Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Normalized Atmospheric Deposition for 2002, Ammonium (NH4)

This tabular data set represents the average normalized (wet) deposition, in kilograms per square kilometer multiplied by 100, of ammonium (NH4) for the year 2002 compiled for every MRB_E2RF1 catchment of the Major River Basins (MRBs, Crawford and others, 2006). Estimates of NH4 deposition are based on National Atmospheric Deposition Program (NADP) measurements (B. Larsen, U.S. Geological Survey, written. commun., 2007). De-trending methods applied to the year 2002 are described in Alexander and others, 2001. NADP site selection met the following criteria: stations must have records from 1995 to 2002 and have a minimum of 30 observations. The MRB_E2RF1 catchments are based on a modified version of the U.S. Environmental Protection Agency's (USEPA) ERF1_2 and include enhancements to support national and regional-scale surface-water quality modeling (Nolan and others, 2002; Brakebill and others, 2011). Data were compiled for every MRB_E2RF1 catchment for the conterminous United States covering New England and Mid-Atlantic (MRB1), South Atlantic-Gulf and Tennessee (MRB2), the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy (MRB3), the Missouri (MRB4), the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf (MRB5), the Rio Grande, Colorado, and the Great basin (MRB6), the Pacific Northwest (MRB7) river basins, and California (MRB8).本表格数据集展示了2002年美国主要流域（Major River Basins，MRBs，Crawford等，2006）内所有MRB_E2RF1汇水区的铵（ammonium，NH₄）平均归一化湿沉降量，单位为每平方千米千克数乘以100。铵态氮沉积量的估算基于美国国家大气沉降项目（National Atmospheric Deposition Program，NADP）的监测数据（B. Larsen，美国地质调查局，私人通信，2007）。针对2002年数据的去趋势化方法详见Alexander等（2001）的研究。NADP监测站点的选取需满足以下标准：监测记录需覆盖1995年至2002年，且有效观测次数不少于30次。 MRB_E2RF1汇水区基于美国环境保护署（U.S. Environmental Protection Agency，USEPA）的ERF1_2修订版本开发，并新增了支持全国及区域尺度地表水水质模拟的功能模块（Nolan等，2002；Brakebill等，2011）。 本数据集覆盖美国本土的所有MRB_E2RF1汇水区，涉及的流域包括：新英格兰与中大西洋地区（MRB1）、南大西洋-墨西哥湾和田纳西流域（MRB2）、五大湖、俄亥俄、上密西西比以及苏里斯-雷德-雷尼流域（MRB3）、密苏里流域（MRB4）、下密西西比、阿肯色-怀特-雷德以及德克萨斯-墨西哥湾流域（MRB5）、里奥格兰德、科罗拉多以及大盆地流域（MRB6）、太平洋西北流域（MRB7）以及加利福尼亚流域（MRB8）。