Stabilization of heavy metals in sediments: A bioavailability-based assessment of carbon adsorbent efficacy using diffusive gradients in thin films

Abstract

This study investigated the effectiveness of carbon adsorbents as remediation material for sediments contaminated with heavy metals and the feasibility of utilizing diffusive gradients in thin films (DGT) as a biomimetic tool to estimate the accumulation of heavy metals in Venerupis philippinaram (Manila clam). The results showed that carbon materials had significant inhibitory effects (14.0–53.0%) on the enrichment of heavy metals in organisms and the order of increasing overall inhibitory effect was: charcoal, peat, activated carbon, and biochar. There were significant correlations (P < 0.0001) between the four heavy metals accumulated in Venerupis philippinaram and those accumulated in DGT devices after 28 days in the laboratory. Observed concentrations of heavy metals enriched in DGT (5.4–42.0%) were less than accumulations in Venerupis philippinaram. The results of in situ DGT applications showed significant correlations between the amount accumulated in DGT and the acid-soluble portion in sediments for both Cu and Pb, with positive linear correlations and R-squares of 0.97 and 0.92, respectively. These results supported the notion that a DGT device can be used as a biomimetic tool that predicts and monitors the accumulation of heavy metals in aquaculture ponds. Future studies should focus on improving the stabilization of heavy metals in sediments using different types of carbon sorbents, as well as minimizing simulation deviations using DGT.