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| Effect of biochar on iron reduction in paddy soils under controlled illumination condition |
| Received:July 13, 2015 |
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| KeyWord:biochar;photosynthetic microorganisms;Fe(Ⅲ) reduction |
| Author Name | Affiliation | E-mail | | YOU Ping | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | JIA Rong | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | | | QU Dong | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | dongqu@nwafu.edu.cn | | TANG Jun-yao | College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China | |
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| Abstract: |
| Photosynthetic cyanobacteria in paddy soils influence soil redox and thus iron oxidation-reduction via their oxygen-producing process. Biochar may affect the habitats for these microorganisms. Here the effects of biochar additions on photosynthetic cyanobacterial growth and redox balance at soil-water interface in paddy soil system were investigated. Three types of calcareous paddy soils amended with biochar with different particle sizes were anaerobically incubated with or without illumination at constant temperature(30 ℃). Fe(Ⅱ) concentration, pH, and chlorophyll a(Chl a) content were determined during incubation. Results showed that under no illumination, microbial iron(Ⅲ) reduction was promoted by biochar additions, but the particle size of biochar did not show significant effects. However, under illumination, Chl a content in TJ, NX and SC paddy soils was reduced by biochar by 35.63%~67.47%, 39.66%~70.56%, and ~46.82%, respectively, while light stimulated photosynthetic microorganism growth, thus causing Fe(Ⅱ) oxidation by 6.009~6.415 mg·g-1, 1.473~2.058 mg·g-1 and 3.037~3.693 mg·g-1 in TJ, NX and SC paddy soils, respectively. Moreover, biochar also promoted the iron oxidation under illumination, but such promotion varied with different soil types and biochar particle sizes. Biochar with <0.25 mm and 0.25~0.5 mm particles showed greater promotion on iron oxidation than that with 0.5~1.0 mm and 1.0~2.0 mm in TJ and SC paddy soils, whereas the iron oxidation by biochar was not obvious in NX paddy soil. Significant correlations existed between chlorophyll a, pH change and oxidized Fe(Ⅱ). |
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