2020-2021年菏泽市大气PM_(2.5)中水溶性离子特征分析

Characteristics of water-soluble ions in atmospheric PM_(2.5)in Heze City,Shandong province from 2020 to 2021

目的了解菏泽市大气PM_(2.5)中F^(-)、Cl^(-)、NO_(3)^(-)、SO_(4)^(2-)和NH_(4)^(+)的污染状况,探讨其污染来源特征。方法2020年12月—2021年11月在菏泽市牡丹区和定陶区分别设立监测点,以中流量采样器采集大气中的PM_(2.5),以离子色谱仪测定样品中5种水溶性离子的含量。结果大气中的PM_(2.5)和水溶性离子具有大致相同的季节变化趋势,整体上看大多呈现冬季最高、春季略高于秋季、夏季最低的特征。菏泽市牡丹区大气PM_(2.5)质量浓度年平均值为69.48 g/m^(3),定陶区大气PM_(2.5)质量浓度年平均值为71.72 g/m^(3),两监测点大气PM_(2.5)中的NO_(3)^(-)、SO_(4)^(2-)、NH_(4)^(+)、Cl^(-)、F^(-)平均质量浓度也有所不同。菏泽市牡丹区和定陶区两监测点全年ρ(NO_(3)^(-))/ρ(SO_(4)^(2-))比值均值分别为1.54和1.53。结论菏泽市牡丹区和定陶区大气PM_(2.5)中F^(-)、Cl^(-)、NO_(3)^(-)、SO_(4)^(2-)和NH_(4)^(+)的质量浓度季节差异明显,移动源已经成为该市两区的主要污染源。

Objective To understand the pollution status of F^(-),Cl^(-),NO_(3)^(-),SO_(4)^(2-)and NH_(4)^(+)in PM_(2.5)and the pollution source characteristics in Heze City,Shandong province.Methods Two monitoring sites were set up in Mudan district and Dingtao district of Heze from December of 2020 to November of 2021.The fine particles in the atmosphere were collected by medium flow sampler,and the content of five water-soluble ions in the samples was determined by ion chromatography.Results PM_(2.5)in the atmosphere and water-soluble ions had the same seasonal variation trend,with the highest in winter,slightly higher in spring than in autumn,and the lowest in summer.The annual average PM_(2.5)mass concentration of the air in Heze,Mudan district was 69.48μg/m^(3),while the annual average PM_(2.5)mass concentration of the air in Dingtao district was 71.72μg/m^(3).The average mass concentrations of NO_(3)^(-),SO_(4)^(2-),NH_(4)^(+),Cl^(-),and F^(-)in atmospheric PM_(2.5)at the two monitoring sites were different also.The average ratio ofρ(NO_(3)^(-))/ρ(SO_(4)^(2-))in Mudan district and Dingtao district of Heze was 1.54 and 1.53 respectively.Conclusion The seasonal differences in the mass concentrations of F^(-),Cl^(-),NO_(3)^(-),SO_(4)^(2-)and NH_(4)^(+)in atmospheric PM_(2.5)in Mudan district and Dingtao district of Heze are obvious,mobile sources have become the main pollution sources in Heze City.