ABSTRACT
Pollutants are chemical stressors that can severely affect the quality of water and groundwater resources and soil quality. These pollutants include nonpoint source pollutants such as herbicides, pesticides, fungicides, etc., spread over large land surface areas and point source pollutants from effluents, waste treatment plants, and liquid discharges as wastes and spills from industrial plants (e.g., heavy metals and organic chemicals). The previous chapters dealing with urbanization and industries have shown that liquid and solid waste discharges, together with rejects, debris, and inadvertent spills in the plants, all combine to create significant threats to the health of biotic receptors and also the environment. To demonstrate the magnitude of the problem, we can give the example of sites contaminated with hazardous wastes and other material discards. Russell et al. (1991) suggests that over the next three decades, the expenditure required to clean up all the sites in the United States contaminated with hazardous materials may lie in the order of between $370 billion and $1.7 trillion.
