2009—2018年拉萨市降水化学组成特征及变化趋势  

Chemical Characteristics and Trends of Atmospheric Precipitation in Lhasa from 2009 to 2018

作　　者：索娜卓嘎 赵矿 陈旭 王彩红 杨凤琴 葛梦娟 张继峰 董慧科 周云桥 SUONA Zhuoga;ZHAO Kuang;CHEN Xu;WANG Caihong;YANG Fengqin;GE Mengjuan;ZHANG Jifeng;DONG Huike;ZHOU Yunqiao(Tibetan Ecology and Environment Monitoring Center,Lhasa 850000,China;Tibet University,Key Laboratory of Tibetan Plateau Biodiversity and Ecological Environment Protection,Ministry of Education,Lhasa 850000,China;Tibet University,Lhasa Urban Wetland Ecosystem Observation and Research Station of Tibet Autonomous Region,Lhasa 850000,China;Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China)

机构地区：[1]西藏自治区生态环境监测中心,西藏拉萨850000 [2]西藏大学青藏高原生物多样性与生态环境保护教育部重点实验室,西藏拉萨850000 [3]西藏大学拉萨城市湿地生态系统西藏自治区野外定位观测站,西藏拉萨850000 [4]中国科学院青藏高原研究所,北京100101

出　　处：《中国环境监测》2024年第6期104-111,共8页Environmental Monitoring in China

基　　金：国家自然科学基金资助项目(42107438,42007359);中国博士后科学基金项目(2020M680696)。

摘　　要：基于2009—2018年采集的拉萨市270个降水样品,分析了降水的pH、电导率、水溶性离子浓度特征及变化趋势;应用相关性分析和主成分分析等溯源方法,探讨了降水中水溶性离子的潜在来源。结果表明:拉萨市降水年均pH变化范围为7.34~7.87,平均值为7.56,呈弱碱性;电导率变化范围为1.24~5.64 mS/m,平均值为3.91 mS/m,低于北京市、西安市等大部分城市。降水中水溶性离子平均浓度大小顺序为Ca^(2+)>SO_(4)^(2-)>Cl^(-)>K^(+)>Mg^(2+)>NO_(3)^(-)>Na^(+)>NH_(4)^(+)>F^(-)。近年SO_(4)^(2-)、Cl^(-)、NO_(3)^(-)等阴离子浓度占比迅速升高的趋势需要格外警惕。来源分析表明:阴离子的来源较为一致,主要来自汽车尾气排放;阳离子Ca^(2+)和Mg^(2+)主要来自地表土壤和浮尘,它们对降水pH起到了中和作用。In this study,we analyze 270 precipitation samples collected in Lhasa city over the past decade(2009-2018)to examine the characteristics and trends of pH,conductivity,and water-soluble ion concentrations in precipitation.By employing traceability methods such as correlation analysis and principal component analysis,we explore the potential sources of watersoluble ions in precipitation.The findings reveal that the annual average pH of precipitation in Lhasa ranges from 7.34 to 7.87,with a mean value of 7.56,indicating weak alkalinity.The conductivity variation ranges from 1.24 to 5.64 mS/m,with an average of 3.91 mS/m,which is lower than that of major cities like Beijing and Xi'an.The average concentration of water-soluble ions in precipitation follows the order:Ca^(2+)>SO_(4)^(2-)>Cl^(-)>K^(+)>Mg^(2+)>NO_(3)^(-)>Na^(+)>NH_(4)^(+)>F^(-).Notably,the percentage of anion concentrations,including SO_(4)^(2-)、Cl^(-)、NO_(3)^(-),has shown a rapid increase in recent years,highlighting a concerning trend that warrants additional attention.Source analysis suggests that anions likely originate from vehicle emissions,exhibiting a more consistent source,while cations such as Ca^(2+)and Mg^(2+)primarily come from surface soil and floating dust,acting as neutralizers of precipitation pH.

关 键 词：特征分析 降水 化学组成 长期观测 拉萨市 

分 类 号：X823[环境科学与工程—环境工程]