Urban Water Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, 971 87, Luleå, Sweden.
Environ Sci Pollut Res Int. 2023 Oct;30(50):109825-109840. doi: 10.1007/s11356-023-30062-1. Epub 2023 Sep 30.
Urban stormwater typically enters sewer networks through gully pots, which allow a primary sedimentation of solids upstream of the piped network. The regular removal and disposal of retained sediment are necessary, costly and can involve environmental risks due to the contamination of sediments with substances from the urban environment such as metals. The concentrations and speciation of Cd, Cr, Cu, Ni, Pb and Zn were analysed in sediments from 26 gully pots located in different land use areas in Stockholm, Sweden. In addition, accumulation rates of both sediment and metal masses were evaluated, providing a basis for optimising maintenance practices and better understanding of impacts of characteristic urban land use types. Metal concentrations varied by at most a factor of eight between samples and were always below Swedish polluted site guidelines for less sensitive land use, with only eight samples exceeding the guideline values for Cu and Zn for sensitive land use. Sequential extraction showed Pb and Zn to be the most mobile metals. Sediment accumulation rates varied from 0.003 to 0.197 kg/m impermeable surface/year. Metal accumulation rates were much more variable than metal concentrations, with a factor of up to 172 between the highest and lowest rates and the highest metal accumulation rates corresponding to the lower range of mass loads in road runoff. Differences in metal concentrations, sediment or metal mass accumulations could not be solely attributed to either traffic or catchment land use. In contrast, traction grit used for winter road maintenance, which has low (but detectable) metal concentrations, is identified as a major component of gully pot sediments, with a combined effect of both moderating metal concentrations and contributing to total mass.
城市雨水通常通过雨水口进入污水管网，在管网之前对固体进行初步沉淀。定期清除和处理截留的沉积物是必要的，但成本很高，并且由于沉积物受到来自城市环境的物质（如金属）的污染，还可能带来环境风险。对来自瑞典斯德哥尔摩不同土地利用区的 26 个雨水口的沉积物中的 Cd、Cr、Cu、Ni、Pb 和 Zn 浓度和形态进行了分析。此外，还评估了沉积物和金属质量的积累速率，为优化维护实践和更好地了解典型城市土地利用类型的影响提供了依据。金属浓度在样品之间的差异最大不超过 8 倍，并且始终低于瑞典受污染场地指南中对敏感性较低土地利用的指导值，只有 8 个样品超过了对敏感性土地利用的 Cu 和 Zn 的指导值。顺序提取表明 Pb 和 Zn 是最具移动性的金属。沉积物积累速率从 0.003 到 0.197 kg/不可渗透表面/年不等。金属积累速率比金属浓度变化更大，最高和最低速率之间的差异高达 172 倍，而最高的金属积累速率与道路径流中较低的质量负荷相对应。金属浓度、沉积物或金属质量的积累不能仅归因于交通或集水区土地利用。相反，冬季道路维护中使用的牵引砂砾，其金属浓度较低（但可检测），被确定为雨水口沉积物的主要成分，具有调节金属浓度和增加总质量的双重作用。
