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Chapter 13
Pesticides and Water Pollution
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The buildup of residual pesticides in
the ecosystem threatens the earth’s ecology
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Both our water and food can be contaminated.
That equals a long term chronic threat
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Pesticide broadly means any material
that is used to kill a pest
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A pest is any organism that competes with
humans for food, fiber or living space or that detrimentally affects the
way of life.
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Pesticides developed today "target" specific
species unlike the broad spectrum pesticides of the past
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The chemical nature of most synthetic pesticides
results in their accumulation and retention in nature
Certain species have
a propensity to bioconcentrate pesticides
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Persistence is the length of time that a pesticide
remains in the environment without it being changed or broken down into
different substances
New pesticides are engineered
to break down quickly
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Resistance = about 5% of any pest population
will be resistant to pesticide effects
Survivors pass on genetic
resistance
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The properties of DDT (and many other
chlorinated pesticides) enable it to disperse, accumulate and biomagnify
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Organophosphories Pesticides were developed
to resolve problems associated with past pesticides. Major drawback
is their toxicity to man
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Pesticides can have sublethal effects such
as: changed behavior patterns.
Reproductive effects = change
in predator/prey relationships and effects on phytoplankton at the bottom
of the food chain
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IPM - (is the new approach) Integrated
Pest Management
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Uses: Improved land use and management
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Better agricultural practices
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Selective use of natural and
synthetic pesticides
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Improved quality of care for
natural mechanisms of ecosystem
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