A group of very common air
pollutants regulated by the U.S.
Environmental Protection agency on
the basis of criteria (information
on health and/or environmental
effects of pollution). Criteria
air pollutants are widely
distributed all over the country
The process by which a substance
is broekn down into component
parts of basic elements. Food and
other plant and animal matter
decompose under the proper
conditions of light, air and
moisture.
Most lakes form three distinct
layers of water during summertime
weather. The epilimnion is the
upper layer and is characterized
by warmer and lighter water.