Early diagenesis of manganese, iron and phosphorus in European continental margin sediments

This thesis describes the results of a project that was carried out as a part of the Sedimentary Manganese and Iron cycLEs (SMILE) research program funded by the Netherlands Organisation of Scientific Research (NWO/ALW). SMILE aimed at studying the biogeochemistry of iron and manganese cycles in sedimentary environments along a carbon-loading gradient, i.e. from estuarine, via shelf and slope sediments to deep-sea sediments. SMILE consists of three components, each focussing on separate sedimentary environments; Mn and Fe cycling in estuarine sediments (Netherlands Institute for Ecology, NIOO-CEMO), Atlantic shelf and slope sediments (Netherlands Institute for Sea Research, NIOZ) and the Mediterranean (Utrecht University- Institute for Earth Sciences, UU-IES). The SMILE objectives include: (1) to establish the role ofMn and Fe in the oxidation of organic matter, (2) to examine the metal reduction rates as a function of organic carbon loading and bioturbation, (3) to investigate the interaction between Mn and Fe cycles and the phosphorus cycle, and (4) to study the formation and preservation of metal-rich layers and their geological information. The work presented here concentrated on Mn and Fe cycling as driven by the input of organic matter and the recycling and burial of phosphorus in sediments of the European continental margin. The problems were addressed by a combination of fieldwork, laboratory work and modelling studies.