Long-term trend of chemical composition of atmospheric precipitation at a regional background station in Northern China
Long-term trend of chemical composition of atmospheric precipitation at a regional background station in Northern China
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华北区域本底站大气降水化学成分长期变化趋势
DOI：
10.1016/j.scitotenv.2016.12.097
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发表时间：
2017
影响因子：
9.8
通讯作者：
Wang Wenyan
中科院分区：
文献类型：
--
作者：
Pu Weiwei;Quan Weijun;Ma Zhioliang;Shi Xuefeng;Zhao Xiujuan;Zhang Linna;Wang Zhenfa;Wang Wenyan
了解降水化学成分的变化趋势对于中国北方地区的空气污染控制策略具有重要意义。 2003年至2014年，在中国北方上甸子区域本底站对降水长期化学成分进行了综合研究。分析所有样品的 pH 值、电导率和主要离子（F−、Cl−、NO3−、SO42−、NH4+、Mg2+、Ca2+、K+ 和 Na+）。这一时期的平均pH值为4.53±0.35，远低于中国其他背景站（临安、瓦里关和龙凤山）报告的pH值。 NH4+、SO42−、Ca2+和NO3−是降水中的主要离子，其浓度（体积加权平均值）分别为212.99μeq L− 1、200.20 μeq L− 1、116.88 μeq L− 1和98.56 μeq L− 1。 SDZ的离子浓度远高于中国其他背景站和特大城市。 NO3−（7.26%year−1）呈显着增加趋势，SO42−/NO3−呈下降趋势，表明SDZ的沉淀从硫酸型演变为以硫酸和硝酸为主的混合型。来源鉴定表明，SO42−、NO3−、NH4+和F−以次要来源为主，Mg2+、Ca2+和Na+主要来自自然来源，K+和Cl−可能与人为来源有关。气团的长距离输送可能会影响 SDZ 降水的酸度、电导率和离子浓度。较高的酸度和离子浓度主要出现在南风和西风轨迹路径中，部分出现在西北路径中。这些路径上的人为污染物和地壳来源对 SDZ 降水的化学成分有重要贡献。
Understanding the trend of chemical composition of precipitation is of great importance for air pollution control strategies in Northern China. A comprehensive study on the long-term chemical compositions of precipitation was carried out from 2003 to 2014 at the Shangdianzi (SDZ) regional background station in northern China. All samples were analyzed for pH, electrical conductivity and major ions (F−, Cl−, NO3−, SO42 −, NH4+, Mg2 +, Ca2 +, K+and Na+). The average pH during this period was 4.53 ± 0.35, which is considerably lower than those reported in other background stations in China (Linan, Waliguan and Longfengshan). NH4+, SO42 −, Ca2 +and NO3−were the dominant ions in precipitation, with concentrations (volume-weighted mean) of 212.99 μeq L− 1, 200.20 μeq L− 1, 116.88 μeq L− 1and 98.56 μeq L− 1, respectively. The ion concentrations at SDZ were much higher than those of other background stations and megacities in China. A significantly increasing trend was observed for NO3−(7.26% year− 1), and a decreasing trend was observed for SO42 −/NO3−, suggesting that the precipitation of SDZ evolved from a sulfuric acid type to a mixed type dominated by both sulfuric and nitric acid. The source identification indicated that SO42 −, NO3−, NH4+and F−were dominated by secondary sources, Mg2 +, Ca2 +and Na+mostly originated from natural sources, and K+and Cl−probably associated with anthropogenic sources. Long-range transport of air masses could influence the acidity, electrical conductivity and ion concentrations of precipitation at SDZ. The higher acidity and ion concentrations mainly occurred in the southerly and westerly trajectory pathways and partially in northwest pathways. Anthropogenic pollutants and crustal sources along these pathways were significant contributors to the chemical composition of precipitation in SDZ.