重金属在灰尘及其水溶解相中的分布特征及其影响因素——以南昌市为例

Partitioning behavior and influence factors of heavy metals between settled dust and its extracted water phase:a case study of Nanchang city

以南昌市为例,分析了不同功能区和公交车站降尘及其水溶解相中重金属浓度的空间分布特征.同时结合多种分析技术,探究降尘及其水溶解相理化性质对降尘重金属在固-液相中分配行为的影响.结果表明:南昌市降尘及其水溶解相中总重金属浓度范围分别为310~4393μg/g和2.17~55.62μg/g.两相中重金属的空间分布可能受到车流量较大的交通干线和汽车轮胎零件磨损的影响,其高值区主要分布于南昌县政府、部分高校以及客运站、驾校附近.风险评价的结果表明,南昌市降尘重金属综合生态风险总体处于中等水平,且Cr和As具有一定的致癌风险.溶解态中重金属所占百分比(K值)的排序为:Ni>Mn>Cu>As>Cr>Zn>Pb,K值的空间分布高值区多分布于人口密集地区、交通道路以及汽车客运站附近.大部分降尘及其水溶解相的理化性质与Pb、As、Mn具有显著正相关关系,降尘溶解相中较高的溶解性有机碳和腐殖化程度对重金属向溶解相中的释放具有重要作用.

The spatial distribution of heavy metal concentrations in dust and its dissolved phase in different functional areas and bus stations was analyzed in Nanchang City.In addition,the influence of the physicochemical properties of dust and its dissolved phase on the partitioning behavior of heavy metals in the solid-liquid phase of dust was investigated by combining various analytical techniques.Results showed that the concentrations of total heavy metals in the dust and its dissolved phase in Nanchang city were 310~4393μg/g and 2.17~55.62μg/g.The spatial distribution of the heavy metals in the dust and its dissolved phase might be influenced by the traffic arteries with high traffic flow and the wear of automobile tire parts,and the high-value areas were mainly located near Nanchang County Government,some colleges and universities,passenger stations and driving schools.Results of the risk assessment indicated that the comprehensive ecological risk of heavy metals from dust in Nanchang City was generally at a medium level,and Cr and As had a certain carcinogenic risk.The percentage of heavy metals in the dissolved phase in the dust(i.e.K value)was ordered as follows:Ni>Mn>Cu>As>Cr>Zn>Pb.The higher K values were primarily located in the densely populated areas,traffic roads,and near passenger stations.Most of the physicochemical properties of the dust and its dissolved phase had a significant positive correlation with the distribution of Pb,As and Mn,and the higher dissolved organic carbon and humification degree in the dissolved phase had a dominant effect on the release of heavy metals from dust to the dissolved phase.