Distributions and transport of typical contaminants in different urban stormwater runoff under the effect of drainage systems

摘要

In recent years, the pollution of receiving water induced by urban stormwater runoff has gained considerable attention. Meanwhile, rainwater is also a potential and valuable water resource, which may effectively mitigate the increasing water shortage. In the present study, the distributions and transport of nutrients and heavy metals in different stormwater runoff of two residential communities (site A and B) under the effect of drainage systems were discussed in detail. Site A with combined drainage system was located in old district featured with a lot of big manufacturing and chemical factories in suburb. Differently, site B with separate system was situated in new district occupied by small shops and residential quarters. The results indicated that air quality was a significant influence factor and reference index in the decision-making of rainwater harvesting and reuse. For nutrients, the anthropic activities contributed adequately ammonia nitrogen and total phosphorus to the road runoff (RD) and sewer overflows, especially in site A with combined drainage system. However, the roof runoff (RF) presented the highest event mean concentrations (EMC) of nitrate and nitrite nitrogen, probably due to the high runoff coefficient of roof and low interference from human activities on dry deposition. Zn(Ⅱ), Cu(Ⅱ), and Pb(Ⅱ) concentrations showed a similar variation pattern, although there were some small differences owing to the erosion of metal materials from rooftops and street lamps. Compared with the "Standards for Drinking Water Quality" in China, the direct rainfall and RF in site B could be harvested and utilized for potential drinking water supply from the perspective of the studied parameters. For site A, at least 33.8% of NH_4~+-N and 50.8% of NO_3~--N in RF must be removed before reuse. The results obtained in this research would provide an important assistance and support in urban rainwater reuse as well as runoff pollution control.