Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Institute of Atmospheric Science, Fudan University, Shanghai, 200433, PR China.
Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Institute of Atmospheric Science, Fudan University, Shanghai, 200433, PR China; Collaborative Innovation Center of Atmospheric Environment and Equipment Technology CICAEET, Nanjing University of Information Science and Technology, Nanjing 210044, PR China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200092, PR China.
Environ Pollut. 2019 Nov;254(Pt A):112941. doi: 10.1016/j.envpol.2019.07.109. Epub 2019 Jul 26.
China continues to suffer from severe acid deposition, despite the government implying a series of policies to control air pollution. In this study, rainwater samples were collected from 2011 to 2016 in Sichuan province to measure the pH values and the concentrations of nine inorganic ions (SO, NO, NH, Cl, Na, Ca, K, Mg, and F), and then to investigate their spatiotemporal variations. Besides, the dominant sources for the acidic ions in the precipitation were also revealed by statistical model. The results showed that the rainwater continued to be highly acidic, and the Volume-Weighted Mean (VWM) pH value was calculated to be 5.18 during 2011 and 2016. NH, Ca, NO, and SO were the dominant water-soluble inorganic ions, accounting for 79.2% of the total ions on average. The remarkable decrease in NO and SO concentrations (from 75.9 to 54.3 μeq L and from 285 to 145 μeq L, respectively) resulted in an increase in the pH value of rainwater from 5.24 in 2011 to 5.70 in 2016. The concentrations of SO, NO, F, Na, and K showed remarkably seasonal variation, with the highest value observed in winter, followed by spring and autumn, and the lowest value observed in summer. High VWM concentration of these ions in winter were mainly due to adverse meteorological conditions (e.g., rare rainfall, lower planetary boundary height, and stagnant air) and intensive anthropogenic emissions. SO, NO, and F ions peaked in the southeastern Sichuan province, which is a typical industrial region. NH concentrations decreased from 268 μeq L in the east to 10.4 μeq L in the western Sichuan province, which could be related to the development of agriculture in the eastern Sichuan province. Ca peaked in southeastern Sichuan province due to intensive construction activities and severe stone desertification. On the basis of Positive Matrix Factorization (PMF) analysis, four sources of inorganic ions in rainwater were identified, including anthropogenic source, crust, biomass burning, and aging sea salt aerosol. Geographically Weighted Regression (GWR) was used to find the spatial correlations between the socio-economic factors and ions in the rainwater. At the regional scale, the influence of fertilizer consumption and Gross Agricultural Production (GAP) on NH increased from east to west; moreover the influence of Gross Industrial Production (GIP) on SO and NO also increased.
尽管政府出台了一系列控制空气污染的政策，但中国仍持续遭受严重的酸沉降问题。本研究于 2011 年至 2016 年在四川省采集雨水样本，测量 pH 值和九种无机离子（SO、NO、NH、Cl、Na、Ca、K、Mg 和 F）的浓度，以探究其时空变化。此外，还通过统计模型揭示了降水酸性离子的主要来源。结果表明，雨水仍呈强酸性，2011 年至 2016 年期间的体积加权平均值（VWM）pH 值为 5.18。NH、Ca、NO 和 SO 是主要的水溶性无机离子，平均占总离子的 79.2%。NO 和 SO 浓度的显著下降（分别从 75.9 μeq L 降至 54.3 μeq L 和从 285 μeq L 降至 145 μeq L）导致雨水 pH 值从 2011 年的 5.24 上升至 2016 年的 5.70。SO、NO、F、Na 和 K 的浓度呈现明显的季节性变化，冬季浓度最高，其次是春季和秋季，夏季浓度最低。冬季这些离子的 VWM 浓度高主要是由于恶劣的气象条件（如降雨稀少、边界层高度较低、空气停滞）和密集的人为排放。SO、NO 和 F 离子在四川东南部达到峰值，该地区是典型的工业区域。NH 浓度从四川东部的 268 μeq L 降至西部的 10.4 μeq L，这可能与四川东部农业的发展有关。Ca 浓度在四川东南部达到峰值，这是由于密集的建设活动和严重的石漠化。基于正定矩阵因子分析（PMF），确定了雨水无机离子的四个来源，包括人为源、地壳、生物质燃烧和老化海盐气溶胶。地理加权回归（GWR）用于发现雨水离子与社会经济因素之间的空间相关性。在区域尺度上，肥料使用量和农业生产总值（GAP）对 NH 的影响从东向西增加；此外，工业生产总值（GIP）对 SO 和 NO 的影响也在增加。
