Total element concentrations (Fe, Al, K) of the solid phase were measured after acid digestion (HF, HNO3 and HClO4) by inductively coupled plasma optical emission spectrometry (Varian ICP 720-ES). Solid phase iron speciation data were measured following single step sodium dithionite extraction (FeD) or sequential Fe extraction (FeAc, FeDith, FeOxal) by inductively coupled plasma optical emission spectrometry (Varian ICP 720-ES). Solid phase pyrite concentrations (FePy) were calculated stoichiometrically from photometrically measured S2- released via chromium(II) chloride reduction. Total organic carbon (TOC) of the sediment samples was measured in an Elemental Analyzer (Euro EA). Prior to analysis carbon bound to carbonate minerals was removed by leaching the sediment with 0.25 N HCl.