[Characterization of Pollutant Wash-off in the Urban Stormwater].

To understand the pollution character of urban road runoff, the concentrations of TSS, EC, N and P in the ring road runoff of Beijing from June to September 2013 were evaluated, the correlations among pollutants were examined, and the load of TSS, N and P were estimated. Result showed that the small particulates in the range of 1-10 µm consisted of 60% TSS in the road runoff. Totally 89 percent of the nitrogen (N) was dissolved phase state in the road runoff, 80 percent of the phosphorus (P) was particular phase state in the road runoff. Based on the characteristics of correlations between EC, TSS and TN, TP, EC and TSS were the surrogate indexes of pollution degree assessment for the dissolved N and particulate P in the urban road runoff, respectively. Based on our results, the SS, N and P year load per unit area in Beijing ring road runoff were 16 725.69, 1777.91 and 24.23 mg x (m2 x a)(-1), respectively. Our findings described the polutant wash off character in urban road runoff, which provide a scientific basis for management of nonpoint pollution in a city and an alternative method for controlling pollution.