Burial efficiency of phosphorus and the geochemistry of iron in continental margin sediments
Burial efficiency of phosphorus and the geochemistry of iron in continental margin sediments
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DOI：
10.4319/lo.1998.43.1.0053
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发表时间：
1998-01-01
影响因子：
4.5
通讯作者：
Gobeil, C
中科院分区：
文献类型：
--
作者：
Anschutz, P;Zhong, SJ;Gobeil, C
我们已经研究了磷和铁在沉积物中的分布，从良好的氧化环境中的大西洋加拿大和葡萄牙大陆边缘和缺氧地区的切萨皮克湾。测量包括总的，柠檬酸盐-连二亚硫酸盐-碳酸氢盐（CDB）提取物，抗坏血酸提取物，溶解的P和Fe;酸挥发性硫化物;和黄铁矿。一个表层（厚度在2和4厘米之间变化）富含P和Fe揭示了CDB和抗坏血酸提取物在所有沉积物中，除了那些从切萨皮克湾。两种试剂提取的磷酸盐量相似，但CDB试剂提取的铁更多，可能是因为其溶解结晶氧化铁的能力。在Fe-和P-富集的表面层内，抗坏血酸提取物中的Fe：P比在窄范围内变化（6-14），可溶性反应性磷酸盐（SRP）浓度也是如此（5-16 μ M），这表明SRP与固相处于吸附平衡。我们的数据是一致的，在许多海洋环境中的P，Fe和硫的循环之间的动态循环和强相互作用。埋藏过程中的非晶铁的还原溶解和黄铁矿的形成减少了沉积物的能力，以螯合P，只有一部分的P，到达沉积物-水界面实际上得到埋藏的沉积物。
We have examined the distributions of phosphorus and iron in sediments from well-oxygenated environments on the Atlantic Canadian and the Portuguese continental margins and from the anoxic region of the Chesapeake Bay. The measurements include total, citrate-dithionite-bicarbonate (CDB) extractable, ascorbate extractable, and dissolved P and Fe; acid volatile sulfide; and pyrite. A surface layer (varying in thickness between 2 and 4 cm) enriched in P and Fe was revealed by both the CDB and the ascorbate extractions in all sediments except those from the Chesapeake Bay. The amount of phosphate extracted by the two reagents was similar, but more iron was extracted by the CDB reagent, probably because of its ability to dissolve crystalline iron oxides. Within the Fe- and P-enriched surface layer the Fe:P ratio in the ascorbate extract varied within a narrow range (6-14), as did the soluble-reactive phosphate (SRP) concentration (5-16 mu M), suggesting that SRP is in sorption equilibrium with the solid phase. Our data are consistent with a dynamic cycling of P and strong interactions between the cycles of P, Fe, and sulfur in many marine environments. The reductive dissolution of amorphous Fe during burial and the formation of pyrite diminish the capacity of the sediment to sequester P, and only a portion of the P that arrives at the sediment-water interface actually gets buried with the sediment.