北京市街道灰尘中重金属元素赋存状态及环境效应

Study on the Occurrence States of Heavy Metals in Street Dusts of Beijing City and Their Environmental Effects

摘要: 采用Tessier的五步提取法,对北京北西—南东剖面所采集的街道灰尘样品粒度 ≤100 μm组分中As、Cd、Cr、Hg、Pb和Zn等6元素的5个形态(可交换态、碳酸盐结合态、铁锰氧化物结合态、有机物结合态、残渣态)的分布特征研究发现,在可交换态和碳酸盐结合态中Cd的含量比都为最高,Pb、Hg、Zn和As在有机物结合态中含量比相近,铁锰氧化物结合态中Pb所占比例最高,而As 和Cr主要存在于残渣态中。6种街道灰尘污染元素的相对活动性和潜在生物利用度顺序为:Cd＞Zn＞Pb＞Cr＞Hg＞As。

Abstract: The street dusts (≤100 μm) were collected from NW-SE transects inside the sixth ring road in Beijing. Tessier sequential extraction method was used for the study on distribution of heavy metals of As, Cd, Cr, Hg, Pb and Zn in five fraction states including exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual, respectively. The results from the study showed that Cd presented higher affinity to the exchangeable fraction and the bound to carbonates fraction. Pb, Hg, Zn and As presented similar affinity to the organic fraction. Pb presented the dominant in the Fe-Mn oxide fraction and As and Cr existed mainly in the residual fraction. The apparent mobility and potential bioavailability for these 6 highly contaminating elements are in order of Cd＞Zn＞Pb＞Cr＞Hg＞As.