杭州夏季一次降雨过程雨水中全氟化合物及主要化学组分的变化特征

Variation Characteristics of Perfluorinated Compounds and Major Chemical Components in Rainwater during A Summer Rainfall in Hangzhou

采用分段采样的方式收集杭州市2018年8月2日—3日一场降水样品,测定其中16种全氟化合物(PFCs)及主要化学组分浓度。结果发现,此次降雨过程水样的pH值范围为5.04~5.32,均为弱酸性降水,酸雨类型为复合型,检出的主要阳离子为NH^+_4,主要阴离子为SO■和NO^-_3;样品中检出7种中短链PFCs,包括2种全氟烷基磺酸(PFSAs)和5种全氟烷基羧酸(PFCAs),ΣPFCs质量浓度范围为4.41 ng/L^25.2 ng/L,主要污染因子全氟辛酸(PFOA)质量浓度范围为0.96 ng/L^13.1 ng/L;降雨过程对大气污染清除作用的统计结果表明,区域大气环境中的主要化学组分及除全氟丁酸(PFBA)之外的PFCs污染主要吸附在云下大气颗粒物上;雨水中各污染因子浓度变化特征及相关性统计结果提示,杭州市大气中PFCAs和PFSAs两类PFCs可能来自不同的污染源。

16 kind of perfluorinated compounds(PFCs)in the rainwater collected by sequential sampling during a rainfall from 2 nd to 3 rd August 2018 in Hangzhou were determined.Results showed that pH value of the samples were from 5.04 to 5.32,indicating the rain was weak acid and of composite type.NH+4 was the main detected cation,SO4^ 2- and NO-3 were the main anions.7 medium-short chain PFCs including 2 types of perfluoroalkyl sulfonic acid(PFSAs)and 5 types of perfluorinated carboxylic acid(PFCAs)were detected.The mass concentration ofΣPFCs ranged from 4.41 ng/L to 25.2 ng/L,the mass concentration of perfluorooctanoic acid which was the main pollution factor ranged from 0.96 ng/L to 13.1 ng/L.Statistical results of atmospheric pollution removal by precipitation indicated that except PFBA,PFCs and the major chemical components in the air were mainly adsorbed on the atmospheric particulates under the clouds.Statistical result from variation characteristics of concentration and the correlation of main pollution factors in the rainwater showed that PFCAs and PFSAs in the atmosphere of Hangzhou might come from different pollution sources.