夏季青岛大气粗细粒子中微量元素的浓度、溶解度及干沉降通量

利用2016年6~7月在青岛采集的PM_(2.5)和总悬浮颗粒物(TSP)样品,分析其中12种微量元素总态和溶解态浓度,讨论了微量元素在粗、细粒子中的浓度及溶解度的分布特征,并估算了微量元素的沉降通量.结果表明,青岛气溶胶中地壳元素Al、Fe、Sr、Mn、Ba总态浓度的55%~60%集中在粗粒子中,人为元素Cr、Ni、V、Zn、Pb、As、Cd的65%~85%集中在细粒子中.但无论是地壳元素还是人为元素其溶解态浓度均主要分布在细粒子中,Al、Fe、Mn、Ba在细粒子中的占比为50%~80%,Cr、Ni、V、Zn、Pb、As、Cd的为70%~90%.微量元素溶解度在细粒子中的高于粗粒子中的,细粒子中微量元素的溶解态浓度与酸组分呈显著正相关,溶解度与p H呈显著负相关,表明酸化作用可能是影响细粒子中微量元素溶解度的主控因子.不同微量元素的总沉降通量中溶解态部分的贡献不同,Al和Fe溶解态部分的贡献仅为1%~2%,Sr、Ba、Cr、Pb的约为30%~40%,Mn、Ni、V、Zn、As、Cd的约为50%~60%.大气沉降的溶解态Fe可支持(194±150)mg·(m2·d)-1浮游植物碳的生产,对黄海初级生产力的贡献约为10%.

Concentration, Solubility, and Dry Deposition Flux of Trace Elements in Fine and Coarse Particles in Qingdao During Summer

PM_2.5 and total suspended particulate (TSP) samples were synchronously collected in Qingdao from June to July 2016. The total and water-soluble concentrations of 12 trace elements in these samples were analyzed to investigate their distribution characteristics in fine and coarse particles as well as their dry deposition fluxes. The results showed that the total mass concentrations of Al, Fe, Sr, Mn, and Ba, which are expected to mainly originate from crustal sources, were generally distributed in the coarse particles, and the part mass in the coarse mode accounted for 55%-60% of their total concentrations. Cr, Ni, V, Zn, Pb, As, and Cd, which mainly originate from anthropogenic contributors, generally existed in fine particles where the part mass accounted for 65%-85% of their total concentrations. The soluble mass concentrations of trace elements, whether from crustal or anthropogenic sources, were mainly distributed in the fine particles. The proportions of Al, Fe, Mn, and Ba in soluble mass concentration existing in the fine particles were 50%-80% and 70%-90% for Cr, Ni, V, Zn, Pb, As, and Cd. The solubility of trace elements was higher in fine particles than in coarse particles. The soluble concentrations of trace elements exhibited a positive correlation with acid compounds, and the solubility exhibited a negative correlation with pH in the fine particles, implying that acidification processes play a key role in determining the solubility of trace elements in fine particles. The soluble fractions in the total dry deposition flux of Al and Fe were only 1%-2%; that of Sr, Ba, Cr, and Pb were about 30%-40%; and that of Mn, Ni, V, Zn, As, and Cd were about 50%-60%. The atmospheric deposition of soluble Fe supported phytoplankton carbon production of (194±150) mg·(m²·d)^-1, contributing about 10% of the primary productivity in the Yellow Sea.