透水砖系统堵塞失效全过程对径流重金属控制效果的评价

ATTENUATION ON CONTROL EFFECT OF HEAVY METALS IN RUNOFF BY PERMEABLE BRICK DURING THE WHOLE PROCESS OF BLOCKAGE

针对透水砖系统堵塞失效对径流控制效果衰减的问题,考察了透水砖堵塞失效演化全过程时雨水径流重金属的输出变化特征,并采用综合污染指数法对不同堵塞节点透水砖铺装径流重金属污染进行风险评价。结果表明:透水砖堵塞程度增加可显著增大其表面径流溶解态和颗粒态重金属输出,且在透水砖堵塞程度达到30%后的场次降雨输出的重金属浓度明显上升;不同堵塞程度透水砖径流中重金属均出现了初期冲刷现象,初期冲刷效应强弱与透水砖堵塞程度呈正相关。透水砖堵塞前期各历时径流重金属污染风险较低,但随着堵塞加剧初期径流重金属污染风险变高,其中Cd和Pb是主要风险源。

Aiming at the attenuation of the control effect on runoff during blockage of a permeable brick system,the output characteristics of heavy metals in permeable brick runoff during the whole process of blockage were investigated,and the integrated pollution index method was adopted to evaluate the pollution risk of heavy metals in the permeable brick runoff with different blockage degrees.The results showed that the output concentration of the dissolved and particulate heavy metals in permeable brick runoff got increased with the increase of blockage degree of permeable brick,and the output concentration of heavy metals in permeable brick runoff increased significantly after the blockage degree of permeable brick reached 30%.The first flush effect of heavy metals in permeable brick runoff during the whole process of blockage all appeared,and the first flush effect of heavy metals in permeable brick runoff was positively correlated with the blockage degree of permeable brick.The heavy metal pollution risk of runoff during the whole runoff period was low in the early stage of permeable brick blockage,but with the increase of blockage,the heavy metals in initial runoff showed high pollution risk,in which Cd and Pb were the main pollution risk sources.