Introducing global peat-specific temperature and pH calibrations based on brGDGT bacterial lipids
Introducing global peat-specific temperature and pH calibrations based on brGDGT bacterial lipids
复制标题
引入基于 brGDGT 细菌脂质的全球泥炭特定温度和 pH 校准
DOI：
10.1016/j.gca.2017.01.038
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发表时间：
2017-07-01
影响因子：
5
通讯作者：
Pancost, R. D.
中科院分区：
文献类型：
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作者：
Naafs, B. D. A.;Inglis, G. N.;Pancost, R. D.
甘油二烷基甘油四醚(GDGT)是细菌和古生物中普遍存在的跨膜脂类，在一系列自然档案中普遍存在，尤其是在泥炭中含量丰富。前人的工作表明，细菌分枝GDGTs(BrGDGts)在矿物土壤中的分布与年平均气温(MAAT)和土壤pH等环境因素有关。然而，这些参数对泥炭中brGDGT分布的影响在很大程度上是未知的。在这里，我们调查了来自全球96个泥炭地的470个样本中brGDGT的分布，这些泥炭地的年平均气温(-8至27摄氏度)和pH(3-8)范围很宽，并首次给出了基于泥炭的特定brGDGT温度和pH校准。结果表明，BrGDGT在泥炭中的环化程度与pH呈正相关，pH=2.49×CBTpeat+8.07(n=51，R2=0.58，RMSE=0.8)；BrGDGTs的甲基化程度与MAAT呈正相关，MAAT(PEAT)(℃)=52.18 x MBT‘(5ME)-23.05(n=96，R2=0.76，RMSE=4.7℃)。这些特定于泥炭的校准与现有的矿物土壤校准不同。鉴于温度校准的误差(类似于4.7摄氏度)，我们敦促在重建全新世晚期气候变异性的任何应用中保持谨慎，因为在这种情况下，气候信号相对较小，漂移的持续时间可能很短。相反，这些指标非常适合重建大范围、更长期的气候变化，如去冰川过渡。事实上，当应用于跨越冰川晚期(类似于15.2KYR)的泥炭沉积时，我们证明了MAAT(泥炭)产生的绝对温度和相对温度变化与其他指标一致。此外，MAAT(泥炭)在化石泥炭(即褐煤)中的应用具有重建新生代陆地气候的潜力。我们的结论是，在泥炭和褐煤中使用brGDGT来重建过去的陆地气候是有明显潜力的。(C)2017年作者。爱思唯尔有限公司出版。
Glycerol dialkyl glycerol tetraethers (GDGTs) are membrane-spanning lipids from Bacteria and Archaea that are ubiquitous in a range of natural archives and especially abundant in peat. Previous work demonstrated that the distribution of bacterial branched GDGTs (brGDGTs) in mineral soils is correlated to environmental factors such as mean annual air temperature (MAAT) and soil pH. However, the influence of these parameters on brGDGT distributions in peat is largely unknown. Here we investigate the distribution of brGDGTs in 470 samples from 96 peatlands around the world with a broad mean annual air temperature (-8 to 27 degrees C) and pH (3-8) range and present the first peat-specific brGDGT-based temperature and pH calibrations. Our results demonstrate that the degree of cyclisation of brGDGTs in peat is positively correlated with pH, pH = 2.49 x CBTpeat + 8.07 (n = 51, R-2 = 0.58, RMSE = 0.8) and the degree of methylation of brGDGTs is positively correlated with MAAT, MAAT(peat) (degrees C) = 52.18 x MBT'(5me) - 23.05 (n = 96, R-2 = 0.76, RMSE = 4.7 degrees C). These peat-specific calibrations are distinct from the available mineral soil calibrations. In light of the error in the temperature calibration (similar to 4.7 degrees C), we urge caution in any application to reconstruct late Holocene climate variability, where the climatic signals are relatively small, and the duration of excursions could be brief. Instead, these proxies are well-suited to reconstruct large amplitude, longer-term shifts in climate such as deglacial transitions. Indeed, when applied to a peat deposit spanning the late glacial period (similar to 15.2 kyr), we demonstrate that MAAT(peat) yields absolute temperatures and relative temperature changes that are consistent with those from other proxies. In addition, the application of MAAT(peat) to fossil peat (i.e. lignites) has the potential to reconstruct terrestrial climate during the Cenozoic. We conclude that there is clear potential to use brGDGTs in peats and lignites to reconstruct past terrestrial climate. (C) 2017 The Authors. Published by Elsevier Ltd.