BIOACCUMULATION Chemical Pollutants Humans have been introducing synthetic

BIOACCUMULATION

Chemical Pollutants Ø Humans have been introducing synthetic (man- made) chemicals into the environment. Some examples are: PCBs (polychlorinated biphenyls) widely used in paints, plastics, lubricants up to 1977 DDT (an insecticide for mosquitos) now banned in many countries Dichloro-diphenyl trichloroethane

Bioaccumulation Ø Bioaccumulation: a slow build up of chemicals in the bodies of organisms.

Ø Some chemicals are persistent in the environment – meaning they last a long time! Ø These chemicals are taken up into environments and food chains and stored in fatty tissues. l DDT was used to kill insects – it persists for a long time in the environment Spraying DDT, 1958

DDT first used in WWII to protect against diseases such as typhus and malaria. cheap and effective insecticide – was manufactured for home use. Before it was banned in 1972 by the EPA for use in agriculture, 1, 350, 000 pounds of DDT had been made in North America.

Biomagnification: consumers in each trophic level receive larger doses of accumulated chemicals than the one before it. .

Measuring Toxins Ø Parts per 10 l ppt One in every 10 parts is contaminated Ø Parts per 100 l pph Ø ppm? Ø ppb?

Ø Some metals also bioaccumulate. l Lead not considered safe at any level, can cause anemia, nervous & reproductive system damage. l Cadmium is toxic to earthworms & causes many health problems in fish. Cadmium causes lung diseases, cancer, nervous & immune system damage in humans l Mercury bioaccumulates in the brain, heart & kidneys of many animals

Bioaccumulation - EFFECTS Ø How it affects organisms: l l Birth defects Failure to reproduce • Amphibians live on both land in the water. – Amphibians are sensitive to chemical changes in the environment and are valuable indicators species for ecosystem health

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How BIOACCUMULATION affects ecosystems: If an important part of the food chain cannot reproduce, the whole food chain is affected. Keystone species = species that can greatly affect population numbers & health of ecosystem.

Undoing the Damage

Rhodococcus bacteria can biodegrade PCBs Bacteria can be used to clean up oil spills and underground leaks

Bioremediation With Plants Ø Plants can also be used to help trap hazardous wastes such as heavy metals Ø The plants uptake the metals and trap them in their tissues Ø Plants also help stabilize by reducing wind and water erosion (that would spread contaminants).