Elemental geochemistry in acid sulphate soils – A case study from reclaimed islands of Indian Sundarban.

Abstract Sundarban along with its networks of rivers, creeks and magnificent mangroves form a unique ecosystem. Acid sulphate soils have developed in this ecosystem under anoxic reducing conditions. In the present study, we have investigated the distribution of acid sulphate soils along with its elemental characterization and possible sources in four reclaimed islands of Indian Sundarban like Maushuni (I1), Canning (I2), Bally (I3) and Kumirmari (I4). Elements show moderate to strong correlation with each other (P < 0.01; P < 0.05). Except Si, Ca and Pb, a higher enrichment factor was observed for K, Cr, Mn, Fe, Ni, Cu and Zn. Geo-accumulation index values of all sampling locations reveal that Cr, Fe, Cu and Zn are in I geo class 1. The pollution load index value of the reclaimed islands of Indian Sundarban varies between 1.31 and 1.48. The observation of this study could help to strategize policies to mitigate and manage acid sulphate soils in Indian Sundarban. Highlights • First ever report of the presence of acid sulphate soil in reclaimed islands of Indian Sundarban. • Accumulation and distribution of major elements and trace metals in acid sulphate soils were studied. • A higher enrichment factor was observed for K, Cr, Mn, Fe, Ni, Cu and Zn. • The enrichment of Al, Si, K, Ca, Ni, Mn, and Pb were found not to be geologic in origin. • The pollution load index value was maximum at Bally Island. [ABSTRACT FROM AUTHOR]