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首页> 外文期刊>Permafrost and periglacial processes >Autochthonous and allochthonous plant contributions to coastal benthic detritus deposits: a dual-stable isotope study in a volcanic lake
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Autochthonous and allochthonous plant contributions to coastal benthic detritus deposits: a dual-stable isotope study in a volcanic lake

机译：原生和异源植物对沿海底栖碎屑沉积的贡献：在火山湖中的双稳态同位素研究

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摘要

The high numbers of primary producers represent multiple sources of organic matter accumulating onto lake bottoms. The difficulty of distinguishing the relative contribution to the mixture presents considerable challenges to the analysis of these organic deposits. In this study, dual-stable isotope analysis and IsoSource model were used to identify allochthonous and autochthonous components of detritus deposits (Particulate Organic Matter: POM) at two different bottom slope sites of a volcanic lake (lake Bracciano). Experiments were carried out to calibrate IsoSource on constructed plant mixtures and assess changes in isotope ratios during plant decomposition. IsoSource satisfactorily discriminated the constructed mixture sources with a few exceptions. Changes in isotopic enrichment during decomposition were low, and thus did not represent a confounding variable in the isotopic analysis. By contrast, chemical and geological differences of the study sites were associated with differences in plant δ~(13)C andδ~(15)N values (more than 2%o within single plant species). At both sites, the isotopic signals of POM fell between polygons delineated by source end members with an evident shift of δ~(13)C toward allochthonous sources. POM amount and diversity were greater at the flatter bottom site, where allochthonous contributions were larger than at the other site. In particular, IsoSource rankedrnspecies contributions as follows: A. glutinosa > P. aus-tralis > A. donax > S. alba > P. nigra > the benthic macroalga Chara sp. at the first site, and A. glutinosa > P. nigra > the aquatic macrophyte C. demersum at the latter. The composition of littoral POM was determined by allochthonous sources in proportion to their relative abundances (as percent land cover) with differences between sites due to bottom slope.
机译：大量的初级生产者代表了堆积在湖底的多种有机物质来源。区分混合物的相对贡献的困难给这些有机沉积物的分析提出了相当大的挑战。在这项研究中，使用双稳态同位素分析和IsoSource模型来识别火山湖（布拉恰诺湖）两个不同底坡部位碎屑沉积物（颗粒有机物：POM）的异质和自生成分。进行了一些实验，以对构建的植物混合物中的IsoSource进行校准，并评估植物分解过程中同位素比的变化。 IsoSource令人满意地区分了构造的混合源，但有一些例外。分解过程中同位素富集的变化很小，因此在同位素分析中不代表混淆变量。相比之下，研究地点的化学和地质差异与植物δ〜（13）C和δ〜（15）N值的差异相关（单个植物物种中大于2％o）。在两个位置上，POM的同位素信号都落在由源端成员划定的多边形之间，并且δ〜（13）C向异源明显转移。在底部较平坦的地方，POM的数量和多样性更大，那里的异位贡献大于其他位置。尤其是，IsoSource按以下方式对物种贡献进行了排序：臀果球菌>南美白对虾>唐氏曲霉>南美白对虾>黑胫病>底栖大藻Chara sp。在第一个位置，A。glutinosa> P. nigra>在后者的水生大型植物C. demersum。沿岸POM的组成由异源根据其相对丰度（土地覆盖百分比）确定，由于底坡，站点之间存在差异。

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