Atmospheric deposition characteristics and fluxes of heavy metals in Lake Ulansuhai

Abstract

重金属元素以大气颗粒物为载体,最终以沉降的方式进入湖泊水体,会引起湖泊的重金属污染.为调查大气沉降对乌梁素海重金属污染的贡献,于2013年7月1日至30日围绕乌梁素海进行大气沉降样品采集,分别测定Cu、Zn、Pb、Cd、Cr、Hg、As 7种重金属元素的含量,并在此基础上估算7月大气重金属沉降通量及入湖量.结果表明,乌梁素海重金属元素大气沉降通量大小依次为:Zn >Pb >Cu >Cr >As >Hg >Cd.结合社会调查情况及数据分析显示,大气微粒携带重金属借助风力迁移,较大的沉降通量出现在主风向的下风向区域,说明风向是影响乌梁素海大气重金属沉降通量的主要因素之一.排干输入与大气沉降方式下的乌梁素海重金属入湖量比较发现,大气沉降是除排干输入外湖泊的另一重要重金属污染源.Zn、Pb、Cu、Cr、As、Hg、Cd等重金属元素月入湖量分别为10.6、1.04、1.02、0.833、0.342、0.00514、0.00281t/月.通过估算底泥重金属增量来评价大气沉降对湖泊重金属的贡献表明,大气Hg、Zn、Pb、Cu、As、Cd、Cr等重金属沉降对湖泊贡献率分别为46.4%、44.7%、14.1%、12.0%、8.48%、4.75%、4.03%.;This paper studied heavy metal pollution of the Lake Ulansuhai caused by atmospheric deposition. Atmospheric deposition samples using a wetting method were collected in 1-30 July, 2013 around the lake. The monthly deposition flux and the heavy metal elements of Cu, Zn, Pb, Cd, Cr, Hg and As deposition to the lake were measured. The element deposition flux ranked in Zn >Pb >Cu >Cr >As >Hg >Cd. The Lake Ulansuhai social investigation and data analysis showed that a larger deposition flux was distributed under the main wind direction as the heavy metals absorbed on the atmospheric particles moved and deposited relying on the wind. Wind is one of the factors affecting the Take Ulansuhai atmospheric heavy metals deposition flux. Besides the large heavy metal amount entering into the lake in the way of draining, the atmospheric deposition was another important pollution sources. The monthly atmospheric deposition amount of Zn, Pb, Cu, Cr, As, Hg and Cd into the lake were 10.6, 1.04, 1.02, 0.833, 0.342, 0.00514 and 0.00281 t/month. The heavy metal pollution contribution by the atmospheric deposition was estimated by the increment of heavy metals in the sediments. The atmospheric deposition contribution of Hg, Zn, Pb, Cu, As, Cd and Cr are estimated with 46.4%, 44.7%, 14.1%, 12.0%, 8.48%, 4.75% and 4.03%, respectively.