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LOAD-RESPONSE RELATIONSHIPS FOR NITROGEN AND CHLOROPHYLL A IN COASTAL EMBAYMENTS
Citation:
Dettmann, E H., L. B. Mason, J S. Latimer, G Cicchetti, D J. Keith, L Coiro, R A. McKinney, S Rego, M Abdelrhman, B J. Bergen, W Nelson, A. F. Santos, M Charpentier, AND E K. Hinchey. LOAD-RESPONSE RELATIONSHIPS FOR NITROGEN AND CHLOROPHYLL A IN COASTAL EMBAYMENTS. In Proceedings, 3rd International Nitrogen Conference: Contributed Papers, Najing, CHINA, October 12 - 16, 2004. Science Press, Beijing, 531-538, (2005).
Impact/Purpose:
to develop relationships between nitrogen loads and responses of submerged aquatic vegetation, dissolved oxygen, and food webs in coastal systems
Description:
The U.S. Environmental Protection Agency is conducting research to develop relationships between nitrogen loads and responses of submerged aquatic vegetation, dissolved oxygen, and food webs in coastal systems. We present an overview of the research program; then we describe in detail one component, a model that calculates annual average concentrations of total nitrogen (TN) in embayments from TN loading rates and ongoing research to extend the model to estimate planktonic chlorophyll a from nitrogen loading.
A simple hybrid model is being developed that combines mechanistic insights and empirical data. A validated model that relates spatially-averaged annual TN concentrations to loading is now being used to calculate average concentrations of TN in U.S. coastal embayments. Research in Long Island Sound (northeastern USA) revealed power-law relationships between chlorophyll a and TN concentrations and provided insights into seasonal and interannual variations in these correlations, as well as their causes. These relationships are being evaluated for possible addition to the nitrogen model to permit prediction of chlorophyll a concentrations from TN loading. Data from other embayments are now being analyzed to determine the generality of these relationships between TN ands chlorophyll a, including the degree of interannual and system-to-system variability. We present relationships obtained for Long Island Sound and discuss implications of our results for studies of coastal eutrophication.