生物炭的电子传递特性对水稻土中甲烷产生的影响

甲烷对全球温室效应的贡献率可达15%-20%。生物炭在土壤中的施用可能加速相关微生物的种间电子传递，进而促进甲烷的产生。因而，如何权衡生物炭施用的正面和负面效应成为生物炭应用的一个重大挑战。生物炭的电子传递特性如何影响种间电子传递是其中的关键问题，而明晰生物炭两种电子传递途径（直接电子传递和氧化还原电子传递）各自发挥的作用是一个重要突破口。本项目首先聚焦生物炭的电子传递特性，定向调控并梯级制备不同电子传递特性的生物炭，着重分析其电导、电容、直接电子传递常数和氧化还原电子传递常数；其次，通过水稻土的生物炭添加实验，阐释以上电子传递特性与甲烷产生之间的响应关系；最后，构建共生产甲烷体系，通过体系电子流的整体核算确定不同电子传递途径对甲烷产生的贡献比重，建立生物炭介导下水稻土甲烷产生种间电子传递模型。该研究不仅可以加深对生物炭多元环境效益的认识，还可以为调控土壤中的温室气体排放提供重要理论指导。

Methane is an important greenhouse gas and contributes to about 15% ~ 20% to the global greenhouse effect. The biochar addition in the soil may accelerate interspecies electron transfer of the corresponding bacteria and promote the production of methane. Thus, it is a major challenge for biochar application to balance between the positive and negative impacts of biochar technique. Thereinto, the key issue is how the electron transfer properties of biochar couple with the interspecies electron transfer among microorganism. To solve this problem, it is essential to identify the roles that different biochar electron transfer channels (direct or oxidation/reduction electron transfer channel) play in accelerating microbial interspecies electron transfer. Therefore, this project will firstly focus on the electron transfer properties of biochar, which will be specifically regulated during biochar modification. Biochar with gradient electron transfer properties will be prepared, and their electron conductivity, electric capacity, and direct electron transfer constant and oxidation/reduction electron transfer constant will be analyzed specifically. Secondly, the methane production in paddy soil after biochar addition will be monitored. The relationship between the enhanced methane production and the electron transfer properties of biochars will also be analyzed. This information will be fundament to interpret methane production mediated by biochars. Finally, the microbial co-culture system for methane production will be established. The contribution of different biochar electron transfer channels to methane production enhancement will be determined by calculating the overall electron transfer in the co-culture system. A model describing methane production in paddy soils through the interspecies electron transfer mediated by biochar will be built up. This study not only deepens our understanding on the virous effect of biochar in the environment, but also provides important theoretical foundation for regulating the greenhouse gas emission from soil.