TY - JOUR
T1 - Sources of nitrogen to estuaries in the United States
AU - Castro, Mark S.
AU - Driscoll, Charles T.
AU - Jordan, Thomas E.
AU - Reay, William G.
AU - Boynton, Walter R.
N1 - Funding Information:
We are extremely grateful for the help that we received from Percy Pacheco (National Oceanic and Atmospheric Administration-Special Projects Office, Silver Spring, Maryland) and R. Sri-nivasan (Texas Agricultural Experiment Station, Temple, Texas). Percy provided us with numerous data sets and without his assistance we would not have completed this project. Srinivasan ran the SWAT model to estimate nonpoint source N runoff from pervious and impervious lands in urban areas. We thank both Bruce Mertz and Thomas Simpson of the Maryland Department of Agriculture-University of Maryland System for their contributions to our agricultural budgets. We are also grateful for the help of Nancy Castro, Amy Hall, and Barbara Jenkins of the Appalachian Laboratory. We also thank Dr. Jim Lynch and anonymous reviewers for helping to improve early drafts of this manuscript. This manuscript is publication 3468 of the Appalachian Laboratory, University of Maryland System Center for Environmental Science, and contribution no. 2398 of the Virginia Institute of Marine Science, College of William and Mary. The work was funded by the U.S. Environmental Protection Agency, the National Atmospheric and Oceanic Administration, and the National Science Foundation.
PY - 2003/6
Y1 - 2003/6
N2 - The purpose of this study was to quantify the nitrogen (N) inputs to 34 estuaries on the Atlantic and Gulf Coasts of the United States. Total nitrogen (TN) inputs ranged from 1 kg N ha-1 yr-1 for Upper Laguna Madre, Texas, to 49 kg N ha-1 yr-1 for Massachusetts Bay, Massachusetts. TN inputs to 11 of the 34 estuaries were dominated by urban N sources (point sources and septic systems) and nonpoint source N runoff (5% of total); point sources accounted for 36-86% of the TN inputs to these 11 urban-dominated estuaries. TN inputs to 20 of the 34 estuaries were dominated by agricultural N sources; N fertilization was the dominant source (46% of the total), followed by manure (32% of the total) and N fixation by crops (16% of the total). Atmospheric deposition (runoff from watershed plus direct deposition to the surface of the estuary) was the dominant N source for three estuaries (Barnegat Bay, New Jersey: 64%; St. Catherines-Sapelo, Georgia: 72%; and Barataria Bay, Louisiana: 53%). Six estuaries had atmospheric contributions ≥ 30% of the TN inputs (Casco Bay, Maine: 43%; Buzzards Bay, Massachusetts: 30%; Great Bay, New Jersey: 40%; Chesapeake Bay: 30%; Terrebonne-Timbalier Bay, Louisiana: 59%; and Upper Laguna Madre: 41%). Results from our study suggest that reductions in N loadings to estuaries should be accomplished by implementing watershed specific programs that target the dominant N sources.
AB - The purpose of this study was to quantify the nitrogen (N) inputs to 34 estuaries on the Atlantic and Gulf Coasts of the United States. Total nitrogen (TN) inputs ranged from 1 kg N ha-1 yr-1 for Upper Laguna Madre, Texas, to 49 kg N ha-1 yr-1 for Massachusetts Bay, Massachusetts. TN inputs to 11 of the 34 estuaries were dominated by urban N sources (point sources and septic systems) and nonpoint source N runoff (5% of total); point sources accounted for 36-86% of the TN inputs to these 11 urban-dominated estuaries. TN inputs to 20 of the 34 estuaries were dominated by agricultural N sources; N fertilization was the dominant source (46% of the total), followed by manure (32% of the total) and N fixation by crops (16% of the total). Atmospheric deposition (runoff from watershed plus direct deposition to the surface of the estuary) was the dominant N source for three estuaries (Barnegat Bay, New Jersey: 64%; St. Catherines-Sapelo, Georgia: 72%; and Barataria Bay, Louisiana: 53%). Six estuaries had atmospheric contributions ≥ 30% of the TN inputs (Casco Bay, Maine: 43%; Buzzards Bay, Massachusetts: 30%; Great Bay, New Jersey: 40%; Chesapeake Bay: 30%; Terrebonne-Timbalier Bay, Louisiana: 59%; and Upper Laguna Madre: 41%). Results from our study suggest that reductions in N loadings to estuaries should be accomplished by implementing watershed specific programs that target the dominant N sources.
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U2 - 10.1007/bf02711991
DO - 10.1007/bf02711991
M3 - Article
AN - SCOPUS:0042427562
SN - 0160-8347
VL - 26
SP - 803
EP - 814
JO - Estuaries
JF - Estuaries
IS - 3
ER -