北京道路灰尘中重金属的污染特征及潜在生态风险

Hu Yue-Qi, Guo Jian-Hui, Zhang Chao, Wang Zheng, Yan Xu, Yang Dong-Yan, Liu Zhao-Ying

Beijing Key Laboratory of Airborne Particulate Matter Monitoring Technology, Beijing Municipal Environmental Protection Monitoring Center, Beijing 100048, China.

Huan Jing Ke Xue. 2019 Sep 8;40(9):3924-3934. doi: 10.13227/j.hjkx.201903094.

Based on the concentrations of 21 inorganic elements in particulate matter with diameters less than 10 μm (PM) in 2004, and PM in 2004 and 2013 of representative road dust in Beijing, the pollution characteristics and potential ecological risks of heavy metals in this dust were analyzed and discussed. The results showed that the six main elements in road dust in Beijing were Si, Ca, Al, Fe, Mg, and K, and the proportions of the total content of the six elements in PM in 2004, PM in 2004, and PM in 2013 accounted for 96.51%, 96.42%, and 96.53% of the total content of all elements tested, respectively. The elemental enrichment level and the pollution degree and the potential ecological risk of heavy metal in road dust in Beijing in 2004 were PM>PM. Se, a characteristic element of coal dust, was highly enriched in PM in 2004, and Cd was high in PM and PM in 2004 with enrichment factors of 1024.03, 68.15, and 871.55, respectively. Co, Zn, Ca, and Cu were significantly enriched in PM and PM in 2004 with enrichment factors of 12.93, 12.33, 8.30, and 8.07 in PM and 17.41, 21.80, 12.83, and 19.73 in PM, respectively; Na and Si were not enriched in the road dust. The pollution load index (PLI) of heavy metals was 3.95 in PM and 7.71 in PM in 2004. Owing to the implementation of dust, motor vehicles, and combustion source control measures in Beijing and the relocation of the Shougang corporation, the elemental enrichment level, pollution degree, and potential ecological risk of heavy metals in road dust PM in 2013 were significantly lower than those in 2004. The enrichment factors of Cd and Se in PM in 2013 decreased to 98.47 and 0.95, respectively; those of Cu, Ca, and Zn decreased to 11.90, 8.84, and 8.20, respectively; and PLI decreased to 2.56. The results showed that the total potential ecological risk of heavy metals in road dust in Beijing was extremely strong. Heavy metal Cd was the most significant pollution factor and the main potential ecological risk source; its potential ecological risk index (RI) contribution to the total RI of heavy metals was more than 85%. In 2004, the pollution degree of heavy metals in road dust of main roads was significantly higher than that for other road types. The pollution degree of heavy metals in PM was main road > expressway entrance to Beijing > secondary main road > ring road; that for PM was main road > ring road > expressway entrance to Beijing > secondary main road. For PM in 2013, however, the order was expressway entrance to Beijing > main road > ring road > secondary main road. The pollution degree of heavy metals in road dust of secondary main roads was significantly lower than that for other road types. In 2013, for road dust PM in Beijing, the correlation of heavy metals Ti, Zn, V, Cr, Cu, Pb, and Ni was significant owing mainly to traffic-related emissions.

基于2004年北京市直径小于10μm颗粒物（PM）中21种无机元素的浓度，以及2004年和2013年北京市代表性道路灰尘的PM数据，分析和讨论了该灰尘中重金属的污染特征和潜在生态风险。结果表明，北京市道路灰尘中的六种主要元素为Si、Ca、Al、Fe、Mg和K，这六种元素在2004年PM、2004年道路灰尘PM和2013年道路灰尘PM中的总含量占所有测试元素总含量的比例分别为96.51%、96.42%和96.53%。2004年北京市道路灰尘中元素的富集水平、污染程度及重金属潜在生态风险为PM＞道路灰尘PM。煤尘特征元素Se在2004年PM中高度富集，Cd在2004年道路灰尘PM和PM中含量较高，富集因子分别为1024.03、68.15和871.55。Co、Zn、Ca和Cu在2004年道路灰尘PM和PM中显著富集，PM中富集因子分别为12.93、12.33、8.30和8.07，PM中分别为17.41、21.80、12.83和19.73；Na和Si在道路灰尘中未富集。2004年道路灰尘中重金属污染负荷指数（PLI），PM为3.95，道路灰尘PM为7.71。由于北京市实施了扬尘、机动车和燃烧源控制措施以及首钢的搬迁，2013年道路灰尘PM中元素的富集水平、污染程度及重金属潜在生态风险均显著低于2004年。2013年道路灰尘PM中Cd和Se的富集因子分别降至98.47和0.95；Cu、Ca和Zn的富集因子分别降至11.90、8.84和8.20；PLI降至2.56。结果表明，北京市道路灰尘中重金属的总潜在生态风险极强。重金属Cd是最显著的污染因子和主要潜在生态风险源；其潜在生态风险指数（RI）对重金属总RI的贡献率超过85%。2004年，主干道道路灰尘中重金属污染程度显著高于其他道路类型。PM中重金属污染程度为：主干道＞进京高速公路入口＞次干道＞环路；道路灰尘PM为：主干道＞环路＞进京高速公路入口＞次干道。然而，2013年PM的污染程度顺序为：进京高速公路入口＞主干道＞环路＞次干道。次干道道路灰尘中重金属污染程度显著低于其他道路类型。2013年，北京市道路灰尘PM中重金属Ti、Zn、V、Cr、Cu、Pb和Ni的相关性显著，主要归因于交通相关排放。