Vavilin Vasily A, Rytov Sergey V, Lokshina Lyudmila Y
a Ecological Department , Water Problems Institute, Russian Academy of Sciences , Moscow , Russian Federation.
Isotopes Environ Health Stud. 2018 Oct;54(5):475-493. doi: 10.1080/10256016.2018.1478820. Epub 2018 May 29.
We described mathematically the process of peat methanization in a boreal mesotrophic fen. Gaseous and dissolved CH and CO as well as their δC signatures were considered in the dynamic equations for incubation bottles. In accordance with the model, acetate, H, and CO were produced during cellulose hydrolysis and acidogenesis. C/C in CO was a key variable reflecting dynamic changes in the rates of cellulose hydrolysis and acidogenesis, acetoclastic and hydrogenotrophic methanogenesis. As CO is the substrate in hydrogenotrophic methanogenesis, δC-CO increased from the start till the dissolved hydrogen concentration became very low. Thereafter, the rate of acetoclastic methanogenesis with the significant current acetate concentration dominated over the rate of hydrogenotrophic methanogenesis leading to the decreasing δC-CO and the increasing δC-CH. The model was validated by describing the system's dynamics under strong and weak inhibition of acetoclastic and hydrogenotrophic methanogenesis by methyl fluoride, respectively. During peat methanization at the lowered temperature of 10 °C, the processes of hydrogenotrophic methanogenesis and homoacetogenesis competing for H may occur. However, based on dynamics of the carbon isotope signatures, especially on dynamics of δC-CO, the model showed no significant contribution of homoacetogens in peat methanization.
我们用数学方法描述了北方中营养型泥炭地的泥炭甲烷化过程。在培养瓶的动力学方程中考虑了气态和溶解态的CH和CO及其δC特征。根据模型，纤维素水解和产酸过程中产生了乙酸盐、H和CO。CO中的C/C是反映纤维素水解和产酸速率、乙酸裂解型和氢营养型甲烷生成速率动态变化的关键变量。由于CO是氢营养型甲烷生成的底物，δC-CO从开始到溶解氢浓度变得非常低时一直在增加。此后，在当前乙酸盐浓度显著的情况下，乙酸裂解型甲烷生成速率超过了氢营养型甲烷生成速率，导致δC-CO降低和δC-CH升高。通过分别描述在甲基氟对乙酸裂解型和氢营养型甲烷生成的强抑制和弱抑制下系统的动态变化，对该模型进行了验证。在10 °C的低温下泥炭甲烷化过程中，可能会发生氢营养型甲烷生成和同型产乙酸作用竞争H的过程。然而，基于碳同位素特征的动态变化，特别是δC-CO的动态变化，该模型表明同型产乙酸菌在泥炭甲烷化中没有显著贡献。
