Emission Characteristic Analysis on Highway Rainwater Runoff Pollution of Asphalt Pavement

In order to investigate the emission characteristics of rainwater runoff pollution from highway with asphalt pavement, simultaneous monitoring method of rainfall-runoff-pollutants was adopted. During 2006 to 2009, rainfall runoff samples from six asphalt pavement highways in 3 typical areas were collected and monitored, including Pearl River Delta Region in South China, Chongqing Province in South-west and Qingdao in East China. Results showed that average concentrations of SS, COD, TN and TP in runoff samples exceeded the Class V standard of surface water defined in Environmental Quality Standard for Surface Water (GB3838-2002). SS was the main pollutant of the highway asphalt pavement runoff, and was an important carrier of other major pollutants (such as heavy metals and chemical oxygen demand, COD) as well. The dust particle size of expressway road surface was generally small (more than 90 % less than 2mm). There was a big difference in concentrations of the same pollutant in particles with various sizes. Pollutant concentrations were increased with the reduction of particle size. Pavement runoff was less biodegradable and the ratio of BOD5/COD was 0.0188. Therefore, the ecological ditch combining percolation and drainage was proposed to purify the highway asphalt pavement runoff.