Stable hydrogen and carbon isotope ratios of methoxyl groups during plant litter degradation
Stable hydrogen and carbon isotope ratios of methoxyl groups during plant litter degradation
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DOI：
10.1080/10256016.2015.1013540
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发表时间：
2015-01-02
影响因子：
1.3
通讯作者：
Keppler, Frank
中科院分区：
文献类型：
--
作者：
Anhaeuser, Tobias;Greule, Markus;Keppler, Frank
植物材料中甲氧基的稳定氢和碳同位素比率（分别为δ H-2（甲氧基）和δ C-13（甲氧基）值）已被证明具有特征性特征。这些同位素特征可用于各种应用，例如限制生物材料的地理来源和真实性。最近，也有人建议，三角洲H-2（甲氧基）值的沉积有机质的地质档案可能作为一个古气候/水文代理。然而，沉积的有机物会受到生物和非生物降解过程的影响，因此，评估其对δ H-2（甲氧基）和δ C-13（甲氧基）值的潜在影响，将有助于对这两种同位素特征进行更可靠的解释。在这里，我们调查了这种潜在的影响，通过暴露叶凋落物的五个不同的树种（西卡莫尔枫树，花楸，欧洲山毛榉，挪威云杉和苏格兰松）自然降解。在27个月的时间内以9个间隔对落叶层进行采样，并测量了大量甲氧基含量以及δ H-2（甲氧基）和δ C-13（甲氧基）值。在实验结束时，测量到本体甲氧基的损失在类似于40 - 70%的范围内。线性回归分析显示，所研究的5个落叶样品中有4个的δ H-2（甲氧基）值与甲氧基含量没有依赖性（R-2在0.03和0.36的范围内，p> 0.05）。相反，对于绝大多数落叶样品，δ C-13（甲氧基）值显示出显著的线性相关性（R-2在0.51和0.73的范围内，p <0.05）。最大的甲氧基损失（花楸，苏格兰松和挪威云杉）的凋落物物种表现出最强的C-13富集，高达类似的千分之五。由于三角洲H-2（甲氧基）在降解过程中没有显示出系统的整体变化，我们建议，有相当大的潜力，它作为一个古气候代理的范围广泛的地质档案，例如，化石木材或沉积有机物。如果将降解有机物的δ C-13（甲氧基）值用于古气候/环境调查，则需要注意。
Stable hydrogen and carbon isotope ratios of methoxyl groups (delta H-2(methoxyl) and delta C-13(methoxyl) values, respectively) in plant material have been shown to possess characteristic signatures. These isotopic signatures can be used for a variety of applications such as constraining the geographical origin and authenticity of biomaterials. Recently, it has also been suggested that delta H-2(methoxyl) values of sedimentary organic matter of geological archives might serve as a palaeoclimate/-hydrology proxy. However, deposited organic matter is subject to both biotic and abiotic degradation processes, and therefore an evaluation of their potential impact on the delta H-2(methoxyl) and delta C-13(methoxyl) values would allow more reliable interpretations of both isotopic signatures. Here, we investigated this potential influence by exposing foliar litter of five different tree species (Sycamore maple, Mountain ash, European beech, Norway spruce and Scots pine) to natural degradation. The foliar litter was sampled at nine intervals over a 27-month period, and the bulk methoxyl content as well as the delta H-2(methoxyl) and delta C-13(methoxyl) values were measured. At the end of the experiment, a loss of the bulk methoxyl in the range of similar to 40-70 % was measured. Linear regression analysis showed no dependence of delta H-2(methoxyl) values with methoxyl content for four out of five foliar litter samples studied (R-2 in the range of 0.03 and 0.36, p > .05). On the contrary, the delta C-13(methoxyl) values showed significant linear correlations for the great majority of the foliar litter samples (R-2 in the range of 0.51 and 0.73, p < .05). The litter species with the greatest methoxyl loss (Mountain ash, Scots pine and Norway spruce) showed the strongest C-13 enrichment, by up to similar to 5 parts per thousand. Since delta H-2(methoxyl) shows no systematic overall change during the course of degradation, we propose that there is considerable potential for its use as a palaeoclimate proxy for a wide range of geological archives containing, for instance, fossil wood or sedimentary organic matter. Care would need to be taken if delta C-13(methoxyl) values of degraded organic matter are used for palaeoclimate/-environmental investigations.