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Soil Contamination
What kind of contamination is it?
Soil contamination is either solid or liquid hazardous
substances mixed with the naturally occurring soil.
Usually, contaminants in the soil are physically or
chemically attached to soil particles, or, if they are not
attached, are trapped in the small spaces between soil
particles.
How did it get there?
Soil contamination results when hazardous substances
are either spilled or buried directly in the soil or
migrate to the soil from a spill that has occurred
elsewhere. For example, soil can become
contaminated when small particles containing
hazardous substances are released from a smokestack
and are deposited on the surrounding soil as they fall
out of the air. Another source of soil contamination
could be water that washes contamination from an
area containing hazardous substances and deposits
the contamination in the soil as it flows over or through
it.
How does it hurt animals, plants and humans?
Contaminants in the soil can hurt plants when they
attempt to grow in contaminated soil and take up the
contamination through their roots. Contaminants in the
soil can adversely impact the health of animals and
humans when they ingest, inhale, or touch
contaminated soil, or when they eat plants or animals
that have themselves been affected by soil
contamination. Animals ingest and come into contact
with contaminants when they burrow in contaminated
soil. Humans ingest and come into contact with
contaminants when they play in contaminated soil or
dig in the soil as part of their work. Certain
contaminants, when they contact our skin, are
absorbed into our bodies. When contaminants are
attached to small surface soil particles they can
become airborne as dust and can be inhaled.
How can we clean it up?
There are three general approaches to cleaning up
contaminated soil: 1) soil can be excavated from the
ground and be either treated or disposed; 2) soil can
be left in the ground and treated in place; or 3) soil can
be left in the ground and contained to prevent the
contamination from becoming more widespread and
reaching plants, animals, or humans. Containment of
soil in place is usually done by placing a large plastic
cover over the contaminated soil to prevent direct
contact and keep rain water from seeping into the soil
and spreading the contamination. Treatment
approaches can include: flushing contaminants out of
the soil using water, chemical solvents, or air;
destroying the contaminants by incineration;
encouraging natural organisms in the soil to break
them down; or adding material to the soil to
encapsulate the contaminants and prevent them from
spreading.