eutrophication
inorganic plant nutrients
- nutrient: a chemical that allows plants and animals to live and grow
- eg. nitrogen, phosphorous compounds
- excesses of nitrogen and phosphorous produce algae blooms (eutrophication)
- the origins of inorganic plant nutrients
- nitrogen and phosphorous are components of fertilizers; after being applied in the fields, they runoff to lakes and rivers
- phosphorous is also present in detergents
eutrophication
- eutrophication: when a body of water receives an excessive amount of nutrients
- results in algae blooms
- when the algae die, the decomposers (eg. bacteria) act on the dead matter and consume high levels of oxygen (O2)
- when the levels of dissolved oxygen (DO) decrease, there are massive deaths of fish
- lake succession
- eutrophication is a process that takes a long time in nature
- cultural eutrophication: eutrophication caused by humans which occurs in a short time
water pollution in the Great Lakes
- water pollution: any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses
sources of pollution
- point source: a source which discharges pollutants at a specific location; easy to identify, monitor, and regulate
- non-point source: a source which is scattered and diffused; cannot be easily traced to any single site
toxic pollutants
- toxic pollutant: an organic compound that can cause illness or death
- toxic organic pollutants eg. oil, gasoline, plastic, detergents, pesticides (DDT), insecticide (mirex), dioxins, polychlorinated biphenyls (PCBs)
- persistent chemicals
- toxic inorganic pollutants eg. acids, salts, arsenic, toxic metals (mercury, lead)
the great lakes
- hold 20% of Earth’s surface freshwater
- cover 95,000 square miles
- surrounded by highly industrialized areas
- over 40 million people in the US and Canada rely on the Great Lakes for water
history
- in the 1960’s, many rivers that end up in the Great Lakes (Buffalo, Chicago, Cuyahoga, St. Louis) were so polluted that they caught fire
- US and Canada signed the Great Lakes Water Quality Agreement in 1972 as an ecosystem approach to combatting pollution
solutions to the toxic pollutant problem
- goals: regulate the discharge of toxic substances from point sources, clean up toxic substances from areas of concern
- fish advisories — statewide safe-eating guidelines
waterborne infectious agents
- infectious agent: an organism that is harmful to human health
- eg. bacteria, viruses, protozoa, worms
- sourced from untreated human and animal waste from sewers, septic tanks, feedlots, etc.
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