Influence Of Urban Surface Roughness On Street Dust Build-up And Wash-off

Rainfall runoff on urban road surfaces is a source of urban receiving water pollution.Asphalt and concrete road surfaces,typical road types in China,exert different effects on road-deposited sediment(RDS)build-up and wash-off owing to differences in roughness,texture,and permeability.Understanding pollutant process is important in estimating pollutant loads for low-impact development(LID)and best management practices(BMP).We collected RDS and runoff from typical asphalt and concrete road surfaces and used a pairing method to analyze the effects of surface roughness on RDS build-up and wash-off.The results show that :(1)The roughness of the cement pavement relative to the asphalt pavement is small,the amount of dust per unit area and the average particle size of the particles are smaller than the asphalt pavement,and the sorting property is also better than the asphalt pavement.(2)There was no significant correlation between the contents of nitrogen and phosphorus and the roughness of the two underlying surfaces,which was mainly affected by environmental factors.The ratio of nitrogen to phosphorus in each particle size is consistent with its mass ratio.The adsorption of nitrogen and phosphorus by fine grain street dust is not obvious.While the heavy metal pollution is affected by the roughness of the two kinds of underlying surface.The cement pavement concentration is higher than that of the asphalt pavement,and the fine particulate matter has heavy load of heavy metal pollution,which is higher than the mass ratio of 2.4% ~ 24.1%.(3)Road dust samples of each particle size segment have similar microcosmic morphology on different underlying surfaces.RDS build-up took approximately 3.9 times longer on asphalt than on concrete.(4)Rainfall reduced total RDS per unit area on concrete roads to a greater extent than on asphalt roads,with a difference of 1.4%–13.4%.Stormwater runoff on asphalt and concrete road surfaces resulted in varying rates of RDS wash-off.The surface roughness of urban roads has a significant impact on the accumulation of street dust-the erosion process.The in-depth system analysis of the impact process will provide an important guiding role in the estimation of pollutant load and the design of low-impact development.