Evidence for methane production by the marine algae Emiliania huxleyi
Evidence for methane production by the marine algae Emiliania huxleyi
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DOI：
10.5194/bg-13-3163-2016
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发表时间：
2016-01-01
期刊：
影响因子：
4.9
通讯作者：
Keppler, Frank
中科院分区：
文献类型：
--
作者：
Lenhart, Katharina;Klintzsch, Thomas;Keppler, Frank
甲烷（CH 4）是影响辐射平衡进而影响地球气候的重要温室气体，其汇和源仍存在不确定性。世界海洋被认为是大气中CH 4的来源，尽管其形成所涉及的地球化学过程尚未完全了解。最近的几项研究提供了强有力的证据表明，甲烷产生在有毒的海洋和淡水，但其来源仍然是一个有争议的话题。对海洋和大型湖泊表层沃茨中甲烷动态的研究得出结论，无论是沿岸的横向输入还是底栖输入，都不能维持浮游甲烷的过饱和。然而，经常出现区域性和时间性的地表沃茨过饱和现象。这包括在表面混合层内观察到甲烷过饱和状态，有时也称为“海洋甲烷悖论”。在这项研究中，我们认为海藻作为一个可能的直接来源的CH 4。因此，球石藻Emiliania huxleyi生长在受控的实验室条件下，并补充了两个C-13标记的碳底物，即碳酸氢盐和位置特异性C-13标记的甲硫氨酸（R-S-（CH 3）-C-13）。甲烷产量为0.7aEuro-A μ g特定有机碳（POC）g（-1）aEuro-d（-1），或30 aEuro-ngaEuro-g（-1）aEuro-POCa Euro-h（-1）。在用C-13标记的底物补充培养物后，在顶空CH 4中观察到同位素标记。此外，没有产甲烷古菌内的藻类培养和甲烷形成过程中的好氧条件表明，广泛分布的海洋藻类Emiliania huxleyi可能有助于观察到的空间和时间限制的海洋表面沃茨的甲烷过饱和。
Methane (CH4), an important greenhouse gas that affects radiation balance and consequently the earth's climate, still has uncertainties in its sinks and sources. The world's oceans are considered to be a source of CH4 to the atmosphere, although the biogeochemical processes involved in its formation are not fully understood. Several recent studies provided strong evidence of CH4 production in oxic marine and freshwaters, but its source is still a topic of debate. Studies of CH4 dynamics in surface waters of oceans and large lakes have concluded that pelagic CH4 supersaturation cannot be sustained either by lateral inputs from littoral or benthic inputs alone. However, regional and temporal oversaturation of surface waters occurs frequently. This comprises the observation of a CH4 oversaturating state within the surface mixed layer, sometimes also termed the 'oceanic methane paradox'. In this study we considered marine algae as a possible direct source of CH4. Therefore, the coccolithophore Emiliania huxleyi was grown under controlled laboratory conditions and supplemented with two C-13-labeled carbon substrates, namely bicarbonate and a position-specific C-13-labeled methionine (R-S-(CH3)-C-13). The CH4 production was 0.7aEuro-A mu g particular organic carbon (POC) g(-1)aEuro-d(-1), or 30aEuro-ngaEuro-g(-1)aEuro-POCaEuro-h(-1). After supplementation of the cultures with the C-13-labeled substrate, the isotope label was observed in headspace CH4. Moreover, the absence of methanogenic archaea within the algal culture and the oxic conditions during CH4 formation suggest that the widespread marine algae Emiliania huxleyi might contribute to the observed spatially and temporally restricted CH4 oversaturation in ocean surface waters.