biological transformation of selenium in soil-plant systems z-q lin 1 and gary bañuelos 2 1...
Post on 20-Dec-2015
215 views
TRANSCRIPT
![Page 1: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/1.jpg)
Biological Transformation of Selenium in Soil-Plant
Systems
Z-Q Lin1 and Gary Bañuelos2
1Environ. Sci. Program & Dept. of Biol. Sci.Southern Illinois Univ., Edwardsville
2USDA-ARS, Water Management Research Lab
![Page 2: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/2.jpg)
Selenium
• A narrow margin between nutritionally required and toxic concentrations– Essential for humans & animals– Not essential for plants
Se
![Page 3: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/3.jpg)
• Se(VI), selenat
• Se(IV), selenite
• Se(0), elemental Se
• Se(-II), selenide– e.g., Selenomethionine (SeMet);
Dimethylselenide (DMSe)
Chemical Forms of Se
![Page 4: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/4.jpg)
• Toxicities of different chemical forms– Toxic to fish: SeMet > selenite > selenate– Elemental Se is not toxic because it is not
water soluble.– DMSe, a volatile Se compound, is less toxic
to rats, compared with inorganic Se.
Toxicity of Se
![Page 5: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/5.jpg)
Toxicity of Different Forms of Se to Fish
Se(-II) Se(IV) Se(VI) CK
T=0
T=24 hrs
![Page 6: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/6.jpg)
What are the major chemical forms of Se accumulated in
soil-plant systems?
![Page 7: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/7.jpg)
Chemical Speciation of Se by X-ray absorption spectroscopy (XAS)
• XAS is one of the most advanced techniques that currently available for chemical speciation of Se and other environmentally important trace elements.
– Element specific– Direct determination & non-destructive– Various complex environmental substrates
![Page 8: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/8.jpg)
Chemical Speciation in
Environmental Samples by XAS
![Page 9: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/9.jpg)
Se X- ray Absorption Spectra
Energy (eV)
12650 12660 12670 12680 12690
Nor
mal
ized
Abso
rban
ce
0.0
0.5
1.0
1.5
2.0
2.5
Se(VI)Se(IV)Se(0)SeMet
Sediment (0-2 cm)
STANDARDS
![Page 10: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/10.jpg)
Factors Affecting Se Transformation in Soil-Plant
Systems • Sulfate
– Chemical similarity between selenate & sulfate
• Redox potential– Anaerobic microbial reduction of selenate
• pH– Enhanced Se methylation in alkaline soils
• Organic matter– Adsorption of selenite
• Soil moisture– Se bioavailability
• Plants & associated microbial communities in soil– Root exudates
![Page 11: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/11.jpg)
• Industry– Oil refinery wastewater with selenite
• Agriculture– Drainage water with ~90% of selenate
Selenium pollution sources & predominant chemical forms
![Page 12: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/12.jpg)
The San Joaquin Valley:– One of the most productive agriculture areas– Subsurface tile-drainage contains Se & other salts.
Soils contain high levels of Se
WestEast
![Page 13: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/13.jpg)
Drainage Water Reuse System- Zero Discharge of Drainage Water into Environment
Solar Evaporator
Halophytes Field
Salt-tolerant Treesand Grasses
192 ha
52 ha 7.6 ha
Alfalfa
Cotton
Lin et al., 2002, Water Research
![Page 14: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/14.jpg)
The Halophyte Study Field
Cordgrass (Spartina sp.)
Pickleweed (Salicornia bigelovii)
![Page 15: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/15.jpg)
Maximum Rates of Se Volatilization
Salico
rnia
Cordg
rass
Saltgr
ass
Atriple
x
Native
gra
ss
µg
Se
m-2
d-1
0
100
200
300
400
500
![Page 16: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/16.jpg)
![Page 17: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/17.jpg)
Distribution of Salicornia bigelovii Torr. in the U.S.(Data from USDA)
![Page 18: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/18.jpg)
Why Does Salicornia Volatilize More Se Than Other Species ?
• Unique physiological processes in Salicornia?
• Volatilization by microbes associated with Salicornia?
• Interaction of Salicornia and microbes in soil?
![Page 19: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/19.jpg)
Major Steps of Se Volatilization Pathway
in Plant
Selenate APSe Se-Cysteine
Se-Methionine
Dimethyl selenide
Selenite
Methyl-SeMet
![Page 20: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/20.jpg)
Selenate in Soil
SeMet
Sel
enat
eS
elen
ate
SeleniteSeMet
SeMet
Soil Microbes
Salicornia
DMSe
Hypothesis:DMSe
![Page 21: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/21.jpg)
Question 1:
• Does Salicornia have an enhanced capacity of reducing selenate into organoselenium (SeMet) compounds?
![Page 22: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/22.jpg)
Lee & Lin et al. 2001. Planta
• Salicornia was supplied with selenate or selenite.
• Experiments were conducted under sterile vs non-sterile conditions.
• Se speciation in Salicornia shoots & roots was determined by XAS.
![Page 23: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/23.jpg)
Findings:
– Compared with other species, Salicornia has an enhanced capacity to reduce selenate into organic forms.• Salicornia reduced >65% of selenate or
selenite into SeMet in tissues.
• Chemical reduction of selenate without the presence of microbes.
![Page 24: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/24.jpg)
Question 2:
• Will chemical forms of selenium (e.g., selenate, selenite, SeMet) affect rates of Se volatilization in the soil-Salicornia system?
![Page 25: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/25.jpg)
Salicornia bigelovii Torr.
Plants Treated With:Selenate,Selenite, or
Selenomethionine
![Page 26: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/26.jpg)
Se Volatilization Measurements
![Page 27: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/27.jpg)
Finding:
The soil-Salicornia system volatilized organic SeMet ~20 times faster than inorganic selenate (or ~15 times with selenite).
![Page 28: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/28.jpg)
Chemcial Forms of Se in Top Soil with Salicornia
Se(VI)
Se(IV)
Se(0)SeMet
![Page 29: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/29.jpg)
Se volatilization by soil bacterial strains isolated from the Salicornia & saltgrass
fields
![Page 30: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/30.jpg)
76% of the total Se accumulated in Salicornia roots were SeMet-like organic compounds, while saltgrass
accumulated 48% of SeMet-like compounds
Salicornia root Saltgrass root
![Page 31: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/31.jpg)
Question 3:
• What is the role of soil microbes in Se volatilization?– Is there a special microbial community
associated with Salicornia?– Are there any microbes that have an
enhanced capacity to volatilize Se?
![Page 32: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/32.jpg)
Soil Microbial Study
• Soil samples were collected from the Salicornia and saltgrass fields.
• Cultureable bacteria were studied only.
• 5 identical bacterial strains were isolated and identified by 16 S rDNA technique.
![Page 33: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/33.jpg)
Volatilization of Se by Bacteria IsolatedFrom the Salicornia and/or Saltgrass fields
![Page 34: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/34.jpg)
Se volatilization by soil bacterial strains isolated from the Salicornia & saltgrass
fields
With
Salic
ornia
With sa
ltgrass
![Page 35: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/35.jpg)
Finding:
• Shewanella putrefaciens, a Salicornia-associated bacterial strain, volatilized more Se than any others.
![Page 36: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/36.jpg)
Volatilization of Se into the Air
• An environmentally-important pathway of Se removal– Volatile Se compound, DMSe, is less toxic– Se removed from polluted ecosystem– Less hazardous waste
![Page 37: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/37.jpg)
Lin et al., 2000, JEQ
Transport of Volatile Se in the Atmosphere
![Page 38: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/38.jpg)
Phytoremediation Approaches:
Phyto-stabilization Phyto-
degradation
Rhizodegradation
PhytoextractionPhytovolatilization
![Page 39: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/39.jpg)
Salicornia:A succulent, crunchy, and tasty vegetable; known as samphire, sea beans, or sea asparagus.
![Page 40: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/40.jpg)
Selenium accumulation in Canola & Broccoli
• Canola:– In soil: ~ 2.5 ppm
• Extractable soil Se: ~0.5 ppm• In irrigation water: ~ 0.25 ppm
– In seed: ~ 1 ppm• Canola oil: ~ 1 ppm• Seed by-products: ~ 1 ppm
– Dried leaves: 2-5 ppm
• Broccoli:– In florets: ~ 4 ppm
![Page 41: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/41.jpg)
Dr. Gary Bañuelos evaluates canola plants grown for cleaning selenium-rich soils. In studies on livestock, he is testing the
potential use of high-selenium canola forage as feed.
![Page 42: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/42.jpg)
Growing Canola in the San Joaquin Valley, California
![Page 43: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/43.jpg)
![Page 44: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/44.jpg)
Se-laden Drainage Sediment & Phytoremediation Studies
Bañuelos & Lin, 2004, Ecotoxicology & Environ. Safety
![Page 45: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/45.jpg)
Se Volatilization in Drainage Sediment
# of measurements (n) varied from 3 to 11in each month.
![Page 46: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/46.jpg)
Phytoremediation: A Perspectiveof Ecosystem Ecology
Salicornia is a staple food for the endangered salt marsh harvest mouse.
![Page 47: Biological Transformation of Selenium in Soil-Plant Systems Z-Q Lin 1 and Gary Bañuelos 2 1 Environ. Sci. Program & Dept. of Biol. Sci. Southern Illinois](https://reader030.vdocuments.us/reader030/viewer/2022032704/56649d485503460f94a23d9f/html5/thumbnails/47.jpg)
ACKNOWLEDGEMENTS
• Graduate Students, Ramya Nadella, Bikram Shrestha, Shawn Lipe, SIU Edwardsville
• Irvin Arroyo, USDA-ARS, Water Management Research Lab
• Drs. N. Terry, A. Tagmount, H. Mohamed, A. Lee, UC Berkeley
• A. Illes, B. “moose” Peterson, H. Castle for the adapted illustration & photos
• California State Agricultural Research Initiative Grant (to Bañuelos)
• The Joint Interagency (DOE/NSF/EPA/ONR) Phytoremediation Research Program– U.S. DOE, Grant No. DE-FG02-03ER63621 (to Lin)