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| Effects of microorganisms on the release of arsenic from paddy soil colloids at different pH levels |
| Received:October 13, 2021 |
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| KeyWord:microorganism;soil colloid;iron reduction;arsenic;release;pH |
| Author Name | Affiliation | E-mail | | CHEN Shuang | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China
Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China | | | ZHANG Chipeng | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China
Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guiyang 550025, China | re.cpzhang@gzu.edu.cn | | HUANG Chenchen | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China
Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China | | | ZHANG Kaixuan | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China
Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China | | | YANG Zeyan | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China
Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China | | | LUO Jianglan | College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China
Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guiyang 550025, China | |
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| Abstract: |
| To explore the biogeoenvironmental behavior of paddy soil colloids and metal-like arsenic, this study mainly analyzed the differences in the effects of microorganisms on the release of arsenic from soil colloids under different acid-base conditions of initial pHs 3 and 7, respectively, and reveals the internal mechanism. The results showed that the microbial effect was relatively weak at an initial pH of 3 and had little effect on the pH and Eh of the colloidal suspension. Compared with the aseptic condition, the content of Fe2+ and As in the solution increased, and the released As was mainly in the oxidation state As（Ⅴ）. At an initial pH of 7, the microbial activity was relatively strong. By the 28th day, the pH of the colloidal suspension increased to 8.12, and the Eh was reduced to -55 mV, forming a strong reducing environment. Therefore, the amounts of iron reduction and dissolution increased significantly. The Fe2+ content was 2.79 times that of the sterile control group. The adsorbed arsenic in the colloid is released with the reduction and dissolution of iron and is finally formed into reduced As（Ⅲ）. Correlation analysis showed that the release of arsenic from soil colloids was related to the reduction and transformation of iron oxides. There was a significant positive correlation between the amount of arsenic released in the solution and Fe2+ content. In particular, under neutral conditions, the As（Ⅲ）concentration was also significantly positively correlated with Fe2+（r=0.798**, P<0.01）. Therefore, strong microbial activity under neutral environmental conditions can increase the dissimilatory reduction of iron oxides in soil colloids and simultaneously enhance the release and transformation of arsenic. |
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