Variability in aerobic methane oxidation over the past 1.2Myrs recorded in microbial biomarker signatures from Congo fan sediments
Variability in aerobic methane oxidation over the past 1.2Myrs recorded in microbial biomarker signatures from Congo fan sediments
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刚果扇沉积物微生物生物标记特征记录了过去 1.2Myrs 的有氧甲烷氧化变化
DOI：
10.1016/j.gca.2014.02.035
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发表时间：
2014
影响因子：
5
通讯作者：
Talbot H
中科院分区：
文献类型：
--
作者：
Talbot H
甲烷(CH4)是一种强烈的温室气体，已知在过去曾扰乱全球气候，特别是当大陆或海洋来源在短时间内大量释放甲烷时。因此，至关重要的是要了解并在可能的情况下量化这些可变甲烷源对自然气候变异性的单独和综合反应。然而，过去温室气藏稳定性的变化仍然是不确定的，受地质证据的约束很差。在这里，我们提供了刚果球迷的记录，一种高度特异的好氧甲烷氧化(AMO)生物标志物-35-氨基细菌碘多元醇(BHP)-30，31，32，33，34-戊醇(氨基戊醇)，它识别出早在1.2 Ma时AMO增加的离散时期。氨基戊醇和其他35种氨基苯并呋喃的浓度波动遵循与第四纪晚期冰川-间冰期气候周期相关的模式，暖期浓度最高。我们在刚果河的背景下讨论了氨基戊醇的可能来源，以及前体甲烷营养菌消耗的甲烷，包括从陆地分水岭和/或海洋来源(天然气水合物和/或深层地下气藏)供应甲烷氧化标志物。ODP1075中BHP的−30‰到−40‰的化合物特定碳同位素值，以及刚果河河口和刚果河盆地内陆泛滥平原湿地的核心和表层沉积物的必和必拓特征之间的强烈相似性，支持扇形沉积物中发现的35氨基BHP的甲烷营养和可能的陆源来源。这一新证据支持了热带深海扇的海洋沉积物BHP记录与供水河流域湿地环境之间的因果联系，从而支持了热带大陆水文。需要进一步研究，以更好地限制甲烷排放的不同来源和途径。然而，这项研究确定了氨基二氢化氢化合物，特别是氨基戊醇的巨大潜力，一旦得到更好的校准和了解，就可以量化过去的甲烷来源和来自陆地来源以及可能也来自海洋来源的通量。
Methane (CH4) is a strong greenhouse gas known to have perturbed global climate in the past, especially when released in large quantities over short time periods from continental or marine sources. It is therefore crucial to understand and, if possible, quantify the individual and combined response of these variable methane sources to natural climate variability. However, past changes in the stability of greenhouse gas reservoirs remain uncertain and poorly constrained by geological evidence. Here, we present a record from the Congo fan of a highly specific bacteriohopanepolyol (BHP) biomarker for aerobic methane oxidation (AMO), 35-aminobacteriohopane-30,31,32,33,34-pentol (aminopentol), that identifies discrete periods of increased AMO as far back as 1.2 Ma. Fluctuations in the concentration of aminopentol, and other 35-aminoBHPs, follow a pattern that correlates with late Quaternary glacial-interglacial climate cycles, with highest concentrations during warm periods. We discuss possible sources of aminopentol, and the methane consumed by the precursor methanotrophs, within the context of the Congo River setting, including supply of methane oxidation markers from terrestrial watersheds and/or marine sources (gas hydrate and/or deep subsurface gas reservoir). Compound-specific carbon isotope values of −30‰ to −40‰ for BHPs in ODP 1075 and strong similarities between the BHP signature of the core and surface sediments from the Congo estuary and floodplain wetlands from the interior of the Congo River Basin, support a methanotrophic and likely terrigenous origin of the 35-aminoBHPs found in the fan sediments. This new evidence supports a causal connection between marine sediment BHP records of tropical deep sea fans and wetland settings in the feeding river catchments, and thus tropical continental hydrology. Further research is needed to better constrain the different sources and pathways of methane emission. However, this study identifies the large potential of aminoBHPs, in particular aminopentol, to trace and, once better calibrated and understood, quantify past methane sources and fluxes from terrestrial and potentially also marine sources.