Arsenic Contamination: Sources, Chemistry and Remediation Strategies

Growing industrialisation, urbanisation and technological advancements have been endlessly increasing the environmentally contaminating heavy metals load. Arsenic contamination as an environmental pollutant has transcended as a major global concern to address. Arsenic contamination of air, soil, water, sediment and crops due to the various anthropogenic (agricultural) and geogenic (geochemical) sources is a major global threat, including India, owing to its hazardous and toxic nature. Primarily, the three and five valency arsenic cause severe human health concerns at an elevated concentration (>0.05 mg/l) affecting millions of people worldwide year-after-year. Generally non-biodegradable, arsenic can be transformed into less toxic forms by adopting chemical, biological and/or composite techniques involving oxidation-reduction, methylation, complexation, precipitation, immobilisation through sorption, etc. Microbial and phyto-remediation of arsenic through adsorption, absorption, extracellular entrapment, precipitation and oxidation-reduction reactions are gaining global attention due to their greater advantages. While phytoremediation includes phytoextraction and phytovolatilisation, microbial biomass remediates through active/passive/combined arsenic binding. The chapter embodies the underlying arsenic toxicity and bioremediation mechanisms for a cleaner and healthier environment. It details the chemical and biological remediation of arsenic highlighting the advantages of biological approaches.