Diagenesis of marine sediments

在有机质再矿化反应的推动下，剧烈的生物地球化学循环发生在覆盖海底的沉积物的表层。这种循环是由氧、硝酸盐、金属氧化物和硫酸盐氧化有机物所推动的，是成岩作用的重要结果，成岩作用是在沉积物被埋藏时引起变化的过程。栖息在沉积物中的生物调解成岩反应，并促进沉积物-水界面上的溶质和气体交换。因此，对于沉入海底的许多成分来说，海底沉积物并不是一个完美的圈闭，其中一些成分可能是有毒的。成岩作用既影响覆盖在沉积物上的水柱，再矿化产物返回到沉积物中，也影响成为沉积档案的沉积物固相成分的组成。我的长期目标是了解成岩作用对生物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)在成岩作用期间，生物扰动--沉积物的挖掘、混合和灌溉--如何影响沉积物-水界面上的溶质交换？2)底层水的含氧量和有机碳流向沉积物的流量如何影响其溶解度随氧化还原电位变化的元素的反应路径和累积速率？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的能力？这些目标将通过实验室实验和成岩模型来实现。我们的研究为明智地管理我们不断变化的环境提供了必要的基础，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。

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.