Evaluating the bioavailability of heavy metals in natural-zeolite-amended aquatic sediments using thin-film diffusive gradients

The effectiveness of natural zeolite amendment of sediments as a restorative material was studied, as was the feasibility of utilizing thin-film gradient diffusion (DGT) as a proxy for the accumulation of heavy metals in Venerupis philippinaram. The results showed that addition of natural zeolite to sediment, significantly decreased the equilibrium partitioning of Cu, Pb, Cd, Cr and As between the sediment pore water and natural zeolite over 24 h by 67%, 81%, 72%, 62% and 71%, respectively. Furthermore, the accumulation of Cu, Pb, Cd, Cr and As in V. philippinaram in the zeolite-amended sediments decreased by 44%, 37%, 54%, 30% and 59%, respectively after 28 days and the absorption rates also declined. The amount of heavy metals enriched into the DGT film and V. philippinaram over 28 days showed a significant correlation (P < 0.001) and indicated that DGT has the potential as a proxy to predict the bioaccumulation of heavy metals in benthic organisms in sediments amended by natural zeolite. Further studies focused on the modification of natural zeolite and the predictive ability of DGT in different sediments/organism scenarios are warranted.