Phosphate geochemistry, mineralization processes, and Thioploca distribution in shelf sediments off central Chile
Phosphate geochemistry, mineralization processes, and Thioploca distribution in shelf sediments off central Chile
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DOI：
10.1016/j.margeo.2010.08.011
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发表时间：
2010-11-15
期刊：
影响因子：
2.9
通讯作者：
Jorgensen, Bo Barker
中科院分区：
文献类型：
--
作者：
Holmkvist, Lars;Arning, Esther T.;Jorgensen, Bo Barker
世界各大洋主要海岸上升流系统的沉积物是现代羟基磷灰石形成的热点，通常与大型的、积累硝酸盐的硫细菌的底栖群落有关。我们研究了磷酸盐释放、有机磷矿化和丝状硫细菌（Thioploca spp.）在智利中部的大陆架上，在南方夏季，当浮游植物的高生产力和缺氧的底层水盛行。新鲜沉积的植物碎屑刺激了极高的硫酸盐还原率，这支持了高达100克生物量每平方米（2）的大型Thioploca社区。有效的细菌硫化物吸收保持低浓度的硫化物，这使得游离铁的积累，从而表明密集的铁还原与硫酸盐还原。释放到孔隙水中的磷酸盐在最高的0 - 5 cm内达到100 - 300 μ M的峰值浓度，磷酸盐损失到上覆的缺氧水柱中。大量的磷酸盐释放与Thioploca的存在没有直接关系，而是新鲜有机碎屑的高沉积和矿化速率的结果。虽然孔隙水相对于羟基磷灰石是过饱和的，但这种矿物只是沉积物中的次要P组分。大多数固相磷酸盐与铁结合。(C)2010 Elsevier B.V.保留所有权利。
Sediments underlying the major costal upwelling systems of the world oceans are hot-spots of modern formation of hydroxyapatites, often associated with benthic communities of large, nitrate-accumulating sulfur bacteria. We studied the association between phosphate release, organic phosphorus mineralization, and occurrence of dense communities of the filamentous sulfur bacteria, Thioploca spp., on the continental shelf off central Chile during the austral summer when high phytoplankton productivity and anoxic bottom water prevailed. Freshly deposited phytodetritus stimulated extremely high sulfate reduction rates, which supported a large Thioploca community of up to 100 g biomass per m(2). Effective bacterial sulfide uptake kept the sulfide concentration low, which enabled the accumulation of free iron, thus demonstrating intensive iron reduction concurrent with sulfate reduction. Phosphate released to the pore water reached 100-300 mu M peak concentrations within the uppermost 0-5 cm and phosphate was lost to the overlying anoxic water column. The large phosphate release was not directly related to the presence of Thioploca but was rather the result of a high deposition and mineralization rate of fresh organic detritus. Although the pore water was super saturated with respect to hydroxyapatite, this mineral was only a minor P-component in the sediment Most solid-phase phosphate was bound to iron. (C) 2010 Elsevier B.V. All rights reserved.