Geochemical data are an indicator of the quality of the human environment. They describe the distribution of nutrients, trace elements and pollutants in rocks, soil, surface water and groundwater. River sediments are derived from the rocks within a catchment area and mirror their chemical composition.
The hydrochemical composition of groundwater results from the geochemical makeup of the aquifer and from anthropogenic input. To evaluate groundwater quality and to detect possible anthropogenic contamination requires the separation of these two sources of input.
The hydrochemical content of groundwater reflects geological background levels. Arsenic occurs mainly in crystalline rocks and can find its way into the groundwater in such areas.