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Groundwater pollution lecture 2016-17
- 2. POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER About half of U.S. population and 95% inAbout half of U.S. population and 95% in rural areas use groundwater for drinkingrural areas use groundwater for drinking Groundwater can be contaminated withGroundwater can be contaminated with fertilizers, pesticides, gasoline, oil, organicfertilizers, pesticides, gasoline, oil, organic solvents, paint thinner, chemicals fromsolvents, paint thinner, chemicals from fracking, etc. – anything put on or in groundfracking, etc. – anything put on or in ground Cannot be effectively cleansed and hard toCannot be effectively cleansed and hard to dilute and disperse pollutantsdilute and disperse pollutants
- 3. Fig. 21-7, p. 501 Coal strip mine runoff Polluted air Deicing road salt Pesticides and fertilizers Hazardous waste injection well Pumping well Gasoline station Water pumping well Landfill Sewer Buried gasoline and solvent tanks Cesspool, septic tank Groundwater flow Confined aquifer Confined freshwater aquifer Unconfined freshwater aquifer Accidental spills Waste lagoon Leakage from faulty casing Discharge
- 4. POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER Pollutants enter aquifer, formPollutants enter aquifer, form plumeplume ofof contaminated water can get into drinking andcontaminated water can get into drinking and irrigation waterirrigation water Degradable wastesDegradable wastes – takes hundreds to– takes hundreds to thousands of years to cleansethousands of years to cleanse Nondegradable wastesNondegradable wastes – (ex: toxic lead,– (ex: toxic lead, arsenic, flouride) are there permanentlyarsenic, flouride) are there permanently Slowly degradable wastesSlowly degradable wastes – (ex: DDT) are– (ex: DDT) are there for decadesthere for decades
- 5. Fig. 21-8, p. 502 Aquifer Water well Migrating vapor phase Contaminant plume moves with the groundwater Free gasoline dissolves in groundwater (dissolved phase) Groundwater flow Water table Gasoline leakage plume (liquid phase) Leaking tank Bedrock
- 6. POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER Leaks from a number of sources haveLeaks from a number of sources have contaminated groundwater in parts of thecontaminated groundwater in parts of the world – not well studied, expensiveworld – not well studied, expensive Industrial waste stored in lagoons/ponds withoutIndustrial waste stored in lagoons/ponds without linersliners Liquid hazardous waste injected into ground –Liquid hazardous waste injected into ground – may leak into aquifersmay leak into aquifers EPA: one or more organic chemicals contaminateEPA: one or more organic chemicals contaminate 45% of municipal groundwater supplies45% of municipal groundwater supplies By 2008, EPA cleaned up of 357,000 of 479,000By 2008, EPA cleaned up of 357,000 of 479,000 underground tanks leaking gasoline, diesel fuel,underground tanks leaking gasoline, diesel fuel, home heating oil or toxic solventshome heating oil or toxic solvents
- 7. POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER MTBEMTBE – methyl tertiary butyl ether – gasoline– methyl tertiary butyl ether – gasoline additive since 1979 – suspected carcinogenadditive since 1979 – suspected carcinogen since 1990since 1990 250,000 gas tanks leaked MTBE and250,000 gas tanks leaked MTBE and contaminated aquiferscontaminated aquifers Being phased out, but will contaminate wells forBeing phased out, but will contaminate wells for decadesdecades
- 9. POLLUTION OF GROUNDWATERPOLLUTION OF GROUNDWATER NitratesNitrates – NO– NO33 -- – especially a problem in– especially a problem in agricultural areas from fertilizersagricultural areas from fertilizers Can be converted to carcinogenic compoundsCan be converted to carcinogenic compounds ““Blue baby syndrome” blood lacks ability to carryBlue baby syndrome” blood lacks ability to carry sufficient oxygensufficient oxygen
- 10. Case Study: Arsenic in Groundwater -Case Study: Arsenic in Groundwater - a Natural Threata Natural Threat Toxic Arsenic (Toxic Arsenic (AsAs) can occur naturally at high) can occur naturally at high levels in soil and rockslevels in soil and rocks Drilling into aquifers can releaseDrilling into aquifers can release AsAs intointo drinking water suppliesdrinking water supplies WHO: > 112 million people drinking waterWHO: > 112 million people drinking water withwith AsAs levels 5-100X the 10 ppb standardlevels 5-100X the 10 ppb standard Mostly in Bangladesh, China and West Bengal,Mostly in Bangladesh, China and West Bengal, IndiaIndia
- 12. PreventingPreventing contaminationcontamination is the mostis the most effective andeffective and cheapest waycheapest way to protectto protect groundwatergroundwater resourcesresources
- 13. Where Does It Come From?
Editor's Notes
- Figure 21.7 Natural capital degradation: principal sources of groundwater contamination in the United States. Another source is saltwater intrusion from excessive groundwater withdrawal (Figure 14-12, p. 315) (Figure is not drawn to scale.)
- Figure 21.8 Natural capital degradation: groundwater contamination from a leaking gasoline tank. As the contaminated water spreads from its source in a widening plume, it can be extracted by wells used to provide water for drinking and irrigation.