天津典型居民区不同下垫面雨水径流污染特征

在对天津典型居民区域的不同下垫面雨水径流水质进行监测的基础上,以典型降雨为例,探讨了雨水径流污染物的特征和事件平均浓度(event mean concentrations,EMC)。结果表明,天津典型居民区主干道和菜市场雨水径流中的污染物质量浓度随着降雨历时的延续呈降低趋势,冲刷效应明显;屋顶雨水径流中污染物的质量浓度随降雨历时的延续变化较小,冲刷效应较弱。3种下垫面雨水径流中污染物质量浓度大小差异明显,菜市场和主干道雨水径流中SS质量浓度相差不大,且都远远超过屋顶雨水径流;雨水径流中COD和TP质量浓度的顺序由大到小依次为菜市场、主干道、屋顶;雨水径流中TN质量浓度的顺序由大到小依次为菜市场、屋顶、主干道。以EMC中值计,菜市场雨水径流中污染物平均浓度要高于主干道和屋顶,菜市场雨水径流中TP的质量浓度是主干道的3倍、屋顶的24倍。天津典型居民区雨水径流污染比较严重,如不经截留或处理直接排入城市河道等接纳水体,会严重影响河道的水质和城市的环境。

Runoff pollution characteristics under different underlying surfaces of typical residential areas in Tianjin City

Based on the monitoring on runoff water quality under different underlying surfaces of typical residential areas in Tianjin, typical rainfall was chosen to investigate the characteristics of runoff pollutants and event mean concentration(EMC). The results show that the pollution mass concentration in runoff of main roads and markets decreases with the rainfall duration and the scouring effect is obvious. The pollution concentration in runoff of roofs changes slightly with the rainfall duration and the scouring effect is weak. There are significant differences between the pollution concentrations in runoff of three kinds of underlying surfaces. The SS concentration in runoff of main roads is similar to that of markets, but much higher than that of roofs. The COD and TP concentrations in runoff ranking from high to low are markets, main roads, and roofs, and the TN concentration in runoff ranking from high to low is markets, roofs, and main roads. Suppose EMC is defined as the mid-value, the mean pollutant concentration in runoff of markets is higher than that of main roads and roofs, and the TP concentration in runoff of markets is 3 times that of main roads and 24 times that of roofs. So the runoff pollution in typical residential areas of Tianjin City is quite serious. The water quality in rivers and water environment of the City will be strongly influenced if the runoff is directly drained into rivers without any interception or treatment.