摘要:泥炭沼泽湿地土壤（泥炭土）分解过程是控制泥炭土碳排放的关键过程，其中可溶性有机质（DOM）是泥炭分解过程的主要输出物。DOM富含具有氧化还原活性的官能团，其中酚基具有抗氧化性质，是DOM氧化还原活性的重要组成部分，对驱动有氧和缺氧条件下的氧化还原过程意义重大。同时，酚基也可抑制泥炭的氧化降解，在泥炭土分解过程中起着重要作用。目前，关于泥炭分解过程中DOM氧化还原能力影响机制的相关研究较少。利用创新介导电化学方法、激发-发射荧光矩阵光谱法（EEM），直接定量、定性评估DOM氧化还原变化程度，进而探讨（1）取自两个泥炭样地（OS/LB）的地表水、地下水、孔隙水样品中DOM的氧化还原性能；（2）来自泥炭样地OS的泥炭孔隙水剖面中DOM的氧化还原能力变化规律以及与泥炭分解的重要指标间的关系（如C/N和δ¹³C_DOC）。结果表明：选取电子转移能力（ETC）作为表征DOM氧化还原能力的指标，不同来源DOM的ETC值主要在2-4 mmole^-/gC之间；在泥炭土中DOM的ETC值与醌基和酚基的光谱性质参数存在强相关，这些基团对DOM氧化还原能力具有较大影响。具体表现为：在采样区OS，5-50 cm深度和0-210 cm深度的泥炭孔隙水剖面中，酚基在任意深度都是主导DOM氧化还原活性的重要组成部分，而醌基仅在没有淹水、有氧的近地表20 cm深度处时起到重要作用。在泥炭分解过程中，DOM氧化还原能力随深度的变化主要是受泥炭分解程度不同所致的泥炭自身酚基含量的变化所影响，特别是在未受地下水位波动影响的较大深度处。研究探讨泥炭分解过程中DOM氧化还原能力变化特征及其影响机制，为厘清有机质与泥炭沼泽湿地生物地球化学过程提供理论支撑。



Abstract:The decomposition process of peat bog soil (peat soil) is a key process to control the carbon emission of peat soil, and dissolved organic matter (DOM) is the main output of the peat decomposition process. DOM is rich in functional groups with redox properties, of which phenol groups have antioxidant properties and are important parts of the DOM redox activity, which are of great significance for driving the redox process under aerobic and anoxic conditions. Moreover, phenolic groups can inhibit the oxidative degradation of peat and therefore play an important role during the decomposition of peat soil. At present, there are few related studies on the influence mechanism of DOM redox capacity during peat decomposition. This study used innovatively mediated electrochemical analysis and excitation-emission fluorescence matrix (EEM) to quantitatively and qualitatively evaluate the degree of DOM redox changes, and then explored (1) DOM redox capacity in the surface water, groundwater, and pore water samples taken from two peat samples (OS/LB); (2) variations of DOM redox capacity and its relationship with important indicators of peat decomposition (such as C/N and δ¹³C_DOC) in the peat pore water profile from peat sample OS. The results showed that we chose the electron transfer capacities (ETC) as the index to characterize the redox ability of DOM, and the ETC values of DOM from different origins were mainly between 2-4 mmole^-/gC. Significant correlation of redox properties of DOM with spectroscopic quality parameters for quinone and phenol moieties supported that these groups had great influence on the redox activity of DOM in peat soil. The specific performance was as follows: in the sampling area OS, 5-50 cm depth and 0-210 cm depth peat pore water profiles, phenol groups were always an important part of the DOM redox activities at any depth, while quinone groups only played an important role near the surface of 20 cm depth, where was no flooding and aerobic. The changes of DOM redox capacity along peat bog pore water profiles were mostly affected by the change of phenolic content of peat itself caused by the different degrees of peat decomposition during peat decomposition, especially in greater depth without the influence of water table fluctuations. This study explores the change characteristics and influence mechanism of the DOM redox capacity during peat decomposition, and provides theoretical support for clarifying organic matter and biogeochemical processes in peat swamp wetlands.





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