Diagenesis of marine sediments

海洋沉积物的成岩作用

• 批准号: 124367-2012
• 负责人: Sundby, Bjorn
• 金额: $ 2.33万
• 依托单位: Université du Québec à Rimouski
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=545435
• 关键词: Diagenesis; marine; sediments

Intense biogeochemical cycling, driven by reactions that remineralize organic matter, takes place in the surface layer of the sediments that cover the seafloor. The cycling, fuelled by oxidation of organic matter by oxygen, nitrate, metal oxides, and sulfate, is an important consequence of diagenesis - the processes that bring about change in a sediment as it is buried. Organisms inhabiting sediments mediate diagenetic reactions and promote exchange of solutes and gases across the sediment-water interface. Bottom sediments are thus an imperfect trap for many of the components that settle to the seafloor, some of which may be toxic. Diagenesis impacts both the water column overlying the sediment, to which the remineralization products are returned, and the composition of the solid phase components of the sediment that become sedimentary archives. My long term objective is to understand the effects of diagenesis on biogeochemical cycling and the influence of diagenesis on both sediment-water interactions and burial of paleosignals. The short term objectives fall into three categories: 1) How does bioturbation - excavation, mixing, and irrigation of sediments - influence exchange of solutes across the sediment-water interface during diagenesis? 2) How do the oxygen content of the bottom water and the flux of organic carbon to the sediment influence reaction pathways and accumulation rates of elements whose solubility can change with the redox potential? 3) How does diagenesis affect our ability to use the distribution of manganese in Arctic Ocean sediments for paleochronology? The objectives will be approached via laboratory experiments and diagenetic modelling. Our research provides an essential underpinning for informed stewardship of our changing environment and will improve our ability to interpret sedimentary archives and extract information about the past.

在使有机物矿化的反应的驱动下，海底表层沉积物发生强烈的地球化学循环。有机物被氧气、硝酸盐、金属氧化物和硫酸盐氧化而产生的循环是成岩作用的重要结果，成岩作用是沉积物被埋藏时发生变化的过程。栖息在沉积物中的生物介导成岩反应，促进溶质和气体在沉积物-水界面上的交换。因此，对于沉降到海底的许多成分来说，海底沉积物是一个不完美的陷阱，其中一些可能是有毒的。成岩作用既影响沉积物上覆的水柱（矿化产物返回到该水柱），又影响成为沉积档案的沉积物固相组分的组成。我的长期目标是了解成岩作用对地球化学循环的影响，以及成岩作用对沉积物-水相互作用和古信号埋藏的影响。短期目标分为三类：1）生物扰动-挖掘，混合，和沉积物的灌溉-如何影响在成岩作用期间的沉积物-水界面的溶质交换？2)底层水的氧含量和有机碳向沉积物的通量如何影响溶解度随氧化还原电位变化的元素的反应途径和累积速率？3)成岩作用如何影响我们利用北冰洋沉积物中锰的分布进行古年代学研究的能力？这些目标将通过实验室实验和成岩模拟来实现。我们的研究为我们不断变化的环境提供了一个重要的基础，并将提高我们解释沉积档案和提取有关过去的信息的能力。