Department of Plant & Soil Sciences, University of Delaware, Newark, DE 19716, USA; Department of Civil & Environmental Engineering, University of Delaware, Newark, DE 19716, USA.
Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409, USA.
J Hazard Mater. 2022 Feb 5;423(Pt B):127161. doi: 10.1016/j.jhazmat.2021.127161. Epub 2021 Sep 11.
Sea-level rise (SLR) has a vital influence on coastal hydrogeological systems, biogeochemical processes, and the fate of coastal contaminants. However, the effects of SLR-induced perturbations on the mobilization of coastal pollutants are not fully understood. In this study, the impact of SLR-induced flooding on the concentration and speciation of arsenic and selected hazardous chemicals is investigated using exceedingly contaminated sediments (5-6% As) collected from an urban coastal site in Wilmington, DE, USA. The release of contaminants from sediments was monitored before, during, and after flooding with different intensities (bottom shear stresses) through laboratory-based erosion chamber experiments. Significantly increased release of As (up to 150%) and NO (up to 50%) from sediments at shear stress levels typically measured in estuaries were found. The release of toxic chemicals from contaminated coastal sediments is thus not restricted to extreme flooding events but can occur throughout the year. The results also suggest that the dissolved concentrations of pollutants continue to be considerably high even after the flooding. SLR-induced flooding can hence increase the release of contaminants not only during erosion events but over longer timescales. The release mechanism proposed here contributes to improving the risk assessment of coastal water pollution as climate change and SLR continue to occur.
海平面上升 (SLR) 对沿海水文地质系统、生物地球化学过程以及沿海污染物的归宿具有重要影响。然而，海平面上升引起的扰动对沿海污染物迁移的影响尚不完全清楚。本研究使用从美国特拉华州威尔明顿市一个城市沿海地区采集的污染非常严重的沉积物（5-6% 的砷），调查了海平面上升引发的洪水对砷和选定的危险化学品浓度和形态的影响。通过实验室侵蚀室实验，在洪水前后监测了不同强度（底部切应力）下污染物从沉积物中的释放情况。结果发现，在通常在河口测量的切应力水平下，沉积物中砷（高达 150%）和硝酸盐（高达 50%）的释放显著增加。因此，受污染的沿海沉积物中有毒化学物质的释放不仅限于极端洪水事件，而是可能全年发生。结果还表明，即使在洪水过后，污染物的溶解浓度仍相当高。因此，海平面上升引发的洪水不仅会在侵蚀事件期间，而且会在更长的时间内增加污染物的释放。这里提出的释放机制有助于提高沿海水污染风险评估，因为气候变化和海平面上升仍在继续发生。
