Interaction between iron and dissolved organic matter in a marine shallow hydrothermal system off Dominica Island (Lesser Antilles)
Interaction between iron and dissolved organic matter in a marine shallow hydrothermal system off Dominica Island (Lesser Antilles)
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DOI：
10.1016/j.marchem.2015.10.003
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发表时间：
2015-12-20
期刊：
影响因子：
3
通讯作者：
Buehring, Solveig I.
中科院分区：
文献类型：
--
作者：
Gomez-Saez, Gonzalo V.;Riedel, Thomas;Buehring, Solveig I.
浅层海底热液系统是具有独特生物地球化学条件的极端环境，起源于热的还原流体和冷的含氧海水的相互作用。热液流体是海洋中铁等基本微量元素的来源之一，其通量由陆地和海洋生态系统内部和之间的溶解有机物(DOM)控制。然而，含铁的DOM在海洋环境中的选择性还不是很清楚。在这里，我们用傅立叶变换离子回旋共振质谱仪(FT-ICR-MS)在分子水平上表征了海洋热液铁与DOM的相互作用。我们的研究地点是多米尼加岛(加勒比海小安的列斯群岛)附近的一个浅水热液系统，与表层海水相比，还原流体强烈富含溶解的铁和硅。热水流体中的溶解有机碳(DOC)浓度较低，这很可能是由于低DOC大气水的影响，但也表明当海水重新循环通过沉积物时，生物或非生物过程消耗或耗尽DOC。热液曝气10h后生成水合三氧化二铁，DOC下降8%，表明铁和DOM共沉淀。铁沉淀物的溶解显示共沉淀物中芳香族化合物的相对丰度增加，这与在陆地环境中观察到的铁凝聚一致。总之，我们提供了DOM与铁在水热体系中共沉淀的证据，这是一个选择性过程，它特征地改变了随水热流体释放的DOM的分子组成。(C)2015爱思唯尔B.V.保留所有权利。
Shallow submarine hydrothermal systems are extreme environments with unique biogeochemical conditions, originating from the interaction of hot, reduced fluids and cold, oxygenated seawater. Hydrothermal fluids represent one of the marine sources of essential trace elements like iron, the flux of which is controlled by dissolved organic matter (DOM) in and between terrestrial and marine ecosystems. However, the selectivity of the DOM with iron in marine environments is not well understood. Here we characterized at a molecular level the marine hydrothermal iron-DOM interaction using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Our study site was a shallow-water hydrothermal system off Dominica Island (Lesser Antilles, Caribbean Sea), where reduced fluids were strongly enriched in dissolved Fe and Si as compared to surface seawater. The dissolved organic carbon (DOC) concentration was lower in the hydrothermal fluids, most likely due to low-DOC meteoric water influence, but also suggesting biotic or abiotic processes consuming or depleting DOC when seawater is re-circulated through the sediment. The formation of hydrous ferric oxides upon aeration of the hydrothermal fluids for 10 h leads to an 8% decrease in DOC, indicating co-precipitation of iron and DOM. Resolubilization of iron precipitates revealed increased relative abundance of aromatic compounds in coprecipitated DOM, which is in accordance with iron-coagulation observed in terrestrial environments. In conclusion, we provide evidence of co-precipitation of DOM with iron at hydrothermal systems as a selective process, which characteristically alters the molecular composition of DOM released with hydrothermal fluids. (C) 2015 Elsevier B.V. All rights reserved.