Air, water, and soil pollution / Pollution de l'air, de l'eau et du sol / Inquinamento dell'aria, dell'acqua e del suolo

Life on our planet is indissolubly linked to the presence of water, a little molecule endowed with particular chemical and physical proprieties. Just because of its characteristic as a solvent, is essential for life, water seldom remains pure. Indeed, extraneous substances are dissolved and dispersed in it in extremely various quantities and types. According to the quality, that we can generically define as pollutants, water re – utilization for living creatures may be more or less compromised. Pollution is an unfavourable modification of a natural environment that is caused entirely or partially by human activities. These interventions may be direct or indirect and they change the chemical – physical characteristics of water, the energy – flow and the structure and abundance of the living associations. Nowadays huge amounts of very toxic and poisonous substances pour into the waters. They destroy aquatic life and may cause big problems also in human health. Atmosphere represents a combination of gas, liquid and solid condensed material, living micro-organisms, spores. Some of these elements come from human activities and could be toxic for organisms. Most works studying the effect of atmospheric contaminants aim to evaluate the impact of a simple element on a species isolated from its natural habitat, even though the atmospheric pollution has an effect at the ecosystem level. However, the study of atmospheric contaminant effects at the ecosystem level seems to be impossible to realize, mainly for spatial and temporal scales. Soil is a complex heterogeneous system whose physical, chemical and biological properties regulate interactions with the chemical species which reach its surface. Soil chemistry is an essential tool for understanding and predicting these interactions. Soil is able to immobilize and transform organic and inorganic molecules by different mechanisms, such as complexing and redox reactions. This behaviour gives soil detoxifying capacities towards pollutants which accumulate in the environment. Pollution by heavy metals is regulated by their solubility in soil solution which in turn depends on soil pH and redox properties and metal speciation. Organic and inorganic colloidal soil fractions can promote the immobilisation, degradation, and diffusion of organic molecules such as agrochemicals, solvents, hydrocarbons and other chemicals which reach the soil by anthropic activities Many years of research have demonstrated that instead of the total concentration of metals in soil, bioavailability is the key to understand the environmental risk derived from metals, since adverse effects only occur when related to biologically available forms of these elements. The knowledge of bioavailability can decrease the uncertainties in evaluating exposure in human and ecological risk assessment. At the same time the efficiency of remediation treatments may be greatly influenced by the availability of contaminants. Consideration of bioavailability processes at contaminated sites could be useful in site specific risk assessment: the fraction of mobile metals, instead of total content should be provided as an estimate of metal exposure.Different physical, chemical and biological processes influence the behaviour of organic contaminants in soils. A better understanding of the organic pollutant behaviour in soils would improve the environmental protection. One possible way for better attenuation of the risk of pollution in agriculture can be achieved through ta better-specified pesticide management based on the adaptation of the pesticide type and application rates to the specific environmental characteristics of the area of application.