昆明市主城区大气降水的化学组成特征及变化分析

Characteristics and Variations Analysis on Chemical Composition of Atmospheric Precipitation of Kunming

为了解昆明市主城区大气降水的化学组成成分及变化,采集2019年1—12月期间昆明市主城区大气降水样品,分析pH、电导率、阴离子(SO_(4)2-、NO_(3)-、Cl-、F-)和阳离子(K^(+)、Na^(+)、Ca^(2+)、Mg^(2+)、NH_(4)^(+))。分析结果表明昆明市主城区降雨量主要集中在6—9月,占全年降雨量的87.6%。全年未监测到酸雨,降水pH值范围为6.93~7.70,年均值为7.28,其中中性降水占26.3%,碱性雨占73.7%。降水阴离子以SO_(4)^(2-)为主,占阴离子总量的53.7%,其次为NO_(3)-;降水阳离子以Ca^(2+)为主,占降水阳离子总量的65.4%,其次为钾离子。与2018年相比,大气降水pH值变化不明显,降水主要离子中SO_(4)^(2-)浓度降低,Ca^(2+)浓度显著升高,其余离子浓度变化不明显。

In order to examine the chemical characteristics and variations of atmospheric precipitation of Kunming,the parameters of rainfall,pH,electrical conductivity and concentrations of anions(SO_(4)^(2)-,NO_(3)-,Cl-,F-)and cations(K^(+),Na^(+),Ca^(2+),Mg^(2+),NH_(4)^(+))were analyzed with samples collected from January to December 2019.The results indicated that the rainfall was mainly concentrated from June to October in 2019 with 87.6%of the whole year.There was no acid rain during the whole year,because the range of pH values was from 6.93 to 7.70.SO_(4)^(2-)was the major anion with 53.7%of the total ions while Ca^(2+)was the main cations with 65.4%of all.Compared to 2018,the concentration of SO_(4)^(2-)reduced while the concentration of Ca^(2+)increased significantly.