重庆市黔江区降水地球化学特征

为了解生态旅游城市重庆市黔江区大气污染状况,2015年采集了91个降水样品,分析了降水中离子组分分布特征,运用富集因子法、海盐示踪法、相关性分析、主成分分析、聚类分析和HYSPLIT模型分析了降水化学组分来源。研究结果表明:黔江区域降水p H为5.66~6.96,加权平均值为6.34,降水离子组分浓度大小次序为SO_4~(2-)Ca~(2+)NH_4~+Mg~(2+)NO_3~-Cl~-Na~+K~+F~-,SO_4~(2-)、Ca~(2+)之和占总离子的63.95%;除Mg~(2+)和K+外,其余组分离子浓度与总离子浓度随季节变化(冬季春季秋季夏季)呈同样的变化特征。Ca~(2+)、Mg~(2+)和K+大部分均来源于陆源贡献,Na~+可能受到了海洋源的影响,SO_4~(2-)和NO_3~-主要来源于人为输入源的贡献,Cl~-是受土壤物质和海洋的双重影响。轨迹水汽运输结果表明:黔江区域的降水主要受到西北气团、西南季风、西风环流和极地气候共同作用输入。降水中各个离子组分均表现出显著性或极显著性关系,主成分分析结果表明,第一主成分上研究的降水离子组分中都具有相对较大正载荷,第二组分pH、降水量和气温为一类。

The Geochemical Character of Precipitation of Qianjiang District in Chongqing

To better evaluate the atmospheric pollutants status of Qianjiang district in Chongqing, which is a typical ecotourism city, 91 precipitation samples were collected in 2015. The characteristics of ionic components in precipitation samples were analyzed, and then the sources of precipitation chemical compositions were studied, using HYSPLIT model, cluster analysis, principal component analysis, correlation analysis, ions tracer techniques and enrichment factor. The results showed that the pH of precipitation samples varied from 5.66 to 6.99, with the volume-weighted average of 6.34. Ionic concentration was SO₄^2- > Ca²⁺ > NH₄⁺ > Mg²⁺ > NO₃^- > Cl^- > Na⁺ > K⁺ > F^- in those precipitation samples, in which SO₄^2- and Ca²⁺ contributed significantly to ions of precipitation and they accounted for 63.95%. Ionic components and total ion concentration changed with the seasons (winter > spring > autumn > summer) except Mg²⁺ and K⁺. Ca²⁺, Mg²⁺ and K⁺ were most derived from terrestrial sources, Na⁺ was be affected by marine, SO₄^2- and NO₃^- were mostly attributed by the anthropogenic activities, Cl^- derived from both the soils and sea sources. Backward trajectory analysis results showed that the transport precipitation in Qianjiang was affected by the northwest air, southwest monsoon, the west wind circulation and the polar climate input joint action. Ionic components in precipitation samples also had a very significant or significant impact. The principal component analysis results showed that the first principal component ion precipitation component had relatively load, and also pH, precipitation and temperature were the second component.