Archaeal Intact Polar Lipids in Polar Waters: A Comparison Between the Amundsen and Scotia Seas
Archaeal Intact Polar Lipids in Polar Waters: A Comparison Between the Amundsen and Scotia Seas
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DOI：
10.5194/bg-2020-333
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发表时间：
2020-11
期刊：
影响因子：
4.9
通讯作者：
C. Spencer-Jones;E. McClymont;N. Bale;E. Hopmans;S. Schouten;J. Müller;E. Povl Abrahamsen;C. Allen;T. Bickert;C. Hillenbrand;E. Mawbey;V. Peck;A. Svalova;James A. Smith
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作者：
C. Spencer-Jones;E. McClymont;N. Bale;E. Hopmans;S. Schouten;J. Müller;E. Povl Abrahamsen;C. Allen;T. Bickert;C. Hillenbrand;E. Mawbey;V. Peck;A. Svalova;James A. Smith
抽象。西南极冰盖（WAIS）是未来海平面上升的最大潜在来源之一，过去40年来，冰川排空西南极冰盖的速度正在加快。由于校准南大洋古海洋学代用指标的复杂性，仍然难以评估在全新世早期是否发生了类似的变化，或者海洋变化是否存在潜在的百年至千年尺度的强迫。基于脂质的代用指标，特别是甘油二烷基甘油四醚（GDGT;例如TEX 86和TEX 86 L），是重建海洋温度的有力工具，但这些代用指标以前已被证明难以应用于南大洋。更好地了解控制南大洋GDGT分布的参数，将改善这些生物标志物代理的应用，从而有助于提供一个长期的角度对南极冰盖变化的海洋强迫。在这项研究中，我们的特点是完整的极性脂质（IPL）-GDGT，代表（最近）生活古菌种群的悬浮颗粒物（SPM）从阿蒙森海和斯科舍海。从阿蒙森海的SPM样品收集了多达四个水柱深度，代表表面沃茨通过环极深水（CDW），而斯科舍海样品收集沿着一个横断面，包括亚南极前线通过南极绕极流的南部边界。在整个水柱中检测到具有低循环多样性的IPL-GDGT，在阿蒙森和斯科舍海中鉴定出羟基化IPL-GDGT的相对丰度较高。斯科舍海的结果显示，南大洋边界清晰的锋面上IPL-GDGT特征发生了变化。表明这些水团的物理化学参数决定了IPL-GDGT分布的变化。阿蒙森海的研究结果表明GDGT在CDW中具有己糖-磷酸己糖头基，表明GDGT在这些深度合成活跃。这些结果表明，GDGT合成在CDW深度可能是一个重要的来源GDGT出口到沉积记录和温度重建的基础上TEX 86或TEX 86 L代理可能会受到显着影响的温暖的沃茨的CDW。
Abstract. The West Antarctic Ice Sheet (WAIS) is one of the largest potential sources of future sea-level rise, with glaciers draining the WAIS thinning at an accelerating rate over the past 40 years. Due to complexities in calibrating palaeoceanographic proxies for the Southern Ocean, it remains difficult to assess whether similar changes have occurred earlier during the Holocene or whether there is underlying centennial- to millennial-scale forcing in oceanic variability. Archaeal lipid-based proxies, specifically glycerol dialkyl glycerol tetraether (GDGT; e.g. TEX86 and TEX86L), are powerful tools for reconstructing ocean temperature, but these proxies have been shown previously to be difficult to apply to the Southern Ocean. A greater understanding of the parameters that control Southern Ocean GDGT distributions would improve the application of these biomarker proxies and thus help provide a longer-term perspective on ocean forcing of Antarctic ice sheet changes. In this study, we characterised intact polar lipid (IPL)-GDGTs, representing (recently) living archaeal populations in suspended particulate matter (SPM) from the Amundsen Sea and the Scotia Sea. SPM samples from the Amundsen Sea were collected from up to four water column depths representing the surface waters through to Circumpolar Deep Water (CDW), whereas the Scotia Sea samples were collected along a transect encompassing the sub-Antarctic front through to the southern boundary of the Antarctic Circumpolar Current. IPL-GDGTs with low cyclic diversity were detected throughout the water column with high relative abundances of hydroxylated IPL-GDGTs identified in both the Amundsen and Scotia seas. Results from the Scotia Sea show shifts in IPL-GDGT signatures across well-defined fronts of the Southern Ocean. Indicating that the physicochemical parameters of these water masses determine changes in IPL-GDGT distributions. The Amundsen Sea results identified GDGTs with hexose-phosphohexose head groups in the CDW, suggesting active GDGT synthesis at these depths. These results suggest that GDGTs synthesised at CDW depths may be a significant source of GDGTs exported to the sedimentary record and that temperature reconstructions based on TEX86 or TEX86L proxies may be significantly influenced by the warmer waters of the CDW.