions such as sulfate.
Table 5. Results of screen for domestic livestock water performed on Pole Canyon overburden french drain water.
PCW1-Na PCW2-Na % change Units EDL
Cl- 231 276 20% µM 56
SO42- 198 3020 1430% µM 21
N as NO32-
+NO22-
7.10 21.4 200% µM 7.1
Total P 2.60 1.00 -63% µM 0.30
Alkalinity 190 270 42% mg/L as CaCO3
2.0
Solids 220 720 227% mg/L 10
Conductance 380 970 155% µmhos/cm 5.0
Total Hardness 190 520 174% Mg CaCO3/L 25
pH 8.07 7.34 0.73 pH units N/A
34
4.2 SOLID MATRIX
For the following soil screens, the air-dried, ground, -3/8 inch fraction of the
overburden from each sample location was used. While some of these analyses are
generally reserved for agricultural soils, this study applied them to the overburden
because the piles are reclaimed for grazing purposes. Other analyses within this
thesis examined composition of the overburden in order to confirm the presence of
selenium and its possible release from minerals into the water.
A general soil screen of the overburden samples revealed the selenium and
other trace microelement concentrations, conductivity, cation exchange capacity,
alkalinity, and percent carbon-hydrogen-nitrogen. Also included is additional testing
on soil fertility and an agitation leach. A sequential extraction determined the
speciation of extractable selenium in the overburden and an organo-selenium
extraction illustrated how much of the selenium is in organic forms. A neutron
activation analysis, performed by Washington State University’s Nuclear Radiation
Center, determined the selenium content of the overburden, and a microprobe
analysis from the University of Hawaii illustrated the distribution of selenium in
mineral fractions within the overburden.
4.2.1 SOIL SCREENS
Fertility test results on the air-dried and ground -3/8 inch fraction of the
overburden give us information about whether the overburden is suitable for use as
a reclamation substrate as is, or requires amendment with fertilizers. These
analyses also aid in characterization by providing alkalinity, extractable sulfate,
carbon, and pH values.
35
The soil testing facility at the ASL analyzed and gave recommendations
concerning soil fertility (Table 6). This analysis reported that plant available
phosphorous is slightly higher than normal, which is expected given that the soils
contain low-grade phosphate ore. Levels of plant available potassium, however, are
low and would require application of fertilizer. Extractable nitrogen levels are normal
for these soils but additional application could increase fertility. Soil boron levels are
reported as normal.
Extractable sulfate levels appear to correlate with amount of weathering, i.e.,
more weathering results in less extractable sulfate. The ‘unweathered’ sample
PCO-03 shows high levels of sulfate, the sample with the most weathering (PC-CH)
Table 6. Results of general soil screen performed on the -3/8 in. soil fraction of Pole Canyon overburden samples.
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL
P 0.633 1.60 1.41 1.90 1.68 mmol/kg-soil 0.078
K 1.82 2.35 1.74 2.07 1.30 mmol/kg-soil 0.16
NO3-N 0.143 0.0714 0.178 0.0642 0.0785 mmol/kg-soil 0.0060
NH4+-N 0.228 0.336 0.236 0.236 0.250 mmol/kg-soil 0.021
B 0.0157 0.0148 0.0120 0.0120 0.0139 mmol/kg-soil 0.0028
SO42-S 2.87 1.19 13.7 1.06 0.237 mmol/kg-soil 0.010
CO32- 0.120 0.130 0.100 0.130 0.100 mmol(+)/L 0.10
HCO3- 3.43 2.65 2.12 3.65 1.86 mmol(+)/L 0.10
Organic C 4.14% 1.93% 4.41% 4.31% 3.90% Percent 0.067
Total C 6.50% 2.50% 5.40% 4.30% 4.40% Percent 0.010
Total H 0.640% 0.470% 0.620% 0.580% 0.590% Percent 0.010
Total N 0.460% 0.270% 0.460% 0.530% 0.580% Percent 0.010
SEC 2.46 0.910 2.82 0.940 0.340 dS/m 0.0018
CEC 10.6 12.4 10.4 21.1 25.1 cmol(+)/kg 0.30
pH 7.30 7.40 7.20 7.30 6.40 N/A
36
shows normal concentrations, and all others are slightly elevated. Alkalinity
(carbonate/ bicarbonate) typifies this soil type and pH range. Percent organic
carbon, total carbon, and total nitrogen levels are slightly high, while hydrogen levels
are normal. For southeastern Idaho soils of this soil texture and type, the electrical
conductivity is considered good (below 4 dS/m), cation exchange capacity is slightly
higher than normal, and the pH range is also typical.
The total microelement screen identifies the major elements in the
overburden samples as calcium, phosphorous, iron, sulfur, potassium, sodium, and
Table 7. Results of total soil microelement screen of samples from the Pole Canyon overburden dump.
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH units EDL
As 1.34 1.47 1.47 1.47 1.34 mmol/kg-soil 0.1281
Ba 0.580 0.590 0.530 0.550 0.500 mmol/kg-soil 0.0012
Be 0.170 0.140 0.180 0.200 0.180 mmol/kg-soil 0.0019
Ca 2990 1750 3240 2990 4240 mmol/kg-soil 0.70
Cd 0.230 0.190 0.340 0.490 0.160 mmol/kg-soil 0.0031
Co 0.160 0.170 0.170 0.190 0.140 mmol/kg-soil 0.019
Cr 15.0 10.6 13.7 18.5 21.2 mmol/kg-soil 0.021
Cu 1.73 1.05 1.51 2.05 2.20 mmol/kg-soil 0.016
Fe 286 286 286 340 304 mmol/kg-soil 0.18
K 128 151 151 143 151 mmol/kg-soil 3.1
Mg 255 156 210 132 78.2 mmol/kg-soil 0.21
Mn 5.82 10.9 4.37 5.46 2.18 mmol/kg-soil 0.0095
Mo 0.420 0.240 0.500 0.440 0.390 mmol/kg-soil 0.041
Na 52.2 37.8 65.3 52.2 91.3 mmol/kg-soil 1.3
Ni 4.94 3.41 4.43 5.62 4.26 mmol/kg-soil 0.0077
P 969 678 1290 1290 1930 mmol/kg-soil 0.27
Pb 0.190 0.200 0.210 0.220 0.200 mmol/kg-soil 0.027
S 240 93.6 274 181 221 mmol/kg-soil 1.5
Zn 18.4 10.9 18.4 24.5 15.3 mmol/kg-soil 0.011
37
magnesium (Table 7). This correlates well with the knowledge that the overburden
from this section of the Meade Peak member consists of a mixture of fluorapatite,
calcite, dolomite, pyrite, and other minor minerals (62). There are also relatively
high concentrations of zinc and chromium, and lesser amounts of nickel,
manganese, copper, and arsenic.
Selenium analysis shows levels of selenium ranging from 0.20 to 0.46
mmol/kg of soil; typical values for this soil type are <0.0063 mmol/kg soil (Table 8).
This confirms that the origin of the selenium is the overburden but still does not
identify the host rocks or minerals.
4.2.2 NEUTRON ACTIVATION
The neutron activation analysis performed at Washington State University
shows selenium concentrations that range from 0.218 mmol/kg in sample PCCH to
0.922 mmol/kg in sample PCO-04. These numbers do not correlate well with the
concentrations determined by the acid digestion of the samples followed by ICP,
indicating a possible incomplete recovery by the digestion method. Zinc
concentrations range from 12.3 mmol/kg in sample PCO-02 to 32.58 mmol/kg in
PCO-03, also slightly higher than the acid digestion method. Zinc results indicate
the presence of minerals such as sphalerite (ZnS).
Table 8. Results of selenium analysis on acid digested Pole Canyon overburden samples.
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH units EDL
Se 0.418 0.253 0.456 0.291 0.203 mmol/kg-soil 0.000050
38
4.2.3 MICROPROBE ANALYSIS
Professor Dennis Geist of the University of Idaho Department of Geology and
Geological Engineering interpreted a limited microscopic and electron microprobe
overburden study conducted by the University of Hawaii (66). Limestone and
siltstone comprise the majority of the overburden. The lighter-colored limestones
contain no visible sulfide and little organic matter, however, it appears that the
siltstones are the host rock for pyrite (FeS2) and sphalerite (ZnS) minerals and also
contain hydrocarbons.
The electron microprobe analysis provided an element map of the distribution
of iron, zinc, selenium, and sulfur from one sample (Figure 5). Pyrite comprises
about 0.2%, by volume, of the siltstones, and sphalerite is even more scarce at only
several grains per sample thin section (66).
Table 9. Results of nuclear activation analysis performed on dried and ground Pole Canyon overburden samples.
Se75 Zn65 units
PCO-01 0.431 21.9 mmol/kg-soil PCO-02 0.484 12.3 mmol/kg-soil PCO-03 0.681 32.6 mmol/kg-soil
PCO-04 0.922 26.3 mmol/kg-soil
PCCH 0.218 18.4 mmol/kg-soil
Table 10. Composition of selected minerals (weight percent) by microprobe analysis of thin sections of Pole Canyon overburden.
Pyrite 1 Pyrite 2 Pyrite 3 Sphalerite EDL
Se 0.680 0.650 0.640 0.0300 % 0.0900 S 51.9 50.9 49.6 32.2 % 0.130
Fe 45.8 44.3 42.3 0.260 % 0.0500 Zn 0.0500 0.0700 0.00 60.8 % 0.210
39
Figure 5. Element map derived from microprobe analysis of Pole Canyon overburden samples.
40
The analytical results show that the concentration of selenium in the pyrite
grains (Figure 5, Table 10) is sufficient to account for most of the selenium
concentration in the overburden. These results also support the theory that acid
rock drainage is most likely occurring in the overburden even though there is no
appreciable increase in acidity of Pole Creek. Limestone is an excellent neutralizer
of acid rock drainage resulting from oxidation of the pyrite, and its presence is
confirmed through this analysis.
4.2.4 SEQUENTIAL EXTRACTION
The sequential extraction scheme of Martens and Suarez (60) identifies
different extractable selenium species in a sample (Table 11). Results from applying
this method to sample PCO-03 indicate that about 2% of the mass of selenium
present in the sample is immediately leachable, and most of it appears to be
selenite, SeO32-. After all of the oxidation/extraction steps of the SES about 0.016
mmol-Se/kg soil is extracted. This is an order of magnitude less than half the bulk
selenium determined for this sample by NAA (0.68 mmol-Se/kg-soil). Therefore, of
the total soil selenium determined by NAA, 2% is extractable selenite with the
Table 11. Results of the sequential extraction procedure performed on unweathered Pole Canyon overburden samples.
Extractant/Species µmol-Se/L-Extract mmol-Se/kg-Soil Water/Se(IV) 0.322 0.213 0.00130
Water/Se(IV) and Se(VI) 0.234 0.198 0.00110 Water/Se(-II) 0.101 0.00890 0.000270 Buffer/Se(IV) 2.60 2.67 0.0130
Buffer/Se(IV) and Se(VI) 2.50 2.53 0.0130 Buffer/Se(-II) 0.00890 0.00890 0.0000450
Persulfate/Se(IV) and Se(-II) 0.238 0.175 0.00100 Total Extractable Se - - 0.0160
41
remaining selenium in the soil present as either selenide (-II) or zero-valent selenium
(67).
4.2.5 ORGANO-SELENIUM EXTRACTION
This analysis revealed that for the weathered samples, methylene chloride
(MeCl) extractable organo-selenium compounds account for less than one percent
of the total selenium as determined by neutron activation analysis (Table 12). In
essentially unweathered samples, MeCl extractable organo-selenium compounds
account for approximately 2.5 percent of the total overburden selenium. Further
examination of the extract by gas chromatography with mass selective detection
revealed the presence of C8 to C25 hydrocarbons (67).
4.2.6 OVERBURDEN LEACHATE STUDIES
The agitation leach provided information from leachate samples of the five
overburden soils collected from the Pole Canyon site. This analysis determined the
concentrations of leachable dissolved elements, selenium, and sulfate in the
leachate. The concentrations of elements in the leachate offer clues to what
Table 12. Comparison of results of organo-selenium extraction and neutron activation analysis of Pole Canyon overburden.
Sample ID Organo-Selenium mmol-Se/kg-soil
Percentage of total Se by NAA
PCO-01a 0.00650 0.96 %
PCO-01b 0.00620 0.91 %
PCO-02a 0.00180 0.26 %
PCO-02b 0.00280 0.41 %
PCO-03a 0.0180 2.65 %
PCO-03b 0.0150 2.21 %
42
weathered and/or soluble minerals may be present in the overburden. Leaching with
water from upper Pole Creek allowed the use of water that has natural carbonate
buffering and is compositionally similar to rainwater. Leaching with 18 MΩ-cm water
allowed a leach with no interference of natural buffering, acidity, and other ions.
With the Pole Creek water as leach solution (Table 13), selenium, barium,
manganese, and nickel did leach into the water in all samples. Other elements such
as aluminum, cadmium, and chromium were below detection limits in all screens.
Table 13. Results of agitation leach of Pole Canyon overburden samples with Pole Creek water as leachate.
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL
Se 0.798 0.380 2.41 0.906 0.00890 µM 0.0089
Al 3.30 3.30 3.30 4.82 3.30 µM 3.3
Ba 1.89 2.15 0.947 1.86 2.48 µM 0.0044
Be 0.0111 0.0111 0.0111 0.0111 0.0111 µM 0.011
Cd 0.0205 0.0205 0.0205 0.0205 0.0205 µM 0.021
Ca 1660 1470 3490 1480 1100 µM 0.25
Cr 0.0846 0.0846 0.0846 0.0846 0.0846 µM 0.085
Co 0.136 0.136 0.136 0.136 0.136 µM 0.14
Cu 0.132 0.132 0.161 0.354 0.132 µM 0.13
Fe 0.0662 0.0662 0.0662 0.0662 0.0662 µM 0.066
Mg 576 535 658 453 453 µM 0.19
Mn 0.144 0.0264 0.101 0.0628 0.0382 µM 0.022
Mo 0.281 0.281 0.818 0.281 0.281 µM 0.28
Ni 0.204 0.119 0.758 0.383 0.426 µM 0.12
K 17.0 15.6 22.0 52.4 15.6 µM 16
Na 250 248 254 244 278 µM 5.2
V 0.295 0.295 0.295 2.36 0.314 µM 0.30
Zn 0.0382 0.0382 0.360 0.130 0.665 µM 0.038
Sulfate 458 250 458 276 219 µM 16
pH 8.16 8.02 7.81 7.84 7.18 N/A N/A
43
Copper, molybdenum, vanadium, and zinc was detected in some of the leachates,
but not all. With 18 MΩ-cm water as leach solution (Table 14), selenium, aluminum,
barium, manganese, and zinc were found in all leachates. The only other element of
concern (See 5.1) that was above detection limits in at least one solution was
cadmium.
Table 14. Results of agitation leach of Pole Canyon overburden with 18 MΩΩΩΩ-cm water as leachate.
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL
Se 1.01 0.494 2.53 0.988 0.0285 µM 0.0089
Al 10.0 98.2 4.87 35.0 96.4 µM 3.3
Ba 1.24 1.42 0.710 1.38 2.55 µM 0.0044
Be 0.0111 0.0111 0.0111 0.0111 0.0111 µM 0.011
Cd 0.0205 0.0205 0.0205 0.0205 0.0205 µM 0.021
Ca 412 243 2330 274 78.6 µM 0.25
Cr 0.175 1.48 0.0846 1.66 4.42 µM 0.085
Co 0.136 0.136 0.144 0.136 0.136 µM 0.14
Cu 0.132 0.132 0.449 0.299 0.132 µM 0.13
Fe 4.74 34.0 0.0662 12.4 31.3 µM 0.066
Mg 65.8 49.4 154 45.3 25.9 µM 0.19
Mn 0.0400 0.482 0.0692 0.110 0.0337 µM 0.022
Mo 0.281 0.281 0.964 0.281 0.281 µM 0.28
Ni 0.119 0.239 0.392 0.494 0.358 µM 0.12
K 15.6 15.6 34.5 34.5 15.6 µM 16
Na 89.2 95.7 115 102 117 µM 5.2
V 0.295 0.717 0.304 2.94 1.13 µM 0.30
Zn 0.367 1.26 0.0451 1.11 3.98 µM 0.038
Sulfate 250 161 437 130 80.2 µM 16
pH 9.00 8.76 8.42 8.55 7.08 N/A N/A
44
4.2.7 CORRELATION ANALYSIS
A correlation analysis of some of the characterization data was performed
using the following correlation equation:
yxxy
YXCovσσ
ρ⋅
=),(
Where 11 ≤≤− xyρ and ∑−
−−=n
jyjxj yx
nYXCov
1))((1),( µµ .
This correlation analysis was completed utilizing the five overburden samples (n =
5), giving the analysis 3 degrees of freedom. For three degrees of freedom, a 5%
level of significance would be achieved when the correlation coefficient ρ is greater
than 0.878. Similarly, a 1% level of significance is achieved with ρ greater than
0.959 (68).
The limited characterization data shows that water extractable selenium
levels (via agitation leach) correlate with total selenium by digestion just outside of
the 5% level of significance (ρ = 0.859), but do not correlate well with total selenium
as determined through NAA (ρ = 0.552). There is essentially no correlation (ρ =
0.337) between total selenium determined by digestion and that determined by NAA.
The correlation coefficient for water extractable selenium and water
extractable sulfate levels, at ρ = 0.946, approaches the 1% level of significance. The
correlation coefficient also falls within the 1% and 5% levels of significance for water
extractable selenium as compared to soil sulfate-sulfur levels, where ρ = 0.927.
There is essentially no correlation between total selenium by NAA and organic
carbon (ρ=-0.290) or total carbon (ρ=0.017). Even with higher ρ values, correlation
45
remains low between total selenium by digestion and organic carbon (ρ=0.475) as
well as total carbon (ρ=0.726).
4.3 SIGNIFICANT FINDINGS
• Selenium is not detected in Pole Creek waters before it enters the french drain.
• Pole Creek selenium concentrations increase from below detection to 8.61 µM
over the length of the french drain.
• Sulfate concentrations show a large increase (190 to 2920 µM) and may indicate
mineral weathering and acid rock drainage.
• Phosphorous species are not detected in the drainage even though the
overburden contains low-grade ore (12-17% P2O5).
• The dissolved metals screen shows large increases in cadmium (BDL to 0.100
µM), calcium (1500 to 4500 µM), nickel (BDL to 2.00 µM), and zinc (0.2 to 7.30
µM) concentrations in the drain.
• The total recoverable metals screen shows a larger increase in zinc
concentrations (0.08 to 10.2 µM), and shows increases in barium (0.23 to 2.30
µM) and copper (BDL to 1.20 µM) concentrations.
• The dissolved solids of the drainage water are predominantly made up of a
CaSO4 solution at about 3 mM in concentration.
• The pH of the system is near neutral; however, the slight pH decrease observed
from the inlet to the exit of the drain (8.10 to 7.30) is consistent with increased
acidity from oxidation of pyrite minerals.
46
• There is a relative absence of dissolved iron in the exit water, even though pyrite
is estimated at 0.2% (v/v) of the siltstone fraction and iron makes up
approximately 300 mmol/kg overburden.
• The soil fraction of the overburden has low to reasonable fertility and may need N
and K amendment for increased fertility.
• The overburden soil fractions demonstrate leachable selenium in both agitation
leaching and sequential extraction schemes. The highest concentration of
selenium in leachates occurred from the least weathered sample (PCO-03).
• The soils contain a range of 0.218–0.922 mmol/kg (17-73 µg/g (ppm)) total
selenium as determined by neutron activation analysis. The least weathered
sample (PCO-03) contained the highest average level of total selenium
(averaging NAA and soil digestion results).
• Speciation and geochemical studies of waste rock soil and leachate indicate that
selenite (SeO32-) is the primary leachable species. Reduced selenium moieties,
present as zero-valent selenium, selenides, or organo-selenium compounds
make up the remaining soil selenium.
• Correlation analyses for total selenium in the overburden soils by digestion and
water extractable selenium show a correlation coefficient of 0.859, just under the
5% level of significance. The coefficient for water extractable selenium and
sulfate is 0.946, just under the 1% level of significance. The coefficient for water
extractable selenium and soil sulfate-sulfur is 0.927, which falls within the 1% to
5% levels of significance.
47
5.0 TREATABILITY STUDIES
The large scope of the problem, potential costs, reliability of the
abatement/control approach, and resources available for evaluation of methods are
determining factors in the applicability of treatment methods. After a review of the
current treatment technologies in Chapter 2, applicable treatments chosen include
co-precipitation, chemical reduction, microbial reduction, adsorption, organic soil
amendments, and various combinations of these methods.
Specific water treatment technologies include precipitation with ferric chloride,
reduction by zero-valent micropowder iron, adsorption on activated carbon and
alumina, and Fe(III)-biopolymer chelation. Soil treatments include removal by
microbes, amendments with various inorganic and organic substrates, and
combinations of amendments with microorganisms. Several approaches to soil
treatment are currently under investigation at the University of Idaho’s Center for
Hazardous Waste Remediation Research and are being field-tested at J.R. Simplot
Company’s Smoky Canyon Mine near Afton, Wyoming.
5.1 IDENTIFICATION OF TARGET ELEMENTS
In April of 1998, the Selenium Subcommittee of the Idaho Mining Association
received the Sampling and Analysis Plan: Southeast Idaho Phosphate Resource
Area Selenium Project - 1998 Regional Investigation, compiled by the firm of
Montgomery-Watson, Inc. in Bellevue, Washington (69). Appendix A of the Plan
details a preliminary ecological risk-based screening process that determines the
constituents of potential concern (COPC) in water resources in this area. The
48
development of aquatic screening criteria for both aquatic populations and possible
riparian/ terrestrial receptors was used to identify the maximum concentrations of
specific elements in surface water that can be tolerated by these receptors.
By comparing the results of the exit water total dissolved multi-element
screen to allowable maximum contaminant levels (MCL), COPC in addition to
selenium that should be addressed at this site can be identified (Table 15). In
addition to selenium, those metals that may be above the MCL (at this sampling) for
chronic exposure are cadmium, copper, nickel, and zinc.
5.2 WATER TREATMENT
Water treatment methods deemed applicable from the previous literature
search were applied to water from the Pole Canyon french drain outlet water. In the
following treatment studies, it was assumed that selenium oxyanions were present in
Table 15. Determination of constituents of potential concern in the Pole Canyon french drain outlet water. After Montgomery-Watson, 1998 (69).
Pole Ck. Max. Concentration
Aquatic Limit Riparian / Terrestrial Limit
Units COPC?
Se 8.61 0.162-2.36 0.279 µM Yes
Al BDL 17.0 20.4 µM No
Ba 2.26 42.2 24.0 µM No
Cd 0.127 0.00979 0.445 µM Yes
Cr 0.423 4.04 19.2 µM No
Cu 1.23 0.189 7.87 µM Yes
Mn 0.255 2.18 104 µM No
Mo 1.04 9.17 NA µM No
Ni 2.90 2.73 17.0 µM Yes
V BDL 1.57 1.96 µM No
Zn 1.02 1.68 78.0 µM Yes
49
their most oxidized state; thus, analyses determined only total selenium in the
samples after treatment. Speciation analyses of deoxygenated, refrigerated water
samples used for these treatment studies have since revealed that the species in the
aged samples was selenate, as assumed. Subsequent selenium speciation studies
have been conducted on samples field frozen on dry ice at the site. Analyses of the
field frozen samples identified the species in the outlet water as approximately 85%
selenite (SeO32-), which is the most treatable aqueous form (70).
The difference in these observations resulted from the refrigerated samples
(PCW1 and PCW2) having been exposed to air, causing the selenite that had been
present originally to oxidize to selenate. Field frozen samples were analyzed
immediately upon thawing, not allowing for further oxidation.
The following treatment studies were conducted on the refrigerated, fully
oxidized PCW2 samples, and represent a worst-case treatment scenario. In
determining which of the methods tested here were best suited for field studies, the
effectiveness in removal of selenium was followed in priority by effectiveness in
removal of other COPC and potential cost of treatment.
5.2.1 SELENIUM
Based on the comparisons made in Section 5.1, selenium concentrations in
the drainage must be reduced by 74%-92% to fall within the allowable MCL range.
Of the three concentrations of ferric ion tested, none of them reduced selenium
concentrations in the outlet water by more than 6% (Figure 6). This is disappointing
since ferric salts have shown much success in conventional wastewater treatment
50
for removal of similar oxyanions. One concentration of ferric-tpA was tested and
removed 11% of the selenium.
Overall, adsorption was more effective at reducing selenium concentrations
than co-precipitation, especially when using activated carbon. Activated neutral
alumina at 1 g/L removed less than 5% of the selenium while the 10 g/L
concentration removed 14%. Activated carbon at 1 g/L was more effective than the
10 g/L alumina, and larger decreases in the concentration of selenium occurred with
the 10 g/L.
Direct reduction from the use of zero-valent, micropowder iron had the
greatest effect on selenium concentrations. The 0.1% concentration treatment
removed a similar amount of dissolved selenium as the activated carbon, while the
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
NT
5 mg/L
Fe3+
10 m
g/L Fe3
+
25 m
g/L Fe3
+
0.1% c-
Fe
1% c-
Fe
10% c-
Fe
10 m
g/L Fe(I
II)-tpA
1 g/L
alumina
10 g/
L alum
ina
1 g/L
carbo
n
10 g/
L carb
on
Con
cent
ratio
n of
Se
(µM
)
Figure 6. Effects of various water treatments on the concentration of selenium in Pole Creek outlet water. Error bars represent sample standard deviation (S.D.) for n=3 runs.
51
1% treatment removed close to 80% of the selenium and the 10% treatment
removed essentially 100%.
5.2.2 OTHER CONSTITUENTS OF POTENTIAL CONCERN
Comparison of Pole Creek concentrations to the allowable MCLs determined
that the elements cadmium, copper, nickel and zinc were also above aquatic criteria.
Water treatment studies that were conducted for removal of selenium from the water
were repeated on refrigerated lower Pole Creek samples and analyzed for total
metals.
5.2.2.1 Cadmium
According to the characterization testing and identification of target elements,
cadmium in the Pole Creek Outlet water should be reduced by at least 92% in order
0.00
0.05
0.10
0.15
0.20
0.25
NT
Fe(III)
5mg/L
Fe(III)
10mg/L
Fe(III)
25mg/L
0.1% c-
Fe
1.0% c-
Fe
10.0%
c-Fe
Fe(III)-
tpA
1g/L
Alumina
10g/L
Alumina
1g/L
Carbon
10g/L
Carb
on
Cd
conc
entra
tion
(µM
)
Figure 7. Effects of various water treatments on the concentration of cadmium in Pole Creek outlet water. Error bars represent sample S.D., n=3.
52
to meet aquatic criteria. Of the five water treatments studied, the two that exhibit the
most potential are ferric iron co-precipitation and cementation onto metallic iron
(Figure 7).
The highest reduction reached by either of these treatments nears 90% and
observation indicates that there is little difference in the effectiveness of various
concentrations. This indicates that the amount of reactant needed to remove the
contaminants can be low. Better mixing of the reagents and water may increase
removal. Adsorption treatments and use of Fe(III)-tpA all had similar results ranging
from 60% to 77%.
5.2.2.2 Copper
Copper concentrations need to be reduced by at least 58% in the lower Pole
Creek water. Of the treatment methods studied, none reached above 48% although
lab conditions were not ideal and better mixing has a chance to increase removal
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
NT
Fe(III)
5mg/L
Fe(III)
10mg/L
Fe(III)
25mg/L
0.1% c-
Fe
1.0% c-
Fe
10.0%
c-Fe
Fe(III)-
tpA
1g/L
Alumina
10g/L
Alumina
1g/L
Carbon
10g/L
Carb
on
Cu
conc
entra
tion
(µM
)
Figure 8. Effects of various water treatments on the concentration of copper in Pole Creek outlet water. Error bars represent sample S.D., n=3.
53
rates (Figure 8). The most promising treatment is using zero-valent, colloidal iron
which showed removal nearing 50%. Ferric ion co-precipitation at 25 mg/L showed
removal near 30% as did adsorption with alumina. The least effective treatments
were Fe(III)-tpA and activated carbon.
5.2.2.3 Nickel
All treatments were successful in reducing nickel concentrations in lower Pole
Creek to below aquatic MCLs (Figure 9). The most effective removal was achieved
with colloidal iron (82%) and activated carbon (85%).
5.2.2.4 Zinc
Zinc concentrations in lower Pole Creek must be lowered by at least 84% in
order to meet the determined MCLs. All of the treatments except one exhibited the
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
NT
Fe(III)
5mg/L
Fe(III)
10mg/L
Fe(III)
25mg/L
0.1% c-
Fe
1.0% c-
Fe
10.0%
c-Fe
Fe(III)-
tpA
1g/L
Alumina
10g/L
Alumina
1g/L
Carbon
10g/L
Carb
on
Ni c
once
ntra
tion
(µM
)
Figure 9. Effects of various water treatments on the concentration of nickel in Pole Creek outlet water. Error bars represent sample S.D., n=3.
54
ability to reduce concentrations of zinc by over 90% (Figure 10). The most effective
treatment was the use of zero-valent colloidal iron, although all treatments
performed similarly well.
5.3 SOIL TREATMENT
Results of the chemical armoring study were used to examine the effect of
concentrated solution amendment treatments on the leaching of selenite from waste
rock soils. The goal of the saturated soil paste study was to compare and contrast
the effects of ten different soil amendments on selenium and COPC leaching.
5.3.1 SELENIUM
As previously mentioned, the major soil extractable selenium species has
been identified as the species selenite (SeO32-). In the following armoring studies,
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
NT
Fe(III)
5mg/L
Fe(III)
10mg/L
Fe(III)
25mg/L
0.1% c-
Fe
1.0% c-
Fe
10.0%
c-Fe
Fe(III)-
tpA
1g/L
Alumina
10g/L
Alumina
1g/L
Carbon
10g/L
Carb
on
Zn c
once
ntra
tion
(µM
)
Figure 10. Effects of various water treatments on the concentration of zinc in Pole Creek outlet water. Error bars represent sample S.D., n=3.
55
analysis for selenite was performed on the leachate samples after treatment, with no
digestion for total selenium. In the saturated paste studies, analysis for total
selenium was performed. Once the concentration of selenium in the paste pore
water was determined, the amount of selenium leached per kilogram of overburden
soil was calculated.
5.3.1.1 Chemical armoring
This experiment examined the soil particle armoring effects of three different
amendment solutions against the leaching of selenite from overburden soils.
Surface treatment of soil particles has the potential to limit short-term selenite
leachability. This study examined the effects of three different concentrations of
each amendment in order to determine the most effective armoring concentration.
Armoring against a 0.1M phosphate buffer is ineffective, so phosphate was used at
the end the study to remove any remaining soluble or exchangeable selenite (s/e
selenite) from the samples.
At the completion of this trial, it was apparent that the highest concentration of
each amendment was the most effective prior to addition of phosphate (Figure 11).
The high concentrations of tpA, Fe(III), and Fe(III)-tpA reduced the amount of s/e
selenite leached over 24 hours from the soil by at least 80%. As the amendment
concentration decreased, the leached amount approached that of not having been
treated. Twenty-four hours later, all of the leached amounts increased, but the 1000
mg/L Fe(III) and 1% Fe(III)-tpA treatments did not increase as much as either the
untreated soil or the soil treated with tpA (67).
56
Soluble and exchangeable selenite was further leached from the same soil
samples after the remaining water was replaced with the phosphate buffer solution.
In this sequential extraction, the greatest amount of s/e selenite leached from the
soils was after this 24-hour extraction. This not only illustrated that phosphate will
enhance s/e selenite leaching, but also showed that all samples contained similar
concentrations of s/e selenite regardless of treatment.
5.3.1.2 Saturated soil paste study
The primary goal of this study was to reduce the amount of selenium leaching
from the overburden. Secondary goals included reducing or not affecting the
leaching of other potential contaminants (COPC) within the overburden. The ten soil
amendments used were anaerobic sulfate reducing bacteria inoculum (SRB),
0.0000
0.0001
0.0010
0.0100
0.1000
control 5.0% tpA 0.5% tpA 0.05% tpA 1000mg/LFe(III)
100mg/LFe(III)
10mg/LFe(III)
1.0%Fe(III)-tpA
mm
ol s
elen
ite le
ache
dpe
r kg
soil
24 hrs. 48 hrs.
Phosphate
Figure 11. Amount of soluble/exchangeable selenite leached from soil after three consecutive leach periods; water/24 hrs, water/24hrs, and phosphate buffer/24 hrs.
57
colloidal iron (c-Fe), mixed mesh scrap iron (mb-Fe), mb-Fe/SRB, potato starch
(PS), PS/SRB, ferric thermal poly-Aspartate (Fe(III)-tpA), Fe(III)-tpA/SRB, potato
waste (PW), and PW/SRB. Figures 12 and 13 show the effects of the ten soil
amendment treatments on the amount of selenium leached after 14 and 28 days.
After 14 days, Fe(III)-tpA, Fe(III)-tpA/SRB, PW and PW/SRB all inhibited the
amount of selenium leached by over 99%. In the same time mb-Fe/SRB, PS, and
PS/SRB reduced the amount leached by at least 95%. Remaining amendments
reduced the selenium leached from 56% to 84%. During this 14 day trial, the
amendments that were mixed with SRBs outperformed those same treatments
without SRB and the SRB alone (Figure 12).
0.01
0.10
1.00
10.00
100.00
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es S
e le
ache
dpe
r kg
soil
Figure 12. Effects of amendments on amount of selenium leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3.
58
After 28 days, with the exception of PS, there was little difference between
the amount of selenium leached in the samples treated with an amendment plus
SRB and those with just the amendment (Figure 13). In some trials, the absence of
SRB inoculation appears to have had a slightly lower Se concentration result. This
may be due to the gradual infiltration of oxygen into the inoculated pastes, which
limits the ability of the anaerobic SRBs to maintain a viable population. Conversely,
natural SRB populations in the non-inoculated media may have increased.
These approaches demonstrated varying ability to inhibit selenium release
within the time frame of the experiment, and none of the approaches showed
significant reversal of positive effects within the time frame of the study. In four
weeks, all treatments except c-Fe (86%) and SRB (82%) showed the ability to inhibit
0.01
0.10
1.00
10.00
100.00
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es S
e le
ache
dpe
r kg
soil
Figure 13. Effects of amendments on amount of selenium leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3.
59
selenium releases by at least 98%. Potato waste demonstrated the most rapid and
effective activity in the term of this experiment.
5.3.2 OTHER CONSTITUENTS OF POTENTIAL CONCERN
In addition to reducing the amount of selenium leached from the overburden,
reduction of other COPC leaching is also a concern. Figures 14-21 summarize the
effects of the ten soil amendments on the leaching of these elements. Manganese
leaching (Figures 22 and 23) was also included because it appears to increase
enough (>10X) from some treatments to raise creek concentrations above the MCL.
Other elements were removed from further consideration after it was determined that
the pore water concentrations were not considerably increased.
5.3.2.1 Saturated soil paste study
Current concentrations of cadmium in Pole creek need to be reduced by more
than 92% to comply with the MCLs. After the 14 day study (Figure 14), there was no
significant difference in amount of cadmium leached from the unamended
overburden and that overburden amended with c-Fe, SRB and mb-Fe. Samples
amended with Fe(III)-tpA showed increases in leaching by 270%, while Fe(III)-
tpA/SRB samples showed a 180% increase, possibly due to the acidity of tpA.
Reductions in amount of cadmium leached occurred in samples with mb-Fe/SRB (-
18%), potato waste (-84%), PW/SRB (-89%) and potato starch (-14%) amendments.
The 28 day data showed a large standard deviation in the cadmium leached
from the unamended sample, which in turn made it difficult to assess whether
60
0.00E+00
5.00E-05
1.00E-04
1.50E-04
2.00E-04
2.50E-04
3.00E-04
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es C
d le
ache
dpe
r kg
soil
Figure 14. Effects of amendments on amount of cadmium leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3.
0.00E+00
5.00E-05
1.00E-04
1.50E-04
2.00E-04
2.50E-04
3.00E-04
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es C
d le
ache
dpe
r kg
soil
Figure 15. Effects of amendments on amount of cadmium leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3.
61
amendments effects were significant (Figure 15). Colloidal iron treatment appeared
to have no effect on cadmium leaching. Amendment with SRB, Fe(III)-tpA and
Fe(III)-tpA/SRB all showed increases in amount of cadmium leached. Inhibition of
cadmium leaching was apparent with potato waste and PW/SRB, and some
inhibition was possible from amendment with mb-Fe, mb-Fe/SRB, potato starch and
PS/SRB.
Copper concentrations in Pole Creek need to be reduced by at least 85% to
meet the MCLs determined in this study. However, the best reduction within the
span of this study was 30-40%. After 28 days (Figure 16), there was little change in
the amount of copper leached from the overburden amended with c-Fe, SRB, mb-Fe
and mb-Fe/SRB. Fe(III)-tpA and Fe(III)-tpA/SRB increased leaching by 220% and
0.00E+00
1.00E-04
2.00E-04
3.00E-04
4.00E-04
5.00E-04
6.00E-04
7.00E-04
8.00E-04
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es C
u le
ache
dpe
r kg
soil
Figure 16. Effects of amendments on amount of copper leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3.
62
180%, respectively. Slight reductions were observed with potato waste (-20%) and
potato starch (-12%) amendments, and the best inhibition was exemplified by
PW/SRB (-42%) and PS/SRB (-47%) amendment. After 28 days, there was not
much change in effectiveness of most amendments (Figure 17). The only change
was with potato waste amendment, which enhanced copper leaching by 140%.
Nickel is just slightly over the recommended MCL and concentrations should
be reduced by about 6%. After 14 days, the only amendment treatments to have a
significant effect on the amount of nickel leached were the Fe(III)-tpA and potato
waste, with and without SRB (Figure 18). Fe(III)-tpA (890%) and Fe(III)-tpA/SRB
(990%) showed drastic increases while potato waste (180%) and potato waste/SRB
(180%) also increased leaching. Mb-Fe/SRB (-13%) showed some potential to
reduce copper leaching within the 14 day study.
0.00E+00
1.00E-04
2.00E-04
3.00E-04
4.00E-04
5.00E-04
6.00E-04
7.00E-04
8.00E-04
9.00E-04
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es C
u le
ache
dpe
r kg
soil
Figure 17. Effects of amendments on amount of copper leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3.
63
The 28 day study had no treatments that significantly inhibited the leaching of
nickel from the overburden (Figure 19). Amendment with Fe(III)-tpA, at over 1000%,
further increased leaching of nickel, while leaching with Fe(III)-tpA/SRB, at 730%,
was not as strong as in the 14 day study. Potato waste and PW/SRB showed
similar effects as in the 14 day study, while potato starch and PS/SRB showed an
increase in leaching of nickel, at 260% and 190%, respectively.
Zinc leaching should be reduced by at least 84% in order to meet MCLs in
Pole Creek. After 14 days, the amount of zinc leached was reduced by addition of
potato waste (-49%), but was essentially not affected by amendment with c-Fe,
SRB, mb-Fe/SRB, PW/SRB, potato starch, or PS/SRB (Figure 20). An increase in
the amount of zinc leached occurred with mb-Fe (150%) and both Fe(III)
amendments (350% and 410%).
0.000
0.002
0.004
0.006
0.008
0.010
0.012
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es N
i lea
ched
per k
g so
il
Figure 18. Effects of amendments on amount of nickel leached from overburden saturated paste after 14 days. Error bars represent samples S.D., n=3.
64
0.000
0.002
0.004
0.006
0.008
0.010
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es N
i lea
ched
per k
g so
il
Figure 19. Effects of amendments on amount of nickel leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3.
0.000
0.001
0.002
0.003
0.004
0.005
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es Z
n le
ache
dpe
r kg
soil
Figure 20. Effects of amendments on amount of zinc leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3.
65
SRB and the two Fe(III) amendments increased leaching of zinc over the 28
days, although the amount being leached was considerably less than at 14 days.
Potato starch and PS/SRB amendment still had little effect on the leaching of zinc
after 28 days (Figure 21). However, c-Fe, mb-Fe, mb-Fe/SRB, potato waste, and
PW/SRB all reduced the amount leached by 57 to 65%. While this did not reach the
targeted 84% reduction for meeting MCLs in Pole Creek, the potential for further
reduction at an extended period of time is apparent.
Of the remaining elements for which the overburden outlet water was tested,
none were above MCLs as calculated in this study. With the exception of
manganese, addition of amendments to the overburden saturated pastes did not
increase the concentrations of any remaining COPCs enough to cause them to
exceed MCLs.
0.000
0.001
0.002
0.003
0.004
0.005
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es Z
n le
ache
dpe
r kg
soil
Figure 21. Effects of amendments on amount of zinc leached from overburden saturated paste after 28 days. Error bars represent sample S.D.
66
Manganese is mobile in reducing conditions and is generally present as
oxides in soil which tend to dissolve in reducing environments (71). Because of
reducing conditions produced by amendment materials used in this study, they all
increased the leaching of manganese to some extent. After 14 days, manganese
leaching was not significantly increased by amendment with c-Fe, SRB, mb-Fe, mb-
Fe/SRB, potato starch, and PS/SRB (Figure 22). However, the Fe(III)-tpA (870%),
Fe(III)-tpA/SRB (1400%), potato waste (4200%) and PW/SRB (4000%) amendments
showed larger increases and would most likely cause outlet concentrations to
exceed MCLs.
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0.080
0.090
0.100
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es M
n le
ache
dpe
r kg
soil
Figure 22. Effects of amendments on amount of manganese leached from overburden saturated paste after 14 days. Error bars represent sample S.D., n=3.
67
Conditions did not improve after the initial 14 days, with only c-Fe, SRB, mb-
Fe, and mb-Fe/SRB treatments remaining below the 1000% increase mark (Figure
23). All remaining treatments increased the amount of manganese leached by
1400% to 3800%.
5.4 SIGNIFICANT FINDINGS
• Comparison of outlet water concentrations to MCL calculations for the creek
water show that, in addition to selenium, other constituents of potential concern
may include cadmium, copper, nickel, and zinc.
• Water treatment studies show the most promise for selenium and COPC removal
with zero-valent iron treatment. Activated carbon is also effective but may be
cost prohibitive.
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0.080
no tm
tc-F
e SRB
mb-Fe
mb-Fe +
SRB
Fe(III)-
tpA
Fe(III)-
tpA +
SRB
potat
o was
te
pw +
SRB
potat
o star
ch
ps +
SRB
µmol
es M
n le
ache
dpe
r kg
soil
Figure 23. Effects of amendments on amount of manganese leached from overburden saturated paste after 28 days. Error bars represent sample S.D., n=3.
68
• Treatments performed on aged outlet water samples could have differing results
on freshly collected outlet water or leachate in which the selenite has not yet
oxidized to selenate.
• Fe(III)-tpA demonstrates the best soil particle chemical armoring activity against
the release of selenite, with Fe(III) also performing well.
• None of the effective saturated soil paste amendments showed significant
reversal of positive effects within the 28 day time frame of the experiment.
• Potato waste amendments demonstrated the most rapid and effective selenium
inhibition in the term of this experiment.
• Over the 28 day saturated soil paste study, mb-Fe, Fe(III)-tpA, potato waste, and
potato starch, with and without SRB inoculation, all showed the ability to stabilize
or reduce dissolved selenium towards MCLs.
• Over the 28 day saturated soil paste study, potato waste, potato starch and mb-
Fe, with and without SRB inoculation all demonstrated the ability to reduce
COPC towards aquatic criteria MCLs.
• Potato waste demonstrated the best overall combined selenium and other COPC
immobilization in saturated overburden soil for the term of this experiment.
• Fe(III)-tpA enhanced the release of all metals of concern from the saturated
pastes.
• Manganese leaching is enhanced by all amendments, and the magnitude of the
increase from amendment with Fe(III)-tpA, potato waste, and potato starch could
cause creek concentrations to exceed MCLs.
69
6.0 CONCLUSIONS
Characterization studies have shown that selenium is not present in
detectable amounts in Pole Creek prior to influence of the overburden french drain.
The french drain is overlain by waste rocks and low grade phosphate ore from the
Meade Peak member of the Phosphoria Formation. The weathering of this
overburden influences the composition of the water in Pole Creek by increasing
concentrations of selenium, sulfur, and other elements.
Although this work does not explore reaction pathway in detail, the data
suggest that the overburden selenium release results from the oxidation of minerals
such as pyrite in the middle waste shales of the Meade Peak member. Associated
acid rock drainage acidity is controlled by the limestone fraction of the overburden.
The absence of soluble iron in this system likely results from availability of
phosphate from the low grade ore; this has the effect of limiting the selenite solubility
control potential of iron-selenite precipitates.
By looking at maximum contaminant load calculations, we see that at the time
of sampling, not only was selenium above water quality criteria, but cadmium,
copper, nickel and zinc were as well. Treating the french drain outlet water directly
by various proven technologies was marginally successful for reduction of selenium
concentrations. Since several months passed between sampling Pole Creek and
final treatment testing, oxidation of any dissolved selenite to selenate is likely
(selenate being more difficult to treat than selenite). Repeat testing of treatment
methods on field frozen samples is recommended prior to discounting any of the
water treatments.
70
The overburden soil treatment studies are specifically designed to look at
potential control strategies for the release of selenium and other contaminants.
Therefore, in addition to immediately treating the existing selenium releases, some
of the treatment methods appear to have potential to function as short-term,
renewable stabilization treatments.
Most significantly, the data from the treatment study suggest that the
selenium release from the phosphate resource area overburden may be controlled
in-situ with chemical or microbial reductive approaches. This is in large part due to
the identification of selenite as the dominant selenium oxyanion present in water
leachable and adsorbed form on the overburden soils. Topical application of the
Fe(III)-tpA solution shows potential for short-term armoring of soils against the
leaching of selenite. Incorporation of amendment materials into the overburden that
would produce a reducing environment also shows promise.
For the control of selenium releases, all overburden amendment approaches
studied in this work were successful. Analysis of COPC in associated pore water of
amended soils suggests that potato waste and granular iron (mb-Fe) offer the best
overall inhibition of contaminant release. The mb-Fe, potato waste, and potato
starch amendments show positive effects for most contaminants of interest.
71
A. APPENDIX OF CHARACTERIZATION DATA PRESENTED IN MASS UNITS
A.1 WATER
A.1.1 CHLORIDE
Method: EPA 325.3: Argentometric Chloride in Water Solution Results:
PCW1-Na PCW2-Na units EDL Cl- 8.20 9.80 mg/L 2.0
A.1.2 SULFATE
Method: EPA 375.4: Sulfate (Turbidimetric) Results:
PCW1-Na PCW2-Na units EDL SO4
2- 19.0 290 mg/L 2.0
A.1.3 NITROGEN, NITRATE-NITRITE:
Method: EPA 353.2: Nitrogen, Nitrate-Nitrite (Colorimetric, Automated, Cadmium Reduction) Results:
PCW1-Na PCW2-Na units EDL N as NO3
2-
+ NO22-
0.100 0.300 mg/L 0.10
A.1.4 PHOSPHOROUS:
Method: EPA 365.4: Total Phosphorous Test Results:
PCW1-Na PCW2-Na units EDL total P 0.0800 0.0300 mg/L 0.010
72
A.1.5 ANIONS
Method: EPA 300.0: Anion Concentrations in Water Using the Dionex DX-100 Ion Chromatograph Results (mg/L):
PCW1-Nb PCW2-Nb units EDL Fluoride 0.0500 0.180 mg/L 0.050 Chloride 1.60 3.60 mg/L 0.050
Nitrite 0.0500 0.0500 mg/L 0.050 Bromide 0.100 0.100 mg/L 0.10 Nitrate 0.0500 0.790 mg/L 0.050
o-Phosphate 0.0500 0.0500 mg/L 0.050 Sulfate 18.0 280 mg/L 0.10 Oxalate 0.100 0.100 mg/L 0.10 Sulfite 5.00 5.00 mg/L 5.0
A.1.6 DISSOLVED MULTI-ELEMENT SCREEN
Method: EPA 200.7: Water Dissolved Multi-element Screen Results:
PCW1-FP PCW2-FP Units EDL Al 0.0890 0.0890 mg/L 0.089 Ba 0.0580 0.0420 mg/L 0.00060 Be 0.00210 0.000100 mg/L 0.00010 Cd 0.00230 0.0130 mg/L 0.0023 Ca 60.0 180 mg/L 0.0099 Cr 0.00440 0.00440 mg/L 0.0044 Co 0.00800 0.00800 mg/L 0.0080 Cu 0.00840 0.0140 mg/L 0.0084 Fe 0.0320 0.00370 mg/L 0.0037 Mg 16.0 28.0 mg/L 0.0047 Mn 0.0280 0.0200 mg/L 0.0012 Mo 0.0270 0.0480 mg/L 0.027 Ni 0.00700 0.120 mg/L 0.0070 K 0.610 1.20 mg/L 0.61
Na 4.00 5.10 mg/L 0.12 V 0.0150 0.0150 mg/L 0.015 Zn 0.0140 0.480 mg/L 0.0025 Ag 0.0300 0.0300 mg/L 0.010 Si 4.30 4.40 mg/L 0.29
73
A.1.7 TOTAL RECOVERABLE MULTI-ELEMENT SCREEN:
Method: EPA 200.7: Total Recoverable Multi-Element Water Screen Results:
PCW1-Nb PCW2-Nb units EDL Ba 0.0320 0.310 mg/L 0.0040 Be 0.000900 0.00120 mg/L 0.00040 Cd 0.00300 0.0140 mg/L 0.0030 Ca 58.0 190 mg/L 0.031 Cr 0.0130 0.0220 mg/L 0.013 Co 0.0170 0.0200 mg/L 0.011 Cu 0.0350 0.0780 mg/L 0.035 Fe 0.0120 0.0120 mg/L 0.012 Mg 15.0 30.0 mg/L 0.0020 Mn 0.00900 0.0140 mg/L 0.0020 Mo 0.0400 0.1000 mg/L 0.040 Ni 0.0200 0.170 mg/L 0.020 K 1.60 3.20 mg/L 1.60 Ag 0.100 0.100 mg/L 0.10 Na 4.30 6.10 mg/L 0.55 V 0.0280 0.0280 mg/L 0.028 Zn 0.00500 0.670 mg/L 0.0030
A.1.8 SELENIUM
Method: Total Selenium in Water by Hydride Generation ICP Results:
PCW1-P PCW2-P Units EDL Se 0.000700 0.680 mg/L 0.00070
74
A.2 SOLID MATRIX
A.2.1 PHOSPHOROUS AND POTASSIUM
Method: Available Phosphorus and Potassium in Soils by Sodium Bicarbonate Results:
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL P 19.60 49.40 43.70 58.80 51.90 mg/kg 2.4 K 71.00 92.00 68.00 81.00 51.00 mg/kg 6.2
A.2.2 SULFATE-SULFUR
Method: Sulfate-Sulfur in Soils Results:
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL SO4
2--S 92.00 38.00 440.00 34.00 7.60 mg/kg 0.96
A.2.3 SOIL NITROGEN - AMMONIUM AND NITRATE
Method: Soil Nitrate and Ammonium Nitrogen Extraction Method Results:
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL NO3
--N 2.00 1.00 2.50 0.90 1.10 mg/kg 0.37 NH4
+-N 3.20 4.70 3.30 3.30 3.50 mg/kg 0.38
A.2.4 SOIL BORON
Method: Soil Boron, Pouch Method Results:
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL B 0.17 0.16 0.13 0.13 0.15 mg/kg 0.030
75
A.2.5 TRACE MICRO-ELEMENT SCREEN
Method: EPA 3050: Acid Digestion of Sediments, Sludges, and Soils Results:
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL As 100 110 110 110 100 mg/kg 9.7 Ba 80.0 81.0 73.0 76.0 69.0 mg/kg 0.16 Be 1.50 1.30 1.60 1.80 1.60 mg/kg 0.017 Ca 120000 70000 130000 120000 170000 mg/kg 28 Cd 26.0 21.0 38.0 55.0 18.0 mg/kg 0.35 Co 9.30 9.90 9.80 11.0 8.50 mg/kg 1.1 Cr 780 550 710 960 1100 mg/kg 1.1 Cu 110 67.0 96.0 130 140 mg/kg 1.0 Fe 16000 16000 16000 19000 17000 mg/kg 10 K 5000 5900 5900 5600 5900 mg/kg 120
Mg 6200 3800 5100 3200 1900 mg/kg 5.1 Mn 320 600 240 300 120 mg/kg 0.52 Mo 40.0 23.0 48.0 42.0 37.0 mg/kg 3.9 Na 1200 870 1500 1200 2100 mg/kg 30 Ni 290 200 260 330 250 mg/kg 0.45 P 30000 21000 40000 40000 60000 mg/kg 8.4
Pb 40.0 41.0 44.0 45.0 41.0 mg/kg 5.6 S 7700 3000 8800 5800 7100 mg/kg 48 Zn 1200 710 1200 1600 1000 mg/kg 0.72
A.2.6 SELENIUM
Method: Total Selenium in Soils by Vapor Generation ICP Results:
PCO-01 PCO-02 PCO-03 PCO-04 PC-CH Units EDL Se 33.0 20.0 36.0 23.0 16.0 mg/kg 0.0039
76
A.2.7 NEUTRON ACTIVATION ANALYSIS
Results: Se (mg/kg) Zn (mg/kg)
PCO-01 34.0 ± 3.0 1430 ± 50 PCO-02 38.2 ± 3.3 804 ± 26 PCO-03 53.8 ± 4.4 2130 ± 70 PCO-04 72.8 ± 5.8 1720 ± 50 PCCH 17.2 ± 1.6 1200 ± 40
A.2.8 SEQUENTIAL EXTRACTION
Results:
Extractant/Species µg-Se/L-Extract mg-Se/kg-Soil Water/Se(IV) 25.4 16.8 0.103
Water/Se(IV) and Se(VI) 18.5 15.6 0.0869 Water/Se(-II) 7.97 0.703 0.0213 Buffer/Se(IV) 205 211 1.03
Buffer/Se(IV) and Se(VI) 197 200 1.03 Buffer/Se(-II) 0.703 0.703 0.00355
Persulfate/Se(IV) and Se(-II) 18.8 13.8 0.0790 Total Extractable Se - - 1.26
A.2.9 METHYLENE CHLORIDE ORGANO-SELENIUM EXTRACTION
Results: Sample ID Organo-Selenium
mg-Se/kg-soil Percentage of
total Se by NAA PCO-01a 0.513 0.96 % PCO-01b 0.490 0.91 % PCO-02a 0.142 0.26 % PCO-02b 0.221 0.41 % PCO-03a 0.142 2.65 % PCO-03b 1.18 2.21 %
A.2.10 AGITATION LEACH
Method: Modified EPA 1311 Toxicity Characteristic Leaching Procedure for Metals in Soil
77
Results: PCO-01 mg/L PCW-01 PCW-02 18MΩ-cm
01 18MΩ-cm
02 Units EDL
Se 0.06100 0.06500 0.0780 0.0820 mg/L 0.0007 Al 0.0890 0.0890 0.2800 0.2600 mg/L 0.0890 Ba 0.2600 0.2600 0.1700 0.1700 mg/L 0.0006 Be 0.0001 0.0001 0.0001 0.0001 mg/L 0.0001 Cd 0.0023 0.0023 0.0023 0.0023 mg/L 0.0023 Ca 66.0000 67.0000 17.0000 16.0000 mg/L 0.0099 Cr 0.0044 0.0044 0.0088 0.0094 mg/L 0.0044 Co 0.0080 0.0080 0.0080 0.0080 mg/L 0.0080 Cu 0.0084 0.0084 0.0084 0.0084 mg/L 0.0084 Fe 0.0037 0.0037 0.2700 0.2600 mg/L 0.0037 Mg 14.0000 14.0000 1.6000 1.6000 mg/L 0.0047 Mn 0.0110 0.0048 0.0020 0.0024 mg/L 0.0012 Mo 0.0270 0.0270 0.0270 0.0270 mg/L 0.0270 Ni 0.0140 0.0100 0.0070 0.0070 mg/L 0.0070 K 0.7200 0.6100 0.6100 0.6100 mg/L 0.6100
Na 5.7000 5.8000 2.0000 2.1000 mg/L 0.1200 V 0.0150 0.0150 0.0150 0.0150 mg/L 0.0150 Zn 0.0025 0.0025 0.0240 0.0240 mg/L 0.0025
Results: PCO-02
mg/L PCW-01 PCW-02 18MΩ-cm 01
18MΩ-cm 02
Units EDL
Se 0.0310 0.0290 0.0380 0.0400 mg/L 0.0007 Al 0.0890 0.0890 2.8000 2.5000 mg/L 0.0890 Ba 0.3000 0.2900 0.2000 0.1900 mg/L 0.0006 Be 0.0001 0.0001 0.0001 0.0001 mg/L 0.0001 Cd 0.0023 0.0023 0.0023 0.0023 mg/L 0.0023 Ca 59.0000 59.0000 9.6000 9.9000 mg/L 0.0099 Cr 0.0044 0.0044 0.0760 0.0780 mg/L 0.0044 Co 0.0080 0.0080 0.0080 0.0080 mg/L 0.0080 Cu 0.0084 0.0084 0.0084 0.0084 mg/L 0.0084 Fe 0.0037 0.0037 2.0000 1.8000 mg/L 0.0037 Mg 13.0000 13.0000 1.2000 1.2000 mg/L 0.0047 Mn 0.0017 0.0012 0.0270 0.0260 mg/L 0.0012 Mo 0.0270 0.0270 0.0270 0.0270 mg/L 0.0270 Ni 0.0070 0.0070 0.0140 0.0140 mg/L 0.0070 K 0.6100 0.6100 0.6100 0.6100 mg/L 0.6100
Na 5.7000 5.7000 2.1000 2.3000 mg/L 0.1200 V 0.0150 0.0150 0.0370 0.0360 mg/L 0.0150 Zn 0.0025 0.0025 0.0870 0.0780 mg/L 0.0025
78
Results: PCO-03 mg/L PCW-01 PCW-02 18MΩ-cm
01 18MΩ-cm
02 Units EDL
Se 0.1900 0.1900 0.1900 0.2100 mg/L 0.0007 Al 0.0890 0.0890 0.0930 0.1700 mg/L 0.0890 Ba 0.1400 0.1200 0.0990 0.0960 mg/L 0.0006 Be 0.0001 0.0001 0.0001 0.0001 mg/L 0.0001 Cd 0.0023 0.0023 0.0023 0.0023 mg/L 0.0023 Ca 140.00 140.00 88.00 99.00 mg/L 0.0099 Cr 0.0044 0.0044 0.0044 0.0044 mg/L 0.0044 Co 0.0080 0.0080 0.0080 0.0090 mg/L 0.0080 Cu 0.0084 0.0120 0.0230 0.0340 mg/L 0.0084 Fe 0.0037 0.0037 0.0037 0.0037 mg/L 0.0037 Mg 16.0000 16.0000 3.6000 3.9000 mg/L 0.0047 Mn 0.0059 0.0052 0.0034 0.0042 mg/L 0.0012 Mo 0.0800 0.0770 0.1000 0.0850 mg/L 0.0270 Ni 0.0430 0.0460 0.0180 0.0280 mg/L 0.0070 K 0.6200 1.1000 1.0000 1.7000 mg/L 0.6100
Na 5.8000 5.9000 2.6000 2.7000 mg/L 0.1200 V 0.0150 0.0150 0.0150 0.0160 mg/L 0.0150 Zn 0.0380 0.0091 0.0025 0.0034 mg/L 0.0025
Results: PCO-04
PCW-01 PCW-02 18MΩ-cm 01
18MΩ-cm 02
Units EDL
Se 0.0720 0.0710 0.0790 0.0770 mg/L 0.0007 Al 0.1600 0.1000 1.0000 0.8900 mg/L 0.0890 Ba 0.2300 0.2800 0.1900 0.1900 mg/L 0.0006 Be 0.0001 0.0001 0.0001 0.0001 mg/L 0.0001 Cd 0.0023 0.0023 0.0023 0.0023 mg/L 0.0023 Ca 59.0000 60.0000 11.0000 11.0000 mg/L 0.0099 Cr 0.0044 0.0044 0.0900 0.0830 mg/L 0.0044 Co 0.0080 0.0080 0.0080 0.0080 mg/L 0.0080 Cu 0.0250 0.0200 0.0210 0.0170 mg/L 0.0084 Fe 0.0037 0.0037 0.7300 0.6600 mg/L 0.0037 Mg 11.0000 11.0000 1.1000 1.1000 mg/L 0.0047 Mn 0.0041 0.0028 0.0062 0.0059 mg/L 0.0012 Mo 0.0270 0.0270 0.0270 0.0270 mg/L 0.0270 Ni 0.0220 0.0230 0.0310 0.0270 mg/L 0.0070 K 1.9000 2.2000 0.9000 1.8000 mg/L 0.6100
Na 5.5000 5.7000 2.4000 2.3000 mg/L 0.1200 V 0.1200 0.1200 0.1500 0.1500 mg/L 0.0150 Zn 0.0097 0.0073 0.0760 0.0690 mg/L 0.0025
79
Results: PC-CH PCW-01 PCW-02 18MΩ-cm
01 18MΩ-cm
02 Units EDL
Se 0.0007 0.0007 0.0025 0.0020 mg/L 0.0007 Al 0.0890 0.0890 2.8000 2.4000 mg/L 0.0890 Ba 0.3500 0.3300 0.3300 0.3700 mg/L 0.0006 Be 0.0001 0.0001 0.0001 0.0001 mg/L 0.0001 Cd 0.0023 0.0023 0.0023 0.0023 mg/L 0.0023 Ca 44.0000 44.0000 3.2000 3.1000 mg/L 0.0099 Cr 0.0044 0.0044 0.2500 0.2100 mg/L 0.0044 Co 0.0080 0.0080 0.0080 0.0080 mg/L 0.0080 Cu 0.0084 0.0084 0.0084 0.0084 mg/L 0.0084 Fe 0.0037 0.0037 1.9000 1.6000 mg/L 0.0037 Mg 11.0000 11.0000 0.6400 0.6200 mg/L 0.0047 Mn 0.0016 0.0026 0.0015 0.0022 mg/L 0.0012 Mo 0.0270 0.0270 0.0270 0.0270 mg/L 0.0270 Ni 0.0220 0.0280 0.0220 0.0200 mg/L 0.0070 K 0.6100 0.6100 0.6100 0.6100 mg/L 0.6100
Na 6.4000 6.4000 2.4000 3.0000 mg/L 0.1200 V 0.0150 0.0170 0.0620 0.0530 mg/L 0.0150 Zn 0.0410 0.0460 0.1100 0.4100 mg/L 0.0025
80
B. APPENDIX OF TABULATED TREATMENT DATA
B.1 WATER
B.1.1 MAXIMUM CONTAMINANT LEVELS
PCW2 Max. Concentration
Aquatic Limit Riparian / Terrestrial
Limit
Units COPC?
Se 0.680 0.0128-0.186 0.022 mg/L Yes Al BDL 0.460 0.550 mg/L No Ba 0.310 5.80 3.30 mg/L No Cd 0.0140 0.00110 0.0500 mg/L Yes Cr 0.0220 0.210 1.00 mg/L No Cu 0.0780 0.0120 0.500 mg/L Yes Mn 0.0140 0.120 57.0 mg/L No Mo 0.100 0.880 NA mg/L No Ni 0.170 0.160 1.00 mg/L Yes V BDL 0.0800 0.100 mg/L No Zn 0.670 0.110 5.10 mg/L Yes
B.1.2 WATER TREATMENTS
Selenium: Initial concentration 0.680 mg/L (0.00861mM).
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.638 0.640 0.663 0.647 mg/L -5% 0.0139 10 mg/L Fe(III) 0.640 0.659 0.631 0.643 mg/L -5% 0.0143 25 mg/L Fe(III) 0.646 0.642 0.635 0.641 mg/L -6% 0.00557 0.1 wt% c-Fe 0.460 0.520 --- 0.490 mg/L -28% 0.0424 1.0 wt% c-Fe 0.050 0.220 --- 0.135 mg/L -80% 0.120 10 wt% c-Fe 0.0014 0.0022 0.0017 0.003 mg/L -100% 0.000395 10 mg/L Fe(III)-tpA 0.648 0.523 0.597 0.589 mg/L -13% 0.0629 1 g/L alumina 0.641 0.642 0.669 0.651 mg/L -4% 0.0159 10 g/L alumina 0.580 0.599 0.568 0.582 mg/L -14% 0.0156 1 g/L carbon 0.532 0.603 0.559 0.565 mg/L -17% 0.0358 10 g/L carbon 0.483 0.393 0.450 0.442 mg/L -35% 0.0455
81
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 8.08 8.11 8.40 8.19 µM -5% 0.176 10 mg/L Fe(III) 8.11 8.35 7.99 8.15 µM -5% 0.181 25 mg/L Fe(III) 8.18 8.13 8.04 8.12 µM -6% 0.07051 0.1 wt% c-Fe 5.83 6.59 --- 6.21 µM -28% 0.537 1.0 wt% c-Fe 0.63 2.79 --- 1.71 µM -80% 1.520 10 wt% c-Fe 0.02 0.03 0.02 0.02 µM -100% 0.0050 10 mg/L Fe(III)-tpA 8.21 6.62 7.56 7.46 µM -13% 0.796 1 g/L alumina 8.12 8.13 8.47 8.24 µM -4% 0.201 10 g/L alumina 7.35 7.59 7.19 7.38 µM -14% 0.198 1 g/L carbon 6.74 7.64 7.08 7.15 µM -17% 0.454 10 g/L carbon 6.12 4.98 5.70 5.60 µM -35% 0.577 Cadmium: Initial concentration 0.0187 mg/L (0.1664 µM).
Trial A Trial B Trial C Avg Units % change S.D. 5 mg/L Fe(III) 0.0022 0.0022 0.0020 0.0021 mg/L -89% 0.000115 10 mg/L Fe(III) 0.0029 0.0035 0.0016 0.0027 mg/L -86% 0.000755 25 mg/L Fe(III) 0.0024 0.0065 0.0020 0.0036 mg/L -81% 0.00249 0.1 wt% c-Fe --- 0.0023 0.0023 0.0023 mg/L -88% 0.00 1.0 wt% c-Fe 0.0016 0.0035 0.0027 0.0026 mg/L -86% 0.000751 10 wt% c-Fe 0.0025 0.0023 0.0045 0.0031 mg/L -83% 0.00122 10 mg/L Fe(III)-tpA 0.0068 0.0044 0.0060 0.0057 mg/L -69% 0.00122 1 g/L alumina 0.0031 0.0048 0.0050 0.0043 mg/L -77% 0.00104 10 g/L alumina 0.0044 0.0077 0.0040 0.0054 mg/L -71% 0.00203 1 g/L carbon 0.0093 0.0071 0.0059 0.0074 mg/L -60% 0.00172 10 g/L carbon 0.0060 0.0043 0.0056 0.0053 mg/L -72% 0.000889
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.0196 0.0196 0.0178 0.0190 µM -89% 0.00102 10 mg/L Fe(III) 0.0258 0.0311 0.0142 0.0237 µM -86% 0.00672 25 mg/L Fe(III) 0.0214 0.0578 0.0178 0.0323 µM -81% 0.0222 0.1 wt% c-Fe --- 0.0205 0.0205 0.0205 µM -88% 0.00 1.0 wt% c-Fe 0.0142 0.0311 0.0240 0.0231 µM -86% 0.00668 10 wt% c-Fe 0.0222 0.0205 0.0400 0.0276 µM -83% 0.0108 10 mg/L Fe(III)-tpA 0.0605 0.0391 0.0534 0.0510 µM -69% 0.0109 1 g/L alumina 0.0276 0.0427 0.0445 0.0383 µM -77% 0.00929 10 g/L alumina 0.0391 0.0685 0.0356 0.0477 µM -71% 0.0181 1 g/L carbon 0.0827 0.0632 0.0525 0.0661 µM -60% 0.0153 10 g/L carbon 0.0534 0.0383 0.0498 0.0471 µM -72% 0.00791
82
Copper: Initial concentration 0.0436 mg/L (0.686 µM).
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.0817 0.0220 0.0308 0.0448 mg/L 3% 0.0322 10 mg/L Fe(III) 0.0323 0.0358 0.0347 0.0343 mg/L -21% 0.00179 25 mg/L Fe(III) 0.0293 0.0312 0.0342 0.0316 mg/L -28% 0.00247 0.1 wt% c-Fe --- 0.0306 0.0257 0.0282 mg/L -35% 0.00347 1.0 wt% c-Fe 0.0270 0.0315 0.0307 0.0297 mg/L -32% 0.00240 10 wt% c-Fe 0.0245 0.0238 0.0200 0.0228 mg/L -48% 0.00242 10 mg/L Fe(III)-tpA 0.0470 0.0400 0.0438 0.0436 mg/L 0% 0.00350 1 g/L alumina 0.0174 0.0373 0.0376 0.0308 mg/L -29% 0.0116 10 g/L alumina 0.0371 0.0450 0.0357 0.0393 mg/L -10% 0.00501 1 g/L carbon 0.0348 0.0437 0.0415 0.0400 mg/L -8% 0.00464 10 g/L carbon 0.0447 0.0265 0.0369 0.0360 mg/L -17% 0.00913
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 1.2857 0.3462 0.4847 0.7055 µM 3% 0.507 10 mg/L Fe(III) 0.5083 0.5634 0.5461 0.5392 µM -21% 0.0282 25 mg/L Fe(III) 0.4611 0.4910 0.5382 0.4968 µM -28% 0.0389 0.1 wt% c-Fe --- 0.4815 0.4044 0.4430 µM -35% 0.0545 1.0 wt% c-Fe 0.4249 0.4957 0.4831 0.4679 µM -32% 0.0378 10 wt% c-Fe 0.3855 0.3745 0.3147 0.3583 µM -48% 0.0381 10 mg/L Fe(III)-tpA 0.7396 0.6295 0.6893 0.6861 µM 0% 0.0551 1 g/L alumina 0.2738 0.5870 0.5917 0.4842 µM -29% 0.182 10 g/L alumina 0.5838 0.7081 0.5618 0.6179 µM -10% 0.0789 1 g/L carbon 0.5476 0.6877 0.6531 0.6295 µM -8% 0.0730 10 g/L carbon 0.7034 0.4170 0.5807 0.5670 µM -17% 0.144 Nickel: Initial concentration 0.187 mg/L (3.19 µM).
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.0998 0.0889 0.0883 0.0923 mg/L -51% 0.00647 10 mg/L Fe(III) 0.0788 0.0731 0.0791 0.0770 mg/L -59% 0.00338 25 mg/L Fe(III) 0.0518 0.1232 0.0549 0.0766 mg/L -59% 0.0404 0.1 wt% c-Fe --- 0.1128 0.0731 0.0930 mg/L -50% 0.0281 1.0 wt% c-Fe 0.0274 0.0350 0.0365 0.0330 mg/L -82% 0.00488 10 wt% c-Fe 0.0290 0.0378 0.0386 0.0351 mg/L -81% 0.00533 10 mg/L Fe(III)-tpA 0.1703 0.1478 0.1389 0.1523 mg/L -19% 0.0162 1 g/L alumina 0.0463 0.0754 0.0640 0.0619 mg/L -67% 0.0147 10 g/L alumina 0.1218 0.1158 0.1119 0.1165 mg/L -38% 0.00499 1 g/L carbon 0.0423 0.0522 0.0480 0.0475 mg/L -75% 0.00497 10 g/L carbon 0.0680 0.0616 0.0702 0.0666 mg/L -64% 0.00447
83
Trial A Trial B Trial C Avg Units % change S.D. 5 mg/L Fe(III) 1.7002 1.5145 1.5043 1.5730 µM -51% 0.110 10 mg/L Fe(III) 1.3424 1.2453 1.3475 1.3118 µM -59% 0.0576 25 mg/L Fe(III) 0.8825 2.0988 0.9353 1.3055 µM -59% 0.688 0.1 wt% c-Fe --- 1.9216 1.2453 1.5835 µM -50% 0.478 1.0 wt% c-Fe 0.4668 0.5963 0.6218 0.5616 µM -82% 0.0831 10 wt% c-Fe 0.4940 0.6440 0.6576 0.5985 µM -81% 0.0907 10 mg/L Fe(III)-tpA 2.9012 2.5179 2.3663 2.5951 µM -19% 0.276 1 g/L alumina 0.7888 1.2845 1.0903 1.0545 µM -67% 0.250 10 g/L alumina 2.0750 1.9727 1.9063 1.9847 µM -38% 0.0850 1 g/L carbon 0.7206 0.8893 0.8177 0.8092 µM -75% 0.0847 10 g/L carbon 1.1584 1.0494 1.1959 1.1346 µM -64% 0.0761 Zinc: Initial concentration 0.515 mg/L (7.88 µM).
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.0612 0.0288 0.0349 0.0416 mg/L -92% 0.0172 10 mg/L Fe(III) 0.0306 0.0292 0.0319 0.0306 mg/L -94% 0.00135 25 mg/L Fe(III) 0.0199 0.2477 0.0434 0.1037 mg/L -80% 0.125 0.1 wt% c-Fe --- 0.0295 0.0116 0.0206 mg/L -96% 0.0127 1.0 wt% c-Fe 0.0299 0.0208 0.0331 0.0279 mg/L -95% 0.00638 10 wt% c-Fe 0.0207 0.0253 0.0170 0.0210 mg/L -96% 0.00416 10 mg/L Fe(III)-tpA 0.0658 0.0483 0.0226 0.0456 mg/L -91% 0.0217 1 g/L alumina 0.0163 0.0288 0.0745 0.0399 mg/L -92% 0.0306 10 g/L alumina 0.0414 0.0425 0.0483 0.0441 mg/L -91% 0.00371 1 g/L carbon 0.0179 0.0204 0.0456 0.0280 mg/L -95% 0.0153 10 g/L carbon 0.0462 0.0165 0.0595 0.0407 mg/L -92% 0.0220
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.9361 0.4405 0.5338 0.6368 µM -92% 0.263 10 mg/L Fe(III) 0.4680 0.4466 0.4879 0.4675 µM -94% 0.0206 25 mg/L Fe(III) 0.3044 3.7886 0.6638 1.5856 µM -80% 1.92 0.1 wt% c-Fe --- 0.4512 0.1774 0.3143 µM -96% 0.194 1.0 wt% c-Fe 0.4573 0.3181 0.5063 0.4272 µM -95% 0.0976 10 wt% c-Fe 0.3166 0.3870 0.2600 0.3212 µM -96% 0.0636 10 mg/L Fe(III)-tpA 1.0064 0.7388 0.3457 0.6970 µM -91% 0.332 1 g/L alumina 0.2493 0.4405 1.1395 0.6098 µM -92% 0.469 10 g/L alumina 0.6332 0.6500 0.7388 0.6740 µM -91% 0.0567 1 g/L carbon 0.2738 0.3120 0.6975 0.4278 µM -95% 0.234 10 g/L carbon 0.7066 0.2524 0.9101 0.6230 µM -92% 0.337
84
Manganese: Initial concentration 0.0085 mg/L (0.155 µM).
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.0044 0.0043 0.0062 0.0050 mg/L -42% 0.00107 10 mg/L Fe(III) 0.0059 0.0061 0.0065 0.0062 mg/L -28% 0.000306 25 mg/L Fe(III) 0.0076 0.0006 0.0111 0.0064 mg/L -25% 0.00536 0.1 wt% c-Fe --- 0.0048 0.0030 0.0039 mg/L -54% 0.00127 1.0 wt% c-Fe 0.0009 0.0016 0.0042 0.0022 mg/L -74% 0.00174 10 wt% c-Fe 0.0006 0.0006 0.0006 0.0006 mg/L -93% 0.00 10 mg/L Fe(III)-tpA 0.0360 0.0388 0.0383 0.0377 mg/L 342% 0.00149 1 g/L alumina 0.0044 0.0058 0.0092 0.0065 mg/L -24% 0.00247 10 g/L alumina 0.0067 0.0085 0.0086 0.0079 mg/L -7% 0.00107 1 g/L carbon 0.0049 0.0068 0.0067 0.0061 mg/L -28% 0.00107 10 g/L carbon 0.0065 0.0053 0.0076 0.0065 mg/L -24% 0.00115
Trial A Trial B Trial C avg Units % change S.D. 5 mg/L Fe(III) 0.0801 0.0783 0.1129 0.0904 µM -42% 0.0195 10 mg/L Fe(III) 0.1074 0.1110 0.1183 0.1122 µM -28% 0.00557 25 mg/L Fe(III) 0.1383 0.0104 0.2020 0.1169 µM -25% 0.0976 0.1 wt% c-Fe --- 0.0874 0.0546 0.0710 µM -54% 0.0232 1.0 wt% c-Fe 0.0164 0.0291 0.0764 0.0407 µM -74% 0.0317 10 wt% c-Fe 0.0104 0.0104 0.0104 0.0104 µM -93% 0.00 10 mg/L Fe(III)-tpA 0.6553 0.7063 0.6971 0.6862 µM 342% 0.0272 1 g/L alumina 0.0801 0.1056 0.1675 0.1177 µM -24% 0.0449 10 g/L alumina 0.1220 0.1547 0.1565 0.1444 µM -7% 0.0195 1 g/L carbon 0.0892 0.1238 0.1220 0.1116 µM -28% 0.0195 10 g/L carbon 0.1183 0.0965 0.1383 0.1177 µM -24% 0.0209
85
B.2 SOLID MATRIX
B.2.1 CHEMICAL ARMORING
Soil Amendment 24 hrs 48 hrs 24 hrs w/ buffer
Units
No Treatment 10 21 290 µg/L 5% tpA 1.9 10 280 µg/L 0.5% tpA 7.2 16 260 µg/L 0.05% tpA 9.8 20 280 µg/L 1000 ppm Fe(III) 1.4 4.7 330 µg/L 100 ppm Fe(III) 7.9 19 290 µg/L 10 ppm Fe(III) 10 21 280 µg/L 1% Fe(III)-tpA 0.40 2.1 170 µg/L
Soil Amendment 24 hrs 48 hrs 24 hrs w/
buffer Units
No Treatment 0.13 0.27 3.7 µM 5% tpA 0.024 0.13 3.5 µM 0.5% tpA 0.091 0.20 3.3 µM 0.05% tpA 0.12 0.25 3.5 µM 1000 ppm Fe(III) 0.018 0.060 4.2 µM 100 ppm Fe(III) 0.10 0.24 3.7 µM 10 ppm Fe(III) 0.13 0.27 3.5 µM 1% Fe(III)-tpA 0.0050 0.027 2.2 µM
B.2.2 SATURATED PASTE
See following pages.
Selenium
14 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-Fe/SRB
Fe(III)-tpA /SRB
PW/SRB PS/SRB units
A 2700 1600 700 180 17.0 8.00 30.0 120 15.0 7.70 32.0 µg/L B 2600 950 300 250 18.0 9.40 38.0 79.0 15.0 8.90 37.0 µg/L C 2700 810 360 720 19.0 11.0 50.0 120 12.0 8.80 40.0 µg/L
Avg 2667 1120 453 383 18.0 9.47 39.3 106 14.0 8.47 36.3 µg/L mole 33.8 14.2 5.74 4.85 0.228 0.120 0.498 1.35 0.177 0.107 0.460 µmol/L
per mL 0.0338 0.0142 0.00574 0.00485 0.000228 0.000120 0.000498 0.00135 0.000177 0.000107 0.000460 µmol per sample 0.608 0.265 0.111 0.0971 0.00433 0.00252 0.00863 0.0265 0.00349 0.00236 0.00782 µmol
12.2 5.30 2.22 1.94 0.0866 0.0504 0.173 0.530 0.0698 0.0472 0.156 µmol/kg soil
28 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-Fe/SRB
Fe(III)-tpA /SRB
PW/SRB PS/SRB units
A 3100 530 480 27.0 16.0 6.90 16.0 33.0 15.0 5.80 23.0 µg/L B 2800 440 150 43.0 19.0 6.70 8.80 38.0 16.0 6.80 26.0 µg/L C 2500 400 430 24.0 14.0 7.70 12.0 41.0 17.0 7.60 24.0 µg/L
Avg 2800 457 353 31.3 16.3 7.10 12.3 37.3 16.0 6.73 24.3 µg/L mole 35.5 5.78 4.48 0.397 0.207 0.0900 0.155 0.473 0.203 0.0850 0.308 µmol/L
per mL 0.0355 0.00578 0.00448 0.000397 0.000207 0.0000900 0.000155 0.000473 0.000203 0.0000850 0.000308 µmol per sample 0.567 0.0983 0.0791 0.00781 0.00366 0.00183 0.00254 0.00819 0.00344 0.00173 0.00545 µmol
11.3 1.97 1.58 0.156 0.0731 0.0366 0.0507 0.164 0.0689 0.0347 0.109 µmol/kg soil
Cadmium
14 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-Fe/SRB
Fe(III)-tpA /SRB
PW/SRB PS/SRB units
A 0.0330 0.0320 0.0270 0.0260 0.0820 0.00470 0.0230 0.0200 0.0550 0.00290 0.0260 µg/L B 0.0310 0.0250 0.0290 0.0260 0.0780 0.00510 0.0230 0.0240 0.0630 0.00260 0.0270 µg/L C 0.0290 0.0290 0.0270 0.0260 0.0750 0.00330 0.0260 0.0260 0.0400 0.00270 0.0320 µg/L
Avg 0.0310 0.0287 0.0277 0.0260 0.0783 0.00437 0.0240 0.0233 0.0527 0.00273 0.0283 µg/L mole 0.000276 0.000255 0.000246 0.000231 0.000697 0.0000388 0.000214 0.000208 0.000469 0.0000243 0.000252 µmol/L
per mL 2.76E-07 2.55E-07 2.46E-07 2.31E-07 6.97E-07 3.88E-08 2.14E-07 2.08E-07 4.69E-07 2.43E-08 2.52E-07 µmol per sample 4.96E-06 4.76E-06 4.76E-06 4.63E-06 1.32E-05 8.16E-07 3.70E-06 4.08E-06 9.22E-06 5.35E-07 4.28E-06 µmol
9.93E-05 9.52E-05 9.52E-05 9.25E-05 0.000265 1.63E-05 7.40E-05 8.17E-05 0.000184 1.07E-05 8.57E-05 µmol/kg soil
no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-
Fe/SRB Fe(III)-tpA
/SRB PW/SRB PS/SRB units
A 0.0160 0.0460 0.0370 0.0160 0.0880 0.00400 0.0230 0.0220 0.0860 0.00370 0.0230 µg/L B 0.0360 0.0420 0.0260 0.0250 0.0760 0.00880 0.0210 0.0240 0.0750 0.00360 0.0260 µg/L C 0.0560 0.0610 0.0290 0.0240 0.0830 0.00810 0.0290 0.0290 0.0730 0.00250 0.0250 µg/L
Avg 0.0360 0.0497 0.0307 0.0217 0.0823 0.00697 0.0243 0.0250 0.0780 0.00327 0.0247 µg/L mole 0.000320 0.000442 0.000273 0.000193 0.000732 0.0000620 0.000216 0.000222 0.000694 0.0000291 0.000219 µmol/L
per mL 3.20E-07 4.42E-07 2.73E-07 1.93E-07 7.32E-07 6.20E-08 2.16E-07 2.22E-07 6.94E-07 2.91E-08 2.19E-07 µmol per sample 5.12E-06 7.51E-06 4.82E-06 3.79E-06 1.29E-05 1.26E-06 3.53E-06 3.85E-06 1.18E-05 5.91E-07 3.88E-06 µmol
1.02E-04 1.50E-04 9.64E-05 7.58E-05 2.59E-04 2.52E-05 7.07E-05 7.71E-05 2.36E-04 1.18E-05 7.75E-05 µmol/kg soil
Copper
14 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-Fe/SRB
Fe(III)-tpA /SRB
PW/SRB PS/SRB units
A 0.0660 0.0610 0.0540 0.0530 0.120 0.0400 0.0540 0.0430 0.100 0.0240 0.0350 µg/L B 0.0540 0.0370 0.0430 0.0440 0.120 0.0400 0.0530 0.0580 0.100 0.0330 0.0320 µg/L C 0.0580 0.0550 0.0530 0.0460 0.130 0.0410 0.0540 0.0390 0.0920 0.0260 0.0320 µg/L
Avg 0.0593 0.0510 0.0500 0.0477 0.123 0.0403 0.0537 0.0467 0.0973 0.0277 0.0330 µg/L mole 0.000934 0.000803 0.000787 0.000750 0.00194 0.000635 0.000844 0.000734 0.00153 0.000435 0.000519 µmol/L
per mL 9.34E-07 8.03E-07 7.87E-07 7.50E-07 1.94E-06 6.35E-07 8.44E-07 7.34E-07 1.53E-06 4.35E-07 5.19E-07 µmol per sample 1.68E-05 1.50E-05 1.52E-05 1.50E-05 3.69E-05 1.33E-05 1.46E-05 1.44E-05 3.01E-05 9.58E-06 8.83E-06 µmol
0.000336 0.000300 0.000304 0.000300 0.000737 0.000267 0.000293 0.000289 0.000603 0.000192 0.000177 µmol/kg soil
28 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-
Fe/SRB Fe(III)-tpA
/SRB PW/SRB PS/SRB units
A 0.0420 0.0680 0.0790 0.0420 0.140 0.0520 0.0650 0.0550 0.120 0.0300 0.0350 µg/L B 0.0590 0.0560 0.0470 0.0490 0.150 0.0700 0.0490 0.0610 0.100 0.0300 0.0400 µg/L C 0.0710 0.0620 0.0550 0.0600 0.130 0.0630 0.0730 0.0540 0.0980 0.0330 0.0310 µg/L
Avg 0.0573 0.0620 0.0603 0.0503 0.140 0.0617 0.0623 0.0567 0.106 0.0310 0.0353 µg/L mole 0.000902 0.00098 0.000949 0.000792 0.00220 0.00097 0.00098 0.000892 0.00167 0.000488 0.000556 µmol/L
per mL 9.02E-07 9.76E-07 9.49E-07 7.92E-07 2.20E-06 9.70E-07 9.81E-07 8.92E-07 1.67E-06 4.88E-07 5.56E-07 µmol per
sample 1.44E-05 1.66E-05 1.68E-05 1.56E-05 3.89E-05 1.97E-05 1.60E-05 1.55E-05 2.84E-05 9.92E-06 9.82E-06 µmol
2.89E-04 3.32E-04 3.36E-04 3.12E-04 7.79E-04 3.95E-04 3.20E-04 3.09E-04 5.67E-04 1.98E-04 1.96E-04 µmol/kg soil
Nickel
14 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-Fe/SRB
Fe(III)-tpA /SRB
PW/SRB PS/SRB units
A 0.220 0.190 0.170 0.160 1.70 0.290 0.200 0.140 1.60 0.240 0.190 µg/L B 0.180 0.170 0.170 0.180 1.60 0.320 0.180 0.160 1.90 0.310 0.220 µg/L C 0.180 0.190 0.180 0.170 1.60 0.280 0.200 0.160 1.80 0.290 0.220 µg/L
Avg 0.193 0.183 0.173 0.170 1.63 0.297 0.193 0.153 1.77 0.280 0.210 µg/L mole 0.00329 0.00312 0.00295 0.00290 0.0278 0.00505 0.00329 0.00261 0.0301 0.00477 0.00358 µmol/L
per mL 3.29E-06 3.12E-06 2.95E-06 2.90E-06 2.78E-05 5.05E-06 3.29E-06 2.61E-06 3.01E-05 4.77E-06 3.58E-06 µmol per sample 5.93E-05 5.83E-05 5.71E-05 5.79E-05 0.000529 0.000106 5.71E-05 5.14E-05 0.000592 0.000105 6.08E-05 µmol
0.00119 0.00117 0.00114 0.00116 0.0106 0.00212 0.00114 0.00103 0.0118 0.00210 0.00122 µmol/kg soil
28 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-
Fe/SRB Fe(III)-tpA
/SRB PW/SRB PS/SRB units
A 0.100 0.230 0.250 0.110 1.70 0.210 0.480 0.140 1.20 0.280 0.290 µg/L B 0.180 0.230 0.160 0.150 1.60 0.290 0.380 0.150 1.30 0.240 0.290 µg/L C 0.230 0.320 0.160 0.160 1.60 0.250 0.420 0.170 1.00 0.230 0.280 µg/L
Avg 0.170 0.260 0.190 0.140 1.63 0.250 0.427 0.153 1.17 0.250 0.287 µg/L mole 0.00290 0.00443 0.00324 0.00239 0.0278 0.00426 0.00727 0.00261 0.0199 0.00426 0.00488 µmol/L
per mL 2.90E-06 4.43E-06 3.24E-06 2.39E-06 2.78E-05 4.26E-06 7.27E-06 2.61E-06 1.99E-05 4.26E-06 4.88E-06 µmol per sample 4.63E-05 7.53E-05 5.72E-05 4.69E-05 0.000492 8.66E-05 0.000119 4.53E-05 0.000338 8.66E-05 8.63E-05 µmol
9.27E-04 1.51E-03 1.14E-03 9.38E-04 9.83E-03 1.73E-03 2.37E-03 9.05E-04 6.76E-03 1.73E-03 1.73E-03 µmol/kg soil
Zinc
14 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-Fe/SRB
Fe(III)-tpA /SRB
PW/SRB PS/SRB units
A 0.280 0.200 0.230 0.220 0.830 0.110 0.150 0.220 0.760 0.190 0.260 µg/L B 0.220 0.230 0.220 0.460 0.910 0.110 0.230 0.290 0.820 0.240 0.300 µg/L C 0.160 0.240 0.180 0.200 0.810 0.0710 0.220 0.250 0.540 0.170 0.310 µg/L
Avg 0.220 0.223 0.210 0.293 0.850 0.0970 0.200 0.253 0.707 0.200 0.290 µg/L mole 0.00336 0.00342 0.00321 0.00449 0.0130 0.00148 0.00306 0.00387 0.0108 0.00306 0.00444 µmol/L
per mL 3.36E-06 3.42E-06 3.21E-06 4.49E-06 1.30E-05 1.48E-06 3.06E-06 3.87E-06 1.08E-05 3.06E-06 4.44E-06 µmol per sample 6.06E-05 6.38E-05 6.21E-05 8.97E-05 0.000247 3.12E-05 5.3E-05 7.62E-05 0.000213 6.73E-05 7.54E-05 µmol
0.00121 0.00128 0.00124 0.00179 0.00494 0.000623 0.00106 0.00152 0.00425 0.00135 0.00151 µmol/kg soil
28 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-
Fe/SRB Fe(III)-tpA
/SRB PW/SRB PS/SRB units
A 0.170 0.550 0.190 0.150 0.600 0.120 0.340 0.160 0.660 0.170 0.280 µg/L B 0.500 0.640 0.220 0.170 0.560 0.160 0.340 0.190 0.570 0.0990 0.290 µg/L C 0.790 0.970 0.150 0.150 0.620 0.120 0.350 0.210 0.660 0.150 0.310 µg/L
Avg 0.487 0.720 0.187 0.157 0.593 0.133 0.343 0.187 0.630 0.140 0.293 µg/L mole 0.00744 0.0110 0.00286 0.00240 0.00908 0.00204 0.00525 0.00286 0.00964 0.00214 0.00449 µmol/L
per mL 7.44E-06 1.10E-05 2.86E-06 2.40E-06 9.08E-06 2.04E-06 5.25E-06 2.86E-06 9.64E-06 2.14E-06 4.49E-06 µmol per sample 0.000119 0.000187 5.04E-05 4.71E-05 0.000160 4.15E-05 8.58E-05 4.95E-05 0.000164 4.34E-05 7.93E-05 µmol
2.38E-03 3.74E-03 1.01E-03 9.43E-04 3.21E-03 8.29E-04 1.72E-03 9.90E-04 3.28E-03 8.69E-04 1.59E-03 µmol/kg soil
Manganese
14 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-Fe/SRB
Fe(III)-tpA /SRB
PW/SRB PS/SRB units
A 0.340 0.600 0.700 0.500 3.10 11.0 2.60 1.50 4.00 10.0 2.70 µg/L B 0.330 0.760 0.890 1.00 3.10 13.0 2.30 1.60 4.70 11.0 2.70 µg/L C 0.310 0.670 1.10 0.590 2.80 12.0 2.30 1.50 4.40 12.0 2.60 µg/L
Avg 0.327 0.677 0.897 0.697 3.00 12.0 2.40 1.53 4.37 11.0 2.67 µg/L mole 0.00595 0.0123 0.0163 0.0127 0.0546 0.218 0.0437 0.0279 0.0795 0.200 0.0485 µmol/L
per mL 5.95E-06 1.23E-05 1.63E-05 1.27E-05 5.46E-05 2.18E-04 4.37E-05 2.79E-05 7.95E-05 2.00E-04 4.85E-05 µmol per sample 0.000107 0.000230 0.000315 0.000254 0.00104 0.00459 0.000757 0.000549 0.00156 0.00440 0.000825 µmol
0.00214 0.00460 0.00631 0.00507 0.0207 0.0917 0.0151 0.0110 0.0313 0.0881 0.0165 µmol/kg soil
28 day no tmt SRB c-Fe mb-Fe Fe(III)-tpA PW PS mb-
Fe/SRB Fe(III)-tpA
/SRB PW/SRB PS/SRB units
A 0.150 0.780 0.970 1.60 4.20 8.70 11.0 2.10 4.20 9.30 5.10 µg/L B 0.320 0.800 1.20 1.40 3.70 9.60 8.50 1.60 4.00 8.70 5.10 µg/L C 0.400 0.950 0.740 1.60 4.20 8.60 9.60 1.80 4.30 7.30 4.50 µg/L
Avg 0.290 0.843 0.970 1.53 4.03 8.97 9.70 1.83 4.17 8.43 4.90 µg/L mole 0.00528 0.0154 0.0177 0.0279 0.0734 0.163 0.177 0.0334 0.0758 0.154 0.0892 µmol/L
per mL 5.28E-06 1.54E-05 1.77E-05 2.79E-05 7.34E-05 1.63E-04 1.77E-04 3.34E-05 7.58E-05 1.54E-04 8.92E-05 µmol per sample 8.45E-05 0.000261 0.000312 0.000549 0.00130 0.00332 0.00288 0.000578 0.00129 0.00312 0.00158 µmol
1.69E-03 5.22E-03 6.24E-03 1.10E-02 2.59E-02 6.64E-02 5.77E-02 1.16E-02 2.58E-02 6.24E-02 3.15E-02 µmol/kg soil
92
REFERENCES
(1) Sargent-Welch Scientific Company Periodic Table of the Elements; 1979.
(2) Environmental Inorganic Chemistry: Properties, Processes, and Estimation Methods; Bodek, I.; Lyman, W. J.; Reehl, W. F.; Rosenblatt, D. H. editors; Pergamon Press: Elmsford, New York, 1988; Chapter 7, Section 12.
(3) Habashi, F. A Textbook of Hydrometallurgy; Métallurgie Extractive Québec, Enr.: Sainte-Foy, Quebec, 1993; Chapters 9 and 25.
(4) Jensen, N. L. “Selenium” Mineral Facts and Problems (U.S. Bureau of Mines) 1989, 705-711.
(5) Brown, R. D. Mineral Industry Surveys: Selenium and Tellurium (U.S. Geological Survey) 1996.
(6) Mayland, H. F. Selenium in the Environment, W. T. Frankenberger, Jr.; S. Benson editors; Marcel Dekker, Inc.: New York, New York, 1994; Chapter 2.
(7) “National Primary Drinking Water Regulations” (United States Environmental Protection Agency) 40 CFR § 141.32; US Government Printing Office, Washington, D.C., 1997.
(8) “National Recommended Water Quality Criteria; Republication” (United States Environmental Protection Agency) 63 FR 68354; US Government Printing Office, Washington, D.C., 1998.
(9) “Identification and Listing of Hazardous Waste” (United States Environmental Protection Agency) 40 CFR § 261.24; US Government Printing Office, Washington, D.C., 1997.
(10) Steinhoff, P. J.; Smith, B. W.; Warner, D. W.; Möller, G. “Interlaboratory Performance Analysis in the Determination of Total Selenium in Water” Journ. AOAC Int.; In press, 1999.
(11) Sharata, S. M. Relation of Vanadium and Nickel in Bitumen to the Depositional Environment of the Meade Peak Member, Phosphoria Formation, Southeastern Idaho (Master’s Thesis); University of Idaho: Moscow, Idaho, 1993; pp. 14-18, 57-61.
(12) McKelvey, V. E.; Williams, J. S.; Sheldon, R. P.; Cressman, E. R. ; Cheney, T. M.; Swanson, R. W. “The Phosphoria, Park City, and Shedhorn Formations in the Western Phosphate Field” in Anatomy of the Western Phosphate Field (Intermountain Association of Geologists); Publisher’s Press: Salt Lake City, Utah, 1967; 15-33.
93
(13) Evangelou, V. P. Pyrite Oxidation and Its Control; CRC Press: Boca Raton, Florida, 1995, Chapter 4.
(14) Presser, T. S.; Sylvester, M. A.; Low, W. H. “Bioaccumulation of Selenium from Natural Geologic Sources in Western States and Its Potential Consequences" Environ. Manag. 1994a, 18, 432-436.
(15) Presser, T. S. “The Kesterson Effect” Environ. Manag. 1994b, 18, 437-454.
(16) Hering, J. G.; Chen, P. Y.; Wilkie, J. A.; Elimelech, M.; Liang, S. “Arsenic Removal by Ferric Chloride” J. Am. Water Works Assn. 1996, 88, 155-167.
(17) Manning, B. A.; Burau, R. G. “Selenium Immobilization in Evaporation Pond Sediments by In-Situ Precipitation of Ferric Oxyhydroxide” Environ. Sci. Technol. 1995, 29, 2639-2646.
(18) Murphy, A. P. “Removal of Selenate from Water by Chemical Reduction” Ind. Eng. Chem. Res. 1988, 27, 187-191.
(19) Miller, T. M.; Goodman, W. H. “Removal of Selenium from Water by Complexation with Polymeric Dithiocarbamates” USA Patent #5,510,040; 1996.
(20) Stumm, W.; Morgan, J. J. Aquatic Chemistry: Chemical Equilibria and Rates in Natural Waters, 3rd ed.; Wiley-Interscience: New York, New York, 1996; Chapter 11, Section 9.
(21) Marchant, W. N. “Method for Removing Soluble Selenium from Acidic Waste Water” USA Patent #3,933,635; 1976.
(22) Baldwin, R. A.; Stauter, L. G.; Terrell, D. L. “Process for the Removal of Selenium from Aqueous Systems” USA Patent #4,405,464; 1983.
(23) Faure, G. Principles and Applications of Inorganic Chemistry; Prentice Hall: Upper Saddle River, New Jersey, 1991; Chapter 16, Section 2.
(24) Reynolds, T. D.; Richards, P. A. Unit Operations and Processes in Environmental Engineering, 2nd ed.; PWS Publishing: Boston, Massachusetts, 1996; Chapters 12 and 13.
(25) Clifford, D.; Subramonian, S.; Sorg, T. J. “Removing Dissolved Inorganic Contaminants from Water” Environ. Sci. Technol. 1986, 20, 1072-1080.
(26) Ferri, T.; Sangiorgio, P.; “Determination of Selenium Speciation in River Waters by Adsorption on Iron(III)-Chelex-100 Resin and Differential Pulse Cathodic Stripping Voltammetry” Anal. Chim. Acta 1996, 321, 185-193.
94
(27) Pyrzynska, K. “Separation of Inorganic Selenium Species on Anion-Exchange Resins” Analyst 1995, 120, 1933-1936.
(28) Guter, G. A. “Process for Purification of Contaminated Water” USA Patent #4,206,048; 1980.
(29) Goodman, W. H. “Removal of Selenium From Water by Ion-Exchange” USA Patent #5,494,582; 1996.
(30) Etzel, J. E.; Kurek, J. “Water Treatment Process” USA Patent #5,591,346; 1997.
(31) Ghosh, M. M.; Cox, C. D.; Yuan-Pan, J. R. “Adsorption of Selenium on Hydrous Alumina” Environ. Prog. 1994, 13, 79-88.
(32) Misra, M.; Nayak, D. C. “Process for Removal of Selenium and Arsenic from Aqueous Streams” USA Patent #5,603,838; 1997.
(33) Balistrieri, L. S.; Chao, T. T. “Adsorption of Selenium by Amorphous Iron Oxyhydroxide and Manganese Dioxide” Geochim. Cosmochim. Acta 1990, 54, 739-751.
(34) Spackman, L. K.; Hartman, K. D.; Harbour, J. D.; Essington, M. E. “Adsorption of Oxyanions by Spent Western Oil Shale: II. Selenite” Environ. Geol. Water Sci. 1990, 15, 93-99.
(35) Haggerty, G. M.; Bowman, R. S. “Sorption of Chromate and Other Inorganic Anions by Organo-Zeolite” Environ. Sci. Technol. 1994, 28, 452-458.
(36) Squires, R. C.; Groves, R. G.; Johnston, W. R. “Economics of Selenium Removal from Drainage Water” J. Irrig. Drain. Eng. 1989, 115, 48-57.
(37) Kharaka, Y. K.; Ambats, G.; Presser, T. S. “Removal of Selenium from Contaminated Agricultural Drainage Water by Nanofiltration Membranes” Appl. Geochem. 1996, 11, 797-802.
(38) Morin, O. J. “Membrane Plants in North America” J. Am. Water Works Assoc. 1994, Dec., 42-54.
(39) Davis, R.; Lomax, I.; Plummer, M. “Membranes Solve North Sea Waterflood Sulfate Problems” Oil Gas J. 1996, Nov., 59-64.
(40) O’Donnell, K. “Membrane Technology Works on North Sea Platform” Oil Gas J. 1996, Dec., 58-63.
(41) Waypa, J. J.; Elimelech, M.; Hering, J. G. “Arsenic Removal by RO and NF Membranes” Am. Water Works Assoc. 1997, 89, 102-114.
95
(42) Awadalla, F. T.; Kumar, A. “Opportunities for Membrane Technologies in the Treatment of Mining and Mineral Process Streams and Effluents” Sep. Sci. Technol. 1994, 29, 1231-1249.
(43) Awadalla, F. T.; Striez, C.; Lamb, K. “Removal of Ammonium and Nitrate Ions From Mine Effluents by Membrane Technology” Sep. Sci. Technol. 1994, 29, 483-495.
(44) Marhaba, T. F.; Medlar, S. J. “Treatment of Drinking Water Containing Bromate and Bromide Ions” in Critical Issues in Water and Wastewater Treatment (Proceedings of the 1994 National Conference on Environmental Engineering); ASCE Publishing: New York, New York, 1994; 476-483.
(45) Lovley, D. R. “Microbial Reduction of Iron, Manganese, and Other Metals” in Advances in Agronomy, Volume 54; Academic Press: San Diego, California, 1995; 205-210.
(46) Baldwin, R. A.; Stauter, J. C.; Kauffman, J. W.; Laughlin, W. C. “Process for the Removal and Recovery of Selenium from Aqueous Solutions” USA Patent #4,519,913, 1985.
(47) Khalafalla, S. E. “Method for Accelerating Recovery of Selenium from Aqueous Streams” USA Patent #4,910,010; 1990.
(48) Oremland, R. S.; Hollibaugh, J. T.; Maest, A. S.; Presser, T. S.; Miller, L. G.; Culbertson, C. W. “Selenate Reduction to Elemental Selenium by Anaerobic Bacteria in Sediments and Culture: Biogeochemical Significance on a Novel, Sulfate-Independent Respiration” Appl. Environ. Microbiol. 1989, 55, 2333-2343.
(49) Oremland, R. S.; Steinberg, N. A.; Maest, A. S.; Miller, L. G.; Hollibaugh, J. T. “Measurement of In-Situ Rates of Selenate Removal by Dissimilatory Bacterial Reduction in Sediments” Environ. Sci. Technol. 1990, 24, 1157-1164.
(50) Gerhardt, M. B.; Green, F. B.; Newman, R. D.; Lundquist, T. J.; Tresan, R. B.; Oswald, W. J. “Removal of Selenium Using a Novel Algal-Bacterial Process” Res. J. Water Pollut. Control Fed. 1991, 63, 799-805.
(51) Carlo, P. L.; Owens, L. P.; Hanna, G. P. Jr.; Longley, K. E. “The Removal of Selenium from Water by Slow Sand Filtration” Water Sci. Technol. 1992, 26, 2137-2140.
(52) Neal, R. H.; Sposito, G. “Selenium Mobility in Irrigated Soil Columns as Affected by Organic Carbon Amendment” J. Environ. Qual. 1991, 20, 808-814.
96
(53) Ross, R. J.; Koskan, L. P. “Production and Use of Thermal Polyaspartates” presented at the 1996 American Chemical Society Presidential Green Chemistry Award Symposium in San Francisco.
(54) Möller, G. Personal Communication, 1997. Center for Hazardous Waste Remediation and Research, University of Idaho, Moscow, Idaho.
(55) “Good Laboratory Practice Standards” 40 CFR § 160; US Government Printing Office: Washington, D.C., 1995.
(56) Methods for Chemical Analysis of Water and Wastes (EPA-600/4-79-020); USEPA: Cincinnati, Ohio, 1983.
(57) Tracy, M. L.; Möller, G. “Continuous Flow Vapor Generation for Inductively Coupled Argon Plasma Spectrometric Analysis. Part 1: Selenium” J. Assoc. Off. Anal. Chem. 1990, 73, 404-410.
(58) Methods of Soil Analysis, 1st ed.; Black, C. A.; Evans, D. D.; Dinauer, R. C. editors; American Society of Agronomy: Madison, Wisconsin, 1965.
(59) Methods of Soil Analysis, 2nd ed.; Page, A. L.; Klute, A. editors; American Society of Agronomy, SSSA: Madison, Wisconsin, 1982.
(60) Martens, D. A.; Suarez, D. L. “Selenium Speciation of Soil Sediment Determined with Sequential Extractions and Hydride Generation Atomic Absorption Spectrophotometry” Environ. Sci. Technol. 1997, 31, 133-139.
(61) “Guidelines for Establishing Test Procedures for the Analysis of Pollutants” 40 CFR § 136; US Government Printing Office: Washington, D.C., 1997.
(62) Gulbrandsen, R. A. “Some Compositional Features of Phosphorites of the Phosphoria Formation” Anatomy of the Western Phosphate Field (Intermountain Association of Geologists) Publisher’s Press: Salt Lake City, Utah, 1967; 99-102.
(63) Matsumoto, N.; Arimitsu, H. “Process for the Purification of Sewage Plant Effluent” USA Patent #3,461,067; 1969.
(64) Hsu, P. H. “Complementary Role of Iron(III), Sulfate, and Calcium in Precipitation of Phosphate From Solution” Environ. Letters 1973, 5, 2, 115-136.
(65) Kavanaugh, M. C.; Krejci, V.; Weber, T.; Eugster, J.; Roberts, P. V. “Phosphorous Removal by Post-Precipitation With Fe(III)” Jour. Water Poll. Control Fed. 1978,50, 216-233.
(66) Geist, D. Personal Communication, 1998. Department of Geology and Geological Engineering, University of Idaho, Moscow, Idaho.
97
(67) Möller, G.; Bond, M.; Steinhoff, P. J. Report of Findings to the J. R. Simplot Company, 1998. Center for Hazardous Waste Remediation and Research, University of Idaho, Moscow, Idaho.
(68) Sokal, R. R.; Rohlf, F. J. Introduction to Biostatistics 2nd ed. W. H. Freeman and Company: New York, New York, 1996; Chapter 12.
(69) Sampling and Analysis Plan: Southeast Idaho Phosphate Resource Area Selenium Project: 1998 Regional Investigation; unpublished report to the Idaho Mining Association Selenium Subcommittee; prepared by Montgomery-Watson: Bellevue, Washington, 1998, Appendix A.
(70) Munkers, J.; Steinhoff, P. J. Personal Communication, 1998. Center for Hazardous Waste Remediation and Research, University of Idaho, Moscow, Idaho.
(71) Allen, B. L.; Hajek, B. F. “Mineral Occurrence in Soil Environments” Minerals in Soil Environments, 2nd ed.; Dixon, J. B.; Weed, S. B. editors; Soil Science Society of America: Madison, Wisconsin, 1989, page 257.