LAUSR

Arsenic in the soil environment has gained renewed interest because of the emerging cognizance that arsenic poisoning is a global concern. Groundwater in the Bengal Basin is significantly polluted by naturally occurring arsenic (As), a toxic metalloid, which adversely affects human health and among the countries facing As contamination problems, India and Bangladesh are the most affected. In soils and sediments, arsenic is often associated with Fe(III) (hydr)oxides and multiple processes/reactions govern its release into groundwater, including abiotic or biotically mediated oxidation-reduction and ligand exchange reactions. Reductive dissolution of arsenic-bearing Fe(III) (hydr)oxides and As(V) reduction to As(III) are the two main mechanisms controlling arsenic partitioning in soils, sediments and groundwater. Even though arsenic reduction is favourable over a wide range of conditions, Fe(III) reduction in nature is dependent on the biotic systems. This review reflects the current state of research for the understanding of arsenic in the soil environment with an emphasis on iron based technologies for its removal. It attempts to collate all the relevant literature such that it can be a useful resource for researchers or policy makers to help recognize and explore useful treatment options.