Microbial sequestration of phosphorus in anoxic upwelling sediments
Microbial sequestration of phosphorus in anoxic upwelling sediments
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DOI：
10.1038/ngeo913
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发表时间：
2010-08-01
影响因子：
18.3
通讯作者：
Zabel, Matthias
中科院分区：
文献类型：
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作者：
Goldhammer, Tobias;Bruchert, Volker;Zabel, Matthias
磷是生命所必需的营养素。在海洋中，磷埋藏调节海洋初级生产（1，2）。通过有机物的沉积，以及随后有机磷转化为磷酸盐矿物（如磷灰石），并最终形成磷块岩沉积物（3，4），磷从海洋中被移除。细菌被认为介导这些过程（5），但隔离的机制仍不清楚。在这里，我们目前的结果，从实验室培养中，我们标记的有机物丰富的沉积物从本格拉上升流系统，纳米比亚，与P-33-放射性示踪剂，并跟踪磷的命运。我们发现，在缺氧和好氧条件下，大型硫化物氧化细菌在细胞中积累P-33，并催化磷酸盐几乎瞬时转化为磷灰石。磷灰石的形成是最大的缺氧条件下。对纳米比亚涌升沃茨和沉积物的营养分析表明，缺氧底层沃茨下磷酸盐向磷灰石转化的速率超过了上层沉积物有机物矿化过程中磷的释放速率。我们认为，细菌磷灰石的形成是一个显着的缺氧底层水条件下的磷汇。在未来气候变化的模拟中，预计氧气最小区将扩大（6），可能会增加海洋磷酸盐的封存，并限制海洋生产力。
Phosphorus is an essential nutrient for life. In the ocean, phosphorus burial regulates marine primary production(1,2). Phosphorus is removed from the ocean by sedimentation of organic matter, and the subsequent conversion of organic phosphorus to phosphate minerals such as apatite, and ultimately phosphorite deposits(3,4). Bacteria are thought to mediate these processes(5), but the mechanism of sequestration has remained unclear. Here, we present results from laboratory incubations in which we labelled organic-rich sediments from the Benguela upwelling system, Namibia, with a P-33-radiotracer, and tracked the fate of the phosphorus. We show that under both anoxic and oxic conditions, large sulphide-oxidizing bacteria accumulate P-33 in their cells, and catalyse the nearly instantaneous conversion of phosphate to apatite. Apatite formation was greatest under anoxic conditions. Nutrient analyses of Namibian upwelling waters and sediments suggest that the rate of phosphate-to-apatite conversion beneath anoxic bottom waters exceeds the rate of phosphorus release during organic matter mineralization in the upper sediment layers. We suggest that bacterial apatite formation is a significant phosphorus sink under anoxic bottom-water conditions. Expanding oxygen minimum zones are projected in simulations of future climate change(6), potentially increasing sequestration of marine phosphate, and restricting marine productivity.