About 78 of the us population is served by some kind

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Unformatted text preview: ning) Cyanide sump pond, California Cyanide heap-leach mining for gold presents special problems in California and other western States. http://www.dep.state.pa.us/dep/deputate/minres/bamr/amd/science_of_amd.htm; http://www.epa.gov/region08/superfund/sites/co/svlpondpic.html 72 Municipal Water Pollution Cities produce an enormous variety of water pollutants – Street runoff – Salts, fertilizers, heavy metals, biocides – Sewage • Three kinds of sewage treatment – Primary (settling & skimming) – Secondary (aerobic decomposition) – Tertiary (chemical & biological purification) • About 78% of the US population is served by some kind of municipal wastewater treatment facility Sources: Statistical Abstract of the US, 2000; http://www.csc.noaa.gov/rvat/environ.html; http://css.snre.umich.edu/css_doc/CSS04-14.pdf 12 73 Agricultural Water Pollution 74 Biological Oxygen Demand When too great a quantity of plant nutrients get into the water, they can set off a series of steps that result in the biological death of a water body. Steps to oxygen depletion Agriculture is the leading source of non-point pollution in the US There are 3 main types of agricultural pollution – FERTILIZERS – BIOCIDES • Herbicides • Pesticides – ANIMAL WASTE – – – – Feedlot, Roman L. Hruska U.S. Meat Animal Research Center, Clay Center, Nebraska Excess nutrients Algal bloom and death Bacterial decomposition Oxygen depletion http://www.ars.usda.gov/is/AR/archive/oct98/odor1098.htm http://www.agnr.umd.edu/users/agron/nutrient/Factshee/Phosphorus/Eutrop.html 75 76 The Aral Sea: 1960s The Aral Sea: 1970s 1964 1973 http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral 77 78 The Aral Sea: 1980s The Aral Sea: 1990s 1987 1999 http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral http://edcwww.cr.usgs.gov/earthshots/slow/Aral/Aral 13 79 80 The Aral Sea: 2003 The Aral Sea Today As recently as the 1980s 60,000 people were employed in the Aral Sea fishing industry. Today, there is no commercial fishing in the area. Surface area is now less than 50% what it was in...
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