2. Today everybody is downwind or downstream from somebody else. -- William Ruckelshaus

3. point sources (e.g., factories, sewage treatment plants, mines, oil wells, oil tankers); nonpoint sources (e.g., acid deposition, substances picked up in runoff, seepage into groundwater); nonpoint source water pollution from agriculture is largest source of water pollution in the U.S. (64% of pollutants into streams & 57% of pollutants entering lakes) Sources of Pollution

4. disease–causing agents (500+ identified) 3.2 mil die yearly from contaminated water complications oxygen demanding wastes Plant debris, animal wastes fertilizers water–soluble inorganic chemicals Acids, salts, metals organic chemicals Pesticides, oil & gasoline, plastics, PCBs sediment water–soluble radioactive isotopes thermal pollution Types & Sources of Water Pollution

5. decomposing wastes deplete dissolved oxygen dissolved oxygen (DO) indicator of water quality Oxygen–Demanding Wastes

6. amount of dissolved oxygen needed by aerobic decomposers to break down organic materials in a certain volume over a 5–day incubation period at 20° C greater BOD --> more rapidly oxygen depleted consequences of high BOD are the same as those for low dissolved oxygen Sources of BOD: leaves and woody debris dead plants and animals animal manure effluents from pulp and paper mills wastewater treatment plants feedlots food-processing plants failing septic systems urban stormwater runoff Biological Oxygen Demand (BOD)

7. Clean Zone Decomposition Zone Septic Zone Recovery Zone Clean Zone Normal clean water organisms (trout, perch, bass, mayfly, stonefly) Trash fish (carp, gar, leeches) Fish absent, fungi, sludge worms, bacteria (anaerobic) Trash fish (carp, gar, leeches) Normal clean water organisms (trout, perch, bass, mayfly, stonefly) 8 ppm Dissolved oxygen (ppm) Biological oxygen demand 8 ppm Types of organisms BOD & DO & Water Quality "oxygen sag curve"

8. Flowing water can often recover rapidly by dilution & decay. © Brooks/Cole Publishing Company / ITP Pollution of Fresh Water

9. results when human activities accelerate input of nutrients (which?) to a lake © Brooks/Cole Publishing Company / ITP Cultural Eutrophication Lakes and reservoirs pollution persists due to Little mixing between layers Little flow into & out of Turnover can take as long as 100 years

10. basin contains >95% of fresh surface water in U.S. & 20% of world severe cultural eutrophication since the 1960s $20 billion pollution–control program improved water quality since 1972 ¾ of shoreline still not suitable for swimming Fig. 12–22 © Brooks/Cole Publishing Company / ITP Great Lakes

11. Organic chemicals pollution: Cuyahoga River, Cleveland OH So polluted that it caught on fire in 1868, 1936, 1959, 1969 and burned for several days. Today: not flammable, water quality is good enough for boating

12. concentrations increase at increasing levels in the food chain -- PCBs (polychlorinated biphenyls), heavy metals, certain pesticides © Brooks/Cole Publishing Company / ITP Biological Magnification

13. Groundwater Supplies nearly ½ of drinking water in the US (95% of drinking water in rural areas) Many pollutants can seep into groundwater (pesticides, fertilizers, gasoline, organic solvents)

14. 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

15. coastal areas most impacted – especially wetlands & estuaries, coral reefs, & mangrove swamps; half of world's population lives within 100 km (60 miles) of oceans & 14 of 15 largest cities coastal; in U.S. about 35% of municipal sewage discharged virtually untreated in marine waters; ocean ultimate repository of waste; dumping of industrial waste directly into ocean off U.S. coasts stopped, but many countries still dump large quantities of toxic substances. © Brooks/Cole Publishing Company / ITP Ocean Pollution

16. Fig. 21-10, p. 505 Healthy zone Clear, oxygen-rich waters promote growth of plankton and sea grasses, and support fish. Oxygen-depleted zone Sedimentation and algae overgrowth reduce sunlight, kill beneficial sea grasses, use up oxygen, and degrade habitat. Red tides Excess nitrogen causes explosive growth of toxicmicroscopic algae, poisoning fish and marine mammals. Farms Runoff of pesticides, manure, and fertilizers adds toxins and excess nitrogen and phosphorus. Toxic sediments Chemicals and toxic metals contaminate shellfish beds, kill spawning fish, and accumulate in the tissues of bottom feeders. Construction sites Sediments are washed into waterways, choking fish and plants, clouding waters, and blocking sunlight. Urban sprawl Bacteria and viruses from sewers and septic tanks contaminate shellfish beds Oxygen-depleted zone Closed beach Cities Toxic metals and oil from streets and parking lots pollute waters; Industry Nitrogen oxides from autos and smokestacks, toxic chemicals, and heavy metals in effluents flow into bays and estuaries. Closed shellfish beds

17. Pacific garbage patch

18. largest estuary in U.S. severely degraded by water pollution from 6 states deposition of air pollutants © Brooks/Cole Publishing Company / ITP Example: Chesapeake Bay What is hypoxia? Where else do we see it in the U.S.?

19. The Gulf of Mexico Dead Zone