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| Effects of humic acid washing on the microbial community composition in heavy metal-contaminated soil |
| Received:November 08, 2022 |
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| KeyWord:heavy metal;soil washing;humic acid;environmental factor;microbial community and structure |
| Author Name | Affiliation | E-mail | | FANG Mingzhi | College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China | | | TANG Siqi | College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China | | | SUN Yucan | College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China | | | CHEN Tan | College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China | | | ZHANG Bing | College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China | | | LIU Yifei | Technical Centre for Soil, Agriculture and Rural Ecology and Environment, Ministry of Ecology and Environment, Beijing 100012, China | | | YANG Ting | College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China | ty672@muc.edu.cn |
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| Abstract: |
| The aim of this study is to elucidate the characteristics of heavy metal speciation, soil physicochemical properties, and microbial community structure changes mediated by humic acid residues after soil washing. Based on soil washing laboratory experiments and highthroughput sequencing technology, pH, NH4+-N and soil organic carbon(SOC) content before and after humic acid washing, further changes in soil microbial community structure and diversity, and the main environmental influencing factors were determined. The results showed that the humic acid washing process could remove Cd and Zn from the soil; however, this process was less effective in removing Pb. The mobility of Cd and Zn in the soil increased, indicating that the two metals were activated after washing. The oxidation and residual fraction of Pb increased, thus the mobility decreased. As for the soil microbial community structure, the bacterial community richness first decreased and then increased, while the community diversity increased within 30 days after washing. The relative abundance of Chloroflexi, Acidobacteria, Gemmatimonadetes, Fibrobacteres, and Armatimonadetes increased, while that of Actinobacteria and Firmicutes decreased after washing. The interactions and network complexity of microbial communities in the soil were enhanced after humic acid washing. Soil microorganisms would utilize materials more efficiently and be more resistant to environmental disturbances after soil washing. The change of microbial community structure was mainly driven by NH4+-N content and changing the acid-soluble fraction of Pb and Zn. Humic acid could remove Cd and Zn from soil effectively; however, activating Cd and Zn and reduced microbial community diversity in soil; The residue of humic acid in soil could immobilize heavy metals, increase microbial community diversity, and improve microbial community structure during incubation. Therefore, humic acid is an efficient and environmentally friendly washing agent, which can remove heavy metals effectively and improve soil microbial community structure. Furthermore, this study can provide scientific guidance for evaluating the microecological response of soil after washing. |
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