Interactions between xenobiotics and microbial and enzymatic soil activity

In the second half the twentieth century, the indiscriminate release of xenobiotic chemicals of different chemical and structural complexity into the environment provoked serious and most often irreversible alterations of the natural environmental balance. Indeed, soil contamination by highly toxic compounds has greatly increased, with negative, irreversible effects on soil quality and health. Several chemical, biological, and biochemical soil properties have been profoundly altered, and their main effect has been the continuous loss of soil functions in sustaining the survival of living organisms. Among chemical pollutants, compounds like pesticides and polycyclic aromatic hydrocarbons arrive to the soil from different anthropic sources and have high toxicity toward humans, plants, and animals. Assessing the soil quality is a basic requirement for sustainable land use. Soil microbial and biochemical activities are sensitive to several natural and human-induced changes and may provide a helpful tool to assess soil status, its quality, and its productivity. This article is a survey of the mutual interactions establishing in a soil among xenobiotic substances with particular reference to pesticides and polycyclic aromatic hydrocarbons and microbial and enzymatic soil activities.