Mixtures of Environmental Pollutants: Effects on Microorganisms and Their Activities in Soils

The presence of unwanted substances in the environment becomes “pollution” when damage or deleterious effects caused by those substances are detected. Pollution is essentially a process by which a natural or a man-made resource becomes unfit for beneficial use (Enger and Smith 2006). Many man-made substances, in addition to certain naturally occurring organic and inorganic compounds, different forms of energy (e.g., heat, light and noise), and other things, add to the diversity of pollutants. Pollutants, which can occur at the local or the global level, render varying influences on soil and water that depend on the nature and spreading rate of the pollutants themselves, and produce short- or long-term effects on elements of an ecosystem. Undesirable changes in air, water, and soil may induce diverse responses from living organisms that are similar to those induced by the presence of pollutants. The effects on organisms caused by pollutants may range from innocuous to toxic. Toxicity, which has been defined as an inherent property of a substance to cause an adverse biological effect, is the result of a chemical disturbance that affects complex and interrelated systems involving cells, tissues, organs, or metabolic processes (ECETOC 1985).