Abstract. Despite the importance of soil organic matter (SOM) in the global carbon cycle, there remain many open questions regarding its formation and preservation. The study of individual organic compound classes that make up SOM, such as lipid biomarkers including n-alkanes, can provide insight into the cycling of bulk SOM. While studies of lipid biomarkers, particularly n-alkanes, have increased in number in the past few decades, only a limited number have focused on the transformation of these compounds following deposition in soil archives. We performed a systematic review to consolidate the available information on plant-derived n-alkanes and their transformation from plant to soil. Our major findings were 1) a nearly ubiquitous trend of decreased total concentration of n-alkanes either with time in litterbag experiments or with depth in open plant-soil systems, 2) a decrease in either Carbon Preference Index (CPI) or Odd-over-Even Predominance (OEP) with depth, indicating degradation of the n-alkane signal or a shift in vegetation composition over time, and 3) preferential degradation of odd chain length and shorter chain length n-alkanes. The review also highlighted a lack of data transparency and standardization across studies of lipid biomarkers, making analysis and synthesis of published data time-consuming and difficult. We recommend that the community move towards more uniform and systematic reporting of biomarker data. Furthermore, as the number of studies examining the complete leaf-litter-soil continuum is very limited as well as unevenly distributed over geographical regions, climate zones, and soil types, future data collection should focus on underrepresented areas as well as quantifying the transformation of n-alkanes through the complete continuum of plant to soil.

中文翻译：

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正构烷烃从植物到土壤的转化：综述

摘要。尽管土壤有机物（SOM）在全球碳循环中非常重要，但关于其形成和保存方面仍存在许多悬而未决的问题。对构成SOM的单个有机化合物类别（例如包括正构烷烃在内的脂质生物标志物）的研究可以为批量SOM的循环提供见解。在过去的几十年中，虽然对脂质生物标志物（尤其是正构烷烃）的研究数量有所增加，但只有极少数研究集中在土壤档案中沉积后这些化合物的转化上。我们进行了系统的综述，以巩固有关植物来源的正构烷烃及其从植物到土壤转化的可用信息。我们的主要发现是：1）在垃圾袋实验中或随着开放式植物土壤系统中深度的增加，正构烷烃总浓度降低的趋势几乎无处不在； 2）碳偏好指数（CPI）或奇数降低-具有深度的偶数优势（OEP），指示正构烷烃信号的降解或植被组成随时间的变化，以及3）奇数链长和较短链长的正构烷烃的优先降解。审查还强调，脂质生物标志物研究缺乏数据透明性和标准化，这使得发布数据的分析和合成既费时又困难。我们建议社区朝着更加统一和系统地报告生物标记数据的方向迈进。此外，