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Effects of AQDS and humic acids on the iron reduction process mediated by microorganisms
Received:April 27, 2021  
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KeyWord:Shewanella putrefaciens;dissimilated iron reduction;humic acid;anthraquione-2, 6-disulfonate (AQDS)
Author NameAffiliationE-mail
NIU Danni School of Resources, Environmental and Chemical Engineering, Nanchang University, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang 330031, China  
GONG Xiaofeng School of Resources, Environmental and Chemical Engineering, Nanchang University, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang 330031, China xfgong@ncu.edu.cn 
LI Yuanhang School of Resources, Environmental and Chemical Engineering, Nanchang University, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang 330031, China  
SUN Yuheng School of Resources, Environmental and Chemical Engineering, Nanchang University, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang 330031, China  
SHU Yao School of Resources, Environmental and Chemical Engineering, Nanchang University, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang 330031, China  
ZENG Huiqing School of Resources, Environmental and Chemical Engineering, Nanchang University, Key Laboratory of Poyang Lake Environment and Resource Utilization, Ministry of Education, Nanchang 330031, China  
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Abstract:
      To explore the effects of electron transport on alienated iron reduction, the effects of humic acids and the humus kinoid anthraquione-2,6-disulfonate(AQDS) on the reduction of dissimilated iron under the anaerobic condition was studied under the mediation of Shewanella putrefaciens(Shewanella), and fitting of the logistic equation was performed. Moreover, elemental analysis, UV-visible spectroscopy, and Fourier transform infrared spectroscopy of humic acids from different sources were carried out. The results showed that soil humic acid added with low mass concentration(10~100 mg·L-1) made little difference in the promotion effect of the alienation iron reduction process, but a high mass concentration(200~500 mg·L-1) of soil humic acid promoted the effect significantly. Compared to the control group, the final amount of Fe(Ⅱ) was increased in the system with peat wetland humic acid added, but the final amount showed little difference along the different mass concentration gradient. AQDS promoted Fe(Ⅲ) reduction, and the reduction effect became stronger with higher concentration. According to the logistic equation, both humic acid and AQDS could accelerate the Fe(Ⅲ) reduction rate and also improve the Fe(Ⅲ) percent reduction effectively. The analysis results of the different sources of humic acids showed that both humic acids had a large number of oxygen reactive functional groups, aromatic substances, and aliphatic substances. However, the degrees of humification and aromatization of soil humic acid were stronger than those of humic acid from peat wetland. In conclusion, humic acids and AQDS, as electron transport substances, play an important role in promoting the iron reduction process mediated by the microorganisms, and the promotion effect is more significant when the degree of aromatization is stronger.