中国东海近海气溶胶的陆源特征

The Continental Characteristic of Atmospheric Aerosol over the East China Sea

源于中国西北部的亚洲沙尘暴频繁发生于春季,经长途传输到中国近海,对大气环境和海洋初级生产力可能产生显著影响.选取中国东海的小洋山岛于2008年春季采集研究了PM2.5和TSP共78个样品.结果表明,TSP和PM2.5的日平均质量浓度分别为133.6μg/m3和53.2μg/m3.陆源特征明显,观测到的海盐气溶胶和矿物气溶胶约占总质量浓度的6%和23%左右,陆地上人为活动排放的污染物对小洋山岛气溶胶的贡献率在70%以上,且在偏西风主导风向下,气溶胶质量和主要离子元素的平均浓度最高,这在一定程度上说明了陆源输送是春季东海近海大气气溶胶的主要来源.陆源气溶胶和海盐粒子发生混合作用使得SO42-,NO3-和NH4+等二次气溶胶离子主要分布在粗颗粒物中.氯亏损率和元素富集系数(EF)也表明陆地上大量的酸污染和Cr,Cu,Pb,Cd,As,Zn等污染元素进入到了东海上空,可能对近海生态系统发生重要影响.

Asian dust originated from Northwestern China happened frequently during spring,reached China coast,and may exerted a significant effect on the atmospheric environment and marine primary productivity.Total 78 Aerosol samples of PM2.5 and TSP were collected at XYS Isle on East China Sea in spring,2008.The average concentrations of PM2.5 and TSP were 133.6μg/m3and 53.2μg/m3 respectively.The continental characteristic is obvious,sea salt and dust contributed to only about 6% and 23% of aerosol respectively,and therefore over 70% of aerosol mass was from the emission of human activities.The average concentrations of aerosol,main ions and elements were significantly higher under the prevailing wind direction of west compared those under other winds,suggesting that aerosol transported from continent was a dominant source for adjacent East China Sea in this season.SO2-4,NO-3 and NH＋4 preferentially distributed in coarse fraction rather than in PM2.5 as a result of the mixing and reaction among mineral,sea salt and pollutant aerosols.Chlorine depletion ratio and enrichment factors（EF） of elements also showed that huge amount of acid pollution and pollution element,e.g.Cr,Cu,Pb,Cd,S,As and Zn,in the aerosol were contributed dominantly by anthropogenic sources.These continental aerosols could influence of the air quality,marine primary production and global climate.