Water quality characteristics of road runoff from urban area of Guangzhou

Many kinds of pollutants such as suspended solid, oil and grease and heavy metals derived from traffic activities were enriched in urban road runoff, and they could significantly degrade the quality of the receiving waters and affect hydro-ecosystem. Water quality of the road runoff from Guangzhou urban area was analyzed with synchronous measurement of the rainfall and runoff volume. The results indicated that the contents of nutritive salts were low, but COD as well as oil and grease and heavy metals were high in the runoff, and the low ratio of BOD to COD suggested low bio-degradability of the road runoff water. Although the mean concentrations of oil and grease, suspended solid and Pb generally fell within the same range of the level from other cities in China, they were considerably higher than the developed countries’ level, reflecting the gap on environment maintenance and management of the roads between China and developed countries. Comparing with Chinese surface water quality criteria type III, the levels of oil grease, COD, suspended solids and Pb in road runoff substantially exceeded the limited concentrations, indicating that untreated discharge of road runoff from Guangzhou urban area could seriously deteriorate the water quality of receiving waters such as Pearl River.