公路地表灰尘及径流中颗粒物附着重金属对比研究

Comparative study on heavy metals distribution on particles in road sediments and stormwater runoff

对北京城区北三环上北太平桥以西约300m处路段地表灰尘及径流中不同粒径颗粒物附着重金属载荷进行对比研究。结果表明:(1)随着颗粒物粒径的增大,地表灰尘中颗粒物附着重金属浓度总体上逐渐降低;地表灰尘中<40.00μm颗粒物附着重金属浓度最高;重金属载荷分布集中度不强,但主要集中在地表灰尘中<300.00μm的颗粒物上。(2)地表径流中大部分重金属附着在<125.00μm颗粒物上;0.45～10.00μm颗粒物附着重金属载荷最高;0.45～40.00μm颗粒物附着重金属载荷平均为77.1%。(3)地表灰尘中<40.00μm的颗粒物的潜在水环境风险不太突出,但是其实际水环境影响却起主导作用。(4)进入水体的小粒径颗粒物质量分数升高是地表灰尘和径流重金属载荷随颗粒物粒径分布不同的重要原因之一;大气湿沉降对小粒径颗粒物重金属载荷可能会有一定的影响。

The heavy metal distribution on particles in road sediments and stormwater runoff of the northern 3- Ring street in Beijing was investigated. In the road sediments, the concentration of heavy mental was obviously correlated with the particle size. The higher heavy mental concentration was found on the particles with smaller size. Most of the heavy mental was adhered on the particles with the diameter of 〈300.00 μm, which occupied the highest mass proportion of road sediments. In the stormwater runoff, particles that affected the water environment were mainly those with the diameter of less than 125.00μm. Heavy metal distributions on particles （〈40.00μm） in road sediments and stormwater runoff were compared and the average heavy metal loads were 97.6 % and 18.7 %, respectively. The most important reasons of this difference was the mass percentage of smaller particles washed into the runoff water. The influence of wet deposition could not be ignored.