贵阳市冬季地表灰尘重金属含量动态变化及原因探析

本研究以贵阳市冬季地表灰尘和家庭燃煤为研究对象,分析了贵阳市冬季不同时段地表灰尘重金属含量的动态变化,以及家庭燃煤取暖排放的煤灰与煤尘对环境中重金属的排放影响.结果表明:贵阳市冬季前后不同时段地表灰尘重金属含量的动态变化规律为:As含量在初冬和晚冬时段均大于初春,Cu和Pb含量表现为晚冬初春初冬,Cd、Ni、Zn在3个时段的含量变化不大;冬季地表灰尘中Cd、Cu、Zn、Pb累积较重;燃煤中元素As、Cd、Pb、Zn主要富集于煤尘中,Ni、Cu则主要富集于煤灰中.贵阳市地表灰尘在晚冬、初春时段,细粒级灰尘所占质量占比明显高于初冬,而且晚冬灰尘中粗粒级所占质量比最低,3个时段中,晚冬时段灰尘中大部分重金属含量随粒级减小而增大的特征表现得最明显.家庭燃煤排放对地表灰尘中的As、Pb含量有一定的影响.

Dynamic changes and cause analysis of heavy metals in street dust in Guiyang City, China

Street dust and coal combustion emissions in Guiyang City, China in winter were collected for analyzing the dynamic changes of heavy metal concentrations in street dust and the contribution by coal combustion emissions. Results show that levels of Cd, Ni and Zn in street dust in Guiyang City are stable through early winter to late winter and early spring. Level of As in dust in early and late winter is higher than that in early spring; levels of Pb and Cu are the highest in late winter, followed by early spring and early winter. Cd, Cu, Zn and Pb are more accumulated in winter in the street dust. In coal combustion residuals, As, Cd, Pb and Zn are mainly accumulated in fly ash, while levels of Ni and Cu are higher in bottom ash than in fly ash. Street dust in late winter and early spring contains more fine fractions than that in early winter. In late winter, compared with fine and medium fractions, mass percentage of coarse fractions in street dusts is the lowest, and concentrations of most heavy metals increase with decreasing particle size. Domestic coal combustion potentially contribute to As and Pb in street dust.