Prof. Xiaomin Li from SERI, collaborating with Prof. Fangbai Li from Guangdong Institute of Eco-Environmental Science & Technology, recently published a cover article titled “Humic substances facilitating arsenic reduction and release in flooded paddy soil” in Environmental Science & Technology.
It is found that three humic fractions (fulvic acid, FA; humic acid, HA; and humin, HM) extracted from soil can substantially enhanced the extent of arsenic reduction and release in flooded paddy soil in the order FA > HA > HM. It is verified that humic substances facilitated arsenic reduction and release via three main pathways: (1) functioning as an electron shuttle, (2) providing labile carbon as an electron donor and increasing the abundance of indigenous soil bacteria (i.e., Azoarcus, Anaeromyxobacter and Pseudomonas), and (3) stimulating the transcriptions of the As(V) respiration-related arrA gene and As(V)-respiring Geobacter species.
Humic substances represent an important fraction of natural organic matter. This study demonstrates the microbial-chemical mechanisms of arsenic reduction and release facilitated by humic substances in flooded paddy soil. The presence of humic substances not only changed the activity and structure of microbial community, but also strongly affected the biogeochemistry cycling of arsenic and iron. These findings are important in the agricultural production of paddy field. (1) Paddy soil with a high content of HS, particularly with high FA levels, can be predicted to highly elevate As(III) concentrations into soil solution during flooding seasons. (2) FA and HA are also commonly used as soil supplements in agriculture. Therefore, introducing HS into arsenic-contaminated paddy soil, particularly during planting season, should be considered very carefully. (3) An arsenic remediation strategy using HS can be developed and applied during the slack season to respond to the demand for safe food and sustainable agriculture because this environmentally friendly substance can effectively mobilize arsenic from arsenic-contaminated paddy soil.
The corresponding author of this paper is Prof. Fangbai Li, and Dr. Jiangtao Qiao and Prof. Xiaomin Li are co-first authors. Please refer to this paper as follow.
Jiangtao Qiao†, Xiaomin Li†, Fangbai Li*, Tongxu Liu, Lily Y. Young, Weilin Huang, Ke Sun, Hui Tong, Min Hu. 2019. Humic substances facilitate arsenic reduction and release in flooded paddy soil. Environmental Science & Technology 53(9), 5034–5042.
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Jiang-tao Qiao†, Xiao-min Li†, Min Hu, Fang-bai Li*, Lily Y. Young, Wei-min Sun, Weilin Huang, Jiang-hu Cui. 2018. Transcriptional activity of arsenic-reducing bacteria and genes regulated by lactate and biochar during arsenic transformation in flooded paddy soil. Environmental Science & Technology 52(1), 61−70.
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