ABSTRACT
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 565 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
Soil can be de ned as the top layer of the Earth’s crust, consisting of mineral particles, organic matter, water, air, and living organisms. As the interface between the Earth’s atmosphere and the lithosphere, soil performs a number of diverse functions essential for life preservation and human activities; it is the substrate necessary for the growth of plants and animals and the basis for all agricultural production, and it serves as a protection and ltering layer necessary for clean groundwater supplies. The rate of soil formation and regeneration is very slow, so soil is practically a nonrenewable resource. In view of the high rates of soil degradation, it has become essential that soil resources be protected against the factors that degrade its quality and limit its availability. Human activities can greatly affect the geochemical cycles of soil constituents, resulting in the contamination
improper environmental management in chemical industries, mining and mineral processing operations, industrial waste disposal sites, municipal land lls, and other facilities, both during operation and after closure. Additionally, widespread soil contamination may occur as a result of emissions from transport and industry, which re-deposit onto the soil surface, as well as from overuse of agricultural chemicals. The result of this diffuse soil contamination is the accumulation of the various contaminants in the soil surface layer and their dissolution and transportation into deeper soil layers and groundwater under the effect of the in ltrating water. In some cases, uncontrolled urban expansion has led to changes in land use, and former mining or industrial sites have been gradually transformed into residential, recreational, or even agricultural areas; in these cases, contaminated land may pose a high risk to human health and agricultural production.
