Modeling atmospheric nitrogen deposition and transport in the Chesapeake Bay watershed.
Modeling atmospheric nitrogen deposition and transport in the Chesapeake Bay watershed.
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DOI：
10.2134/jeq2002.1194
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发表时间：
2002-07
影响因子：
2.4
通讯作者：
Scott A. Sheeder;J. Lynch;J. Grimm
中科院分区：
文献类型：
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作者：
Scott A. Sheeder;J. Lynch;J. Grimm
大气中硝态氮和氨氮的沉积已被确定为切萨皮克湾水质下降的主要因素。报告表明，大气沉积可能占进入海湾的总氮负荷的25%至80%。然而，在这些研究中使用的大气沉积输入、氮保持系数和流中养分吸收速率的准确性方面存在不确定性。该项目旨在通过使用高分辨率湿沉降模型、改进的干湿沉降和养分保留量估算、现有土壤和土地利用数据以及地理信息系统软件，重新评估大气氮沉积对海湾的潜在输入。模型结果表明，以往研究中使用的方法可能高估了大气硝酸盐和氨氮沉降对切萨皮克湾流域(CBW)的贡献。1984年至1996年间，对CBW的干湿大气硝酸盐和氨氮沉降量的估计值分别为52.7至141.9公斤/年和41.9至6,010万公斤/年。分水岭的干负荷和总大气沉积负荷大大低于以前的估计。据估计，大气中沉积的氮对切萨皮克湾的贡献占所有氮源向流域输送的硝酸盐和氨氮总量的20%至32%。虽然这些估计值低于许多其他公布的估计值，但对模型参数、氮保留系数、产量和测量的溪流氮负荷的回归分析表明，计算的氮负荷可能仍然过高。
Atmospheric deposition of nitrate nitrogen and ammonium nitrogen has been identified as a major factor in the decline of water quality in the Chesapeake Bay. Reports have indicated that atmospheric deposition may account for 25 to 80% of the total nitrogen load entering the bay. However, uncertainties exist regarding the accuracy of the atmospheric deposition inputs, nitrogen retention coefficients, and in-stream nutrient uptake rates used in these studies. This project was designed to reassess the potential inputs of atmospheric nitrogen deposition to the bay through the use of a high-resolution wet deposition model, improved wet and dry deposition and nutrient retention estimates, existing soils and land use data, and geographic information systems software. Model results indicate that the methods used in previous studies may overestimate the contribution of atmospheric nitrate and ammonium deposition to the Chesapeake Bay watershed (CBW). Wet and dry atmospheric nitrate and ammonium nitrogen deposition estimates to the CBW ranged from 52.7 to 141.9 and 41.9 to 60.1 million kg/yr, respectively, between 1984 and 1996. Dry and total atmospheric deposition loads to the watershed are substantially less than previous estimates. Estimates of the percent contribution of atmospherically deposited nitrogen to the Chesapeake Bay represent between 20 and 32% of the total nitrate and ammonium nitrogen load to the watershed from all nitrogen sources. While these estimates are lower than many other published estimates, regression analysis of model parameters, nitrogen retention coefficients, output, and measured in-stream nitrogen loads indicate that the calculated nitrogen loads may still be too high.