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区域环境与生态

On-line analysis the water-soluble chemical of PM_2.5 in late summer and early autumn in Beijing

摘要：利用大气细颗粒物快速捕集分析系统和微量天平方法实时、在线分析了北京夏末秋初PM_2.5中水溶性无机盐和PM_2.5质量浓度的变化,并结合气象资料和部分前体物SO₂、NO_x监测数据进行了相关分析.结果表明,北京夏末秋初空气质量良好时,PM_2.5日平均浓度为61.0±30·6μg·m^-3,其中水溶性无机盐占PM_2.5的40%～56%,(亚)硝酸盐、硫酸盐、铵盐是水溶性无机盐中的主要成分,占所测水溶性组分的80%以上.SO₂向硫酸盐的转化率高于NO_x向(亚)硝酸盐的转化率.亚硝酸盐浓度受气象要素和大气化学过程影响,白天亚硝酸盐有向硝酸盐转化的趋势.

Abstract：The concentration of water-soluble chemical in PM_2.5 and the mass concentration of PM_2.5 during 19 August to 15 September in Beijing was analyzed by using the system of rapid collection of fine particles and RP1400a, and at the same time, the meteorological data and SO₂, NO_x data were also analyzed. The results showed that the average concentration of PM_2.5 was (61.0±30.6)μg·m^-3 in the good air quality period , and the proportion of water-soluble chemical in PM_2.5 was 40%～56%. Nitrite, nitrate, sulfate and ammonium were the dominant water-soluble chemical, constituting more than 80% of water-soluble chemical, and they appeared daily variation obviously. The ratio of SO₂ to SO₄^2- was higher than that of NO_x to NO₂^- and NO₃^-. The concentration of nitrite had relation with meteorological element and atmospheric chemistry reactions, and nitrite transformed into nitrate in daytime.