Inorganic Nutrients: Nitrogen, Phosphorus, and Other Nutrients

Abstract

Compounds of nitrogen, and especially those of phosphorus, are major cellular components of organisms. Since the availability of these elements may be less than the biological demand, environmental sources can regulate or limit the productivity of organisms in freshwater ecosystems. Other elements such as iron and sulfur are essential cellular constituents but are required in relatively low concentrations in relation to availability in fresh waters. The major base cations, calcium, magnesium, sodium, and potassium, usually are required in very low quantities, but their concentrations in fresh water can influence the osmoregulation of organisms.