土壤有机碳稳定性影响因素的研究进展

A review of the factors influencing soil organic carbon stability

  • 摘要: 增加土壤碳汇是应对全球气候变化的有效措施,作为土壤碳汇来源之一的有机碳在其中发挥重要作用。过去几十年,土壤有机碳的分子结构性质被认为是预测有机碳在土壤中循环的主要标准。然而最近的研究结果表明有机碳的分子结构并非绝对地控制着土壤有机碳的稳定,而土壤环境因子与有机碳的相互作用显著降低了土壤有机碳被降解的可能性。土壤微生物不仅参与有机碳的降解,其产物本身也是土壤有机碳的重要组成成分。非生物因子直接或间接地控制着土壤有机碳的稳定,包括土壤中的无机颗粒、无机环境以及养分状况等。其中,有机碳与土壤矿物的吸附作用和土壤团聚体的闭蓄作用被普遍认为高效地保护了有机碳。土壤矿物的吸附作用取决于其自身的矿物学性质和有机碳的化学性质。土壤团聚体在保护有机碳的同时也促进了有机碳与矿物的吸附,而有机-矿物络合物同样可以参与形成团聚体。此外,土壤无机环境也影响着有机碳循环。总之,土壤有机碳的稳定取决于有机碳与周围环境的相互作用。同时,有机碳的结构性质也受控于环境因素。然而,无论有机碳的结构性质,还是其所处的生物与非生物环境,都是生态系统的基本属性,且各属性间相互影响、相互作用。因此,土壤有机碳的稳定是生态系统的一种特有性质。

     

    Abstract: Increasing soil carbon sequestration is an effective measure to deal with global climate change. As an important carbon sink, soil organic carbon (SOC) is a critical medium for carbon sequestration. In recent decades, the molecular structure of SOC has been identified as the most important element in predicting SOC cycle. However, new studies have proven that the recalcitrance of the molecular structure of organic carbon limits the determination of SOC stability in the soil. Also the interaction between SOC and the surrounding environment significantly limits the possibility of degradation of SOC. Soil micro-organisms influence SOC cycle not only through decomposing, but also through microbial products which are the primarily components of SOC. Abiotic factors including inorganic soil particles, inorganic soil environment and nutrient conditions directly or indirectly control SOC dynamics. Among these factors, adsorption to soil minerals and occlusion within soil aggregates have been determined to strong support the long-term stability of SOC. The role of minerals in SOC adsorption and stability depends on the mineralogy and chemical property of SOC. Soil aggregates not only physically protect SOC from mi-crobial and enzymatic attack, but also promote the adsorption of SOC to minerals. On the contrary, organic mineral complex can also combine with other inorganic or organic materials to form aggregates so that SOC adsorbed to minerals can be further occluded by aggregation. Therefore, SOC adsorption to minerals and occlusion within aggregates complement each other. Moreover, inorganic environment (e.g., temperature and moisture) also acts on SOC dynamics. Put together, we suggest that the persistence of SOC was mainly due to complex interactions between SOC and the surrounding environment, including micro-organism, reactive mineral surfaces, soil aggregates, temperature, water and nutrient. Meanwhile the biochemical property of SOC also depends on environment conditions. However, whether the inherent quality of SOC or its surrounding environment is an ecosystem property; and each property affects and interacts with each other. Therefore, the persistence of SOC is a specific property of ecosystem that integrates each property.

     

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