The acidification process under the cloud in Southwest China : Observation results and simulation
The acidification process under the cloud in Southwest China : Observation results and simulation
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DOI：
10.1016/s1352-2310(96)00247-6
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发表时间：
1997-03
影响因子：
5
通讯作者：
Hengchi Lei;P. Tanner;Mei Huang;Zhi-Lai Shen;Yulin Wu
中科院分区：
文献类型：
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作者：
Hengchi Lei;P. Tanner;Mei Huang;Zhi-Lai Shen;Yulin Wu
报告了 1985 年至 1989 年采样期间中国西南 (SW) 和东部 (E) 城市、郊区和农村地区雨水 (RW) 和云水 (CW) 中的平均离子浓度。在中国西南地区，氨、钙、氢阳离子以及硫酸根阴离子在RW城市中含量较高。这些离子的平均浓度在 CW 中均较低，因此冲洗是导致酸化的主要过程。冲刷对郊区也很重要，但降雨提供了农村地区降水的大部分酸度。短时间间隔内对 CW 和 RW 浓度的同时观测证实了重庆和贵阳等大城市的冲刷过程占主导地位。 CW 和 RW 的化学成分随着天气系统行为以及采样位置的变化而变化。在中国东部，降雨的酸度很大程度上被碱性颗粒物中和。 1985年至1988年，RW的平均离子浓度呈上升趋势。同期，中国环境空气质量恶化，二氧化硫和悬浮颗粒物浓度较高。云下酸化过程已通过包括气体和气溶胶物质清除的模型进行了模拟。发现降雨、气体冲刷或气溶胶冲刷过程的重要性随位置和所考虑的不同离子种类而变化。气体冲刷总是导致整体酸化。一些郊区已发现气溶胶碱化。还模拟了二氧化硫气体排放减少对雨水酸化的影响，预计在重庆和贵阳可以忽略不计。这些地区降雨 pH 值的控制因素是过氧化氢氧化剂的浓度，而不是污染物二氧化硫的浓度。
Mean ionic concentrations in rain water (RW) and cloud water (CW) for urban, suburban and rural locations in southwest (SW) and eastern (E) China, from sampling periods between 1985 and 1989 are reported. In SW China the ammonium, calcium and hydrogen cations, and the sulphate anion are present at elevated levels in urban RW. The mean concentrations of these ions are all lower in CW, so that washout is the predominant process leading to acidification. Washout is also important over suburban regions but rainout provides most of the acidity of precipitation in rural areas. Simultaneous observations of CW and RW concentrations over short time intervals have confirmed the dominance of washout processes in the large cities Chongqing and Guiyang. The chemical compositions of CW and RW exhibit changes with the weather system behaviour as well as with the sampling location. In E China the acidity of rainfall is largely neutralized by alkaline particulates. The mean ionic concentrations in RW show an increasing trend from 1985 to 1988. The ambient air quality in China has deteriorated over the same period, with concentrations of sulphur dioxide and suspended particulates at high levels. The below-cloud acidification process has been simulated by a model which includes scavenging of both gas and aerosol species. The importance of rainout, gas washout or aerosol washout processes is found to vary with the location and with the different ion species considered. Gas washout always leads to overall acidification. Aerosol alkalization has been identified in some suburban areas. The effects on the rainwater acidification predicted from the reduction of sulphur dioxide gas emissions have also been simulated, and are expected to be negligible at Chongqing and Guiyang. The concentration of the hydrogen peroxide oxidant, not that of the pollutant sulphur dioxide, is the controlling factor for the pH of the rainfall in these regions.