Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter.
Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter.
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DOI：
10.1038/srep44864
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发表时间：
2017-03-22
影响因子：
4.6
通讯作者：
Hinrichs KU
中科院分区：
文献类型：
--
作者：
Lin YS;Koch BP;Feseker T;Ziervogel K;Goldhammer T;Schmidt F;Witt M;Kellermann MY;Zabel M;Teske A;Hinrichs KU
海洋边缘沉积物被认为是深海溶解有机碳（DOC）的重要来源，但平流环境的贡献才刚刚开始得到认可。在这里，我们提供的证据表明，瓜伊马斯盆地（一个年轻的伸展凹陷）沉积物的近地表加热导致反应性溶解有机物（DOM）的大量产生和排放。在加热至约 100°C 的沉积物中，我们发现孔隙水中的 DOC 浓度出乎意料地低，这反映了热解吸和平流流体流动的综合作用。加热实验表明 DOC 的产生是一个快速的非生物过程，DOC 浓度随温度呈指数增加。高比例的总可水解氨基酸以及与活性碳氢化合物、碳水化合物和肽相关的化学物质的存在表明 DOM 的高反应性。模型模拟表明，在局部尺度上，沉积物的近地表加热会产生短暂而大量的 DOC 排放事件，从而提高底水 DOC 浓度。由于高热流区域的不均匀分布，反应性 DOM 的排出在任何给定时间都是不稳定的。我们得出的结论是，年轻裂谷沉积物的热液加热改变了深海生物可利用的 DOM 预算，为底栖生物创造了富含有机物的栖息地。
Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating of sediment creates short and massive DOC discharge events that elevate the bottom-water DOC concentration. Because of the heterogeneous distribution of high heat flow areas, the expulsion of reactive DOM is spotty at any given time. We conclude that hydrothermal heating of young rift sediments alter deep-ocean budgets of bioavailable DOM, creating organic-rich habitats for benthic life.