Beschreibung:
The mobilization and enrichment of arsenic(As) in groundwater is considered to be mainly affected by microbial dissimilation reduction, however competitive adsorption and complexation of natural organic matter(OM) complicate its mobilization in field scene. High concentration of biodegradable OM and high-As aquifer sediment were cultivated in batch experiment to focus on the microbial affected As release patterns and its controlling process. The small molecular OM(glucose and sodium lactate) with no potential competitive adsorption and complexation effects on As mobilization were used. We have shown that active OMs can rapidly stimulate indigenous microorganisms. As a driving factor of redox reaction, OM could remove As from sediments through microbial mediated reduction and dissolution of Fe oxide, and HA can promote this process. OMs can increase the relative abundance and activity of anaerobic/facultative anaerobic metal dissimilation reducing bacteria, including Proteobacteria, Firmicutes, Actinobacteria and Bacteroides. The change of microbial community is a comprehensive reaction of mobilization of As, Fe, Mn, OM degradation, redox conditions and pH changes. The results support that microorganisms participate in the process of As mobilization by using active OMs. This study shows the potential risk of surfaced derived OM could degrade groundwater quality by stimulating groundwater As, Fe and Mn release