Biochar
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2024
·Vol. 6
·期 1
·1-14
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IF 13.1
Wang Shengsen,Li Wenjing,Ding Chengyu,Zhang Jian,Zhang Ni,Li Yuncong C.,Gao Bin,Wang Bing,Wang Xiaozhi
Arsenic (As) detoxification in polluted soils by iron-based materials can be mediated by the endogenous soil organic matter (SOM), nevertheless the mechanisms remain unclear. Herein, endogenous SOM in a paddy soil was substantially removed to understand its roles on As immobilization by biochar-supported zero-valent iron (ZVI/BC). The results demonstrated that ZVI/BC application significantly decreased As bioavailability by 64.2% compared with the control soil under the anaerobic condition. XPS and HR-TEM suggested As immobilization by ZVI/BC mainly invoked the formation of ternary complexes (i.e., As-Fe-SOM). However, SOM depletion compromised the efficacy of ZVI/BC for As immobilization by 289.8%. This is likely because SOM depletion increased the fulvic acid and OH − contents in soils. Besides, ZVI/BC increased the proportion of As(III) in available As fraction, but SOM depletion altered the mechanisms associated with As(V) reduction. That is, As(V) reduction resulted from the reductive capacity of ZVI in the pristine soil, but the As(V)-reducing bacteria contributed greater to As(V) reduction in the SOM-depleted soil. Additionally, SOM depletion boosted the abundances of Fe(III)- and As(V)-reducing bacteria such as Bacillus and Ammoniphilus in soils, which enhanced the dissimilatory arsenate reduction. Thus, this work highlighted the importance of SOM in the remediation of As-contaminated soils by ZVI/BC. Graphical Abstract
研究领域:
环境科学
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土壤化学
·
微生物学
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产品关联
DOI
高影响因子
Journal of Geophysical Research-Biogeosciences
·
2025
·Vol. 130
·期 3
·e2024JG008675
·
IF 3.5
Zhengqi Su,Huaming Guo,Zhipeng Gao,Tiantian Ke,Xiaojun Feng,Lingzhi Zhang
Although the reduction of pentavalent arsenic (As(V)) bound to Fe(III) (hydr)oxides (As(V)-containing FeOOH) coupled with organic matter (OM) degradation has received extensive attention, little is known about in situ reduction of FeOOH mineral-bound As(V) (As(V) (s) ) via electron shuttling in the presence of As(V)-reducing bacteria (AsRB). Here, anthraquinone-2,6-disulfonate (AQDS), Suwannee River humic acid (SRHA), and fulvic acid (SRFA) were used to establish an agar electron shuttle system with ferrihydrite-As(V)/goethite-As(V) and AsRB, which was isolated from high-As groundwater as the candidate strain (RA-1). We found that AQDS was more efficient in shuttling electrons to reduce As(V) (s) and Fe(III) than SRHA and SRFA. High contents of quinone moieties in AQDS indicated that quinone moieties were conducive to As(V) (s) and Fe(III) reduction. The reduction kinetic rates ( K red ) of As(V) (s) were higher than those of Fe(III), indicating the occurrence of in situ As(V) (s) reduction via electron shuttling. Furthermore, K red of As(V) (s) for ferrihydrite-As(V) systems was greater than that of goethite-As(V) systems, demonstrating that As(V) bound to ferrihydrite via monodentate was more easily reduced than that bound to goethite via bidentate. The relative expression levels of As metabolic genes ( ars C, arr A, and ars B) initially increased and then decreased in the late stage of experiments. High As concentrations in suspension inhibited the transcriptional activity of As metabolic genes in the late stage, reducing the electron production efficiency of RA-1 and subsequently slowing in situ reduction of As(V) (s) . This study highlights the importance of OM electron shuttling in the reduction of As(V) (s) , offering new perspectives in As enrichment in groundwater. Plain Language Summary OM can promote microbial As(V) reduction in high As groundwater systems. As a result, we explored how FeOOH mineral-bound As(V) could be in situ reduced via electron shuttling between AsRB and different OM. Our findings showed that AQDS was more effective than other two natural organic matter (NOM, i.e., SRHA and SRFA) in reducing both As(V) (s) and Fe(III), due to its high content of quinone moieties. The results of kinetic analysis demonstrated in situ reduction of As(V) (s) , and As(V) bound to ferrihydrite was more readily reduced than As(V) bound to goethite. In addition, the transcriptional activities of three As metabolic genes initially increased but later declined due to high As concentrations, which further slowed the As(V) (s) reduction process. Overall, these findings provide new insights into organic-mediated As cycling in contaminated groundwater. Key Points High quinone contents in AQDS led to a higher reduction extent of As(V) (s) than in SRHA and SRFA The values of K red, As were greater than those of K red, Fe , demonstrating in situ reduction of As(V) (s) Changes in As metabolic genes affected the electron production efficiency of RA-1 and As(V) (s) reduction
研究领域:
环境科学
·
微生物学
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DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2020
·
IF 9.038
Guowen Dong,Ruiwen Han,Yajing Pan,Chengkai Zhang,Yu Liu,Honghui Wang,Xiaoliang Ji,Randy A. Dahlgren,Xu Shang,Zheng Chen,Minghua Zhang
This study examined the role of intermittent illumination/dark conditions coupled with MnO 2 -ammendments to regulate the mobility of As and Fe in flooded arsenic-enriched soils. Addition of MnO 2 particles with intermittent illumination led to a pronounced increase in the reductive-dissolution of Fe(III) and As(V) from flooded soils compared to a corresponding dark treatments. A higher MnO 2 dosage (0.10 vs 0.02 g) demonstrated a greater effect. Over a 49-day incubation, maximum Fe concentrations mobilized from the flooded soils amended with 0.10 and 0.02 g MnO 2 particles were 2.39 and 1.85-fold higher than for non-amended soils under dark conditions. The corresponding maximum amounts of mobilized As were at least 92 % and 65 % higher than for non-amended soils under dark conditions, respectively. Scavenging of excited holes by soil humic/fulvic compounds increased mineral photoelectron production and boosted Fe(III)/As(V) reduction in MnO 2 -amended, illuminated soils. Additionally, MnO 2 amendments shifted soil microbial community structure by enriching metal-reducing bacteria (e.g., Anaeromyxobacter , Bacillus and Geobacter ) and increasing c -type cytochrome production. This microbial diversity response to MnO 2 amendment facilitated direct contact extracellular electron transfer processes, which further enhanced Fe/As reduction. Subsequently, the mobility of released Fe(II) and As(III) was partially attenuated by adsorption, oxidation, complexation and/or coprecipitation on active sites generated on MnO 2 surfaces during MnO 2 dissolution. These results illustrated the impact of a semiconducting MnO 2 mineral in regulating the biogeochemical cycles of As/Fe in soil and demonstrated the potential for MnO 2 -based bioremediation strategies for arsenic-polluted soils.
研究领域:
环境科学
·
土壤学
·
微生物学
·
生物地球化学
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产品关联
DOI
PubMed
高影响因子
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