Chemical Diagenesis in the Tamar Estuary

Estuaries are sites of high primary productivity, resulting in substantial fluxes of organic matter. Bacterial decomposition of this material in the underlying sediment gives rise to significant remobilisation of organic decomposition products and of inorganic reactants that undergo redox transformations during diagenesis, such as the oxides of Mn and Fe. These reactions promote fluxes of solutes across the sediment-water interface at rates which are influenced by the nature and rate of supply of reactants, the extent of sediment reworking and the occurrence of diagenetic mineralisation and sorption reactions leading to their removal from the porewaters. The aim of this paper is to document the porewater distributions of organic decomposition products and associated species and to evaluate the significance of benthic exchange to their distributions in the overlying water of the Tamar estuary, southwest England, a shallow estuary of high organic productivity.