为研究植草沟对降雨径流污染的削减效果,于校园绿化带路段建立植草沟示范点,并在研究校园总体降雨水质和不同下垫面降雨径流特性基础上,开展植草沟对屋面雨水和地表径流中污染物的控制效果研究.结果表明,校园降雨径流中COD和NH3-N浓度较高,需进行控制;且屋面雨水相较于道路径流水质污染更为严重,可能的原因是沥青油毡屋面材料中有机物的释出增加了径流水质的有机物污染程度;屋面雨水降雨初期污染较为严重,但屋面雨水与道路径流各污染物浓度随着降雨历时的延长均呈现逐渐下降并趋于稳定的变化规律;植草沟对屋面雨水COD的去除率为 59%~98%,浊度的去除率为 50%~83%,TP的去除率为 59%~93%,NH3-N的去除率为 49%~88%.可见,渗透型生态植草沟作为一种植被生态排水沟渠,有助于减少不透水下垫面的覆盖程度,对控制城市面源污染效果十分显著.
In view of an inquiry into the reduction effect of grass planting ditches on rainfall runoff pollution,a demonstration site for the grass-swale has thus been established on the campus green belt section.Based on the findings of the overall rainfall water quality and rainfall runoff characteristics of different underlying surfaces on the campus,a further study is conducted on the control effect of the grass-swale on pollutants in roof rainwater and surface runoff.The results show that the COD and NH3-N concentrations in the campus rainfall runoff are high and need to be controlled.Moreover,the roof rainwater is more seriously polluted than the road runoff,possibly due to the release of organic matter in asphalt felt roofing materials,which increases the degree of organic matter pollution in runoff water.The initial pollution of roof rainwater during rainfall is relatively severe,while the concentrations of various pollutants in roof rainwater and road runoff decreases gradually,showing a tendency to stabilize with the rainfall duration.The removal rates of COD,turbidity,TP,and NH3-N from roof rainwater by the grass-swale are 59%to 98%,50%to 83%,59%to 93%,and 49%to 88%,respectively.It can be seen that the permeable ecological grass-swale,as a kind of vegetated ecological drainage ditch,helps to reduce the degree of coverage of impervious subsurface,thus verifying its effectiveness in controlling the urban surface pollution.