Spatiotemporal distribution characteristics of runoff-pollutants from three types of urban pavements

Abstract

Pavement runoff is recognized as a primary source of non-point pollution in the urban area. It is difficult to treat the runoff-pollutants from different pavements because of complex distribution characteristics and influencing factors. This study presents the results of an experimental investigation aimed at determining the impact of three types of urban pavements, i.e., portland cement concrete pavements (PCC), dense asphalt concrete pavements (DAC) and permeable asphalt concrete pavements (PAC) on the rainfall-runoff process, concentration levels, and spatiotemporal distribution characteristics of typical runoff-pollutants. Runoff samples from the three types of urban pavements were collected and analyzed at different time-intervals beginning from runoff formation. The results indicated that PAC could better intercept and retain runoff-pollutants than DAC and PCC. In addition to the types of pavements, road-traffic characteristics and the surrounding environment significantly impacted the event mean concentrations of the selected rainfall events. Concentrations of suspended solids and heavy metals were higher at intersections and crosswalks, while those of organic pollutants were high in commercial areas. Besides, three parameters were proposed to characterize the first-flush effect intensity for runoff-pollutants. These findings help better understand the spatiotemporal distribution characteristics of runoff-pollutants from different types of urban pavements, which could also help strategically select measures to treat pavement runoff pollution.