Sources of Nutrients and the Scale of Eutrophication Problems in Estuaries

A comprehensive analysis of external sources of nutrients is presented including an impact, comparison of external loadings, and the resulting scale of eutrophication. The major emphasis of the analysis is on nitrogen and phosphorus. The relative contribution of various external sources for five major ecosystems is delineated. Discussion of seasonal and long-term trends of external sources is presented. The impact of external sources on the eutrophication process is evaluated. A scale of eutrophication for estuarine ecosystems is suggested for comparing the impact of nutrient enrichment. Comparisons of external nutrient loadings and the scale of eutrophication for 13 estuarine and freshwater ecosystems are made. A detailed comparison of the five estuaries of the Chesapeake Bay is presented from which relationships between external nutrient loadings (g/m 2 /yr) and eutrophic conditions are suggested. Analysis of the relationship between external nutrient loadings, nitrogen/phosphorus ratio, and eutrophic state suggests that, for the East Coast estuarine ecosystems, if the phosphorus loading is 1.0 g/m 2 /yr or less, excessive eutrophic conditions can be prevented. The favorable response of the Potomac estuary to phosphorus control demonstrates that excessive eutrophic conditions may be alleviated with advanced wastewater treatment, depending on many factors including nutrient loadings. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.