Sources of nitrogen to estuaries in the United States
Sources of nitrogen to estuaries in the United States
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DOI：
10.1007/bf02711991
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发表时间：
2003-06-01
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影响因子：
--
通讯作者：
Boynton, WR
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文献类型：
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作者：
Castro, MS;Driscoll, CT;Boynton, WR
本研究的目的是量化氮（N）输入到美国大西洋和海湾沿岸的34个河口。总氮（TN）输入范围从德克萨斯州上拉古纳马德雷的1 kg N ha（-1）年（-1）到马萨诸塞州的马萨诸塞州湾的49 kg N ha（-1）年（-1）。TN输入到34个河口的11个主要由城市N源（点源和化粪池系统）和非点源N径流（总的5%）;点源占36-86%的TN输入到这11个城市为主的河口。TN输入的34个河口的20个占主导地位的农业N源，N施肥是占主导地位的来源（46%的总），其次是粪便（32%的总）和N固定的作物（16%的总）。大气沉积（从流域径流加上直接沉积到河口的表面）是三个河口（Baratriat湾，新泽西：64%;圣凯瑟琳斯萨佩洛，格鲁吉亚：72%;和巴拉塔里亚湾，路易斯安那州：53%）的主要氮源。六个河口的大气贡献30%的总氮输入（卡斯科湾，缅因州：43%;马萨诸塞州的布扎德湾：30%;大海湾，新泽西：40%;切萨皮克湾：30%;特雷邦-廷巴利埃湾，路易斯安那州：59%;和上拉古纳马德雷：41%）。从我们的研究结果表明，减少氮负荷的河口，应通过实施流域的具体方案，针对占主导地位的氮源。
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.