Passive Sampling-Based versus Conventional-Based Metrics for Evaluating Remediation Efficacy at Contaminated Sediment Sites: A Review.

Passive sampling devices (PSDs) are increasingly used at contaminated sites to improve the characterization of contaminant transport and assessment of ecological and human health risk at sediment sites and to evaluate the effectiveness of remedial actions. The use of PSDs after full-scale remediation remains limited, however, in favor of evaluation based on conventional metrics, such as bulk sediment concentrations or bioaccumulation. This review has three overall aims: (1) identify sites where PSDs have been used to support cleanup efforts, (2) assess how PSD-derived remedial end points compare to conventional metrics, and (3) perform broad semiquantitative and selective quantitative concurrence analyses to evaluate the magnitude of agreement between metrics. Contaminated sediment remedies evaluated included capping, in situ amendment, dredging and monitored natural recovery (MNR). We identify and discuss 102 sites globally where PSDs were used to determine remedial efficacy resulting in over 130 peer-reviewed scientific publications and numerous technical reports and conference proceedings. The most common conventional metrics assessed alongside PSDs in the peer-reviewed literature were bioaccumulation (39%), bulk sediments (40%), toxicity (14%), porewater grab samples (16%), and water column grab samples (16%), while about 25% of studies used PSDs as the sole metric. In a semiquantitative concurrence analysis, the PSD-based metrics agreed with conventional metrics in about 68% of remedy assessments. A more quantitative analysis of reductions in bioaccumulation after remediation (i.e., remediation was successful) showed that decreases in uptake into PSDs agreed with decreases in bioaccumulation (within a factor of 2) 61% of the time. Given the relatively good agreement between conventional and PSD-based metrics, we propose several practices and areas for further study to enhance the utilization of PSDs throughout the remediation of contaminated sediment sites.