Phosphorus (usually in the form of phosphate, PO^3-₄) is a normal part of the environment. It occurs in the form of phosphate-containing rocks and as the excretory and decay products of plants and animals. Human contributions to the phosphorus cycle result primarily from the use of phosphorus-containing detergents and fertilizers.

The increased load of phosphorus in the environment as a result of human activities has been a matter of concern for more than four decades. The primary issue has been to what extent additional phosphorus has contributed to the eutrophication of lakes, ponds, and other bodies of water. Scientists have long recognized that increasing levels of phosphorus are associated with eutrophication. But the evidence for a direct cause and effect relationship is not entirely clear. Eutrophication is a complex process involving nitrogen and carbon, as well as phosphorus. The role of each nutrient and the...