Physico-chemical and microbial processes governing the decay of organic substance in sediment under anoxic conditions

缺氧条件下控制沉积物中有机物质腐烂的物理化学和微生物过程

• 批准号: 396708702
• 负责人: Professor Dr. Christian Gerhard Ballhaus
• 金额: --
• 依托单位: Abteilung Paläontologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/396708702?language=en
• 关键词: Physico; chemical; microbial; processes; governing

To fossilize soft tissue of marine taxa it is essential that a carcass be transferred rapidly to anoxic conditions and isolated from potential scavengers. A practical way to achieve this is by burying a decaying carcass or a living sessile species in sediment. The oxidation of organic carbon to HCO3- and CO32- within the sediment will reduce the major electron acceptors in sediment and seawater, i.e. ferric iron and sulfate. The decay reactions will create local Eh and pH haloes around a carcass within which FeS sulfide, siderite, and other carbonate phases may be stabilized. These phases may then replace or template organic tissue, or encase the organic material in concretions. Within the research unit FOR 2685 the applicant will develop experimental routines that allow to investigate in-situ the anoxic decay of fish and echinoderms within a marine sediment. The major aim is to quantify the rates by which replacement can take place. While an experiment is progressing, organic material will be sampled from time to time. Inorganic precipitates will be identified by Raman spectroscopy. Bacterial communities emerging will be characterised in close collaboration with members of the research unit. It is expected that the templation by inorganic material - FeS phases, siderite, calcite - may be a matter of weeks to months. The characterisation of bacterial communities, an important aspect in the present proposal, will elucidate if pseudomorphic replacement reaction are inorganic by nature and driven only by pH and Eh gradients, or if they must be mediated by bacteria in order to be efficient.

为了化石海洋分类群的软组织，必须迅速将尸体转移到缺氧条件下，并从潜在的清除剂中分离出来。实现这一目标的一种实用方法是将腐烂的尸体埋在沉积物中。在沉积物中，有机碳氧化为HCO3-和CO32-将减少沉积物和海水中的主要电子受体，即铁和硫酸铁。衰减反应将在尸体周围产生局部EH和pH光环，在该尸体中，可以稳定FES硫化物，副岩和其他碳酸盐相。然后，这些阶段可以替换或模板有机组织，或将有机材料包含在混凝土中。在2685年的研究部门内，申请人将开发实验性的例程，以便在原位调查海洋沉积物内鱼类和棘皮动物的缺氧衰变。主要目的是量化替换的速率。尽管实验正在进行，但有机材料将不时进行采样。无机沉淀将通过拉曼光谱鉴定。新兴的细菌群落将与研究部门的成员密切合作。可以预期，无机材料的模板-FES相，副岩，方解石 - 可能是数周到几个月的问题。细菌群落的表征是本提案中的一个重要方面，它将阐明伪形替代反应是否本质上是无机的，并且仅由pH和EH梯度驱动，或者必须由细菌介导，以便有效。