Water is fundamental to the biophysical processes that sustain ecosystem functions. Moisture stored in different soil layers is recognized as an important driver of the productivity and sustainability of semi-arid terrestrial ecosystems. Soil erosion by rainfall and overland flow is a widespread threat to soil fertility and water quality. Soil loss and its spatial distribution are often needed for pollutant risk analyses, reservoir management, agriculture productivity forecasts, and soil and water conservation.
Several factors, such as the texture, organic matter content, drainage, soil horizons and vegetation influenced on the concentration and distribution of metals in soils. The overall content of metals in soil and sediments depends on the geochemical nature of the parent rocks material redistributed by pedological processes. Metal can exist as water-soluble and exchangeable forms, precipitate in carbonates, occluded in Mn, Fe of Al oxides, bind to organic matter, or appear in residuals phases – most frequently included in silicate matrix. 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 the lability and biological uptake of metals. Water-soluble and exchangeable forms are considered readily mobile and available to biota but metals incorporated in crystalline forms are relatively inactive.