重庆市不同材质屋面径流水质特性

2010年雨季对重庆市6场降雨时段的屋面径流进行采样监测,分析了水泥屋面和瓦屋面径流污染物的出流过程和初始冲刷现象,并且运用多元统计方法分析了降雨特征对径流水质的影响.结果表明:2种材质屋面径流水质参数中CODCr和TN的次降雨平均浓度(EMC,以ρ计)均超出GB 3838—2002《地表水环境质量标准》的Ⅴ类标准,为屋面径流主要污染物.水泥屋面的CODCr、TN、NO3--N、TSS、Cu和Zn的EMC明显高于瓦屋面,分别高出1.63、1.57、1.15、1.70、1.50和1.88倍.在水泥屋面上,ρ(CODCr)、ρ(TN)、ρ(TP)和ρ(TSS)变化幅度大于瓦屋面,并且其峰值滞后或同步于最大雨强;在瓦屋面上,ρ(CODCr)、ρ(TN)、ρ(TP)和ρ(TSS)的峰值提前或同步于最大雨强.瓦屋面各污染物FF30(初期30%径流携带的污染负荷)的平均值均高于水泥屋面;水泥屋面各污染物(除Zn和Cd外)FF30的标准差均高于瓦屋面.各污染物的EMC与降雨量、平均雨强、径流量和最大雨强呈负相关;溶解态重金属的EMC与前期晴天数呈负相关,其余指标均与前期晴天数呈正相关. 

Characteristics of Runoff from Different Material Roofs in Chongqing Urban Area

Based on investigations of surface runoff from roofs in the Chongqing urban area,we assessed the variations of pollutant concentrations in the runoff as well as the first flush phenomenon of both concrete and tile roofs.We also analyzed the effects of rainfall characteristics on runoff water quality using multivariate statistical analysis.The results indicated that CODCr and TN in the runoff from both kinds of roofs were at high concentrations,with the even mean concentrations(EMC) exceeding the Class Ⅴ of surface water,and therefore regarded as the main pollutants.The EMC of CODCr,TN,NO3——N,TSS,Cu and Zn in the runoff from the concrete roof were significantly higher than those from the tile roof,being 1.63,1.57,1.15,1.70,1.50 and 1.88 times higher,respectively.From the concrete roof,the CODCr,TN,TP and TSS concentrations varied more greatly than those from the tile roof.The peak concentrations of CODCr,TN,TP and TSS from the concrete roof occurred after or synchronously with the maximum rainfall intensity,while from the tile roof,the CODCr,TN,TP and TSS concentration peaks occured before or synchronously with the maximum rainfall intensity.The average first 30% of runoff volume(FF30) of all the pollutants from the tile roof was higher than from the concrete roof.From the concrete roof,except for Zn and Cd,the standard deviation of FF30 for each pollutant was larger than from than the tile roof.The values of EMCs were negatively correlated with precipitation,runoff volume and rainfall intensity.The concentrations of dissolved heavy metals were negatively correlated with dry weather deposits,but the concentrations of the other pollutants showed positive correlation with dry weather deposits.