THE WATERWHEEL: A series dedicated to one of our most treasured resources - Water
THE WATERWHEEL - Site Evaluation
by Don Janssen, UNL Extension Educator
The effect of farm, ranch or homesite practices on groundwater depends, in part, on the physical characteristics of your site: soil type, subsurface characteristics and depth to groundwater. That's why evaluating the soils and geologic characteristics of your site is such an important step in protecting the groundwater you drink. Soil characteristics are very important in determining whether a contaminant breaks down to harmless compounds or leaches into groundwater. Because most breakdown occurs in the soil, where is a greater potential for groundwater contamination in areas where contaminants are able to move quickly through the soil. Sandy soils have large "poor" spaces between individual particles and the particles provide relatively little surface area for "sorption" or physical attachment of most contaminants. Large amounts of rainfall can move through these soils and dissolved contaminants can move rapidly down through the soil and into groundwater. Clay soils, on the other hand, are made up of extremely small particles that slow the movement of water and dissolve contaminants through the soil. Contaminants also "stick" tightly to clay surfaces. While held securely to soil particles, contaminants are broken down by bacteria and other soil organisms and by chemical reactions with minerals and natural chemicals in the soil.
Finally, soil organic matter is important in holding contaminants. Soils high in organic matter provide an excellent environment for chemical and biological breakdown of most contaminants -- before they reach the groundwater. Organic matter also provides an important site for contaminants to absorb or stick to soil particles.
This article appeared in the NEBLINE Newsletter.
PHOTO Credit: Rita Shelley
University of Nebraska-Lincoln in Lancaster County
Web site: lancaster.unl.edu
444 Cherrycreek Road, Suite A, Lincoln, NE 68528 | 402-441-7180
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