This study investigated the effectiveness of acid-base modified activated carbon in reducing the mobility and bioavailability of heavy metals (Cd, Pb, Zn) in contaminated sediments using Diffusive Gradient in Thin films (DGT) analysis and bioaccumulation assessment with Lumbriculus variegatus. Microcosm experiments were conducted for 7, 14, 21, and 28 days using stabilizer application rates of 5% and 10%, with mechanical mixing and bioturbation methods. DGT analysis showed that the modified activated carbon achieved maximum stabilization efficiencies of 91.67% for Cd, 83% for Pb, and 98.25% for Zn, effectively decreasing the concentrations of bioavailable heavy metals over time. In the bioaccumulation assessment, the accumulation of heavy metals in L. variegatus decreased by up to 9.4 times at the 10% application rate compared to the 5% rate, confirming the dose-dependent effect of the stabilizer. Initially, the population decreased temporarily due to the intake of stabilizers in benthic organisms, but the survival population recovered over time, indicating that the long-term negative impact was not significant. These results indicate that the acid-base modified activated carbon is an effective stabilizing agent for heavy metal-contaminated sediments and highlight the importance of determining optimal application rates by balancing stabilization efficiency and ecological stability.

Keywords: Acid-base modified activated carbon (HNO₃–NaOH modified activated carbon), Heavy metals, Adsorption, Diffusive Gradient in Thin films (DGT), Bioaccumulation