Zeng Jie, Han Guilin, Wu Qixin, Peng Meixue, Ge Xin, Mao Shijun, Wang Zhong-Jun, Ma Qing
Key Laboratory of Karst Georesources and Environment (Guizhou University), Ministry of Education, College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China; Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, China; North Alabama International College of Engineering and Technology, Guizhou University, Guiyang 550025, China.
Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing 100083, China.
Sci Total Environ. 2024 Feb 1;910:168567. doi: 10.1016/j.scitotenv.2023.168567. Epub 2023 Nov 21.
Rainfall chemistry is a vital indicator for reflecting anthropogenic/natural input on atmospheric quality, and the rainfall process is also the main sink of air contaminants, which has received widely concerns by all walks of life. However, the chemical compositions, sources of major solutes, historical evolution, and their determinants of rainwater in Chinese urban area, which is hotspot of atmospheric pollutant emission, are unclear under the dual background of fast economic development and eco-civilization construction. To decipher these issues, the latest year data of observation-based rainwater chemistry and the historical rainwater data, and air pollution data of China's first eco-civilization demonstration city were integrated and studied. The results presented that SO (53.4 %) and NO (28.8 %), Ca (46.5 %) and NH (37.9 %) dominated the present rainwater anions and cations. The historical changes in the relative proportion of rainwater ions (e.g., the holistic decreasing trend of SO) revealed the reduction and management achievement of atmospheric pollutant emission driven by different stages of eco-civilization city construction. The atmospheric components were well removed by rainfall scouring and all the rainwater ions showed obvious temporal variations. The concentrations of most of ions were higher in winter but lower in summer due to the key factors of meteorological factor (mainly rainfall amount) and the seasonal variations of source contribution. The stoichiometry-based source identification and relative contribution calculation reflected that anthropogenic input was the most primary contributor of NO (99.4 %) and SO (95.4 %), and the contribution of fixed emission source was relatively higher than that of traffic sources. The NH was defined as the anthropogenic input ion (urban wastes and fuel combustion), while all Cl and Na were from oceanic input. In contrast, terrigenous input represented the most important origin of Ca, K, and Mg, with relative contribution of 99.5 %, 97.0 %, and 90.7 %, respectively. The high neutralization factor (NF, about 2.0) values and neutralizing to acidifying potential (NP/AP, about 1.7) ratios and their increasing trend in past few decades revealed the fact of rainwater acid being highly neutralized under the background of eco-civilization city construction.
降雨化学是反映人为/自然因素对大气质量影响的重要指标，降雨过程也是空气污染物的主要汇，这已受到各界广泛关注。然而，在经济快速发展和生态文明建设的双重背景下，作为大气污染物排放热点地区的中国城市地区雨水的化学成分、主要溶质来源、历史演变及其影响因素尚不清楚。为了解决这些问题，整合并研究了中国首个生态文明示范城市基于观测的雨水化学最新年份数据、历史雨水数据以及空气污染数据。结果表明，当前雨水中阴离子以硫酸根（53.4%）和硝酸根（28.8%）为主，阳离子以钙离子（46.5%）和铵根离子（37.9%）为主。雨水离子相对比例的历史变化（如硫酸根的整体下降趋势）揭示了生态文明城市建设不同阶段大气污染物排放的减少和治理成效。降雨冲刷对大气成分有良好的去除作用，所有雨水离子均呈现明显的时间变化。由于气象因素（主要是降雨量）和源贡献的季节变化等关键因素，大多数离子浓度冬季较高而夏季较低。基于化学计量学的源识别和相对贡献计算表明，人为输入是硝酸根（99.4%）和硫酸根（95.4%）的最主要贡献源，固定排放源的贡献相对高于交通源。铵根离子被定义为来自人为输入（城市废弃物和燃料燃烧），而所有氯离子和钠离子均来自海洋输入。相比之下，陆源输入是钙离子、钾离子和镁离子的最重要来源，相对贡献分别为99.5%、97.0%和90.7%。高中和因子（NF，约2.0）值和中和与酸化潜力比（NP/AP，约1.7）及其在过去几十年的上升趋势揭示了在生态文明城市建设背景下雨水酸度被高度中和的事实。
