Fig. 7 Geochemical sediment profiles from the centre of LPM and from LGM cores. (a, b) Profiles, showing coincidence between Fetotal and Stotal peaks in the sediment cores 4 m and 6 m from the shallow water area. (c) Fe/Mn fractionation in LPM and LGM. In the steeply inclining sector of the LGM basin, Fe is distinctly enriched versus Mn by precipitation of Fe-oxihydroxides. The dissolved Fe concentrations in the monimolimnion of LPM exceeded 100 mg/l in 1995 (Chiodini et al. 1997); dissolved Fe is precipitated as FeS; formation of Fe(Mn,Ca)carbonates is prevented by pH-lowering associated with high CO2 concentrations in the deep water of the lake. (d, e) Ptotal and TOC/P profiles of LGM sediments document that the burial rate of P in the sediments from the lake centre is higher than that of littoral sediments
...read more