Precipitation and dry deposition chemistry concentrations and fluxes, Andrews Experimental Forest, 1969 to present

Collection and analyses of precipitation chemistry were initiated in 1969 at the low-elevation Primary Met site, and in 1973 at a mid-elevation Hi-15 site. Rain collection samples accumulate from one week to three weeks in bulk and NADP type collectors and then are transported to Cooperative Chemical Analytical Laboratory (CCAL) for analysis. Analytes include nitrogen, phosphorus, carbon, and cations and anions as well as pH, conductivity, alkalinity and particulate sediment. Concentration and volume of precipitation are combined for inflow. Dry deposition chemistry concentrations began in 1989 and are analyzed 2-4 times per year at one site. The original objectives were to evaluate precipitation chemistry inputs versus chemistry outputs in streamflow from forested watersheds. The study has evolved into a general monitoring effort for precipitation chemistry that is among the least contaminated of any within the USA. This study is conducted in conjunction with Andrews streamflow chemistry (CF002) and the U.S. National Atmospheric Deposition Program (NADP).降水化学的采集与分析工作于1969年在低海拔主要气象（Primary Met）站点启动，并于1973年在中海拔Hi-15站点展开。雨水样品采用积雨式与美国国家大气沉降项目（National Atmospheric Deposition Program, NADP）型采样器采集，采样周期为1至3周，随后将样品运送至合作化学分析实验室（Cooperative Chemical Analytical Laboratory, CCAL）进行分析。分析项目涵盖氮、磷、碳、阴阳离子，以及pH值、电导率、碱度与颗粒沉积物。将降水浓度与体积数据相结合，用于入流相关分析。干沉降化学浓度监测工作始于1989年，每年在1个站点开展2至4次分析检测。该研究的初始目标为评估森林流域径流中降水化学输入与输出的对应关系。如今该研究已发展为一套通用的降水化学监测体系，其监测数据是全美受污染程度最低的数据集之一。本研究与安德鲁斯径流化学（CF002）项目以及美国国家大气沉降项目（NADP）联合开展。