Evidence of microbiological control of arsenic release and mobilization in aquifers of Brahmaputra flood plain

摘要

Brahmaputra flood plain is one of the severely arsenic (As) affected areas in India. Published results suggest groundwater is enriched with geogenic As but the mobilization process of As in shallow aquifers remain less understood. Studies have shown that reductive dissolution was a key factor affecting mobility of As between sediments and groundwater systems. Here, we suggest that the mobility of As is greatly affected by microbial organisms, and this remains unstudied so far. The results from this study suggested that As reducing bacteria Pseudomonas aeruginosa (ArsC), found at the study area, helps in conversion of As(V) to As(III) and As(III) gets dissolved easily in aqueous phase helping in easier mobilization of the compound. The phylogenetic relationship obtained by comparing 16S rDNA sequences showed the abundance of P. aeruginosa, a facultative- aerobic bacteria helping in As(V)-reduction. This facilitates the presence of As in high concentration in the groundwater of the study region.