Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Environ Pollut. 2019 Feb;245:725-734. doi: 10.1016/j.envpol.2018.11.050. Epub 2018 Nov 21.
This study assessed the effectiveness of dredging in controlling arsenic (As), selenium (Se), and antimony (Sb) contamination in sediments, by examining contaminant concentrations in sediments six years after dredging was completed. High-resolution diffusive gradients in thin films (DGT) and dialysis (HR-Peeper) techniques were used to monitor the concentrations of DGT-labile metalloids and soluble metalloids in sediments, respectively. Results revealed that dredging effectively remediated metalloid contamination in sediments only in April, July and/or January. Compared to non-dredged sediments, the concentrations of soluble and DGT-labile As, Se, and Sb in dredged sediments decreased on average by 42%, 52%, and 43% (soluble), and 54%, 50%, and 53% (DGT), respectively. The effectiveness of the dredging was primarily due to the transformation of metalloids from labile to inert fractions, which increased the ability of the sediments to retain the metalloids, and the slowed rate of resupplied metalloids from available solid pools. In contrast, negligible/negative effects of dredging were seen in October, and the concentrations of soluble and DGT-labile metalloids even increased in some profiles of dredged sediments. This was mainly caused by a release of the metalloids from algal degradation, which may offset the dredging effectiveness.
本研究通过在疏浚完成六年后检测沉积物中污染物浓度，评估了疏浚在控制砷（As）、硒（Se）和锑（Sb）污染方面的效果。采用高分辨率扩散梯度薄膜（DGT）和透析（HR-Peeper）技术分别监测沉积物中 DGT 不稳定类金属元素和可溶性类金属元素的浓度。结果表明，疏浚仅在 4 月、7 月和/或 1 月有效修复了沉积物中的类金属污染。与未疏浚沉积物相比，疏浚沉积物中可溶性和 DGT 不稳定砷、硒和锑的浓度平均分别降低了 42%、52%和 43%（可溶性）和 54%、50%和 53%（DGT）。疏浚的有效性主要归因于类金属从不稳定态向惰性态的转化，增加了沉积物保留类金属的能力，并减缓了从可用固相库中补充类金属的速度。相比之下，10 月疏浚的效果微不足道/为负，一些疏浚沉积物的剖面中可溶性和 DGT 不稳定类金属元素的浓度甚至增加。这主要是由于藻类降解导致类金属释放，这可能抵消了疏浚的效果。
