公路路面径流重金属污染特征

对广州地区市内,城乡结合部和郊区的3条不同的公路路面雨水径流的降雨、径流流量同步监测以及径流瞬时样品中Cu、Zn、Pb、Cd、Ni和Cr 6种重金属的测试表明,在路面重金属被雨水径流的冲洗过程中,基于浓度的初期冲洗现象明显,即在径流发生的初始阶段浓度最高,随着降雨和径流过程的进行,重金属浓度持续降低,在径流流量峰值部分,重金属的浓度达到最低值,随后随着流量的减小略有上升;路面雨水径流中的重金属彼此相关性强且都与径流中悬浮固体存在明显相关,绝大部分的重金属都以悬浮固体吸附或直接的颗粒态形式存在;公路路面雨水径流的重金属污染程度与公路周围的环境关系密切,市内道路的重金属次径流平均浓度最高,城乡结合部和郊区公路路面径流的次径流平均浓度相差不大,Pb是路面径流中主要的重金属污染元素。

Characteristics of Heavy Metal Pollution in Highway Rainfall Runoff

Rainfall,flow rate and heavy metal concentrations of Cu,Zn,Pb,CA,Ni and Cr were monitored during the rainfall-runoff occurred on three highways located in urban,urban-rural fringe and rural area of Guangzhou.The results showed that the initial flush of concentration was evident for the metals during their wash-off from the highway surface by rainfall-runoff,the highest concentrations appeared in the initial phase of the runoff and the concentrations continuously decreased to the lowest values at the flow peaks.When the flow declined,their concentrations rose slightly.High correla- tions existed among the heavy metals and suspended solids,and the great mass of heavy metals existed as particulate or particulate-bounded.The heavy metal pollution of the highway rainfall-runoff was highly related to surrounded land use, the event mean concentrations of heavy metals in runoff from the urban highway were the highest among the three sites, and the runoff from urban-rural fringe and rural highways had the equal level,Pb was the major element of the heavy metal pollution in the highway runoff.