城市道路沉积物氮、磷溶出特性

国内外众多研究表明,城市不透水表面沉积物是雨水径流中污染物的重要来源。以北京市某道路沉积物为研究对象,对城市道路沉积物的粒径分布进行了分析,并通过批量实验,研究了不同粒径道路沉积物中氮、磷营养物及有机物(COD)的溶出特性。实验结果表明,粒径较大的沉积物中氮含量较高,而粒径较小的沉积物中磷含量较高;虽然TP、PO3-4、TN、NO-3、NH+4、COD的溶出浓度、溶出速率变化特征各不相同,但总体趋势是粒径越小氮、磷及COD溶出浓度和溶出速率越大,且最大溶出速率都出现在前5 min。因此,为实现对城市雨水径流污染的有效控制,应采用源头控制措施对小粒径道路沉积物和初期雨水进行有效控制。

Characteristics of nitrogen and phosphorus dissolved from urban road-deposited sediment

A great deal of domestic and foreign studies showed that urban impervious surface sediments are important sources of pollutants in stormwater runoff. Taking the road-deposited sediment (RDS) of Beijing as research object, the particle size distribution of RDS was analyzed, and the dissolvable characteristics of nitrogen, phosphorus and organic substances chemical oxygen demand (COD) from RDS with different size distribution were studied by batch experiments. The experimental results show that the nitrogen and phosphorus are mainly distributed on RDS with larger and smaller size, respectively. Although the dissolved concentration and rate of TP, PO₄^3-, TN, NO₃^-, NH₄⁺, and COD are various among RDS with different particle size distribution, the overall trend on substances' dissolved characteristics is similar. The smaller the size of RDS is, the larger the dissolved concentration and rate of the pollutants is. In addition, the largest dissolved rate of all substances appears at the first five minutes. Therefore, in order to effectively control the pollution from the stromwater runoff, the RDS with small size and the first flush of the stormwater should be analyzed and controlled as priority.