Oxygen isotope ratios (18O/16O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy I: Insight from a climate chamber experiment
Oxygen isotope ratios (18O/16O) of hemicellulose-derived sugar biomarkers in plants, soils and sediments as paleoclimate proxy I: Insight from a climate chamber experiment
复制标题
DOI：
10.1016/j.gca.2013.10.048
复制
发表时间：
2014-02-01
影响因子：
5
通讯作者：
Glaser, Bruno
中科院分区：
文献类型：
--
作者：
Zech, Michael;Mayr, Christoph;Glaser, Bruno
纤维素的氧同位素组成是古气候研究中的一个有价值的指标。然而，由于纤维素的提取和纯化，其在沉积档案中的应用具有挑战性。在这里，我们展示了使用气相色谱-热解-同位素比质谱法测定的半纤维素衍生糖生物标志物的化合物特异性 Delta O-18 结果，该方法克服了上述分析挑战。生物标志物是从不同气候条件下在气候室实验中生长的不同植物（蓝桉、蚕豆和甘蓝）的茎材料中提取的。阿拉伯糖和木糖的 Delta O-18 值范围分别为 31.4 ppm 至 45.9 ppm 和 28.7 ppm 至 40.8 ppm，并且彼此高度显着相关。 （R = 0.91，p < 0.001）。此外，Delta O-18（半纤维素）（阿拉伯糖和木糖的平均值）与 Delta O-18（叶）水高度显着相关（R = 0.66，p < 0.001），并且与模型 Delta O-18（纤维素）显着相关（R = 0.42，p < 0.038），以及与相对空气湿度（R = -0.79，p < 0.038）。 0.001）和温度（R = -0.66，p < 0.001）。这些发现证实，半纤维素衍生的糖生物标志物（如纤维素）反映了植物源水的氧同位素组成因气候控制的叶水蒸发蒸腾 O-18 富集而改变。虽然相对空气湿度对蒸散 O-18 富集的控制最为严格，但直接温度影响不太重要。然而，温度可以通过植物生理反应间接产生影响，即通过影响蒸腾速率，从而由于佩克莱特效应而影响δ O-18（叶）水。在另一篇配套论文（Tuthorn 等人，本期）中，我们证明了半纤维素衍生糖生物标志物 Delta O-18 方法对土壤的适用性，并提供了气候样线研究的证据，证实相对空气湿度对叶水蒸发蒸腾 O-18 富集发挥主导控制作用。最后，我们提出了一个解释 Delta(18Ohemi纤维素) 记录的概念模型，并提出了一个组合的 Delta O-18(半纤维素) 方法。 Delta H-2（正烷烃）生物标志物方法有望在未来的古气候研究中将 Delta O-18（降水）变异性与蒸散 O-18 富集变异性分开。 (C) 2013 Elsevier Ltd. 保留所有权利。
The oxygen isotopic composition of cellulose is a valuable proxy in paleoclimate research. However, its application to sedimentary archives is challenging due to extraction and purification of cellulose. Here we present compound-specific delta O-18 results of hemicellulose-derived sugar biomarkers determined using gas chromatography-pyrolysis-isotope ratio mass spectrometry, which is a method that overcomes the above-mentioned analytical challenges. The biomarkers were extracted from stem material of different plants (Eucalyptus globulus, Vicia faba and Brassica oleracea) grown in climate chamber experiments under different climatic conditions.The delta O-18 values of arabinose and xylose range from 31.4 parts per thousand to 45.9 parts per thousand and from 28.7 parts per thousand to 40.8 parts per thousand, respectively, and correlate highly significantly with each other (R = 0.91, p < 0.001). Furthermore, delta O-18(hemicellulose) (mean of arabinose and xylose) correlate highly significantly with delta O-18(leaf) water (R = 0.66, p < 0.001) and significantly with modeled delta O-18(cellulose) (R = 0.42, p < 0.038), as well as with relative air humidity (R = -0.79, p < 0.001) and temperature (R = -0.66, p < 0.001). These findings confirm that the hemicellulose-derived sugar biomarkers, like cellulose, reflect the oxygen isotopic composition of plant source water altered by climatically controlled evapotranspirative O-18 enrichment of leaf water. While relative air humidity controls most rigorously the evapotranspirative O-18 enrichment, the direct temperature effect is less important. However, temperature can indirectly exert influence via plant physiological reactions, namely by influencing the transpiration rate which affects delta O-18(leaf) water due to the Peclet effect. In a companion paper (Tuthorn et al., this issue) we demonstrate the applicability of the hemicellulose-derived sugar biomarker delta O-18 method to soils and provide evidence from a climate transect study confirming that relative air humidity exerts the dominant control on evapotranspirative O-18 enrichment of leaf water.Finally, we present a conceptual model for the interpretation of delta(18Ohemicellulose) records and propose that a combined delta O-18(hemicellulose) and delta H-2(n-alkane) biomarker approach is promising for disentangling delta O-18(precipitation) variability from evapotranspirative O-18 enrichment variability in future paleoclimate studies. (C) 2013 Elsevier Ltd. All rights reserved.