Concentrations and δ2H values of cuticular n-alkanes vary significantly among plant organs, species and habitats in grasses from an alpine and a temperate European grassland
Concentrations and δ2H values of cuticular n-alkanes vary significantly among plant organs, species and habitats in grasses from an alpine and a temperate European grassland
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DOI：
10.1007/s00442-015-3278-6
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发表时间：
2015-08-01
期刊：
影响因子：
2.7
通讯作者：
Kahmen, Ansgar
中科院分区：
文献类型：
--
作者：
Gamarra, Bruno;Kahmen, Ansgar
正构烷烃是陆生植物角质层中含有的长链烃。它们的氢同位素比值（δ H-2）已被用作环境和植物生理生态过程的代表。旨在解决确定正构烷烃的δ H-2值的机制的校准研究专门集中在来自叶子的正构烷烃上。然而，目前还不清楚其他植物器官（如根或花序）也产生多少正构烷烃，或者不同的植物器官是否产生不同的正构烷烃δ H-2值。为了解决这些悬而未决的问题，我们取样叶，鞘，茎，花序和根，共15种欧洲C3草在瑞士的高山和温带草原。我们的数据显示，略有增加的正构烷烃浓度和正构烷烃δ H-2值相比，在高寒温带草原。更重要的是，花序的正构烷烃浓度通常比其他器官高得多，而根的正构烷烃浓度非常低。最有趣的是，碳自主植物器官叶、鞘和茎的Δ H-2值与一个物种的总体平均Δ H-2值相比通常是耗尽的，而非碳自主器官如根和花序的Δ H-2值与一个物种的总体平均Δ H-2值相比更高。我们属性器官特异性δ H-2值的差异，在不同的植物器官中的H-NADPH生物合成的起源作为其碳关系的函数。最后，我们采用简单的质量平衡计算表明，树叶实际上是沉积物中正构烷烃的主要来源。因此，研究评估的环境和生理驱动程序的正构烷烃，侧重于树叶产生的关系，可以用来解释三角洲H-2值的正构烷烃来自沉积物。尽管我们发现不同植物器官中的δ H-2值存在显著差异，但这一点仍然存在。我们的研究带来了新的见解的自然变异的正烷烃三角洲H-2值，并在生态和古水文研究的正烷烃三角洲H-2值的解释有影响。
n-Alkanes are long-chained hydrocarbons contained in the cuticle of terrestrial plants. Their hydrogen isotope ratios (delta H-2) have been used as a proxy for environmental and plant ecophysiological processes. Calibration studies designed to resolve the mechanisms that determine the delta H-2 values of n-alkanes have exclusively focused on n-alkanes derived from leaves. It is, however, unclear in which quantities n-alkanes are also produced by other plant organs such as roots or inflorescences, or whether different plant organs produce distinct n-alkane delta H-2 values. To resolve these open questions, we sampled leaves, sheaths, stems, inflorescences and roots from a total of 15 species of European C3 grasses in an alpine and a temperate grassland in Switzerland. Our data show slightly increased n-alkane concentrations and n-alkane delta H-2 values in the alpine compared to the temperate grassland. More importantly, inflorescences had typically much higher n-alkane concentrations than other organs while roots had very low n-alkane concentrations. Most interestingly, the delta H-2 values of the carbon autonomous plant organs leaves, sheaths and stems were in general depleted compared to the overall mean delta H-2 value of a species, while non-carbon autonomous organs such as roots and inflorescences show delta H-2 values that are higher compared to the overall mean delta H-2 value of a species. We attribute organ-specific delta H-2 values to differences in the H-NADPH biosynthetic origin in different plant organs as a function of their carbon relationships. Finally, we employed simple mass balance calculations to show that leaves are in fact the main source of n-alkanes in the sediment. As such, studies assessing the environmental and physiological drivers of n-alkanes that focus on leaves produce relationships that can be employed to interpret the delta H-2 values of n-alkanes derived from sediments. This is despite the significant differences that we found among the delta H-2 values in the different plant organs. Our study brings new insights into the natural variability of n-alkane delta H-2 values and has implications for the interpretation of n-alkane delta H-2 values in ecological and paleohydrological research.