Nitrogen-Fixing Anabaena sp.Mediated As(Ⅲ)Oxidation and Its Response to Ammonium Input
Ammonium plays an important role in the biogeochemical cycle of arsenic,but the mechanism of ammonium input on algae-mediated As(Ⅲ)bio-oxidation remains unexplored.The arsenic-resistant cyanobacteria Anabaena sp.was used in this study.Through laboratory simulation experiments,the toxicity,oxidation of different As(Ⅲ)concentrations mediated by Anabaena sp.was investigated.The influences of the input of exogenous ammonium on the growth of Anabaena sp.and the oxidation of As(Ⅲ)were also explored.The results show that the IC50 value of Anabaena sp.was 15.59 mg/L,and 0.1 mg/L,1 mg/L and 10 mg/L As(Ⅲ)were completely oxidized to As(Ⅴ)within 1 d,2 d and 7 d,respectively,after inoculating Anabaena sp.,With the concentration of As(Ⅲ)increased,the nitrogen fixation effect of Anabaena sp.is enhanced.Furthermore,the growth of Anabaena sp.was promoted within 234 mg/L NH4+.With the increase of NH4+concentration from 0 mg/L to 1 mg/L,45 mg/L and 234 mg/L,1 mg/L As(Ⅲ)was completely oxidized at 48 h,36 h,24 h and 12 h,respectively,as the concentration of NH4+increases,the adsorption of Anabaena sp.to arsenic increases,and the oxidation of As(Ⅲ)accelerates.The research results help to interpret the role of ammonium nitrogen in the process of arsenic biotransformation in natural waters.
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