Ionic characteristics and sources of atmospheric precipitation and its impacts on environment at typical cities in China
Based on the observation data from sampling and the data from the Acid Deposition Monitoring Network in East Asia,the chemical composition,acidity and its causes,wet deposition fluxes,and pollution sources of atmospheric precipitation at typical cities in North,Northwest,Southwest,South and East China in 2019 were studied,and the ecological effects of the precipitation on the environment were evaluated.The results showed that the total ion concentrations in the precipitations showed an obvious seasonal variation with the order of dry season＞rainy season,and also presented a significant spatial distribution with the order of Beijing(706.87μeq/L)＞Xi'an(369.26μeq/L)＞Chongqing(265.17μeq/L)＞Xiamen(244.54μeq/L)＞Zhuhai(134.31μeq/L)＞Wuzhishan(81.88μeq/L).NH4+,Ca2+,SO42-and NO3-were the main ions of precipitation in the inland cities,while Cl-and Na+had a higher fraction in the coastal cities.The precipitation at the city in North China was mainly neutral,with acid rain events only accounting for 2.3％of the annual precipitation.The precipitation at the city in Northwest China was weakly alkaline,without any acid rain events occurring.The acid rain problem at the city in Southwestern China was severe,with acid rain frequencies reaching 30.3％and 80.3％at the urban and suburban stations,respectively,and presenting significant seasonal changes.The precipitation at the urban station in the city of East China was mainly neutral,however the acid rain problem at the station in remote area was extremely severe,with an annual acid rain rate of 99％.The summer precipitation at the city in Southern China was mainly neutral,while the other seasons were all acidic,and acid rain events accounted for 62.2％of the total precipitation events throughout the entire year.The neutralization capacity indicated that the areas with severe acid rain problems were mainly due to insufficient alkaline components in precipitation.Influenced by precipitation,the wet deposition fluxes of nitrogen and sulfur in each city were larger in the rainy season than those in the dry season,and played an important role in promoting the ecological environment in the rainy season.The wet deposition fluxes of nitrogen and sulfur in China showed a spatial distribution pattern decreasing from the east to the west and from the coastal areas to the inland areas.There were significant differences in the sources and contributions of precipitation ions in different cities,especially in cities with severe acid rain problems.The contribution of dust sources mainly composed of Ca2+and Mg2+to precipitation was smaller than that of secondary sources mainly composed of SO42 and NO3-.
万方数据
维普
