典型土壤生物炭固碳减排的微观机制及影响因素

This project aims to understand the micromechanism of physico-chemical, biological process and their coupling effects of biochar carbon sequestration in soil. Both biochar made from rice, wheat, corn straw and typical soils including paddy soil, moisture soil, red soil, black soil are selected as model subject, then the environmental interfacial behaviors such as dissolution, adsorption-desorption of soluble biochar and inorganic carbonate are investigated. The research focuses on the distribution of CO2oH2O、HCO3-、CO32- in soil solution, then examines the effects of soil composition, pH, Eh on migration and transformation process such as CO2 release. Besides, influence of indigenous microorganism and the mechanism on uptake, utilization, transforming of soluble biochar and inorganic carbonate will be studied. This research also considers the interaction mechanisms such as adsorption, aggregation and biodegradation between aromatic ring stable bichar, soil organic matter/minerals and microorganisms as well as their influence on biochar stability, CO2 release. Furthermore, coupling effects of physio-chemical process such as adsorption, aging, microbial degradation on CO2 release will be investigated. Based on the above, key factors to affect biochar carbon sequestration and CO2 emission reduction are examined. Then practical methods to increase biochar stability as well as decrease CO2 emission are proposed, mathematical model for better prediction of biochar carbon sequestration potential in soil will be improved. This research will provide scientific basis for economicial and effective biochar carbon sequestration technology.

本项目旨在探明土壤生物炭固碳的物理化学、生物过程及耦合作用的微观机制。拟选择水稻、小麦、玉米秸秆及木质源生物炭，水稻土、潮土、红壤、黑土等典型土壤，以CO2为主要评价指标，利用模拟固碳实验装置，探讨可溶性及无机碳酸盐生物炭溶解、吸附-脱附等界面行为，重点研究土壤溶液中CO2.H2O、HCO3-、CO32-的分布，土壤组成、含水率、pH、Eh等对CO2释放的影响；并探讨土著微生物对可溶性生物炭及无机碳酸盐吸收利用及转化的机制；研究芳环稳定结构生物炭与土壤有机质/矿物质、微生物之间的吸附、聚集、生物降解等相互作用机制,土壤中生物炭吸附、老化锁定等物理化学过程与微生物降解的耦合作用对生物炭稳定性和CO2释放的影响。试图探明影响土壤生物炭固碳减排的关键因素，并提出增强典型土壤环境中生物炭稳定性及阻控CO2释放的方法，为完善预测土壤生物炭固碳潜力的数学模型，发展经济高效的土壤生物炭固碳减排技术提供科学依据。

本项目选择水稻秸秆生物炭及水稻土、潮土、红壤、黑土等典型土壤，重点研究了土壤生物炭固碳的物理化学、生物过程及其耦合作用，探讨了土壤生物炭固碳减排的微观机制及关键影响因素，取得了一些有价值的信息：（1）土壤pH通过影响生物炭无机碳排放、表面官能基团、可溶性生物炭溶出及土壤有机质的构成，改变土壤微生物总量及结构，从而影响土壤CO2释放，最终影响生物炭固碳效果；生物炭促进酸性土壤CO2排放，抑制碱性土壤CO2排放。（2）阐明了不同含水率和氮肥施加条件下生物炭对土壤N2O排放的影响；当土壤含水率较低时，生物炭促进土壤N2O排放；当土壤含水率较高时，生物炭则抑制土壤N2O排放；土壤TC/IN是影响N2O排放的关键因素，当TC/IN较高时，生物炭明显地抑制土壤N2O排放；当TC/IN较低时，生物炭显著促进土壤N2O排放；（3）阐述了不同农艺条件下生物炭对土壤CH4释放的影响及其微观机制，在不施加秸秆的土壤中，低温生物炭能显著提高土壤CH4排放，而高温生物炭对土壤CH4排放没有显著影响；在施加秸秆的土壤中，生物炭能显著抑制土壤CH4排放，高温生物炭的抑制程度强于低温生物炭，为评价土壤生物炭固碳潜力、发展经济高效的土壤生物炭固碳减排技术提供了科学依据。