Anaerobic oxidation of methane in paddy soil: Role of electron acceptors and fertilization in mitigating CH4 fluxes
Anaerobic oxidation of methane in paddy soil: Role of electron acceptors and fertilization in mitigating CH4 fluxes
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水稻土中甲烷的厌氧氧化：电子受体和施肥在缓解 CH4 通量中的作用
DOI：
10.1016/j.soilbio.2019.107685
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发表时间：
2020-02-01
影响因子：
9.7
通讯作者：
Dorodnikov, Maxim
中科院分区：
文献类型：
--
作者：
Fan, Lichao;Dippold, Michaela A.;Dorodnikov, Maxim
海洋生态系统中甲烷的厌氧氧化（AOM）无处不在，并且很大程度上与硫酸盐还原有关。相比之下，AOM 在陆地环境中的作用以及驱动陆地 AOM 的主要电子受体需要更深入的了解。大量产生甲烷的水田具有很高的 AOM 潜力，这对于温室气体减排战略非常重要。在这里，我们使用 (CH4)-C-13 来量化有机（猪粪、生物炭）和矿物（NPK）施肥下稻田土壤中的 AOM 率。研究了用于 CH4 氧化的替代氧电子受体，包括 Fe3+、NO3、SO42- 和腐殖酸，并通过缺氧条件下 (CH4)-C-13 氧化为 (CO2)-C-13 来评估它们对稻田 CH4 缓解的潜力。在厌氧培养 84 天期间，累积 AOM（13CH4 衍生的 CO2）达到 0.15-1.3μg C g-1干土，视施肥情况而定。 NO3-是最有效的电子受体，猪粪下干土的AOM率为0.80 ng C g(-1) h(-1)。 Fe3+ 在 AOM 中的作用尚不清楚，而 SO42- 抑制 AOM，但强烈刺激未标记的 CO2 的产生，表明硫酸盐诱导有机物的强烈分解。腐植酸是 AOM 的第二有效电子受体，但在所有施肥处理中将产甲烷量增加了 5-6 倍。我们首次证明有机电子受体（腐殖酸）是 AOM 的关键驱动因素之一，并且在水稻土中至关重要。稻田土壤中 AOM 最明显的是猪粪，其次是对照和 NPK，而生物炭下 AOM 最低。我们估计，全球稻田中依赖硝酸盐（亚硝酸盐）的 AOM 消耗量约为 3.9 Tg C-CH4 yr-1，从而抵消了全球 CH4 排放量约 10-20%。因此，从更广泛的农业生态学角度来看，有机和矿物肥料控制着淹没生态系统中厌氧条件下重要的CH4汇。因此，适当调整土壤施肥管理策略将有助于减少进入大气的甲烷净通量，从而减少全球变暖。
The anaerobic oxidation of methane (AOM) in marine ecosystems is ubiquitous and largely coupled to sulfate reduction. In contrast, the role of AOM in terrestrial environments and the dominant electron acceptors driving terrestrial AOM needs deeper understanding. Submerged rice paddies with intensive CH4 production have a high potential for AOM, which can be important for greenhouse gas mitigation strategies. Here, we used (CH4)-C-13 to quantify the AOM rates in paddy soils under organic (Pig manure, Biochar) and mineral (NPK) fertilization. Alternative-to-oxygen electron acceptors for CH4 oxidation, including Fe3+, NO3, SO42-, and humic acids, were examined and their potential for CH4 mitigation from rice paddies was assessed by (CH4)-C-13 oxidation to (CO2)-C-13 under anoxic conditions.During 84 days of anaerobic incubation, the cumulative AOM (13CH4-derived CO2) reached 0.15-1.3 mu g C g-1 dry soil depending on fertilization. NO3- was the most effective electron acceptor, yielding an AOM rate of 0.80 ng C g(-1) dry soil h(-1) under Pig manure. The role of Fe3+ in AOM remained unclear, whereas SO42- inhibited AOM but strongly stimulated the production of unlabeled CO2, indicating intensive sulfate-induced decomposition of organic matter. Humic acids were the second most effective electron acceptor for AOM, but increased methanogenesis by 5-6 times in all fertilization treatments. We demonstrated for the first time that organic electron acceptors (humic acids) are among the key AOM drivers and are crucial in paddy soils. The most pronounced AOM in paddy soils occurred under Pig manure, followed by Control and NPK, while AOM was the lowest under Biochar. We estimate that nitrate (nitrite)-dependent AOM in paddy fields globally consumes similar to 3.9 Tg C-CH4 yr-1, thereby offsetting the global CH4 emissions by similar to 10-20%. Thus, from a broader agroecological perspective, the organic and mineral fertilizers control an important CH4 sink under anaerobic conditions in submerged ecosystems. Appropriate adjustments of soil fertilization management strategies would therefore help to decrease the net CH4 flux to the atmosphere and hence the global warming.