ABSTRACT
From the beginning of the second half of the last century, thousands of tons of xenobiotics such as agrochemicals and many other chemicals have reached the soil in a voluntary or accidental way. As discussed in Chapter 1, most of those chemicals are organic compounds, mainly pesticides and organic solvents used as part of pesticides formulations and others forming part of municipal, industrial wastes and composts of different origin applied to the soil as fertilizers and/or amendments. The use of pesticides has coincided with a tremendous increase in agricultural productivity. Pesticides are used worldwide in plant protection to control or destroy weeds, insects, fungi, and other pests. The recent trend toward conservation-tillage systems has also led to increasing reliance on chemical pesticide use (Logan et al., 1987). Most pesticides reach the soil during or immediately after treatment. The soil, which is the main recipient of all pesticides, plays a leading role in the environmental fate of these chemicals and in the protection of surface and ground waters.
