冻融交替对土壤CO2排放影响的研究进展

在全球气候变暖背景下，愈加广泛和频繁的冻融现象将会对土壤碳的生物地球化学循环过程产生深远的影响，因此归纳总结冻融作用对土壤二氧化碳（CO₂）排放的影响，可为科学揭示冻融作用对土壤CO₂排放的影响机理提供理论支撑。在总结相关文献的基础上，系统地分析了冻融格局（冻融温度、循环次数及持续时间等）对土壤CO₂排放量的影响，并从土壤理化性质、土壤微生物等方面归纳总结土壤CO₂排放对冻融作用的响应机制。冻融作用能降低土壤团聚体稳定性，促进溶解性有机碳的释放，并能够使微生物的数量降低，细胞破裂，释放碳氮营养物质以供存活的微生物利用，从而促进土壤CO₂排放的增加，且与冻结温度和冻融循环次数密切相关。但由于生态系统类型、土壤理化性质、冻结温度等的差异，冻融作用也可能会促进土壤团聚体稳定性增加，抑制活性碳的释放和微生物的活性，减少土壤CO₂的排放。虽然目前已有研究能够对冻融作用对土壤CO₂排放的影响及其驱动机制作出初步解释，但由于存在实验参数缺乏原位性、对土壤微生物的研究不够深入和数据难以量化等不足，致使研究结果存在较大的差异和不确定性，因此还需进一步深入研究。

Freeze-thaw Regime Effects on Soil CO2 Emission: A Review

In the context of global warming, the increasingly widespread and frequent freeze-thaw phenomenon will have far-reaching effects on the biogeochemical cycling of soil carbon, therefore, summarizing the effects of freeze-thaw on soil carbon dioxide (CO₂) emissions can provide theoretical support to scientifically reveal the mechanism of freeze-thaw effects on soil CO₂ emissions. Based on the summary of related literatures, the influence of freeze-thaw patterns (freeze-thaw temperature, cycle number and duration, etc.) on soil CO₂ emissions was systematically analyzed, and summarized the response mechanisms of soil CO₂ emissions to freeze-thaw effects in terms of soil physicochemical properties and soil microorganisms. Freeze-thaw can reduce the stability of soil aggregates, promote the release of dissolved organic carbon, and can reduce the number of microorganisms, cell rupture, and release carbon and nitrogen nutrients for use by surviving microorganisms, thus promoting the increase of soil CO₂ emissions, and is closely related to the freezing temperature and the number of freeze-thaw cycles. However, due to differences in ecosystem types, soil physicochemical properties, and freezing temperatures, freeze-thaw action may also may also promote increased stability of soil aggregates, inhibit the release of reactive carbon and microbial activity, and reduce soil CO₂ emissions. Although studies have been able to provide preliminary explanations for the effects of freeze-thaw on soil CO₂ emissions and its driving mechanisms, there are shortcomings such as the lack of in-situ experimental parameters, the lack of in-depth research on microorganisms and the difficulty in quantifying data, resulting in large differences and uncertainties in the research results, so further in-depth studies are needed.