Do you know where your drinking water comes from?

Do you know where your drinking water comes from?

An overview of hydrogeology and health

Jean M. BahrUniversity of Wisconsin -

Madison

An overview of hydrogeology and health

Jean M. BahrUniversity of Wisconsin -

Madison

Sometimes the sources are obvious

Sometimes the storage systems are obvious, but the sources are not

Reservoirs of fresh water on Earth

Reservoir % Fresh % Unfrozen Atmosphere 0.04 0.2Ice 73.9 ---Lakes + Streams 0.36 1.4Ground water 25.7 98.4

Residence time – 11 days

1000 to >10,000 yrs weeks to decades

decades to 1000s of yrs

The hydrologic cycle

Water used in the US in 2000 for public domestic supply

(serves 85% of population)

Two main sources: ground water and surface water

Figures from USGS Circular 1268http://pubs.usgs.gov/circ/2004/circ1268/

63% 37%

Self supply for remaining 15% of population(almost entirely ground water)

Figure from USGS Circular 1268

Northfield Minnesota is supplied by 4 wells with depths ranging from 365 to 410 feet – so YOU are drinking ground water

http://www.ci.northfield.mn.us/cityhall/departments/publicworks/water

Some Ground Water BasicsSome Ground Water Basics

Common misconceptions

about ground water

Ground water is primarily water held in “pores”

Micropores in sandstones and carbonates Virtually no pores in granite

Macropores in limestone, basalt, crystalline rocks

Major types of geologic materials and associated porosity

Unconsolidated sediment

Carbonaterocks

(e.g. limestone)

Volcanicrocks (basalt)

Fractured igneousand metamorphic rocks

Sandstone and carbonate

Extent and thickness of the Jordan Sandstone

Zones of Subsurface Water

Soil water in the Unsaturated Zone (air and water in pores)Ground water below the “water table” (in the Saturated Zone)

Some Water Quality BasicsSome Water Quality Basics

Health-based standards for drinking water quality

Non-enforceable “Secondary Standards” based on cosmetic and

aesthetic effects

Another important property

pH: a measure of hydrogen ions in solution,commonly referred to as “acidity”

Acidic

Basic

Neutral

Comparison of drinking water and other standards

Human Drinking WaterTDS < 500 ppmpH 6-5-8.5Chloride < 250 ppmSulfate < 250 ppmIron < 0.3 ppm

Dairy CowsTDS < 4000 ppmpH 6-5-8.5Chloride < 1600 ppm

TroutTDS – wide rangepH 6-5-8.0Hardness 10-400Oxygen >5 ppmTemp. optimum 50-60oF

TDS – measure of “salinity” (but not only sodium and chloride)

“fresh” <2000 ppm

35,000 ppm< 10 ppm

“brackish” 2000-20,000 ppm

“hypersaline brine” >100,00 ppm

What do we find dissolved in ground water?

Precipitation chemistry controlled by interaction with the atmosphere

Resulting water composition • Dissolved nitrogen• Dissolved oxygen• Dissolved carbon dioxide

• carbonic acid• pH around 5

Earth’s atmosphere

pH of infiltrating water is further altered in the unsaturated zone

Microbial degradation of organic carbon consumes dissolved oxygen and produces CO2

Water entering the saturated zone has low pH, enhancing mineral dissolution, and may be “reducing” (low dissolved oxygen), which can enhance solubility of trace metals

Continued chemical evolution along ground water flow paths

Ground water composition reflects abundance of elements in geologic materials mineral solubility

Saline ground water in coastal areas or in deep basin “brines”

Examples of naturally occurring constituents with health effectsExamples of naturally occurring constituents with health effects

• Fluoride• Arsenic • Radium and radon• Water “hardness”• Naturally occurring organics

• Fluoride• Arsenic • Radium and radon• Water “hardness”• Naturally occurring organics

Effects of fluoride deficiency and excess

Combined effects of poor nutrition and excess F

Understanding of the fluorine cycle aids in anticipating F concentrations in ground water

Areas of high F in Arizona and California associated with extensional basins

Arsenic poisoning in Bangladesh

Source: MPCA Ground Water Monitoring and Assessment Program

Arsenic in Minnesota and Wisconsin Wells

Source: Wisconsin Dept. of Nat. Resources

Arsenic in Wisconsin’s Fox Valley

Arsenic bearing sulfide minerals at the top of the St. Peter Sandstone

O2

O2

Ground water use lowers water table and exposes sulfide minerals to oxygen

Pumping in the Fox Valley and near Green Bay has lowered the water table and

introduced oxygen to the aquifer

The City of Green Bay now uses Lake Michigan water delivered by a pipeline

ASRWater

ASRWater

SurficialAquifer

ConfiningUnit

ASR Storage

Zone

LowerConfining Unit

Storage Recovery

Proposal to use ASR (aquifer storage recovery) as an alternative to surface reservoirs

Green Bay Well 10

medium

shallow

deep

Monitoring intervals

Borehole flowmeter logging to identify possible preferential flow zones

0

50

100

150

200

250

300

0 4 8 12 16 20 24

Weeks of Storage

Ars

en

ic (

ug

/L)

Deep

Medium

Shallow

Arsenic concentrations during storage phase of Green Bay pilot test

0

50

100

150

200

250

300

0 50 100 150 200 250 300

Percent Recovery

Ars

en

ic (

ug

/L)

ASR Well

Medium

Shallow

Deep

Arsenic concentrations during recovery phase of Green pilot test

Lower, but still problematic, concentrations of arsenic found in ground water from glacial deposits and shallow bedrock of SE Wisconsin

Health effects of chronic exposure to low concentrations are not well established

Tara Root

Core hole at Woods Schoolnear Lake Geneva WICore hole at Woods Schoolnear Lake Geneva WI

Measurable, but not dramatically high, concentrations of arsenic through most of the core below upper sand and gravel

Sampling, field and laboratory analyses from private wells

Arsenic released from iron oxides where oxygen is depleted – below the Foxhollow Till

Products of uranium decay

From USGS Circular 1156

Radon and radium in WI ground water associated with trace concentrations of uranium in the St. Peter Sandstone

Calcium + magnesium concentrations:“hardness”

Hard water “stops heart attacks”Drinking hard water may protect against heart disease, researchers have claimed.

Researchers from the Geographical Survey of Finland looked at 19,000 men who had suffered heart attacks. They found for every unit increase in water hardness, there was a 1% decrease in the risk of having a further attack. Writing in the Journal of Epidemiology and Community Health, the researchers said the findings explained regional variations in heart attack rates.

Correlation between natural organics in drinking water and Balkan endemic

nephropathy (kidney disease)

High nitrate concentrations also occur in ground water of the affected area

Lignite mine in affected areaBEN Areas

Anthropogenic contaminants from “point” and “non-point” sources

Anthropogenic contaminants from “point” and “non-point” sources

Non-point human, animal and agricultural sources of nitrate

Point sources generate a contaminant “plume”

Eau ClaireWell Field

TCE plume, 1992

Large plumes from small sources

Some contaminants are “retarded” by interactions with aquifer solids

Retarded transport of contaminants that adsorb to aquifer solids

A “conservative”

contaminant

Slower migration of plumes, but also slower removal by pumping

Non-aqueous phase liquid (NAPL) contaminants move separately from

ground water

LNAPL e.g. gasoline

DNAPLe.g. chlorinated solvents

Emerging contaminants – Pharmaceuticals and personal care products

Compounds detected in ground water samples collected by the USGS from selected

sites in Minnesota, 2000-2002

Modified from Canter and Knox, 1985

Fate of emerging contaminants from on-site waste disposal systemsJeff Wilcox

Sampling from conventional and advanced septic systems

Source: Univ. of Minnesota Extension

MoundDistribution Systems

Source: Converse and Tyler, 1987

Aerobic Treatment Units

Compounds detected in 15 septic systems

Compound (Frequency) Max Conc. (ng/L)

Caffeine (15) 134,000

Paraxanthine (13) 79,000

Acetaminophen (10) 1,000,000

Fluoxetine (2) 280

-estradiol (1) 190

Chlorpropamide (1) 140

Estrogenic activity (e-screen) detected in 14 samples

Laboratory experiments to investigate contaminant transport

Multiple breakthrough curves

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0Time (days)

C/C

o

Bromide Carbamazepine Caffeine Fluoxetine

1. Chlorpropamide

2. Carisoprodol

3. Warfarin

4. Carbamazepine

5. Paraxanthine

6. Estriol

7. Estrone

8. Ethynyl estradiol

9. Acetaminophen

10. Caffeine

11. B-estradiol

Fenofibrate

Fluoxetine

Relative mobility

Decreasing mobility

Increasingmobility

Eau ClaireWell Field

TCE plume, 1992

The challenge of estimating health riskThe challenge of estimating health risk

Risk analysis using RISC4 Software

Maximum concentrations in 1985 when added to

the Superfund List

Maximum Concentrations in 1985

Child Adult

8 x 10- 5

Of the contaminants of interest, only TCE has a quantified carcinogenic risk

Source of health risk data

Risks for Concentrations in EC2, 1991

Cancer

1 x 10- 5

Injestion Skin Shower Inhalation

Calculated life-time carcinogenic risks for 1991 concentrations in drinking water are on the order of 6 x 10-6 for adults (assuming 9 years of exposure).How many excess cancers would be expected in Eau Claire if all residents drank water for 9 years with concentrations of contaminants found in monitoring well EC2 in 1991?Eau Claire population in 2000 census was 61,704

61,704 x 6 x 10-6 = 0.4Less than one case of excess cancer - would not be expected to show up in epidemiologic studies!

Difficulty in detecting health effects in populations

Some future (global) challengesSome future (global) challenges

• Other emerging contaminant issues– antibiotic resistant microbes– synergistic or antagonistic effects of multiple

contaminants• Increasing demand for water by increasing

population with potential health effects from– wastewater treatment and re-use– desalination– shifts from ground water to surface water or

from one aquifer source to another– artificial recharge and aquifer storage recovery

• Sea level rise and saltwater intrusion

• Other emerging contaminant issues– antibiotic resistant microbes– synergistic or antagonistic effects of multiple

contaminants• Increasing demand for water by increasing

population with potential health effects from– wastewater treatment and re-use– desalination– shifts from ground water to surface water or

from one aquifer source to another– artificial recharge and aquifer storage recovery

• Sea level rise and saltwater intrusion