Comparison of pollutants in stormwater runoff from asphalt and concrete roads

Controlling non-point source pollutants (NPSPs) is critical in achieving good surface water quality; the contribution of road runoff has recently received increased attention. This study monitored the runoff characteristics of NPSPs, including suspended solids, particle size distribution, heavy metals, organic matter, and nutrients, from asphalt and concrete roads. Water quality parameters, including biochemical oxygen demand (BOD), chemical oxygen demand (COD), and nutrients of the receiving reservoir, were also investigated. During the first flush, the changes in pollutant concentrations over time were higher on concrete roads than asphalt roads. Concentrations peaked over a short period, while an increased pollutant concentration may be present several days after rain. The runoff concentration and particle size distribution were higher on concrete roads, whereas the concentrations of heavy metals were similar in asphalt and concrete roads. The organic matter concentration of asphalt roads was higher, or identical, to that in the first flush from concrete roads; this may be associated with the road location. Water quality analysis of the reservoir showed relatively good results for BOD, COD, and nutrient concentrations. Road construction was a factor that determined the characteristics of NPSPs in road runoff.