Eutrophication Model for the Patuxent Estuary: Advances in Predictive Capabilities
Publication: Journal of Environmental Engineering
Volume 133, Issue 9
Abstract
A robust eutrophication and sediment diagenesis model has been developed for the Patuxent Estuary to study the impact of different nutrient loadings on phytoplankton biomass and dissolved oxygen (DO) levels. The modeling approach was to begin with an existing water quality model (CE-QUAL-W2) for the Patuxent Estuary (hereafter referred to as the Estuary). First, formulations for the water column kinetics were completely replaced with routines based on the WASP/EUTRO5 water quality model. Then, a sediment diagenesis component was added to simulate the accumulation and mineralization of organic matter in the sediment, the generation of sediment oxygen demand, and the flux of phosphate and ammonia from the sediment. Loadings from the tributaries for nutrients and flow were based on a combination of watershed modeling and sampling by scientists at the Smithsonian Environmental Research Center. The new model was able to reproduce the ambient water quality data from 1997 to 1999 by adequately simulating the high concentrations of phytoplankton and low DO levels in the Estuary. The model was then used to evaluate the response to various hypothetical nutrient loading scenarios. Model results show that phytoplankton growth in the upper Estuary is much more sensitive to nutrient loading from tributaries than in the lower estuary. Further, model results indicate that DO concentrations in the lower Estuary are largely influenced by levels of nutrients and organic carbon at the mouth of the Estuary.
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Acknowledgments
The writers owe a special debt of gratitude to Denise Breitburg of the Smithsonian Environmental Research Center for her insightful and valuable comments on the manuscript. Additional acknowledgment is due to Donald Weller and Thomas Jordan of the Smithsonian Environmental Research Center for use of nutrient and flow loading results from their watershed sampling and modeling efforts. The study was funded by the National Oceanic and Atmospheric Administration as part of the multidisciplinary research study, Complexity and Stressors in Estuarine Systems (COASTES).
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Information & Authors
Information
Published In
Journal of Environmental Engineering
Volume 133 • Issue 9 • September 2007
Pages: 917 - 930
Copyright
© 2007 ASCE.
History
Received: Mar 22, 2006
Accepted: Jan 30, 2007
Published online: Sep 1, 2007
Published in print: Sep 2007
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