State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China.
Institute of International Rivers and Eco-security, Yunnan University, Kunming 650091, China.
Water Res. 2023 Sep 1;243:120393. doi: 10.1016/j.watres.2023.120393. Epub 2023 Jul 20.
Road-deposited sediments (RDS) on urban impervious surfaces are important carriers of heavy metals (HMs), and can contribute to urban runoff pollution. With the outbreak of COVID-19, chlorinated disinfectants (CDs) have been extensively sprayed on these surfaces. This practice may have a superposed or priming effect on HMs contaminants in RDS, yet this remains unknown. This study examined the effects of seven CDs concentration gradients (0, 250, 500, 1000, 2000, 5000, 60,000 mg/L) on the leaching and chemical forms of HMs (Cd, Cr, Ni, Pb, and Zn) in seven particle size fractions (<44, 44-63, 63-105, 105-149, 149-250, 250-450, 450-1000 μm). The results showed that CDs can promote the leaching of HMs in RDS, at the recommended CDs dose (2000 mg/L), except for Pb, the leaching amounts increased by 21.8%-237.2% compared with the untreated RDS. The alteration in the leaching were primarily attributed to the redistribution of chemical forms of HMs in RDS, specifically, the acid-extractable fractions percentage increased by 0.23%-24.39%, and the reducible fractions percentages decreased by 3.21%-38.35%. The lower oxidation-reduction potential (ORP) and alkalinity of CDs as strong oxidants were responsible for the redistribution of forms. The leaching and chemical forms of HMs vary among different particle sizes, but in any case, finer particle sizes (< 105 μm) still dominate their contribution. The current control measure of street sweeping is ineffective in removing these particles. These findings will facilitate the development of strategies for controlling urban diffuse pollution from RDS during the pandemic. Finally, this study suggests potential directions for future research.
道路沉积物（RDS）在城市不透水表面上是重金属（HMs）的重要载体，并可能导致城市径流污染。随着 COVID-19 的爆发，氯化消毒剂（CDs）已广泛喷洒在这些表面上。这种做法可能对 RDS 中的 HMs 污染物产生叠加或启动效应，但这一点尚不清楚。本研究考察了七种 CDs 浓度梯度（0、250、500、1000、2000、5000、60000mg/L）对七种粒径分馏物（<44、44-63、63-105、105-149、149-250、250-450、450-1000μm）中 HMs（Cd、Cr、Ni、Pb 和 Zn）浸出和化学形态的影响。结果表明，在推荐的 CDs 剂量（2000mg/L）下，CDs 可以促进 RDS 中 HMs 的浸出，除了 Pb 之外，与未经处理的 RDS 相比，浸出量增加了 21.8%-237.2%。浸出的变化主要归因于 RDS 中 HMs 化学形态的再分配，具体而言，酸可提取分数的百分比增加了 0.23%-24.39%，可还原分数的百分比减少了 3.21%-38.35%。作为强氧化剂的 CDs 的较低氧化还原电位（ORP）和碱度是形态再分配的原因。HMs 的浸出和化学形态在不同粒径之间存在差异，但无论如何，粒径较小的（<105μm）仍占主导地位。目前的街道清扫控制措施在去除这些颗粒方面效果不佳。这些发现将有助于制定大流行期间控制 RDS 引起的城市弥散污染的策略。最后，本研究提出了未来研究的潜在方向。
