2. Sources: 1. sewage, industrial wastes, agricultural wastes 2. ocean dumping 3. oil spills

3. Coastal areas most affected by sewage : Bangladesh. India Pakistan. Indonesia, Malaysia, Thailand and Philippines – NO TREATMENT Latin America - 98% not treated Mediterranean basin -85% not treated US - 35% not treated

4. Toxic Chemicals and Plastics toxic chemicals kill/harm marine organisms especially fish and shellfish  affect fishery whales, seals, dolphins, sea lions sea turtles die when they ingest/become entangled in plastic wastes and plastic rings

5. Eutrophication: ~ nitrogen and phosphorous rise sharply in coastal waters (from sewage and agriculture)  fast reproduction of microscopic algae, i.e. algal bloom (or red tides)  oxygen m water used up  other marine organisms suffocate  some algae produce toxins  kill marine organisms

6. - oceans can dilute, disperse and degrade large amounts of wastes especially in deep water areas - the dilution and renewal capacity of the ocean is limited. Controversy over ocean dumping - affect coastal tourism industry and fishing industry - safer and cheaper than land dumping (landfill) and incineration

7. Oil Pollution ~ Sources: 1. tanker accidents 10-15% 2. blowouts at drilling rigs 3. waste oil dump onto land  oceans 4. washing tankers with seawater 5. environmental terrorism/ wars

8. Effects: 1. toxic components kill marine organisms 2. floating oil coats feathers of birds and fur of mammals  die from drowning / cold 3. heavy components sink  kill bottom dwelling organisms e.g. crabs, shrimps (not fit for human consumption)

23. Working with nature to purify sewage: 1. Channel sewage into holding ponds solids fall to bottom, bacteria decompose them after 20-30 days; water used for irrigation, raising fish in ponds 2.Divert sewage to natural wetlands (marshes or mangroves) - decompose organic matter decomposed - nitrogen and phosphorous nutrients absorbed - toxic materials filtered out

24. 3. Artificial wetlands used in some towns in N. America 4. Green houses containing rows of large tanks of aquatic plants - organic matter decomposed by bacteria into nutrients - nutrients absorbed by plants - toxic metals absorbed into trees - water passes to aquariums: microorganisms  snails and zooplankton  fish  for sold

25. Compared with sewage treatment plants: - cheap - easy to maintain - but require more land