Chen Ying, Wang Zhao, Wu Ya-Gang, Zhao Jian-Qiang, Yang Wen-Juan
Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, School of Environmental Science and Engineering, Chang'an University, Xi'an 710054, China.
Shaanxi Provincial Land Engineering Construction Group Limited Liability Company, Xi'an 710075, China.
Huan Jing Ke Xue. 2017 Jul 8;38(7):2828-2835. doi: 10.13227/j.hjkx.201612153.
Urban road runoff contains pollutants such as particulate matters, organic chemicals, heavy metals, nutrients, oil and grease that can cause significant degradation of receiving water quality. Eliminating the pollutant mass loading of road runoff and protecting the receiving water bodies have been the focuses in environmental field in recent years. To accomplish pollutant reduction and develop a cost-effective treatment method, knowledge of water quality characteristics, as well as the pollutant effluent characteristics of road runoff is required. In order to investigate the impacts of rainfall characteristics and occurrence of pollutant on the variation of pollutant concentrations during the duration of runoff events and pollutant load effluent characteristics of road runoff, 207 road runoff samples in the durations of 13 storm events occurred at Taibai Interchange of the south second-ring road in Xi'an, Shaanxi province from July 2014 to September 2015 were collected by the manual time-interval sampling method, and concentrations of SS, COD, dissolved COD, Cu, dissolved Cu, Pb, dissolved Pb, Cr, dissolved Cr, Cd and dissolved Cd of the samples were determined. The results indicated that, the road runoff of Xi'an city was seriously polluted by SS and COD, which were the main contaminants in road runoff. Meanwhile, concentrations of Pb and Cr in road runoff were also at a high level. The variation of pollutant concentrations during the duration of runoff was closely related to rainfall characteristics and occurrence states of the pollutants. Emission of the dissolved pollutants was not affected by the type of rainfall. The concentration of the dissolved pollutants in the runoff reached a peak in the initial duration of runoff, and then, decreased continuously. However, the peak concentration of particulate pollutants in the runoff only occurred after the peak of sufficiently large rainfall intensity. The concentration of particulate pollutants in the runoff fluctuated sharply with the variation of rainfall intensity, and impacted by the rainfall duration and rainfall depth as well. Rainfall characteristics didn't have a great impact on the load emission of the dissolved pollutants, therefore, had a significant influence on the load emission of the particulate pollutants. Compared with the rainfall type Ⅲ, first flush effects of pollutant loads of SS, COD, Cu, Pb, Cr, Cd in rainfall type Ⅰand type Ⅱ were more obvious. Besides, first flush effect of pollutant loads was not ubiquitous. All the pollutants in the monitoring 13 runoff events didn't exhibit an obvious first flush effect. The descending order of the first flush effect of those pollutants was COD, SS, dissolved COD, Cu, Pb, Cr, dissolved Cu, Cd, dissolved Pb, dissolved Cr, dissolved Cd.
城市道路径流含有颗粒物、有机化学品、重金属、营养物质、油脂等污染物，这些污染物会导致受纳水体水质显著恶化。消除道路径流的污染物负荷并保护受纳水体一直是近年来环境领域的重点。为了实现污染物减排并开发一种经济高效的处理方法，需要了解水质特征以及道路径流的污染物排放特征。为了研究降雨特征和污染物的出现对径流事件持续期间污染物浓度变化以及道路径流污染物负荷排放特征的影响，采用人工时间间隔采样法，收集了2014年7月至2015年9月在陕西省西安市南二环路太白立交发生的13场暴雨事件持续期间的207个道路径流样本，并测定了样本中SS、COD、溶解性COD、Cu、溶解性Cu、Pb、溶解性Pb、Cr、溶解性Cr、Cd和溶解性Cd的浓度。结果表明，西安市道路径流受到SS和COD的严重污染，它们是道路径流中的主要污染物。同时，道路径流中Pb和Cr的浓度也处于较高水平。径流持续期间污染物浓度的变化与降雨特征和污染物的出现状态密切相关。溶解性污染物的排放不受降雨类型的影响。径流中溶解性污染物的浓度在径流初始阶段达到峰值，然后持续下降。然而，径流中颗粒污染物的峰值浓度仅在足够大的降雨强度峰值之后出现。径流中颗粒污染物的浓度随降雨强度的变化而急剧波动，并且也受降雨持续时间和降雨深度的影响。降雨特征对溶解性污染物的负荷排放影响不大，因此，对颗粒污染物的负荷排放有显著影响。与Ⅲ型降雨相比，Ⅰ型和Ⅱ型降雨中SS、COD、Cu、Pb、Cr、Cd污染物负荷的首次冲刷效应更明显。此外，污染物负荷的首次冲刷效应并非普遍存在。监测的13场径流事件中的所有污染物均未表现出明显的首次冲刷效应。这些污染物首次冲刷效应的降序排列为COD、SS、溶解性COD、Cu、Pb、Cr、溶解性Cu、Cd、溶解性Pb、溶解性Cr、溶解性Cd。
