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.