Pollutants in stormwater runoff in Shanghai (China): Implications for management of urban runoff pollution

Runoff samples were collected from four functional areas (traffic, residential, commercial and industrial) and four roof types (old concrete, new concrete, old clay and new clay) in central Shanghai, China, during rain events. The event mean concentrations (EMCs) of three forms of nitrogen (NH₄⁺ -N,NO₃^--N,NO₂^--N) and the temporal variations of total phosphorus (TP) were then measured to evaluate the effects of runoff from different areas on water quality management. The results revealed that the TP levels varied significantly in the samples collected from different functional areas and roof types during rain events. In addition, although the NO₃^--N and NO₂^--N concentrations in runoff remained well below the fifth class values of the national surface water quality standards, the NH₄⁺-N levels were 1.36, 1.17, 1.10 and 0.85 times higher than the standard value in samples collected from commercial, traffic, industrial, and residential areas, respectively. Similarly, the concentrations of NH₄⁺-N in samples collected from old concrete, new concrete, old clay and new clay roofs exceeded the fifth class standard by 6.66, 5.72,4.32 and 3.32 times, respectively. And the NO₃^--N levels were 1.86 and 1.53 times higher than the standard values in runoff samples collected from new and old concrete roofs, respectively.