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Bdale Envir Ch 14 – Water Resources and Water Pollution - page 6 / 7





6 / 7

Oil hurts organisms several diff ways….

Larvae get killed

Bird feathers and marine mammal fur gets coated, destroying insulation and buoyancy

Heavy oil can sink to ocean floor, smother bottom-dwelling organisms

Crude, unrefined oil appears to be less damaging to environment; many forms of life can recover within 3 years.

Refined oil causes longer recovery time, perhaps 10 years…also, spill effects in confined areas tend to last longer

Oil-polluted beaches washed by waves can get clean in about a year, whereas those in sheltered areas may remain contaminated for several years.

14-8 solutions: preventing and reducing surface water pollution

nonpoint sources:

reduce fertilizer input from land

create vegetation buffer zones between crops and surface water

reduce pesticide runoff

reduce manure runoff

reduce soil erosion

point sources:

big diff between developing and developed countries – point source pollution is regulated in developed countries, so some cleanup occurs prior to discharge

Clean Water Act of 1972 resulted in many improvements in US by 1998:

fishable/swimmable rivers & lakes incr from 36% to 62%

topsoil loss reduced by 1 billion tons

% US population served by sewage treatment incr from 32% to 74%

annual wetland loss decr 83%

Sewage treatment – complex issue

In many older US cities, it’s too expensive to create separate systems to handle both sewage and stormwater runoff, so when heavy rains occur and cause potential overflow of waste treatment facilities, the entire system dumps untreated waste into rivers, lakes, etc

Sewage treatment process:

Primary – mechanical filtering process, allows solids to settle out

Secondary – biological process, where aerobic bacteria remove up to 90% of “oxygen-demanding” organic wastes

14- 9 achieving a more sustainable water future

the Incas said “the frog does not drink up the pond in which it lives”

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