Barite Precipitation on Suspended Organic Matter in the Mesopelagic Zone
Barite Precipitation on Suspended Organic Matter in the Mesopelagic Zone
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DOI：
10.3389/feart.2020.567714
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发表时间：
2020-10
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影响因子：
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通讯作者：
F. Martínez-Ruiz;A. Paytan;M. T. González-Muñoz;F. Jroundi;M. M. Abad-M.;P. Lam;T. Horner;M. Kastner-M.
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作者：
F. Martínez-Ruiz;A. Paytan;M. T. González-Muñoz;F. Jroundi;M. M. Abad-M.;P. Lam;T. Horner;M. Kastner-M.
海水中重晶石沉淀的机制以及水柱中重晶石沉淀的精确深度已经争论了几十年。在这里，我们通过分析使用太平洋、大西洋和印度洋的多个单元大容量原位过滤系统收集的样本，对公海不同站点的中层带水柱重晶石分布进行了详细研究。我们的结果表明，无论重晶石的饱和状态如何，重晶石都是一种在世界海洋中间深度特别丰富的有机矿物。这证实了在强烈的有机质矿化深处发生沉淀的概念。我们的观察进一步支持重晶石形成和微生物活动之间的联系，这通过重晶石颗粒与有机物聚集体和细胞外聚合物质的关联来证明。微生物介导的证据与之前的实验工作一致，表明在细菌生物膜中 Ba 与细胞表面和细胞外聚合物内的磷酸基团结合。这种有机积累促进了 Ba 的高浓度，导致饱和的微环境和有利于沉淀的成核位点。水体和颗粒物中 Ba 同位素的分布也与所提出的降水机制一致。
Mechanisms underlying barite precipitation in seawater and the precise depths of barite precipitation in the water column have been debated for decades. Here we present a detailed study of water column barite distribution in the mesopelagic zone at diverse stations in the open ocean by analyzing samples collected using multiple unit large volume in-situ filtration systems in the Pacific, Atlantic and Indian oceans. Our results demonstrate that barite is an organo-mineral particularly abundant at intermediate depths throughout the world’s ocean regardless of saturation state with respect to barite. This is confirming the notion of precipitation at depths of intense organic matter mineralization. Our observations further support the link between barite formation and microbial activity, demonstrated by the association of barite particles with organic matter aggregates and with extracellular polymeric substances. Evidence for microbial mediation is consistent with previous experimental work showing that in bacterial biofilms Ba binds to phosphate groups on cell surfaces and within extracellular polymeric substances. This organo-accumulation promotes high concentrations of Ba leading to saturated microenvironments and nucleation sites favoring precipitation. The distribution of Ba isotopes in the water column and in particulate matter is also consistent with the proposed precipitation mechanism.