Millions of chemicals are released into the environment and end up for causing soil and water pollution. The most common chemicals involved are hydrocarbons, pesticides, solvents, and heavy metals. While some of these are mainly anthropogenic (e.g. pesticides, poly aromatic hydrocarbons, etc), others have partly natural and partly man-made sources (such as trace elements or organic compounds). The physicochemical properties of pollutants influence their behaviour in the environment, and determine their interactions with inorganic and organic soil phases. The mobility and the persistence of pollutants in soil depend on chemical, physical and biological processes: sorption, plant uptake, volatilization, wind erosion, run-off, leaching and chemical and microbial degradation. Concerning metals, the moisture, pH, texture, organic matter, clay mineralogy, and Fe-Mn oxides have been found as the most important soil and sediment properties and components that influence their liability and biological uptake. Water-soluble and exchangeable forms are considered readily mobile and available to biota but metals incorporated in crystalline forms are relatively inactive.
In order to limit chemicals environmental impact, it is strategic to improve knowledge of the different transport and degradation processes which control their movement and fate in the environment.