自贡市空气PM2.5及4种水溶性离子污染监测结果分析

Analysis of fine particulate air pollution(PM2.5)and four kinds of water soluble ion pollution in Zigong

目的根据常规监测与重污染天监测结果分析自贡市城市环境空气PM2.5质量浓度及4种水溶性离子污染分布特征。方法于2016-2018年选择自贡市自流井、贡井城区作为研究的监测区,以每月10-16日作为开展研究常规监测天,以每月1-9日、17-31日上午8时AQI>200作为开展研究重污染天监测;用滤膜法进行空气采样,重量法进行PM2.5质量浓度监测;用浸水超声提取、离子色谱法进行离子浓度监测。结果常规监测PM2.5质量浓度年平均均在80μg/m^3及以下,日平均浓度超标率39.3%,2016-2018年不同年度常规监测PM2.5年平均质量浓度的超标率差异有统计学意义(χ^2=21.66,P<0.05),SO42-、NO3^-、Cl^-、NH4^+离子浓度总和占PM2.5质量浓度49.0%,日平均浓度排列为:NO3^->SO4^2->NH4^+>Cl^-。重污染天监测PM2.5质量浓度年平均130μg/m^3以上,2016年重污染天占总重污染天53.7%;冬季和1月份分别占重污染天监测总天数82.9%、68.3%,SO4^2-、NO3^-、Cl^-、NH4^+离子浓度总和占PM2.5质量浓度60.0%,日平均浓度排列为:NO3^->NH4^+>Cl^->SO4^2。常规监测与重污染天监测PM2.5质量浓度的年度、季度、月度及地区等分布与4种离子浓度分布一致。结论减少4种水溶性离子污染是防控重污染发生及降低PM2.5污染重要措施。

Objective To analyze mass concentration of PM2.5 and distribution of water soluble ion pollution in urban Zigong based on emergency and routine monitoring results.Methods Ziliujing and Gongjing region in urban Zigong were selected as the monitoring areas from Apr 2016 to Mar 2018.The emergency monitoring days were defined as AQI>200 on eight in the morning from 1st to 9th and 17th to 31st on each month,and the regular monitoring days were defined from 10th to 16th on each month.Air sampling was collected by filter membrane method,and PM2.5 mass concentration was measured by gravimetric method.Both immersion ultrasonic extraction and ion chromatography were used to measure ion concentration.Results In the regular monitoring days,the annual average mass concentration of PM2.5 was at or under 80μg/m^3;the daily average polluted rate was 39.3%;The difference in the exceeding rate of PM2.5 arerage mass concentration in different years from 2016 to 2018 was statistically significant.SO4^2-、NO3^-、Cl^-、NH4^+ion concentration accounted for 49.0%of PM2.5 mass concentration;the daily average concentration was arranged as follows:NO3^->SO4^2->NH4^+>Cl^-.In emergency monitoring days,the annual average mass concentration of PM2.5 was at or above 130μg/m3;the daily average polluted rate was 53.7%;the winter and January accounted for 82.9%and 68.3%of the total number of haze days,respectively;SO4^2-、NO3^-、Cl^-、NH4^+ion concentration accounted for 60.0%of PM2.5 mass concentration;the daily average concentration was arranged as follows:NO3^->NH4^+>Cl^->SO4^2-.The annual,quarterly,monthly and regional distribution of PM2.5 mass concentration was consistent with the distribution of four kinds of ion concentration in emergency and regular monitoring days.Conclusion Reducing water soluble ion pollution is an important measure to prevent and control the occurrence of haze and PM2.5 pollution.