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He Q.,Chongqing University | Pan W.,Chongqing University | Wang S.,Chongqing Key Laboratory of Environmental Material and Restoration Technology | Hao Y.,Chongqing University | And 2 more authors.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2014

In order to reveal the first flush effect of mountainous cities, eight rainfall events were selected to monitor the quality of the stormwater runoff in Chongqing city, which is regard as a typical mountainous city. The results, which were analyzed by comparing the data in plain cities, showed that the traffic road posed much higher contribution in TSS, COD and TP, though the traffic road and the concrete roof posed the same contribution in TN and NH3-N; the EMC values of heavy metals from the traffic road were higher than that from the concrete roof except Cd. For the traffic road, 53%±16% TSS, 66%±10% COD, 59%±2% TN, 58%±2% NH3-N, 51%±5% TP were found in the initial 40% of the stormwater runoff; while 64%±20% TSS, 66%±17% COD, 55%±14% TN, 52%±14% NH3-N, 56%±3% TP from the concrete roof; therefore, it should be an effective way in controlling the stormwater runoff pollution by collecting and treating the initial 40% runoff. The pollution of TSS and COD in the initial 40% of the stormwater runoff, were 16% and 22% higher than the plain cities, indicating the first flush effect is more obviously.

Long J.,University of Sichuan | Long J.,Chongqing Three Gorges University | Li X.,Chongqing Key Laboratory of Environmental Material and Restoration Technology | Wang S.,Chongqing Three Gorges University | And 2 more authors.
Chinese Journal of Environmental Engineering | Year: 2014

Runoff from urban imperious roofs has been one of the major sources of urban nonpoint source pollution. We monitored the water quality of 20 rainfall events selected from five different roofs in Chongqing City in order to understand the water quality properties. The results show that pollutant concentrations in runoff from imperious roofs decreased with the extension of rainfall duration. Event mean concentrations (EMCs) of COD, TP, TN and NH3-N in concrete roof runoff are 1.6, 1.7, 1.4 and 1.5 times higher than that in tile roof runoff, respectively. 70%~80% of TN is inorganic nitrogen, while 20%~32% of TP is comprised of PO4 3--P in impervious roofs runoff. EMCs of COD, TN, TP, NH3-N and NO3 --N in extensive green roof are 0.25~0.26, 0.3~0.5, 0.07~0.09, 0.3~0.6 and 0.05~0.06 times lower than that from intensive green roofs. NO3 --N is the major species of TN in all green roofs runoff. Both the EMC of TN for concrete roof and EMC of NH3-N for sambucus roof are positively correlated with the antecedent dry days. In addition, the rainfall intensity is correlated with EMC of TP for tile roof, and rainfall duration is significantly correlated with EMC of TSS for tile roof. The study results provide important reference for the management of roof runoff in urban region.

Wang S.-M.,Chongqing Key Laboratory of Environmental Material and Restoration Technology | Wang S.-M.,Chongqing University | Li X.-Y.,Chongqing Key Laboratory of Environmental Material and Restoration Technology | Zhang J.-H.,Chongqing University | And 3 more authors.
Chinese Journal of Applied Ecology | Year: 2014

Green roof is widely used in advanced stormwater management as a major measure now. Taking Huxi catchment in Chongqing University as the study area, the relationships between green roof installation with runoff volume and water quality in urban region were investigated. The results showed that roof greening in the urban region contributed to reducing the runoff volume and pollution load. In addition, the spatial distribution and area of green roof also had effects on the runoff water quality. With the conditions that the roof area was 25% of the total watershed area, rainfall duration was 15 min and rainfall intensity was 14.8 mm·h-1, the peak runoff and total runoff volume were reduced by 5.3% and 31%, the pollution loads of total suspended solid (TSS), total phosphorus (TP) and total nitrogen (TN) decreased by 40.0%, 31.6% and 29.8%, their peak concentrations decreased by 21.0%, 16.0% and -12.2%, and the EMCs (event mean concentrations) were cut down by 13.1%, 0.9% and -1.7%, respectively, when all impervious roofs were greened in the research area. With the increase of roof greening rate, the reduction rates of TSS and TP concentrations increased, while the reduction rate of TN concentration decreased on the whole. Much more improvement could be obtained with the use of green roofs near the outlet of the water-shed.

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