Abstract :
Soil is a complex and heterogeneous mixture of organic and inorganic matter, as well as different components that determine the physical, chemical and biological properties of the soil. There are at least 68 trace elements in soil, representing only about 0.6% of their total composition, while 12 minor and major elements —Si, Al, O, Ca, Fe, K, Ti, Mg, Mn, Na, Cr, Ni— account for the rest. However, significant local or regional imbalances (relative to gross pedological averages) may occur in the soil composition. In contrast to soils in agricultural areas, soils in urban environments, particularly in parks and gardens, have a direct influence on public health that is unrelated to production of food because they easily come into contact with humans and are transferred to them, either as suspended dust or by direct contact. Furthermore, even though urban soils are rarely used for food production, they receive higher than normal loads of contaminants from traffic and industrial activities in heavily industrialized cities. Heavy metals in soils can also generate airborne particles and dusts, which may affect the environmental air quality. Heavy metal enrichment factors have been proposed as indicators for diffuse soil contamination.
