ABSTRACT
Agricultural, urban, and industrial activities have increased the variety and quantity of chemicals and wastes released into the environment. In agriculture, fertilizers, pesticides, and animal wastes have led to widespread pollution. Non-point source pollution is particularly difficult to predict and control. Pollutants and chemicals in soil are dissipated by various fate and transport processes. Concentrations are reduced by chemical and microbial degradation and transformation, by plant uptake, and through volatilization, and chemicals are transported by flowing water. Chemical flow pathways can be across the soil surface and downwards through the soil profile or vadose zone, and terminate via lateral subsurface flow and deep drainage in surface water bodies and aquifers. Transport pathways are diverse and difficult to predict with certainty.
