What Is Refractory Organic Matter in the Ocean?
What Is Refractory Organic Matter in the Ocean?
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DOI：
10.3389/fmars.2021.642637
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发表时间：
2021-04-01
影响因子：
3.7
通讯作者：
Lonborg, Christian
中科院分区：
文献类型：
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作者：
Baltar, Federico;Alvarez-Salgado, Xose A.;Lonborg, Christian
在阳光照射的海洋表面产生的有机碳中，约有20%以溶解、悬浮和下沉颗粒的形式被输送到海洋内部，以溶解无机碳（DIC）、沉积颗粒有机碳（POC）或“难降解”溶解有机碳（rDOC）的形式被矿化和隔离。最近，与粒子泵相关的物理和生物机制已经被重新审视，表明可接受的通量可能被严重低估（Boyd等人，2019; Buesseler等人，2020年）。也许更不了解的是驱动rDOC生产及其在海洋中的潜在积累的机制。最近的矛盾的证据的基础上，DOC降解的深海的相关性，我们重新审视的概念，rDOC在其“耐火”的性质，以了解其在全球碳循环中的作用。在这里，我们解决的问题，各种定义和方法来表征rDOC（如周转时间与海洋过境时间，分子丰度，化学成分和结构）。我们建议，rDOC应在操作上进行定义。然而，我们认识到有多种方法来操作定义rDOC，因此，统一未来研究的主要重点应该是明确说明如何定义rDOC和用于测量rDOC的分析窗口，而不是坚持一个单一的操作定义。根据最近的证据，我们还得出结论，rDOC的持久性从根本上取决于内在的（化学组成和结构，例如，分子性质）和外在性质（量或外部因素，例如，分子浓度、生态系统特性）。最后，我们提出了具体的研究问题，旨在刺激研究的性质，动态和作用的rDOC固碳现在和未来的气候变化的情况。
About 20% of the organic carbon produced in the sunlit surface ocean is transported into the ocean's interior as dissolved, suspended and sinking particles to be mineralized and sequestered as dissolved inorganic carbon (DIC), sedimentary particulate organic carbon (POC) or "refractory" dissolved organic carbon (rDOC). Recently, the physical and biological mechanisms associated with the particle pumps have been revisited, suggesting that accepted fluxes might be severely underestimated (Boyd et al., 2019; Buesseler et al., 2020). Perhaps even more poorly understood are the mechanisms driving rDOC production and its potential accumulation in the ocean. On the basis of recent conflicting evidence about the relevance of DOC degradation in the deep ocean, we revisit the concept of rDOC in terms of its "refractory" nature in order to understand its role in the global carbon cycle. Here, we address the problem of various definitions and approaches used to characterize rDOC (such as turnover time in relation to the ocean transit time, molecule abundance, chemical composition and structure). We propose that rDOC should be operationally defined. However, we recognize there are multiple ways to operationally define rDOC; thus the main focus for unifying future studies should be to explicitly state how rDOC is being defined and the analytical window used for measuring rDOC, rather than adhering to a single operational definition. We also conclude, based on recent evidence, that the persistence of rDOC is fundamentally dependent on both intrinsic (chemical composition and structure, e.g., molecular properties), and extrinsic properties (amount or external factors, e.g., molecular concentrations, ecosystem properties). Finally, we suggest specific research questions aimed at stimulating research on the nature, dynamics, and role of rDOC in Carbon sequestration now and in future scenarios of climate change.