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| Effects of iron-modified biochar on arsenic and iron reduction in paddy soil |
| Received:August 25, 2021 |
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| KeyWord:iron-modified biochar;paddy soil;arsenic;iron;dissolved organic carbon;microbial community structure |
| Author Name | Affiliation | E-mail | | HE Xuan | School of Metallurgy and Environment, Central South University, Changsha 410083, China | | | QIAN Ziyan | School of Metallurgy and Environment, Central South University, Changsha 410083, China | | | WU Chuan | School of Metallurgy and Environment, Central South University, Changsha 410083, China | wuchuan@csu.edu.cn | | CUI Mengqian | School of Metallurgy and Environment, Central South University, Changsha 410083, China | | | XUE Shengguo | School of Metallurgy and Environment, Central South University, Changsha 410083, China | |
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| Abstract: |
| In order to study the effect of iron-modified biochar on arsenic（As）/ iron（Fe）speciation transformation in paddy soil, Ascontaminated paddy soils near a mining area in Hunan Province were collected to study the effects of iron-modified biochar on As/Fe speciation and microbial community abundance. Treatments included control（CK）, biochar （CS）, iron-modified biochar（CFS）, and AQDS （AS）. At 49 d, the As（Ⅲ）concentrations of the different treatments were in the order of CS（383.6 μg · L-1）>AS（335.7μg · L-1）> CK（296.9μg·L-1）>CFS（109.7μg·L-1）, and the Fe（Ⅱ）concentrations varied as CFS（166.3 mg·L-1）>AS（155.1 mg·L-1）>CS（123.8 mg· L-1）>CK（72.43 mg·L-1）. Dissolved organic carbon（DOC）was utilized at proportions of 52.37%, 56.96%, 55.29%, and 53.52% in the CK, CS, CFS, and AS treatments, respectively. The humification degree of DOC in the liquid layer of CFS, AS, and CS was significantly higher than that of CK. The sequencing results of the 16S rRNA gene showed that the dominant microorganisms were Proteobacteria, Firmicutes, Actinobacteria, and Chloroflexi, which accounted for about 70.0% of the total bacteria. The relative abundance of As/Fe reducing bacteria （Clostridium, Geobacter, and Anaeromyxobacter） was highest in the CFS treatment. The introduction of the iron-modified biochar simultaneously alters the DOC bioavailability and the microbial community composition, thus affecting the reduction of As（Ⅴ）/Fe（Ⅲ）. It is potential for understanding the mechanism of As remediation in contaminated paddy soils. |
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