北京城区大气金属元素干湿沉降特征  

Concurrent Measurement of Wet and Bulk Deposition of Trace Metals in Urban Beijing

作　　者：张国忠[1,2] 潘月鹏 田世丽[2] 王永宏[2] 熊秋林 李广 顾梦娜[2] 吕雪梅 倪雪 何月欣 黄威 刘博文 王跃思 ZHANG Guo-zhong;PAN Yue-peng;TIAN Shi-li;WANG Yong-hong;XIONG Qiu-lin;LI Guang;GU Meng-na;LU Xue-mei;NI Xue;HE Yue-xin;HUANG Wei;LIU Bo-wen;WANG Yue-si(College of Forestry,Gansu Agricultural University,Lanzhou 730070,China;State Key Laboratory of Atmospheric BoundaryLayer Physics and Atmospheric Chemistry,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China;Faculty of Geomatics,East China University of Technology,Nanchang 330013,China)

机构地区：[1]甘肃农业大学林学院,兰州730070 [2]中国科学院大气物理研究所大气边界层物理和大气化学国家重点实验室,北京100029 [3]东华理工大学测绘工程学院,南昌330013

出　　处：《环境科学》2019年第6期2493-2500,共8页Environmental Science

基　　金：国家重点研发计划项目(2016YFD0800302;2016YFC0201802)

摘　　要：为研究北京市大气中金属元素的干湿沉降特征,评估不同观测方法的差异性,于2014年5月至2015年4月在北京城区同步采集了混合沉降和湿沉降样品.利用电感耦合等离子体质谱仪(ICP-MS)测定了样品中19种金属(Na、Mg、Al、K、Ca、V、Cr、Mn、Fe、Cu、Zn、As、Se、Mo、Cd、Sb、Tl、Th和U)的浓度.结果表明,混合沉降样品中各金属浓度[7 160.68μg·L^(-1)(Ca)～0.02μg·L^(-1)(Th)]普遍高于湿沉降样品[4 237.74μg·L^(-1)(Ca)～0.01μg·L^(-1)(Th)].两种样品中相同金属的富集因子差异较小,其中Cu、As、Tl、Zn、Cd、Se和Sb的富集因子均大于100,表明这些重金属主要来自人为污染源.气团轨迹分析表明,北京城区降水过程主要受偏南气团的影响,其中来自西南气团的降水样品中Ca、Mg、Fe、Al、Cu、Mo、U和Th等金属浓度较高,而来自南部的气团K、Zn、Mn、Sb、Cd和Tl等金属浓度较高.观测期间大气中金属元素的混合沉降通量变化于3 591.35 mg·(m^2·a)^(-1)(Ca)～0.01 mg·(m^2·a)^(-1)(Th),湿沉降通量变化于1 847.78 mg·(m^2·a)^(-1)(Ca)～0.01mg·(m^2·a)^(-1)(Th).混合沉降与湿沉降差减得到19种金属的干沉降通量变化于1 743.57 mg·(m^2·a)^(-1)(Ca)～0.01mg·(m^2·a)^(-1)(Th).大气颗粒物的粒径大小对金属的干湿沉降过程具有重要影响.To characterize the dry and wet deposition of atmospheric trace elements in urban Beijing,both active and passive samplers were used to collect bulk and wet sedimentation samples between May 2014 and April 2015.The concentrations of 19 trace elements ( Na,Mg,Al,K,Ca,V,Cr,Mn,Fe,Cu,Zn,As,Se,Mo,Cd,Sb,Tl,Th,and U) in the samples were analyzed by inductively coupled plasma mass spectrometry ( ICP-MS).The results show that the concentrations of metals in bulk deposition samples [7 160. 68 μg·L ^-1 ( Ca)-0. 02 μg·L^-1 ( Th)] were generally higher than those in wet deposition samples [4 237. 74 μg·L ^-1 ( Ca)-0. 01 μg·L^-1 ( Th)],but the enrichment factors of each metal in the two kinds of samples were less different.Of note,the enrichment factors of Cu,As,Tl,Zn,Cd,Se,and Sb were all larger than 100,thus indicating that these heavy metals were mainly from anthropogenic sources.The statistical analysis of the air mass trajectory shows that the precipitation chemistry in urban Beijing is mainly affected by southward air flows.The air mass originating from the southwest region always had higher concentrations of Ca,Mg,Fe, Al,Cu,Mo,U,and Th,whereas the air mass from the south had higher concentrations of K,Zn,Mn,Sb,Cd,and Tl.During the observation period,the bulk deposition fluxes of metals varied from 3 591. 35 mg·( m^2·a)^-1 ( Ca)-0. 01 mg·( m^2·a)^-1 ( Th),and wet deposition fluxes varied from 1 847. 78 mg·( m^2·a)^-1 ( Ca)-0. 01 mg·( m^2·a)^-1 ( Th).The dry deposition fluxes of the 19 metals varied from 1 743. 57 mg·( m^2·a)^-1 ( Ca)-0. 01 mg·( m^2·a)^-1 ( Th).The particle size has important implications in the evaluation of the relative importance of dry deposition versus wet deposition during the scavenging of trace elements in air.

关 键 词：大气污染 金属 干沉降 湿沉降 混合沉降 

分 类 号：X513[环境科学与工程—环境工程]