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.