多级雨水塘径流污染特征及底泥氮、磷污染风险评价研究

Runoff Pollution Characteristics of Multi-level Storm Water Ponds and Risk Assessment of Nitrogen and Phosphorus Pollution in Sediments

以全国首批海绵试点城市雨水塘为例,探究其在受到降雨径流污染时其水质变化,以及底泥中氮、磷营养元素的污染特征。通过对二级联用和三级联用的两组雨水塘实测,结果表明:在设计雨水截留量为4 mm时,雨水塘能有效缓冲初期雨水径流带来的污染。降雨期间和降雨后5日水体水质四、五类水占比分别为20%、22.9%和22.8%、25.7%。两组雨水塘底泥中氮总体表现为下降趋势,监测期间两组分别降低了331 mg/kg(削减57%)、272 mg/kg(削减46%);底泥氮、磷综合污染指数法评价显示,除了三级雨水塘底泥磷污染处于轻度污染外,其余各塘整体处于尚清洁和清洁状态,总体看运行5年的雨水塘底泥氮磷污染水平不高。

Taking the rainwater ponds of the first batch of sponge pilot cities in China as examples,the water quality changes and the pollution characteristics of nitrogen and phosphorus nutrients in the sediment were explored when they were polluted by rainfall runoff.Through the actual measurement of two groups of rainwater ponds with two-level and three-level combination,the results show thatwhen the design rainwater interception is 4 mm,the rainwater pond can effectively buffer the pollution caused by the initial rainwater runoff.During the rainfall period and 5 days after the rainfall,the proportions of the fourth and fifth grades of water quality were 20%,22.9%,22.8%,and 25.7%,respectively.Nitrogen in the bottom sediment of the two groups of rainwater ponds generally showed a downward trend.During the monitoring period,the two groups decreased by 331 mg/kg(57%reduction)and 272 mg/kg(46%reduction).The sediment nitrogen and phosphorus comprehensive pollution index method evaluation shows that except for the slight pollution of phosphorus pollution in the bottom sediment of the third-level rainwater pond,the rest of the ponds are still clean and clean.Overall,the level of nitrogen and phosphorus pollution in the bottom sediment of the rainwater pond that has been in operation for 5 years is not high.