基于一次典型降雨过程形成的地面径流污染负荷研究——以内江城区为例

Research on the Pollution Load Produced by Typical Rainfall in Urban Area——Taking Neijiang Urban Areas as an Example

选取COD、氨氮、溶解氧、铬、铜5个污染指标,利用SCS降雨模型模拟一次典型降雨在内江城区工矿用地、商业用地、住宅用地、交通用地、建筑用地5种不同土地利用方式下所形成的地面径流非点源污染特征。结果表明:一次典型降雨在内江城区产生的COD、氨氮、溶解氧、铬和铜污染负荷浓度分别为37.20,0.67,3.72,0.01,0.03mg/L;产生的COD、氨氮、溶解氧、铬和铜污染负荷总量分别为2 361.08,35.20,197.57,1.47,1.28kg。在5种土地利用方式中,工矿用地、商业用地、住宅用地、交通用地、建筑用地的COD污染负荷比例分别为12.49%,66.56%,4.52%,13.27%,3.16%;氨氮污染负荷比例分别为17.35%,41.25%,15.03%,14.90%,11.47%;溶解氧污染负荷比例分别为20.25%,37.93%,23.85%,10.11%,7.86%;铬污染负荷比例分别为8.57%,76.36%,3.88%,7.75%,3.40%;铜污染负荷比例分别为21.95%,21.95%,10.39%,39.84%,5.86%。内江城区在一次典型降雨中,商业用地在5种土地利用方式中对内江城区产生的非点源污染贡献率最大,COD为66.56%,氨氮为41.25%,溶解氧为37.93%,铬为76.36%,铜为21.95%。降雨径流将对研究区河道、湖泊以及河口产生短期或中长期污染。

Chemical oxygen demand, ammonia nitrogen, dissolved oxygen, chromium and cooper have been chosen as pollution indices in this research. In this typical rainfall in NeiJiang urban area, the characteristics of nonpoint source of surface runoff formed in five distinct ways of land utilization including land for mining, commerce, residence, traffic and construction was simulated by SCS rainfall model. The results revealed in a typical rainfall of urban district the pollution load thickness of those five elements above were 37.20, 0.67, 3.72, 0.01, 0.03 mg/L, respectively. Sums of pollution load were 2 361.08, 35.20, 197.57, 1.47, 1.28 kg, respectively. As for the five different ways of land utilization, the COD pollution load contained in min- ing land was 12.49%, 66.56% in commercial land, 4.52% in residential land, and 13.27% in traffic land and 3.16% and in construction land. Pollution load of ammonia nitrogen was 17.35%, 41.25%, 15.03%, 14.90%, 11.47%, respectively, and pollution load of dissolved oxygen was 20.25%, 37.93%, 23.85%, 10. 11%, 7.86% in the above different types of lands. Moreover, the pollution load of the other two elements including chromium and cooper in those lands were 8.57%, 76.36%, 3.88%, 7. 75%, 3.40% and 21.95%, 21.95%, 10.39%, 39.84%, 5.86%, respectively. As a result, we figured out that the nonpoint source produced in the land for commerce take up largest proportion in a typical rainfall and COD was 66.56%, ammonia nitrogen was 41.25%, dissolved oxygen was 37.93%, chromium was 76.36% and cooper was 21.95%. Finally, we summarized that rainfall runoff would pollute the rivers, lakes and the estuaries which we investigated, either in the short term or long term.