REACTIVE IRON IN MARINE-SEDIMENTS
REACTIVE IRON IN MARINE-SEDIMENTS
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DOI：
10.1016/0016-7037(89)90005-7
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发表时间：
1989-03-01
影响因子：
5
通讯作者：
CANFIELD, DE
中科院分区：
文献类型：
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作者：
CANFIELD, DE
已进行实地/实验室联合研究，以探索海洋沉积物中铁的矿物学、浓度和反应性（对硫化物）。还考虑了细菌Fe释放在调节孔隙水化学中的重要性。包括两种对比鲜明的海洋环境；一个是相对缺铁的FOAM场地，另一个是密西西比三角洲水下富铁沉积物。结果表明，氧化矿物是早期成岩黄铁矿形成中最重要的铁相。然而，单独观察，绢云母和水合铁比针铁矿和赤铁矿对硫化物的反应性更强。当铁氧化物以相对高浓度存在时，沉积物孔隙水中几乎不存在溶解的硫化物（伴随着高浓度的溶解铁），即使存在硫酸盐还原产生的活性硫化物。实验结果与成岩模拟相结合表明，在某些沉积物孔隙水中，铁来源于氧化铁的细菌还原。即使硫化物与氧化铁反应还原了大量的铁，情况似乎也是如此。海洋沉积物中可能存在不同的微环境，在一个微环境中，硫化物与铁氧化物发生反应，局部沉淀出硫化铁矿物。在另一种情况下，被微生物还原和溶解的铁可以自由地迁移到溶液中。
A combined field/laboratory study has been undertaken to explore the mineralogy, concentrations and reactivity (towards sulfide) of iron in marine sediments. Also considered is the importance of bacterial Fe liberation in regulating pore-water chemistry. Two contrasting marine environments are included; one is the relatively Fe-poor FOAM site and the other is the Fe-rich sediment of the subaqueous Mississippi Delta. Results show that oxide minerals are the most important Fe phases in early diagenetic pyrite formation. However, viewed separately, lepidocrocite and ferrihydrite are more reactive towards sulfide than goethite and hematite. When Fe oxides are present in relatively high concentrations, dissolved sulfide is nearly absent from sediment pore waters (with concomitant high concentrations of dissolved Fe), even in the presence of active sulfide production by sulfate reduction. A combination of experimental results and diagenetic modelling shows that in some sediments pore water Fe finds it origin in the bacterial reduction of iron oxides. This seems the case even though greater amounts of Fe are reduced by reaction of sulfide with iron oxides. It apepars that distinct microenvironments may exist in marine sediments, where, in one microenvironment, sulfide reacts with Fe oxides locally precipitating Fe sulfide minerals. In another, Fe reduced and solubilized by microorganisms migrates freely into solution.