EarthTrends: Featured Topic Title Dirty Water: Pollution Problems Persist Author(s): Carmen Revenga and Greg Mock Pilot Anab sis of Global Ecosy stems: Freshwater Systems Date written: October 2000 The sight and smell of grossly industrialized countries have and new pollutants like polluted waterways provided greatly reduced the effects of pesticides have combined to some of the original impetus to these pollutants, with heavily degrade water qualit the environmental movement consequent improvements in particularly near urban in the 1970s. Nearly a century water quality. Pollution laws industrial centers and intensive before that, the dangers of and pollution control ltural areas polluted water to human health technologies have succeeded ( Shiklomanov 1997: 28 drove what became known as especially well in cutting UNEP/GEMS 1995: ).An the"sanitary revolution?"in emissions from concentrated estimated 90 percent of Europe and the United States, "point sources"like factories wastewater in developing emphasizing clean water and sewage treatment plants. countries is still disch supplies and sewer systems in For example, from 1972 to directly to rivers and streams cities.Today, despite progress 1992 the amount of sewage without any waste processing in cleaning up waterways in treated at wastewater treatment treatment (WMO 1997: 11) some areas, water pollution slants in the United States remains a serious global increased by 30 percent, yet the Nutrient Pollution: The problem, with impacts on the organic pollution(measured as New Danger health of freshwater the Biological Oxygen ecosystems and the human Demand) from these plants The level of nutrients such as communities that rely on them dropped 36 percent(CEQ nitrates and phosphorous in for water supply 1995:22 freshwater ecosystems is a Unfortunately, a new suite problem worldwide The Changing pollution of contaminants from intensive ( Shiklomanov 1997: 34-36). In agriculture and development most cases, the major cause of activities in watersheds has these contaminants is the Water pollution spans a wide kept the cleanup from being increased use of manure and range of chemical, physical, omplete. In general, national manufactured fertilizer in and microbial factors, but over water clean-up programs have global agriculture. In the the years the balance of major not been effective in reducing United States, for example, pollutants has shifted markedly "nonpoint pollutants such as agriculture is the single greatest in most industrialized countries nutrients, sediments, and toxics source of pollution degrading (see Figure 1 for a summary of that come in runoff from the quality of surface wate major pollution sources and agriculture, urban and like rivers and lakes. with their effects). One hundred suburban stormwater, mining, croplands alone accounting for years ago, the main water ations ly 40 percent of the contamination problems were RC1992:47;EEA nitrogen pollution and 30 fecal and organic pollution 1999:178 percent of the phosphorous from untreated human waste Meanwhile in most (Faeth 2000: 6-7).(See Figure and the byproducts of early developing countries, th industries. Through improved problems of traditional Natural waters have very treatment and disposal, most pollution sources like sewage low concentrations of nitrates OEarthTrends 2001 World Resources Institute. All rights reserved. Fair ed on a limited scale and for educational
©EarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational purposes. EarthTrends: Featured Topic Title: Dirty Water: Pollution Problems Persist Author(s): Carmen Revenga and Greg Mock Source: Pilot Analysis of Global Ecosystems: Freshwater Systems Date written: October 2000 The sight and smell of grossly polluted waterways provided some of the original impetus to the environmental movement in the 1970s. Nearly a century before that, the dangers of polluted water to human health drove what became known as the “sanitary revolution” in Europe and the United States, emphasizing clean water supplies and sewer systems in cities. Today, despite progress in cleaning up waterways in some areas, water pollution remains a serious global problem, with impacts on the health of freshwater ecosystems and the human communities that rely on them for water supply. The Changing Pollution Profile Water pollution spans a wide range of chemical, physical, and microbial factors, but over the years the balance of major pollutants has shifted markedly in most industrialized countries (see Figure 1 for a summary of major pollution sources and their effects). One hundred years ago, the main water contamination problems were fecal and organic pollution from untreated human waste and the byproducts of early industries. Through improved treatment and disposal, most industrialized countries have greatly reduced the effects of these pollutants, with consequent improvements in water quality. Pollution laws and pollution control technologies have succeeded especially well in cutting emissions from concentrated “point sources” like factories and sewage treatment plants. For example, from 1972 to 1992 the amount of sewage treated at wastewater treatment plants in the United States increased by 30 percent, yet the organic pollution (measured as the Biological Oxygen Demand) from these plants dropped 36 percent (CEQ 1995:229). Unfortunately, a new suite of contaminants from intensive agriculture and development activities in watersheds has kept the cleanup from being complete. In general, national water clean-up programs have not been effective in reducing “nonpoint” pollutants such as nutrients, sediments, and toxics that come in runoff from agriculture, urban and suburban stormwater, mining, and oil and gas operations (NRC 1992:47; EEA 1999:178). Meanwhile, in most developing countries, the problems of traditional pollution sources like sewage and new pollutants like pesticides have combined to heavily degrade water quality, particularly near urban industrial centers and intensive agricultural areas. (Shiklomanov 1997:28; UNEP/GEMS 1995:6). An estimated 90 percent of wastewater in developing countries is still discharged directly to rivers and streams without any waste processing treatment (WMO 1997:11). Nutrient Pollution: The New Danger The level of nutrients such as nitrates and phosphorous in freshwater ecosystems is a problem worldwide (Shiklomanov 1997:34–36). In most cases, the major cause of these contaminants is the increased use of manure and manufactured fertilizer in global agriculture. In the United States, for example, agriculture is the single greatest source of pollution degrading the quality of surface waters like rivers and lakes, with croplands alone accounting for nearly 40 percent of the nitrogen pollution and 30 percent of the phosphorous (Faeth 2000:6-7). (See Figure 2.) Natural waters have very low concentrations of nitrates
WIDE RANGE OF POLLUTANTS STILL DEGRADE WORLD'S WATER Figure 1: Common Water Pollutants and their Effects POLLUTANT PRIMARY SOURCE EFFECTS Organic matter Industrial wastewater and Depletes en from the water column as it decomposes, stressing or suffocating aquatic life Excess nutrients(nitrates, Runoff from agricultural lands and Overstimulates growth of algae(a process eutrophication), which then decomposes, ro levels of nitrates in drinking water lead to illness in Heavy metals Industries and mining sites. Persists in freshwater environments like river sediments and wetlands for long periods. Accumulates in the tissues of fish and shellfish Toxic to both acquatic organisms and humans who Microbial contaminants (e. g p Domestic sewage, cattle, natural Spreads infectious diseases through contaminated cryptospori-dium, cholera, and sources water supplies, causing millions of cases of her bacteria, amoebae, etc.) diarrheal diseases and intestinal parasites, and providing one of the principal causes of childhood mortality in the developing world oxic organic compounds(oil, Wide variety of sources, from Displays a range of toxic effects in aquatic fauna pesticides, some plastics, dustrial sites, to automobiles, to and humans, from mild immune suppression, to industrial chemicals) farmers, and home gardeners. acute poisoning, or reproductive failure Dissolved salts(salinization) Leached from alkaline soils by eads to salt build-up in soils, which kills crops or overirrigation, or drawn into cuts yields Renders freshwater supplies oastal aquifers from overdrafting undrinkable. Acid precipitation or acidic runoff Deposition of sulfate particles, Acidifies lakes and streams, which harms or kills mostly from coal combustion aquatic organisms and leaches heavy metals such Acid runoff from mine tailings and as aluminum from soils into water bodies Silt and suspended particles Soil erosion and construction Reduces water quality for drinking and recreation activities in watersheds and degrades aquatic habitats by smothering them ith silt, disrupting spawning, and interfering with feeding Thermal pollution Fragmentation of rivers by dams Affects oxygen levels and decomposition rate of and reservoirs, slowing water and organic matter in the water column May shift the allowing it to warm Industrial species compostion of a river or lake uses such as cooling towers Sources: Taylor and Smith 1997: Shiklomanov 1997; UNEP/GEMS 1995. a soluble from of nitrogen) the water column of dissolved The relevant water data from oxygen, kill aquatic organisms, the UN,s Global Environment levels increase with runoff and degrade water quality Monitoring System(GEMS), Dissolved nitrates in drinking for example, only cover 1976- from urban and industrial water can also harm human 1990. Of these globally wastewater. Dissolved health monitored watersheds. the nutrients act as fertilizers Data on nutrient trends in hest nutrient concentrations stimulating algal blooms and global waters are spotty and come from sampling stations the eutrophication of many only give the most generalized in Europe. Nitrate inland waters. This can rob picture of current conditions concentrations are higher in OEarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational I
©EarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational purposes. 2 (a soluble from of nitrogen) and phosphorous, but nutrient levels increase with runoff from farm lands as well as from urban and industrial wastewater. Dissolved nutrients act as fertilizers, stimulating algal blooms and the eutrophication of many inland waters. This can rob the water column of dissolved oxygen, kill aquatic organisms, and degrade water quality. Dissolved nitrates in drinking water can also harm human health. Data on nutrient trends in global waters are spotty and only give the most generalized picture of current conditions. The relevant water data from the UN’s Global Environment Monitoring System (GEMS), for example, only cover 1976- 1990. Of these globally monitored watersheds, the highest nutrient concentrations come from sampling stations in Europe. Nitrate concentrations are higher in POLLUTANT PRIMARY SOURCE EFFECTS Organic matter Industrial wastewater and domestic sewage. Depletes oxygen from the water column as it decomposes, stressing or suffocating aquatic life. Excess nutrients (nitrates, phosphorous) Runoff from agricultural lands and urban areas. Overstimulates growth of algae (a process called eutrophication), which then decomposes, robbing water of oxygen, and harming aquatic life. High levels of nitrates in drinking water lead to illness in humans. Heavy metals Industries and mining sites. Persists in freshwater environments, like river sediments and wetlands for long periods. Accumulates in the tissues of fish and shellfish. Toxic to both acquatic organisms and humans who eat them. Microbial contaminants (e.g., cryptospori-dium, cholera, and other bacteria, amoebae, etc.) Domestic sewage, cattle, natural sources. Spreads infectious diseases through contaminated water supplies, causing millions of cases of diarrheal diseases and intestinal parasites, and providing one of the principal causes of childhood mortality in the developing world. Toxic organic compounds (oil, pesticides, some plastics, industrial chemicals) Wide variety of sources, from industrial sites, to automobiles, to farmers, and home gardeners. Displays a range of toxic effects in aquatic fauna and humans, from mild immune suppression, to acute poisoning, or reproductive failure. Dissolved salts (salinization) Leached from alkaline soils by overirrigation, or drawn into coastal aquifers from overdrafting of groundwater. Leads to salt build-up in soils, which kills crops or cuts yields. Renders freshwater supplies undrinkable. Acid precipitation or acidic runoff Deposition of sulfate particles, mostly from coal combustion. Acid runoff from mine tailings and sites. Acidifies lakes and streams, which harms or kills aquatic organisms and leaches heavy metals such as aluminum from soils into water bodies. Silt and suspended particles Soil erosion and construction activities in watersheds. Reduces water quality for drinking and recreation and degrades aquatic habitats by smothering them with silt, disrupting spawning, and interfering with feeding. Thermal pollution Fragmentation of rivers by dams and reservoirs, slowing water and allowing it to warm. Industrial uses such as cooling towers. Affects oxygen levels and decomposition rate of organic matter in the water column. May shift the species compostion of a river or lake. Sources: Taylor and Smith 1997; Shiklomanov 1997; UNEP/GEMS 1995. WIDE RANGE OF POLLUTANTS STILL DEGRADE WORLD'S WATER Figure 1: Common Water Pollutants and their Effects
AGRICULTURE IS PRIMARY SOURCE OF NUTRIENT POLLUTION IN U. S central and western Europe Figure 2: Nitrogen and Phosphorous Discharges to U.S. Surface Waters from show the highest levels(Eea Point and Nonpoint Sources(in thousands of metric tons per year) 1999: 174). In general, phosphorous concentrations SOURCE NITROGEN PHOSPHOROUS have decreased significantly onpoint sources since 1985, mostly due to Croplands 3,20 615 use Pastures 292 95 treatment and the reduced of phosphorous in detergents Rangelands 242 However, phosphorus levels Forests 1,035 remain a problem in most er rur 659 regions of Europe (EEa 1999: 174). Despite some Total nonpoint discharges 6,663 1,658 positive trends, the overal Total point sources 1,495 30 state of many European rivers Total discharge(point nonpoint) 8 2,015 with respect to nutrient Nonpoint as a percentage of total concentrations remains poor Source: Carpenter et aL. 1998. CEEA1998:194-196 Figure 3 shows water watersheds that have been lower fertilizer application quality data for the United intensively used and modified rates, compared to Europe. States for the 1980s. For the by human activity, such as the More detailed and recent 1980-89 period, nitrate Weser, Seine, Rhine, Elbe, and data available in Europe show concentrations remained egal. High levels are also distinct regional trends in the latively stable, with most found in such watersheds in concentrations of nitrates and monitoring stations showing China, South Africa, and the ph phosphorous in rivers. Nitrate no discernable trend. This Nile and Mississippi basins loadings are highest in areas probably reflects the fact that (UNEP/GEMS 1995: 33-35). with intensive livestock and nitrogen fertilizer use in the In South America, nitrate crop production, especially in concentrations in the the northern parts of western Steady increases in the 1970s monitored watersheds are Europe. Nitrate concentrations Fertilizer application rates elatively low and follow increased for the period 1974- are lowest in Finland, Norway, 1981 and nitrate human land use. The highest and Sweden. Overall nitrate nitrate concentrations are concentrations in monitored concentrations increased as found in the Uruguay European rivers have not well during that period watershed, where some of the changed significantly since Average nitrate concentration most intensive agriculture on 1980, despite lower nitrogen were greater in agricultural and the continent is found. Nitrate fertilizer application rates since urban areas than in forested also greater the 1990s(EEA 1998: 194-197: areas( Smith et al 1994: 122) in the Magdalena watershed of EEA 1999: 176-177) Trends in phosphorou Colombia than in the less Similar regional patterns are concentrations in the United densely populated watersheds also evident in phosphorous greater of the amazon basin trends. Rivers in Finland improvement, with five times (UNEP/GEMS 1995: 33-35) Norway, and Sweden have the more states showing The nitrate concentrations in lowest phosphorous downward trends than upward South America correspond to concentrations, whereas areas trends. Decreases were more from southern england likely to be found in the East Midwest, and the great Lakes OEarthTrends 2001 World Resources Institute. All rights reserved. Fair ed on a limited scale and for educational
©EarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational purposes. 3 watersheds that have been intensively used and modified by human activity, such as the Weser, Seine, Rhine, Elbe, and Senegal. High levels are also found in such watersheds in China, South Africa, and the Nile and Mississippi basins (UNEP/GEMS 1995:33-35). In South America, nitrate concentrations in the monitored watersheds are relatively low and follow human land use. The highest nitrate concentrations are found in the Uruguay watershed, where some of the most intensive agriculture on the continent is found. Nitrate concentrations are also greater in the Magdalena watershed of Colombia than in the less densely populated watersheds of the Amazon basin (UNEP/GEMS 1995:33–35). The nitrate concentrations in South America correspond to lower fertilizer application rates, compared to Europe. More detailed and recent data available in Europe show distinct regional trends in the concentrations of nitrates and phosphorous in rivers. Nitrate loadings are highest in areas with intensive livestock and crop production, especially in the northern parts of western Europe. Nitrate concentrations are lowest in Finland, Norway, and Sweden. Overall nitrate concentrations in monitored European rivers have not changed significantly since 1980, despite lower nitrogen fertilizer application rates since the 1990s (EEA 1998:194–197; EEA 1999:176–177). Similar regional patterns are also evident in phosphorous trends. Rivers in Finland, Norway, and Sweden have the lowest phosphorous concentrations, whereas areas from southern England across central and western Europe show the highest levels (EEA 1999:174). In general, phosphorous concentrations have decreased significantly since 1985, mostly due to improvements in wastewater treatment and the reduced use of phosphorous in detergents. However, phosphorus levels remain a problem in most regions of Europe (EEA 1999:174). Despite some positive trends, the overall state of many European rivers with respect to nutrient concentrations remains poor (EEA 1998:194-196). Figure 3 shows water quality data for the United States for the 1980s. For the 1980–89 period, nitrate concentrations remained relatively stable, with most monitoring stations showing no discernable trend. This probably reflects the fact that nitrogen fertilizer use in the United States leveled off after steady increases in the 1970s. Fertilizer application rates increased for the period 1974– 1981, and nitrate concentrations increased as well during that period. Average nitrate concentrations were greater in agricultural and urban areas than in forested areas (Smith et al. 1994:122). Trends in phosphorous concentrations in the United States showed greater improvement, with five times more states showing downward trends than upward trends. Decreases were more likely to be found in the East, Midwest, and the Great Lakes SOURCE NITROGEN PHOSPHOROUS Nonpoint sources Croplands 3,204 615 Pastures 292 95 Rangelands 778 242 Forests 1,035 495 Other rural lands 659 170 Other nonpoint sources 695 68 Total nonpoint discharges 6,663 1,658 Total point sources 1,495 330 Total discharge (point + nonpoint) 8,158 2,015 Nonpoint as a percentage of total 82% 84% Source: Carpenter et al. 1998. AGRICULTURE IS PRIMARY SOURCE OF NUTRIENT POLLUTION IN U.S. WATERS Figure 2: Nitrogen and Phosphorous Discharges to U.S. Surface Waters from Point and Nonpoint Sources (in thousands of metric tons per year)
regions, while the majority of Groundwater Contamination industry can cause serious increases occurred in the human health problems Southeast(Smith et al Surface waters like streams and(Shiklomanov 1997: 42) 1994:124) lakes are not the only water Global data on the qualit The decreased sources that suffer from of groundwater resources are oncentrations of phosphorous pollution. Groundwater lacking. Even where available in streams and rivers in the aquifers, which are critical data usually are not United States is attributable to sources of both drinking water comparable because of the reduced phosphorous in and irrigation water, are also different measures and affected. The major causes of standards used, which vary by improved controls in groundwater pollution are country(Shiklomanov 1997: 42, wastewater treatment plants. leaching of pollutants from Scheidleder et al. 1999: 11: S The increased number of agriculture, industry, and Foster, personal sewage treatment plants has untreated sewage, as well as communication, 2000) also reduced the amount of saltwater intrusion caused by However there is evidence nitrogen in the form of pumping that groundwater ammonium, which is toxic to Once pollutants enter a contamination from fertilizers fish. However, the sewage roundwater aquifer, the pesticides, industrial effluents, treatment process converts environmental damage can be sewage, and hydrocarbons is ammonium to nitrates that are severe and long lasting, partly occurring in many parts of the still released into waterways. because of the very long time world Thus, the greater number of needed to flush pollutants out As with surface waters sewage treatment facilities has of the aquifer (UNEP nitrate pollution is one of not necessarily decreased the 1996: 14). Because groundwater groundwaters most serious total amount of nitrogen is primarily used for drinking threats. In general, the risk of flowing into waterways water, pollution from untreated nitrate pollution for (Mueller and Helsel 1996) sewage, intensive agriculture groundwater supplies is directly solid waste disposal, and related to the amount of fertilizers or other nitrogen NITRATE CONCENTRATION STABILIZE IN THE 1980s Figure 3: Trends in U.s. Stream Water Quality, 1980-89 inputs to the land, as well as the permeability of the soil Stations For example, half the Statio groundwater samples in a Upward with Down. with No heavily fertilized region of Number of Trend in ward TrendConcen northern China contain nitrate Water Quality SamplingConcen- Stations tration levels above the safe limit for Dissolved Solids 8 drinking water(Zhang et al. 344 2 295 1996: 224). In the United Total Phosphorous 410 19 299 States, where groundwater Suspended Sediments supplies drinking water for Dissolved Oxygen more than half the population, inary analysis of nitrate Fecal coliform 313 contamination found that high Source: Data are from the USGs National Stream Quality Accounting Network nitrate concentrations are (NASQAN), quoted in CEQ 1995 widespread in shallow groundwater aquifers Note: Although data on stream water quality are continuously monitored, these are the latest aggregated figures published for all monitoring stations agricultural areas ( USG 1999: 41). Groundwater OEarthTrends 2001 World Resources Institute. All rights reserved. Fair ed on a limited scale and for educational
©EarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational purposes. 4 regions, while the majority of increases occurred in the Southeast (Smith et al. 1994:124). The decreased concentrations of phosphorous in streams and rivers in the United States is attributable to reduced phosphorous in laundry detergents and improved controls in wastewater treatment plants. The increased number of sewage treatment plants has also reduced the amount of nitrogen in the form of ammonium, which is toxic to fish. However, the sewage treatment process converts ammonium to nitrates that are still released into waterways. Thus, the greater number of sewage treatment facilities has not necessarily decreased the total amount of nitrogen flowing into waterways (Mueller and Helsel 1996). Groundwater Contamination Surface waters like streams and lakes are not the only water sources that suffer from pollution. Groundwater aquifers, which are critical sources of both drinking water and irrigation water, are also affected. The major causes of groundwater pollution are leaching of pollutants from agriculture, industry, and untreated sewage, as well as saltwater intrusion caused by overpumping. Once pollutants enter a groundwater aquifer, the environmental damage can be severe and long lasting, partly because of the very long time needed to flush pollutants out of the aquifer (UNEP 1996:14). Because groundwater is primarily used for drinking water, pollution from untreated sewage, intensive agriculture, solid waste disposal, and industry can cause serious human health problems (Shiklomanov 1997:42). Global data on the quality of groundwater resources are lacking. Even where available, data usually are not comparable because of the different measures and standards used, which vary by country (Shiklomanov 1997:42; Scheidleder et al. 1999:11; S. Foster, personal communication, 2000). However, there is evidence that groundwater contamination from fertilizers, pesticides, industrial effluents, sewage, and hydrocarbons is occurring in many parts of the world. As with surface waters, nitrate pollution is one of groundwater’s most serious threats. In general, the risk of nitrate pollution for groundwater supplies is directly related to the amount of fertilizers or other nitrogen inputs to the land, as well as the permeability of the soil. For example, half the groundwater samples in a heavily fertilized region of northern China contain nitrate levels above the safe limit for drinking water (Zhang et al. 1996:224). In the United States, where groundwater supplies drinking water for more than half the population, a preliminary analysis of nitrate contamination found that high nitrate concentrations are widespread in shallow groundwater aquifers in agricultural areas (USGS 1999:41). Groundwater Water Quality Indicator Number of Sampling Stations Stations with Upward Trend in Concentration Stations with Downward Trend in Concentration Stations with No Concentration Trend Dissolved Solids 340 28 46 266 Nitrate 344 22 27 295 Total Phosphorous 410 19 92 299 Suspended Sediments 324 5 37 282 Dissolved Oxygen 424 38 26 360 Fecal Coliform 313 10 40 263 NITRATE CONCENTRATION STABILIZE IN THE 1980s Figure 3: Trends in U.S. Stream Water Quality, 1980-89 Source: Data are from the USGS National Stream Quality Accounting Network (NASQAN), quoted in CEQ 1995. Note: Although data on stream water quality are continuously monitored, these are the latest aggregated figures published for all monitoring stations
pollution in Europe is similarly degraded in almost all regions pollution. In addition, the widespread (Scheidleder et with intensive agriculture and massive loss of wetlands at a al1999 rapid urbanization global level has greatly Unfortunately, little impaired the capacity of Conclusion information is available to freshwater systems to filter and evaluate the extent to which purify water. Groundwater Surface water quality has chemical contamination has quality suffers from many of improved in most developed impaired the health of the same pollution problems as countries during the past freshwater ecosystem surface waters and faces the years, but nitrate and pesticide However, incidents of alg additional challenge of being contamination remain blooms and eutrophication are very difficult to restore once persistent problems. Data on widespread in freshwater the underlying aquifer is water quality in other regions systems all over the world-an contaminated of the world are sparse, but indicator that these systems are water quality appears to be profoundly affected by water REFERENCES Carpenter, S, N. Caraco, D. Correll, R Howarth, A Sharpley, and V Smith. 1998. Nonpoint Pollution of Surface W aters with Phosphorous and Nitrogen, Issues in Ecology. Washington, DC: Ecological Society of america CEQ (Council on Environmental Quality). 1995. Enriromental Quality-Twenty-Fiftb anniversary Report. Washington, DC: The Council for Environmental Quality EEA(European Environment Agency). 1999. Emironment in the European Union at the Turn of the Centun. Environmental Assessment Report No. 2. Copenhagen, Denmark: European Environment agency EEA ( European Environment Agency). 1998. Europe's Emironment: The Second Assessment. Copenhagen, Denmark: European Environment Agency Faeth, P. 2000. Fertile Ground: Nutrient Trading's Potential to Cost-Effectineby Improre W ater Quali Washington, DC: World Resources Institute Foster, S. British Geological Survey. 2000. Personal Communication. 5 July Mueller, D.K. and D.R. Helsel. 1996. Nutrients in the Nation's w aters-Too Much of a Good Thing? USGS Circular 1136. Reston, Virginia: U.S. Geological Survey NRC (National Research Council). 1992. Restoration of Aquatic Eco sy stems. Washington, DC: National Academy press heidleder, J. Grath, G. Winkler, U. Stark, C. Koreimann, and C Gmeiner. 1999. Groundwater Quality and Quantity in Europe. Environmental Assessment Report No. 3. S. Nixon, ed OEarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational I
©EarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational purposes. 5 pollution in Europe is similarly widespread (Scheidleder et al.1999). Conclusion Surface water quality has improved in most developed countries during the past 20 years, but nitrate and pesticide contamination remain persistent problems. Data on water quality in other regions of the world are sparse, but water quality appears to be degraded in almost all regions with intensive agriculture and rapid urbanization. Unfortunately, little information is available to evaluate the extent to which chemical contamination has impaired the health of freshwater ecosystems. However, incidents of algal blooms and eutrophication are widespread in freshwater systems all over the world—an indicator that these systems are profoundly affected by water pollution. In addition, the massive loss of wetlands at a global level has greatly impaired the capacity of freshwater systems to filter and purify water. Groundwater quality suffers from many of the same pollution problems as surface waters and faces the additional challenge of being very difficult to restore once the underlying aquifer is contaminated. REFERENCES Carpenter, S., N. Caraco, D. Correll, R. Howarth, A. Sharpley, and V. Smith. 1998. Nonpoint Pollution of Surface Waters with Phosphorous and Nitrogen, Issues in Ecology. Washington, DC: Ecological Society of America. CEQ (Council on Environmental Quality). 1995. Enviromental Quality — Twenty-Fifth Anniversary Report. Washington, DC: The Council for Environmental Quality. EEA (European Environment Agency). 1999. Environment in the European Union at the Turn of the Century. Environmental Assessment Report No. 2. Copenhagen, Denmark: European Environment Agency. EEA (European Environment Agency). 1998. Europe’s Environment: The Second Assessment. Copenhagen, Denmark: European Environment Agency. Faeth, P. 2000. Fertile Ground: Nutrient Trading’s Potential to Cost-Effectively Improve Water Quality. Washington, DC: World Resources Institute. Foster, S. British Geological Survey. 2000. Personal Communication. 5 July. Mueller, D.K. and D.R. Helsel. 1996. Nutrients in the Nation’s Waters—Too Much of a Good Thing? USGS Circular 1136. Reston, Virginia: U.S. Geological Survey. NRC (National Research Council). 1992. Restoration of Aquatic Ecosystems. Washington, DC: National Academy Press. Scheidleder, J. Grath, G. Winkler, U. Stärk, C. Koreimann, and C. Gmeiner. 1999. Groundwater Quality and Quantity in Europe. Environmental Assessment Report No. 3. S. Nixon, ed
Copenhagen, Denmark: European Environment Agency, European Topic Centre on Inland Water Shiklomanov, I.A. 1997. Compreben sine Assessment of the Freshwater Resoures of the W orld: Assessment of W ater Resources and w ater Araiabilify in the World. Stockholm, Sweden: World Meteorological Organization and Stockholm Environment Institute Smith, R.A.,R. B. Alexander, and K.J. Lanfear. 1994. Stream w ater Quality in the Coterminous State sTatus and Trends of Selected Indicators During the 1980s. USGS Water Supply Paper Reston, Virginia: U.S. Geological Survey Taylor, R. and I Smith. 1997. State of New Zealand's Entironment 1997. Wellington, New Zealand: The Ministry for the Environment. available on-line at: http://www.mfe.govt.nz/about/publications/ser/frontpdf. UNEP (United Nations Environment Programme). 1996. Groundwater: A Threatened Resoure. UNEP Environment Library No 15. Nairobi, Kenya: UNEP UNEP/GEMS (United Nations Environment Program Global Environment Monitoring System/Water). 1995. W ater Quality of W orld Rirer Basins. Nairobi, Kenya: UNEP USGS(U.S. Geological Survey). 1999. The Quality of Our Nation's W aters- Nutrients and pesticides. USGS Circular 1225. Reston, Virginia: US Geological Survey WMO (World Meteorological Organization). 1997. Compre bensine Assessment of the Freshwater resource of the world. Stockholm, Sweden: WMO and Stockholm Environment Institute Zhang, W.L., Z.X. Tian, N. Zhang, and X.Q. Li. 1996."Nitrate Pollution of Groundwater in Northern China. Agriculture, Ecosystems and Entironment 59: 223-31 EarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational I
©EarthTrends 2001 World Resources Institute. All rights reserved. Fair use is permitted on a limited scale and for educational purposes. 6 Copenhagen, Denmark: European Environment Agency, European Topic Centre on Inland Waters. Shiklomanov, I.A. 1997. Comprehensive Assessment of the Freshwater Resources of the World: Assessment of Water Resources and Water Availability in the World. Stockholm, Sweden: World Meteorological Organization and Stockholm Environment Institute. Smith, R.A., R.B. Alexander, and K.J. Lanfear. 1994. Stream Water Quality in the Coterminous United States—Status and Trends of Selected Indicators During the 1980s. USGS Water Supply Paper 2400. Reston, Virginia: U.S. Geological Survey. Taylor, R. and I. Smith. 1997. State of New Zealand’s Environment 1997. Wellington, New Zealand: The Ministry for the Environment. Available on-line at: http://www.mfe.govt.nz/about/publications/ser/front.pdf. UNEP (United Nations Environment Programme). 1996. Groundwater: A Threatened Resource. UNEP Environment Library No. 15. Nairobi, Kenya: UNEP. UNEP/GEMS (United Nations Environment Program Global Environment Monitoring System/Water). 1995. Water Quality of World River Basins. Nairobi, Kenya: UNEP. USGS (U.S. Geological Survey). 1999. The Quality of Our Nation’s Waters — Nutrients and Pesticides. USGS Circular 1225. Reston, Virginia: US Geological Survey. WMO (World Meteorological Organization). 1997. Comprehensive Assessment of the Freshwater Resources of the World. Stockholm, Sweden: WMO and Stockholm Environment Institute. Zhang, W.L., Z.X. Tian, N. Zhang, and X.Q. Li. 1996. “Nitrate Pollution of Groundwater in Northern China.” Agriculture, Ecosystems and Environment 59: 223-31
