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Production and preservation of organic matter: The significance of iron

机译：有机物的生产和保存：铁的意义

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[1] '' Iron fertilization '' has been previously recognized as a potential mechanism for enhanced organic matter burial in marine sediments. However, the singular view of iron as a control on primary production overlooks its role in sedimentary diagenesis, a factor that must be evaluated when considering organic matter accumulation. This study examines the role of iron as a buffer of pore water sulfide and its implications for marine organic matter burial. Biogeochemical model experiments indicate that dissolved sulfide buildup in surficial marine sediments is highly sensitive to reactive iron concentration. A reduction in reactive iron concentration can initiate dissolved sulfide accumulation, the consequences of which include inhibition of bioturbation/bioirrigation, a decrease in oxygen exposure time, and enhanced organic matter burial. Alternatively, an increase in reactive iron concentration can serve to decrease organic matter burial. The coupling of iron and phosphorous cycling within marine sediments provides an important positive feedback, and therefore this mechanism is designated the '' sulfide buffer/phosphorous trap hypothesis.'' Given sufficient organic carbon supply, carbonate-rich and opal-rich sediments should be especially prone to the development of sulfidic conditions because of a deficiency in terrigenous iron. Widespread chalk and marl deposition during the Cretaceous, in association with the evolutionary expansion of calcareous plankton, may have predisposed many benthic marine environments to the accumulation of toxic hydrogen sulfide and fostered the development of '' oceanic anoxic events.'' Comparison of model results with proxy data from oceanic anoxic event II (middle Cretaceous) suggests a complex role of iron as a control on both organic matter production and preservation.
机译：[1]以前已认识到“铁肥”是增强海洋沉积物中有机物埋藏的潜在机制。但是，铁作为主要生产控制的单一观点却忽略了其在沉积成岩作用中的作用，而沉积成岩作用是考虑有机质积累时必须评估的一个因素。这项研究探讨了铁作为孔隙水硫化物缓冲剂的作用及其对海洋有机物埋藏的影响。生物地球化学模型实验表明，表层海洋沉积物中溶解的硫化物积累对反应性铁浓度高度敏感。反应性铁浓度的降低可引发溶解的硫化物积聚，其后果包括抑制生物扰动/生物灌溉，减少氧气暴露时间和增加有机物埋葬。或者，反应性铁浓度的增加可用来减少有机物的埋葬。海洋沉积物中铁与磷循环的耦合提供了重要的正反馈，因此，该机制被称为“硫化物缓冲/磷阱假说”。鉴于有机碳供应充足，应富含碳酸盐和蛋白石的沉积物特别是由于源铁的缺乏，容易产生硫化物。白垩纪时期广泛的白垩和泥灰沉积，以及钙质浮游生物的演化扩张，可能使许多底栖海洋环境易于沉积有毒的硫化氢，并促进了“海洋缺氧事件”的发展。模型结果的比较来自海洋缺氧事件II（中白垩纪）的代理数据表明，铁作为有机物生产和保存控制的复杂作用。

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