Origin and fate of methane in the Eastern Tropical North Pacific oxygen minimum zone.
Origin and fate of methane in the Eastern Tropical North Pacific oxygen minimum zone.
复制标题
DOI：
10.1038/ismej.2017.6
复制
发表时间：
2017-06
期刊：
影响因子：
--
通讯作者：
Trimmer M
中科院分区：
文献类型：
--
作者：
Chronopoulou PM;Shelley F;Pritchard WJ;Maanoja ST;Trimmer M
最小含氧区（OMZ）包含最大的海洋甲烷池，但其起源和命运知之甚少。高分辨率（<15米）水柱剖面显示，在最大的OMZ-热带北太平洋东部-的缺氧核心中有300米厚的甲烷层（20-105纳米）。沉积物芯孵育确定了一个明确的底栖甲烷源的OMZ满足大陆架，在350和650米之间，与通量反映甲烷的浓度在上覆缺氧水。进一步的培养表征了在孔隙水硫酸盐和硝酸盐存在下，沉积物表层中的产甲烷潜力高达88 nmol g−1day−1。在这些产甲烷的沉积物中，大多数（85%）甲基辅酶M还原酶α亚基（mcrA）基因序列与甲烷球菌科（Methanococcoides sp.）聚簇，能够进行非竞争性产甲烷的家族。与13 C-CH 4孵育表明，潜在的好氧和厌氧甲烷氧化的沃茨内和以上的OMZ。好氧和厌氧甲烷氧化都是通过颗粒甲烷单加氧酶（pmoA）基因序列的存在来证实的，所述基因序列与I型甲烷营养菌和已知分别进行亚硝酸盐依赖的厌氧甲烷氧化（N-DAMO）的Methylomirabilis oxyfera的谱系相关。
Oxygen minimum zones (OMZs) contain the largest pools of oceanic methane but its origin and fate are poorly understood. High-resolution (<15 m) water column profiles revealed a 300 m thick layer of elevated methane (20–105 nM) in the anoxic core of the largest OMZ, the Eastern Tropical North Pacific. Sediment core incubations identified a clear benthic methane source where the OMZ meets the continental shelf, between 350 and 650 m, with the flux reflecting the concentration of methane in the overlying anoxic water. Further incubations characterised a methanogenic potential in the presence of both porewater sulphate and nitrate of up to 88 nmol g−1day−1 in the sediment surface layer. In these methane-producing sediments, the majority (85%) of methyl coenzyme M reductase alpha subunit (mcrA) gene sequences clustered with Methanosarcinaceae (⩾96% similarity to Methanococcoides sp.), a family capable of performing non-competitive methanogenesis. Incubations with 13C-CH4 showed potential for both aerobic and anaerobic methane oxidation in the waters within and above the OMZ. Both aerobic and anaerobic methane oxidation is corroborated by the presence of particulate methane monooxygenase (pmoA) gene sequences, related to type I methanotrophs and the lineage of Candidatus Methylomirabilis oxyfera, known to perform nitrite-dependent anaerobic methane oxidation (N-DAMO), respectively.