Contaminant Cycling Through Earth Systems. A 7 th grade Science Webquest. Go on ->. Introduction.
A 7th grade Science Webquest
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This webquest presents a short history of pollution and the self-cleaning abilities of the Earth. It begins with a brief history of the pollution and subsequent revival of Lake Erie. You will learn how people and their actions harmed the lake ecosystem, but then conservation measures coupled with natural environmental processes allowed it to heal itself. Go on->
a) In what year did the U.S. and Canada sign the Great Lakes Water Quality Agreement?
b) List all the ways suggested that individuals can do their part in reducing water pollution.
a) What chemical was the main culprit in the pollution of Lake Erie?
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1970- Lake Erie declared dead as dead fish and decaying algae ring the shores. (Bacteria on decaying algae consumed oxygen in the lake, effectively suffocating many fish).
1820’s-Human population increases dramatically. Raw sewage (oil,sawdust,animal carcasses, and human waste) dumped directly into the lake.
Present- Lake Erie is popular for boating, fishing (walleye, pike, trout, perch, others) and swimming.
Present- Consumers are warned not to eat catfish over 16 inches caught anywhere in Lake Erie.
1820’s- Population of fish species that migrate to spawn are reduced or eliminated.
1960’s- Phosphorus used in soaps causes algae to bloom and over populate.
1988- Ohio passes ban on the sale of detergents containing phosphorus.
1669-1st European sees Lake Erie
Pre-1820-Thousands of acres of wild rice grow at the mouths of the rivers feeding the lake, acting as filters for sediment.
1820’s-Mills built to grind corn and wheat on most of the streams and rivers leading into the river.
1936- The Cuyahoga River catches fire.
1969- The Cuyahoga River catches fire for a second time.
1972-President Nixon of the United States and Pierre Trudeau of Canada sign the Clean Water Act.
Present- Lake Erie considered one of the cleanest of the Great Lakes.
Present- Lake Erie still in danger from continued non point source pollution and past pollution by PCB’s, dioxin, mercury and DDT. (Trapped in the sediment).
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