Area IV: Pollution

1. Area IV: Pollution IVA3: Water Pollution

2. 22-1 Types, Effects, Sources of Water Pollution • water is polluted by infectious bacteria, inorganic and organic chemicals, and excess heat • water pollution: any chemical, biological, or physical change in water quality that has a harmful effect on living organisms • the WHO estimates that 3.4 million people/yr people die prematurely from waterborne diseases • an estimated 1.5 million people/yr in U.S. become ill from infectious agents

3. 22-1 Types, Effects, Sources of Water Pollution • scientists monitor water quality by using bacterial counts, chemical analysis, and indicator organisms • number of colonies of fecal coliform bacteria present in a water sample • drinking water: 0 colonies/100 mL • swimming water: < 200 colonies/100 mL • bacterial source tracking (BST) • biological oxygen demand (BOD): the amount of dissolved oxygen consumed by aquatic decomposers

4. Fig. 22-2 Fecal coliform bacteria

5. 22-1 Types, Effects, Sources of Water Pollution • scientists monitor water quality, cont. • chemical analysis: inorganic and organic chemicals present, sediment content, and turbidity of water • indicator species • genetic techniques are being used to develop organisms that will glow in the presence of specific pollutants such as toxic heavy metals in the ocean and carcinogens in food

6. Fig. 22-3 Water quality and dissolved oxygen

7. 22-1 Types, Effects, Sources of Water Pollution • water pollution can come from a single source or variety of dispersed sources • point sources discharge at specific locations • examples: drainpipes, sewer lines • easy to identify, monitor, and regulate • non-point sources are scattered and diffuse and can’t be traced to any single site of discharge • examples: runoff from croplands, livestock feedlots • difficult and expensive to identify and control these discharges

8. Fig. 22-4 Point and nonpoint sources

9. 22-1 Types, Effects, Sources of Water Pollution • sources of water pollution, cont. • leading sources: agriculture, industries, mining • agricultural activities: • erosion • overgrazing • fertilizers • pesticides • excess salt from irrigated soils

10. 22-1 Types, Effects, Sources of Water Pollution • too much rain and too little rain can increase water pollution • increased moisture with more intense rains can flush harmful chemicals, plant nutrients, and microorganisms into waterways • prolonged drought can reduce river flows so there is less dilution available • warmer water contains less dissolved oxygen

11. 22-2 Pollution of Freshwater Streams • streams can recover from moderate levels of degradable water pollutants if the flows are not reduced • dilution and biodegradation can allow recovery of stream pollution if: • they are not overloaded • do not have reduced flow due to damming, agricultural diversion, or drought

12. 22-2 Pollution of Freshwater Streams • stream recovery, cont. • breakdown of pollutants by bacteria creates an oxygen sag curve • organisms with a high oxygen demand can’t survive in the curve • factors in size of curve: • volume of the stream • volume of wastes entering • flow rate • temperature • pH levels

13. Fig. 22-5 Dilution and decay of wastes

14. 22-2 Pollution of Freshwater Streams • most developed countries have reduced point source pollution, but toxic chemicals and pollution from non-point sources are still problems • the U.S. has avoided increases in pollution from point sources in most streams • cleanup of rivers: Cuyahoga River in Ohio and the Thames River in Great Britain • there are sometimes large fish kills, and contamination of drinking water from industry, mining, and non-point runoff of fertilizers and pesticides

15. 22-2 Pollution of Freshwater Streams • stream pollution in most developing countries is a serious and growing problem • half of the world’s 500 major rivers are heavily polluted • many run through developing countries where waste treatment is minimal or nonexistent

16. 22-2 Pollution of Freshwater Streams • the Ganges River in India is severally polluted • ~350 million people live in the Ganges River basin with little treatment of sewage • Hindu beliefs compound problem • air pollution from cremated bodies • water pollution from bodies thrown in river • government solutions: • waste treatment plants in the 29 large cities along the Ganges • electric crematoriums on its banks • introduction of snapping turtles as body scavengers

17. 22-3 Pollution of Freshwater Lakes • lakes are less effective at diluting pollutants that enter them • often stratified with little vertical mixing • very little flow occurring • may take from 1–100 years to flush and change water in lakes and reservoirs • much more vulnerable to runoff contamination of all kinds of materials • chemical concentrations build up as they pass through the food webs in lakes

18. Fig. 22-6 Biomagnification of PCBs

19. 22-3 Pollution of Freshwater Lakes • human activities can reduce dissolved oxygen and kill some aquatic species • natural eutrophication: nutrient enrichment of lakes from runoff • depends on composition of the surrounding drainage basin • can enrich abundance of desirable organisms • cultural eutrophication occurs due to runoff • usually near urban or agricultural areas and in coastal water, enclosed estuaries, and bays • can lead to serious pollution problems

20. Oligotrophic lake

21. Eutrophic lake

22. Fig. 22-7 Cultural eutrophication

23. 22-3 Pollution of Freshwater Lakes • human activities, cont. • cultural eutrophication, cont. • the EPA states that 85% of large lakes near major population centers in U.S. have some amount of cultural eutrophication • can be reduced or prevented by: • banning or limiting phosphates in detergents • advanced treatment methods to remove nitrates and phosphates from wastewater • use of soil conservation to reduce runoff

24. 22-3 Pollution of Freshwater Lakes • human activities, cont. • hot weather or drought -> “blooms” of organisms -> reduction in lake productivity • reduced sunlight + decomposition -> increase in bacteria populations -> decrease in DO -> fish kills -> anaerobic bacteria take over • cleanup of lakes includes removing excess weeds, controlling plant growth, and pumping air through lakes and reservoirs to avoid oxygen depletion • pollution prevention is cheaper than cleanup

25. 22-3 Pollution of Freshwater Lakes • Case Study in lake recovery: Lake Washington, Seattle • sewage diverted from the lake to Puget Sound, where rapid water exchange dilutes sewage • recovery took 4 years • lake had not filled with weeds and sediment • concern about Puget Sound due to increased urban runoff and growing population • What is the best way to deal with pollution?

26. Lake Washington

27. Lake Washington

28. 22-3 Pollution of Freshwater Lakes • Case Study: pollution of the Great Lakes has dropped but is still a problem • the Great Lakes contain about 95% of the fresh surface water in the United States, and 20% of the world’s fresh surface water • > 38 million people obtain drinking water from the lakes • vulnerable due to less than 1% outflow to the St. Lawrence River but lots of inputs • Lake Erie: shallowest; was the most polluted; high concentration of people and industry

29. Fig. 22-8 Great Lakes basin

30. Western Lake Eerie

31. 22-3 Pollution of Freshwater Lakes • Case Study: Great Lakes pollution, cont. • since 1972, the U.S. and Canada have worked together to reduce pollution • there is still a large area of depleted oxygen that occurs in the center of the lake each August for unknown reasons • a 2000 survey by the EPA stated that more than ¾ of the shoreline is not clean enough for swimming or use as drinking water • non-point land runoff is now a greater problem than industrial pollution

32. 22-3 Pollution of Freshwater Lakes • Case Study: Great Lakes pollution, cont. • biomagnification of the depositions from atmospheric contaminants means that one fish in four is unsafe for human consumption • EPA funding for cleanup has also dropped by 80% since 1992 • environmentalists call for banning the use of bleach, building new incinerators, and stopping the discharge into the lakes of 70 toxic chemicals

33. 22-4 Pollution of Groundwater • groundwater is vulnerable to pollution • spilling gasoline, oil, paint thinners, etc. onto the ground can contaminate groundwater • low-risk ecological problem • high-risk health problem • contaminated water in the aquifer will slowly flow, creating a plume of contaminated water • contaminants in groundwater are not diluted or dispersed because this water moves usually less than 0.3 meter per day

34. 22-4 Pollution of Groundwater • groundwater vulnerability, cont. • cleansing is slow; factors: • lower oxygen content • colder temperature of the water • smaller populations of decomposing bacteria • it can take hundreds of years to cleanse degradable wastes; nondegradable wastes are there permanently

35. 22-4 Pollution of Groundwater • the extent of groundwater contamination is generally unknown • EPA and U.S. Geological Survey figures state that one or more organic chemicals contaminate about 45% of municipal groundwater supplies in the U.S. • ~26,000 industrial waste ponds and lagoons in U.S. do not have a liner to prevent seepage • many underground storage tanks have leaks • determining the extent of a leak is costly, and the cost of cleanup is more costly yet

36. Fig. 22-9 Groundwater contamination

37. 22-4 Pollution of Groundwater • groundwater contamination, cont. • nitrates can contaminate groundwater, esp. in agricultural areas; form nitrites in the body • arsenic is released into drinking water when a well is drilled into arsenic-rich soils and rock • WHO estimates that more than 112 million people drink water containing 5–100 times the recommended level of 10 parts/billion • Bangladesh has a serious problem with arsenic, but the UN and several NGOs have begun to assess wells and tag them

38. 22-4 Pollution of Groundwater • prevention is the most effective and affordable way to protect groundwater from pollutants • underground tanks in the U.S. and some other developed countries are now strictly regulated • old, leaky tanks are being removed, and the surrounding soils are being treated

39. Fig. 22-10 Groundwater pollution

40. 22-5 Ocean Pollution • oceans can disperse and break down large quantities of degradable pollutants if they are not overloaded • raw sewage, sludge, oil, and some degradable industrial wastes can be degraded, especially in deep-water areas • some marine animals have been less affected by pollutants than expected • there is controversy as to whether this is a viable solution to the problem

41. 22-5 Ocean Pollution • pollution near heavily populated areas • ~40% of the world’s population lives on or within 62 miles of the coast • in most coastal developing countries and some developed countries, sewage is dumped into the sea without treatment • human viruses (not removed by waste treatment) have been found in coastal waters • nutrient enrichment from nitrate and phosphate runoffs causes algal blooms, killing fish and fish-eating birds

42. Fig. 22-11 Pollution of coastal waters

43. 22-5 Ocean Pollution • pollution near populated areas, cont. • extensive non-point runoffs have caused seasonal, large oxygen-depleted zones in temperate coastal waters • the second largest of these zones forms each summer at the mouth of the Mississippi River in the Gulf of Mexico • scientists are investigating whether fine clay particles can pull algae out of the water • preventive measures: restore wetlands, reduce nitrogen inputs, sewage treatment

44. Fig. 22-

45. 22-5 Ocean Pollution • pollutants from six states contaminate the shallow Chesapeake Bay estuary • a huge drainage basin adds both point and non-point pollutants to the waters • point sources: 60% of phosphates • nonpoint sources: 60% of nitrates • the bay is shallow, so only 1% of the waste that enters is flushed into the Atlantic Ocean • commercial harvest of oysters, crabs, and fish has fallen sharply since 1960 because of overfishing, pollution, and disease

46. Fig. 22-13 Chesapeake Bay

47. 22-5 Ocean Pollution • Chesapeake Bay estuary, cont. • in 1983, the U.S. started an integrated coastal management plan • reduction of runoff • upgrading waste treatment plants • better monitoring of industrial discharges • banning phosphates from detergents • between 1985 and 2000, 27% decline in phosphorus levels, 16% drop in nitrogen levels, recovery of grasses on bottom of bay • reduction in funding has slowed progress

48. Fig. 22-14 Coastal water pollution

49. 22-5 Ocean Pollution • Chesapeake Bay estuary, cont. • introduction of disease-resistant oysters could greatly reduce water pollution because oysters filter algae and silt from water • oysters recycled the entire volume of the bay in 3–4 days • over-harvesting and two parasitic oyster diseases reduced the oyster population • several ways to reintroduce oysters into the bay are being considered

50. 22-5 Ocean Pollution • oceans as dump sites • dumping industrial wastes off U.S. coasts has stopped, dumping of dredge spoils continues • many countries dump sewage sludge (banned in U.S. since 1992) • 50 countries with >80% of world’s merchant fleet agreed not to dump ship waste at sea • the London Dumping Convention of 1972: 100 countries agreed not to dump highly toxic pollutants, high-level radioactive wastes in open sea