Multiple stable isotopic signatures corroborate the predominance of acetoclastic methanogenesis during CH4 formation in agricultural river networks

文献类型： 外文期刊

第一作者： Qin, Xiaobo

作者： Qin, Xiaobo;Li, Yu'e;Wan, Yunfan;Wang, Bin;Gao, Qingzhu;Wu, Hongbao;Chen, Xuan;Fan, Meirong;Liao, Yulin;Li, Yong

作者机构：

关键词： Multiple isotope signature; Biogenic CH4 production pathway; Acetoclastic methanogenesis; Agricultural river networks

期刊名称：AGRICULTURE ECOSYSTEMS & ENVIRONMENT （ 影响因子：5.567； 五年影响因子：6.064 ）

ISSN： 0167-8809

年卷期： 2020 年 296 卷

页码：

收录情况： SCI

摘要： Methane (CH4) emitted from river networks provides a globally significant, yet poorly constrained barrier for the refinement of national greenhouse gas (GHG) inventories and the global CH4 budget. This study employed three isotopic methodologies, i.e., a simple mixing model, apparent fractionation factor, and dual isotopes (delta C-13-CH4 and delta D-CH4) to identify the biogenic CH4 production pathway (BMPP) in a typical agricultural river network in subtropical China. The results indicated that the contribution of acetoclastic methanogenesis (AM) to BMPP in the Tuojia River network (TRN) ranged from 85 to 99%, with the first reach (S1) supporting the most biogenic CH4 production. Furthermore, the alpha(C) value ranged from 1.00 to 1.039 and increased spatially over the four reaches (S1 to S4), while the alpha(D) value varied from 1.393 to 1.394, with S1 having the lowest value. The dual isotopes of delta C-13 and delta(D) reflected a mixed BMPP. Clearly, the isotopic composition of CH4 corroborated the predominance of AM in the BMPP in the TRN. Additionally, there was a remarkable spatiotemporal variation in delta C-13-CH4 and delta D-CH4, as well as alpha(C) and alpha(D). In combination with the correlation between the two paired isotopic signatures (antipathetic and positive, p < 0.05, respectively), this suggested a change in the BMPP in the TRN. The findings of our study implied that there was great impact of agricultural production and residential activities on environmental behavior of stable isotopes. Consequently, we recommend that multiple isotopic measures, based on long-term in situ isotopologue monitoring, should be applied when the uncertainties of CH4 emissions from river networks are addressed.

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