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Effects of straw addition and Eh on dissolved organic matter composition and metal release in paddy soil
Received:December 09, 2021  Revised:February 23, 2022
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KeyWord:redox;straw;metal;dissolved organic matter(DOM);three-dimensional fluorescence spectroscopy
Author NameAffiliationE-mail
LUO Xueting Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science & Technology, Nanjing 210044, China
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China 
 
ZHOU Fengwu School of Geography, Nanjing Normal University, Nanjing 210023, China  
ZHAN Juan Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China  
ZHANG Yu Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China  
HU Pengjie Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China pjhu@issas.ac.cn 
XU Defu Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science & Technology, Nanjing 210044, China  
LI Zhenxuan Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Nanjing University of Information Science & Technology, Nanjing 210044, China  
WU Longhua Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China  
LUO Yongming Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China  
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Abstract:
      A typical paddy soil that was contaminated with heavy metals was selected to explore the effects of straw addition on the release of metals in the soil under redox change, and the dynamic relations among soil solution chemistry, dissolved organic matter(DOM), and metal release were studied via micro-universe test and three-dimensional fluorescence spectrum analysis method. The results demonstrated that straw addition enhanced Fe, Mn, As, and Cd release at the anaerobic stage, and had a significant effect on DOM composition. The C3 protein content in DOM was significantly decreased during anaerobic to aerobic(P<0.05). The humus-like content increased in the anaerobic stage and then decreased in the aerobic stage. Structural equation model(SEM)analysis showed that Eh change was negatively correlated with the dissolution of Mn and As(path coefficients -0.662 and -0.528, P<0.01). Meanwhile, Eh influenced soil humic acid C2(path coefficient -0.816, P<0.01)to control As release(path coefficient 0.244, P<0.05). Therefore, the change of Eh caused by alternate wetting and drying of both the paddy soil and the straw returning can not only directly affect the dissolution of heavy metals but also control their release through DOM content and composition, which are conducive to further clarification of the mechanism of metal release in farmland soil.