Environmental Engineering Reference
In-Depth Information
6
PESTICIDES AND INDUSTRIAL
ORGANIC CHEMICALS
What are the sources of pesticides to the marine environment?
Pesticides from agriculture, lawns, golf courses, and gardens
wash into streams and rivers and ultimately down into estu-
aries. These chemicals are designed to kill agricultural pests
(generally insects) on land. After being sprayed on land, they
wash into the water when it rains and can affect aquatic ani-
mals. Some spraying happens directly in coastal habitats.
Because salt marshes are well-known as breeding areas for
mosquitoes, biting lies, and other nuisance insects, they are
sites of direct pesticide applications. On the West Coast, where
burrowing shrimp are considered pests in oyster-growing
estuarine areas, the pesticide carbaryl is used to kill the
shrimp. Estuarine and marsh organisms can also be exposed
to herbicides used on the marshes to kill unwanted plants
such as common reeds on the East Coast and cord grass on the
West Coast. In addition to the pesticides used directly in salt
marshes or estuaries, other insecticides and herbicides wash
in from upland areas.
What happens to these chemicals after they enter the water?
Those chemicals of greatest concern are those that are persis-
tent (i.e., that don't break down), that bioaccumulate in organ-
isms, and that are toxic at very low concentrations. Some of
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