Chang Xuan, Jia Ziliang, Feng Jiashen, Duan Tingting, Li Ying-Xia
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, 19 Xinjiekouwai Street, Haidian District, Beijing, 100875, China.
School of Environment, Tsinghua University, 30 Shuangqing Road, Haidian District, Beijing, 100084, China.
Environ Pollut. 2022 Jul 1;304:119194. doi: 10.1016/j.envpol.2022.119194. Epub 2022 Mar 21.
Spatiotemporal variability complicates source apportionment of metals in urban lakes, especially when rainfall drives urban non-point source pollution. As, Cd, Cr, Pb, Hg, Ag, Co, Cu, Fe, Mn, Ni, Sb, Sr and Zn concentrations in 648 water samples collected before and after rain in 6 urban lakes of Beijing, China were determined during 2013-2015. The response of metals concentrations after rain to the interaction between rainfall and antecedent dry days was significant. Metals concentrations were normalized pursuant to the interaction effect as the input of positive matrix factorization (PMF) to develop the interaction normalized-PMF (IN-PMF). Four primary pollution sources were diagnosed. Sediment release was considered to be the main source of Fe, Co and Ni independent of rainfall. Hg, As and some Cr associated with pesticides and fertilizers were likely to come from soil erosion and runoff from green space. It is probable that road runoff was the dominant source for heavy metals related to traffic emissions, including Pb, Cd, Cu, Sb, Mn and Zn. Cr, Sr and some Cu and Zn as key elements of rooftops can be regarded as from roof runoff. The IN-PMF lowered roof and road runoff contributions and raised the contribution of soil erosion from green space, with Pb, Sb, Cu, Zn, Cd and Mn increasing by 15.9%, 10.7%, 13.1%, 12.2%, 13.3% and 16.8%. The results shed more light on the stormwater runoff pollution mitigation on impervious surfaces and metals enrichment problems in infiltration soil on green space in the low impact development (LID) setting. The Bayesian network revealed the spatial variability of transport and fate of metal elements from land surfaces to urban lakes, supplementing the secondary pollution sources from different land use. This study will provide new insights for source apportionment of non-point source pollution under the background of sponge city construction.
时空变异性使城市湖泊中金属的源解析变得复杂，尤其是当降雨驱动城市面源污染时。在2013 - 2015年期间，对中国北京6个城市湖泊降雨前后采集的648个水样中的砷、镉、铬、铅、汞、银、钴、铜、铁、锰、镍、锑、锶和锌浓度进行了测定。降雨后金属浓度对降雨与前期干旱天数之间相互作用的响应显著。根据相互作用效应将金属浓度进行归一化处理，作为正定矩阵因子分解（PMF）的输入，以开发相互作用归一化PMF（IN - PMF）。诊断出四个主要污染源。沉积物释放被认为是铁、钴和镍的主要来源，与降雨无关。与农药和化肥相关的汞、砷和一些铬可能来自土壤侵蚀和绿地径流。道路径流很可能是与交通排放相关的重金属（包括铅、镉、铜、锑、锰和锌）的主要来源。作为屋顶关键元素的铬、锶以及一些铜和锌可被视为来自屋顶径流。IN - PMF降低了屋顶和道路径流的贡献，并提高了绿地土壤侵蚀的贡献，铅、锑、铜、锌、镉和锰分别增加了15.9%、10.7%、13.1%、12.2%、13.3%和16.8%。研究结果为低影响开发（LID）背景下不透水表面雨水径流污染缓解和绿地渗透土壤中金属富集问题提供了更多启示。贝叶斯网络揭示了金属元素从陆地表面到城市湖泊迁移和归宿的空间变异性，补充了不同土地利用的二次污染源。本研究将为海绵城市建设背景下面源污染的源解析提供新的见解。
