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Sources of Nitrogen and Phosphorus in an Estuary of the Chesapeake Bay
Author(s) -
Kunishi H. M.
Publication year - 1988
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1988.00472425001700020003x
Subject(s) - estuary , tributary , brackish water , nutrient , environmental science , bay , phosphorus , salinity , hydrology (agriculture) , water quality , watershed , eutrophication , environmental chemistry , ecology , chemistry , oceanography , biology , geography , geology , cartography , geotechnical engineering , organic chemistry , machine learning , computer science
This study examined the contribution of agriculture to the nutrient (N and P) concentrations in the Wye River, an estuarine tributary the Chesapeake Bay. The river drains a watershed that is devoted mainly to farming and is devoid of any sources of municipal and industrial wastes. Water samples were analyzed for NO 3 ‐N + NO 2 ‐N and molybdate‐reactive P (MRP). The concentrations of these forms nutrients were then examined in relation to sampling site, sample salinity, and time of year. Freshwater entering the river (brackish) from the watershed contained consistently high concentrations of NO 3 ‐N (about 4 mg L −1 ) and low concentrations of PO 4 ‐P (about 40 µ g L −1 ). Once these nutrients entered the estuarine part of the river, however, the concentrations of NO 3 ‐N decreased to low levels within a short distance (500–700 m) from the point of riverine discharge, through both dilution with brackish water and apparent microbial action. The concentrations of MRP increased markedly through release from within estuary sources. Concomitantly, the estuary released large quantities of NH 4 . The estuary itself, therefore, was the immediate major source of N (as NH 4 ) and P.