Analytical, Environmental and Geo-Chemistry Department (AMGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium.
Analytical, Environmental and Geo-Chemistry Department (AMGC), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Center for Water Research, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, 519087, China.
Sci Total Environ. 2022 Sep 15;839:156353. doi: 10.1016/j.scitotenv.2022.156353. Epub 2022 May 30.
The biogeochemical cycle of trace metals and oxyanions in marine sediments is mainly controlled by early diagenesis of organic material, but anthropogenic activities such as dumping of dredged sludge or shipyard activities can strongly perturb these natural processes. Therefore, the impact of dumping of dredged sludge, shipyard activities such as blasting of boat hulls and the mixing of polluted Scheldt estuary water with less polluted coastal water on the mobilization of trace metals and oxyanions in the sediments was studied in the pre- and post-bloom period (March and October) in Belgian Coastal Zone (BCZ). Vertical profiles of total and labile dissolved trace element concentrations, dissolved sulfide, pH and redox potential were assessed in sediment porewaters. Generally, total and labile dissolved element profiles in the porewaters are well correlated, showing higher concentrations in March when the redox potential is lower and sulfide concentrations higher. Low pH levels were documented together with high amounts of Fe and associated elements in March at the dumping station. At the coastal station in the vicinity of the shipyards, sediment porewaters are enriched in dissolved Zn while at the mouth of the Scheldt estuary the highest dissolved Cu levels were found. Theoretical calculations with Visual MINTEQ confirm the increased Fe and associated element concentrations in March (lower pH) and the lower metal concentrations in October (lower Eh). R values, ratio of labile dissolved to total dissolved concentrations, reflect the potential of the solid sediment phase to supply labile elements to the porewater. They were lowest for Cu and highest for V. This study showed that anthropogenic activities in the BCZ such as dumping of dredged sludge and blasting of boat hulls have a serious impact on the levels, distribution and bioavailability of contaminants in the sediments, which may form a real threat to the benthic ecosystem.
海洋沉积物中痕量金属和含氧阴离子的生物地球化学循环主要受有机物质的早期成岩作用控制，但人为活动，如疏浚污泥的倾倒或造船厂活动，会强烈干扰这些自然过程。因此，本研究调查了在比利时沿海带（BCZ）的赤潮前和赤潮后时期（三月和十月），疏浚污泥的倾倒、船体爆破等造船厂活动以及受污染的斯海尔德河口与污染较少的沿海水混合对沉积物中痕量金属和含氧阴离子的迁移的影响。评估了沉积物孔隙水中总溶解态和可溶解态痕量元素浓度、溶解态硫化物、pH 值和氧化还原电位的垂直分布。通常，孔隙水中总溶解态和可溶解态元素的分布具有很好的相关性，在氧化还原电位较低且硫化物浓度较高的三月，显示出更高的浓度。在倾倒站，三月记录到低 pH 值以及大量的 Fe 和相关元素。在靠近造船厂的沿海站，沉积物孔隙水中溶解态 Zn 富集，而在斯海尔德河口的河口处，发现了最高的溶解态 Cu 水平。使用 Visual MINTEQ 进行的理论计算证实了三月（更低的 pH 值）Fe 和相关元素浓度的增加，以及十月（更低的 Eh）金属浓度的降低。R 值（可溶解态与总溶解态浓度的比值）反映了固体沉积物向孔隙水提供可溶解元素的潜力。Cu 的 R 值最低，V 的 R 值最高。本研究表明，BCZ 中的人为活动，如疏浚污泥的倾倒和船体的爆破，对沉积物中污染物的水平、分布和生物可利用性产生了严重影响，这可能对底栖生态系统构成真正的威胁。
