Abstract Continuous monitoring of precipitation chemistry began at the Hubbard Brook Experimental Forest, NH in June 1963, and it was there that acid rain was discovered in North America. Some independent monitoring of precipitation chemistry in central New York was done in 1970–1971. The MAP3S network (Charlottesville, VA, Ithaca, NY, Penn State, PA, Whiteface Mt., NY) began in 1976 and became part of the National Atmospheric Deposition Program (NADP) in 1992. Using data from these long-term sites, and other published information, we show the status and temporal change of precipitation chemistry in the northeastern U.S. from 1963 to present. Combining records from all stations and networks gave better insights into the status and temporal trends of precipitation chemistry for the region particularly as detailed regional maps could be constructed from these data. Early maps of predicted pH (1955-56 and 1965-66) and individually measured pH values (1975-76), as well as cartoons provided important visual information about the occurrence and spread of acid rain in the northeastern U.S. These indicators of changing atmospheric chemistry were key in initiating federal policy necessary for improving air quality and for reducing atmospheric pollutant loading, which had led to acid rain in this area, starting in the 1950s. Analyzing combined records from Hubbard Brook and the 5 longest operating MAP3S/AIRMoN sites (IL11, NY67, DE02, PA15 and TN00) with a random coefficient model showed overall declines in annual concentrations of H+, SO42− and NO3− from 1981 to 2017 of 85%, 80% and 66%, respectively. Calcium concentration declined by 14% and NH4+ showed no change during this period. Dry deposition of sulfur, NO3− and Ca2+ measured at co-located Clean Air Status and Trends Network (CASTNET) sites showed declines of 87%, 64% and

中文翻译：

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美国降水化学的长期监测：洞察变化和条件

摘要 1963 年 6 月在新罕布什尔州哈伯德布鲁克实验森林开始对降水化学进行连续监测，并在那里发现了北美的酸雨。1970-1971 年对纽约中部的降水化学进行了一些独立监测。MAP3S 网络（弗吉尼亚州夏洛茨维尔、纽约州伊萨卡、宾夕法尼亚州宾夕法尼亚州、纽约州怀特菲斯山）始于 1976 年，并于 1992 年成为国家大气沉积计划 (NADP) 的一部分。使用来自这些长期站点的数据，和其他已发表的信息，我们展示了美国东北部从 1963 年至今降水化学的状态和时间变化。结合所有站点和网络的记录，可以更好地了解该地区降水化学的状态和时间趋势，特别是因为可以根据这些数据构建详细的区域地图。预测的 pH 值（1955-56 和 1965-66）和单独测量的 pH 值（1975-76）的早期地图以及卡通提供了有关美国东北部酸雨发生和蔓延的重要视觉信息 这些大气变化的指标化学是启动改善空气质量和减少大气污染物负荷所必需的联邦政策的关键，这导致该地区从 1950 年代开始出现酸雨。分析来自 Hubbard Brook 和 5 个运行时间最长的 MAP3S/AIRMoN 站点（IL11、NY67、DE02、PA15 和 TN00) 与随机系数模型显示 H+、SO42− 和 NO3− 年浓度从 1981 年到 2017 年的总体下降幅度分别为 85%、80% 和 66%。在此期间，钙浓度下降了 14%，NH4+ 没有变化。在并置的清洁空气状况和趋势网络 (CASTNET) 站点测量的硫、NO3− 和 Ca2+ 的干沉降显示下降了 87%、64% 和