ABSTRACT
Of the 16 or so essential plant nutrients,* nitrogen (N), phosphorus (P), and sulfur (S) are the three nutrients that currently are of greatest environmental concern because of elevated concentrations in environmental waters. According to the U.S. Environmental Protection Agency (EPA), nutrient enrichment ranks as one of the top causes of water resource impairment. In environmental waters that failed to meet their designated use criteria, nutrients (mainly nitrogen and phosphorus) were listed as a primary cause of impairment in 40% of rivers, 51% of lakes, and 57% of estuaries (EPA 2000).
