Effect of pH and Salinity on Sorption of Antimony (III and V) on Mangrove Sediment, Sundarban, India Sanjay Kumar Mandala, Natasha Majumderb, Chumki Chowdhuryb, Tapan Kumar Janab, and Buddhadeb Duttac aDepartment of Chemistry, Calcutta University, Sundarban Hazi Desarat College, Pathankhali, 24 Pgs (South), West Bengal, India; bDepartment of Marine Science, Calcutta University, 35, B. C. Road, Kolkata, India; cDepartment of Chemistry, West Bengal State University, Ramakrishna Mission Vivekananda Centenary College, Rahara, Kolkata, India,SOIL AND SEDIMENT CONTAMINATION 2017, VOL. 26, NO. 7, 1–12 https://doi.org/10.1080/15320383.2017.1400519, ABSTRACT The extent of toxic metalloid retention and bioavailability and mobility in the sediment is of interest for understanding their biogeochemical cycling and for accurate risk assessment in an ecosystem. Intensification of monsoon and rainfall, believed to be related to global warming, could drive future changes of temperature, salinity, and pH distribution pattern affecting antimony cycling in the Sundarbans. This study investigated sorption kinetics of antimony (Sb) (III and V) as a function of temperature, salinity, and pH following the Langmuir model, and demonstrated that clayey silt type mangrove sediment was an effective adsorbent with higher efficiency for Sb (V) than Sb (III). Background level of Sb in the sediment was 0.35–0.78% of the maximum adsorption capacity (Gm). Out of the two distinct type of sorption sites governing mobility and bioavailability of Sb in the sediment, site 1 (Humic acid) showed higher affinity for Sb than the site II (oxyhydroxide). Sb adsorption was strongly influenced by temperature, salinity, and pH, which may be altered by long-term changes in climate and rainfall pattern. KEYWORDS Antimony; mangrove sediment; pH; salinity; sorption