城市不同材料屋面径流的污染负荷特性

Pollution Load Characteristics of Runoff from Urban Roofs of Different Materials

分析不同材料屋面径流污染负荷特性,对于提高城市面源污染负荷估算精度和确定初期径流截流比具有重要意义.以扬州市为研究区域,通过对小青瓦屋面、水泥瓦屋面和混凝土屋面这3种屋面进行降雨径流监测,比较不同材料屋面径流污染物浓度、冲刷规律以及初期冲刷效应.结果表明暴雨事件中,小青瓦屋面径流中总氮(TN)、总磷(TP)、高锰酸盐指数和总悬浮物(TSS)的事件平均浓度(event mean concentration,EMC)约为水泥瓦屋面的4～9倍;小青瓦屋面径流污染物浓度变化受雨强影响程度大于水泥瓦屋面,其中TP和TSS的浓度变化趋势和雨强变化趋势的Pearson相关系数r分别为0. 853和0. 822;各材料屋面的初期冲刷强度呈水泥瓦屋面>混凝土屋面>小青瓦屋面,分别截流3种屋面初期径流的31. 5%、58. 0%和60. 4%,可以完成削减60. 0%的屋面径流污染负荷量的目标.如果未具体区分瓦屋面材料,用水泥瓦屋面径流污染物的EMC估算古建筑聚集区的屋面污染负荷量,将严重低估暴雨事件中TN、TP、TSS和高锰酸盐指数的实际排放量,表明精细化区分屋面材料对提高城市面源负荷估算精度具有重要意义.

It is of great significance to analyze the runoff pollution load characteristics of different roof materials to improve the estimation accuracy of urban non-point source pollution loads.Yangzhou City was selected as the study area.There,three types of roofs were chosen for rainfall-runoff monitoring,including a Chinese style tile roof,cement tile roof,and concrete flat roof.The pollutant concentrations,scour law,and first flush effect of the three types of roofs were compared.The results show that the event mean concentration(EMC)of total nitrogen(TN),total phosphorus(TP),permanganate index,and total suspended solids(TSS)in the runoff of Chinese style tile roofs are around 4-9 times that in the runoff of cement tile roofs.The rainfall intensity exhibits stronger effect on the change in pollutant concentrations of runoff from the Chinese style tile roof than that from the cement tile roof.The Pearson correlation coefficients(r)of rainfall intensity against TP and TSS in time series were 0.853 and 0.822,respectively.The first flush intensities of the three types of roof materials were in the order cement tile roof>concrete flat roof>Chinese style tile roof.It was found that 60.0%of the roof runoff pollution load could be reduced by intercepting 31.5%,58.0%,and 60.4%of the initial runoff for the Chinese style tile roof,the cement tile roof,and the concrete flat roof,respectively.The actual emissions of TN,TP,and TSS,and the permanganate index in rainstorm events would be significantly underestimated when roof materials are not distinguished.This would have negative effects on the pollution control of urban non-point sources.It is demonstrated that the fine distinction of roof materials is able to improve the estimation accuracy of urban non-point source loads.