ABSTRACT
The chemical composition of natural inland waters is complex because of the large number of dissolved ions and organic substances resulting from the natural conditions of drainage basins and human activities. Another contributing source of substances and elements is the atmosphere. The chemistry of natural waters varies greatly due to the geochemistry of soil and rocks that constitute the substratum of water basins. Activities of organisms (excretion, respiration, bioperturbation) also play a role in the balance of materials in aquatic systems.
