Evaluation of sediment dredging in remediating toxic metal contamination — a systematic review

Toxic metal pollution is a leading environmental concern for aquatic systems globally, and remedial dredging has been widely employed to mitigate its harmful impacts. In terms of the short-term impacts of remedial dredging, mixed results are reported in several studies. Despite its immediate negative impacts including saturation of water with toxic metals, increased turbidity, and sediment resuspension, positive impacts can be recorded over a stabilization period of 6–24 months after dredging. Nevertheless, the sustainability of these recorded positive effects cannot be ascertained as some studies have reported long-term regression in remediated sites’ conditions. Evaluation of success determinants, site-measure compatibility, and determination of supplementary measures are keys to achieving and sustaining the projected benefits of remedial dredging and justifying its overall cost. This multicomponent study reviewed published literatures that documented the outcomes of short- and long-term dredging projects in toxic metal-polluted systems globally with a broad goal of examining how sediment removal impacts toxic metal dynamics in the aquatic system and understanding why the sustenance of positive impacts is controversial. In the meantime, this study also explored the preventative and remedial management strategies for attaining and sustaining positive dredging outcomes. The purpose of this study is to provide key recommendations for decision-making and policy development in aquatic toxic metal remediation.