• 关键词：三峡库区  降水化学  酸雨  时空特征  大气污染

• 基金项目：国家水体污染控制与治理科技重大专项 (No.2012ZX07104-001)

• 鲁群岷
• 西南大学资源环境学院, 重庆 400715

• 赵亮
• 西南大学化学化工学院, 重庆 400715

• 李莉
• 重庆市环境监测中心, 重庆 401147

• 杨复沫
• 1. 中国科学院重庆绿色智能技术研究院三峡生态环境研究所, 重庆 401122;
  2. 重庆三峡学院三峡库区水环境演变与污染防治重庆高校市级重点实验室, 重庆 404100;
  3. 长江师范学院三峡库区生态环境监测和灾害防治工程技术研究中心, 重庆 408100

• 杨清玲
• 重庆市环境监测中心, 重庆 401147

• 魏世强
• 西南大学资源环境学院, 重庆 400715

• 欧阳文娟
• 中国科学院重庆绿色智能技术研究院三峡生态环境研究所, 重庆 401122

• 贺克斌
• 清华大学环境学院, 北京 100084

• 陈刚才
• 1. 重庆市环境监测中心, 重庆 401147;
  2. 长江师范学院三峡库区生态环境监测和灾害防治工程技术研究中心, 重庆 408100

• 摘要：对2000-2009年三峡库区巴南、涪陵和万州3个观测点降水的pH、电导率及其主要化学成分的时空变化进行了分析研究. 结果表明, 巴南、涪陵、万州降水pH平均值分别为5.76、6.03和5.52, 平均电导率分别为117.3、72.3和63.1 μS·cm^-1, 降水酸化趋势在逐渐增强, 污染程度高于北京、成都、深圳、湖南等地. 降水中SO₄^2-占阴离子总量的77%, NH₄⁺和Ca²⁺为主要的阳离子. 巴南、涪陵、万州3个监测点的/比值较低, 分别为0.125、0.164和0.169, 表明降水酸化类型为硫酸型. 由于排放与气象条件(包括降雨量等)的季节性变化, 各离子组分呈现明显的时空变化特征, 总体表现为冬春季降水中离子浓度高于夏秋季, 污染程度为巴南>涪陵>万州.

• Abstract：In order to understand the main chemical constituents within precipitations and their spatiotemporal variations in the Three Gorges Reservoir Region, the atmospheric precipitation samples were collected from three stations along the reservoir during 2000 to 2009. pH, conductivity, and ions were analyzed. Average pH values were 5.76, 6.03, and 5.52, and average conductivity were 117.3, 72.3, and 63.1 μS·cm^-1 in Banan, Fuling and Wanzhou, respectively. The rainwater in these districts exhibited a significant acidification trend over the past decade with more serious pollution levels than those in Beijing, Chengdu, Shenzhen, and Hunan. The concentration of SO₄^2- accounted for 77% of total anions, while NH₄⁺ and Ca²⁺ were the major cations. The relatively low mass ratio of NO₃^- to SO₄^2- in the three stations indicated that the type of rain acidity was still dominantly from sulfuric acid. The ionic constituents of precipitation presented clear spatial-temporal variations, due to seasonal variations in emissions and meteorology, including the rainfall intensity. The ion concentrations were higher in winter and spring and lower in summer and autumn. Precipitation pollution in the three stations exhibited a clearly decreasing trend with distance from downtown Chongqing.

• Key words：Three Gorges Reservoir Region  precipitation chemistry  acid rain  spatial-temporal variation  air pollution

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