Wild and prescribed fires are important sources of a broad suite of organic compounds collectively termed pyrogenic carbon (PyC). Most PyC compounds have additional sources beyond fire, adding uncertainty to their use as tracers. However, members of the anhydrosugar family of isomeric compounds—levoglucosan, galactosan and mannosan—are generated exclusively by the pyrolysis and combustion of cellulose and hemicellulose. Although anhydrosugars are some of the only unique organic markers for fire, they have not yet seen wide use as tracers in terrestrial or marine research because our understanding of their biogeochemistry and transport through the Earth system is poorly constrained. Anhydrosugars are chemically reactive in all phases (gaseous, aqueous and particulate), molecularly diffusive in semisolid matter, semivolatile, water-soluble, and biodegradable. Their chemical composition also suggests that they sorb to soil mineral surfaces. Together, these characteristics mean that anhydrosugars are not conservative tracers. While these traits have historically been perceived as drawbacks, here we argue that these characteristics present opportunities for new research avenues, including tracking organic matter transport and degradation in multiple environments. We review evidence for anhydrosugar production, degradation and detection in various environments, and use this information to propose new research on PyC and organic matter in the Earth system.

中文翻译：

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脱水糖作为地球系统中的示踪剂

野火和规定的火灾是一系列广泛的有机化合物的重要来源，统称为热解碳 (PyC)。大多数 PyC 化合物除了火之外还有其他来源，这增加了它们作为示踪剂的不确定性。然而，脱水糖异构化合物家族的成员——左旋葡聚糖、半乳糖和甘露聚糖——完全由纤维素和半纤维素的热解和燃烧产生。尽管脱水糖是唯一独特的火灾有机标志物，但它们尚未在陆地或海洋研究中广泛用作示踪剂，因为我们对其生物地球化学和通过地球系统的运输的了解很少受到限制。脱水糖在所有相（气态、水相和颗粒）中都具有化学反应性，在半固体物质中具有分子扩散性，半挥发性，水溶性，并且可生物降解。它们的化学成分也表明它们会吸附到土壤矿物表面。总之，这些特征意味着脱水糖不是保守的示踪剂。虽然这些特征历来被认为是缺点，但在这里我们认为这些特征为新的研究途径提供了机会，包括跟踪多种环境中的有机物质运输和降解。我们回顾了各种环境中脱水糖生产、降解和检测的证据，并利用这些信息提出了对地球系统中 PyC 和有机物的新研究。虽然这些特征历来被认为是缺点，但在这里我们认为这些特征为新的研究途径提供了机会，包括跟踪多种环境中的有机物质运输和降解。我们回顾了各种环境中脱水糖生产、降解和检测的证据，并利用这些信息提出了对地球系统中 PyC 和有机物的新研究。虽然这些特征历来被认为是缺点，但在这里我们认为这些特征为新的研究途径提供了机会，包括跟踪多种环境中的有机物质运输和降解。我们回顾了各种环境中脱水糖生产、降解和检测的证据，并利用这些信息提出了对地球系统中 PyC 和有机物的新研究。