DGT Passive Samplers as Monitoring Alternatives When Heavy Metal Toxicity Eliminates Bioindicators in Contaminated Sediments.

Heavy metal pollution in sediments impacts benthic ecosystems. This study evaluated the adverse effects of Cd, Cu, and As on Tubifex tubifex and compared bioaccumulation with diffusive gradients in thin-films (DGT) passive samplers at three exposure doses. In medium (1.87 mg kg-1 Cd, 228 mg kg-1 Cu, 44.7 mg kg-1 As) and high concentrations, 100% lethality occurred after 12 h, preventing bioaccumulation evaluation. Only low concentrations (0.4 mg kg-1 Cd, 48 mg kg-1 Cu, 15 mg kg-1 As) allowed 10-day monitoring. DGT samplers provided quantitative physicochemically labile metal fraction measurements across all treatments, with reliable linear accumulation observed for Cd (R2=0.99, p=0.001) and As (R2=0.93, p=0.008) including at lethal concentrations. Cu accumulation at the High treatment showed poor linearity (R2=0.01, p=0.847), attributed to potential binding layer saturation under extreme contamination. DGT provides a complementary physicochemical exposure assessment tool when indicator mortality prevents traditional biomonitoring in contaminated sediments.