On the distribution of iron and manganese at the sediment/water interface: thermodynamic versus kinetic control

摘要: Abstract Iron and manganese solubility at the sediment/water interface has been studied a water depth of 20 m in Kiel Bight, Western Baltic. By means an situ bell jar system enclosing 3.14 2 sediment surface 2094 l complete redox turn-over bottom was simulated experiment lasting 99 days. The concentration dissolved Fe never exceeded 0.041 μmol · dm −3 during first 50 days then rose abruptly as Eh fell from +600 to −200 mV. under oxic anoxic conditions seems be limited by equilibria with solid Fe-phases (hydroxides amorphous sulphide, respectively). In contrast Fe, released continuously leading exponentially increasing concentrations water. During this time O had become ready depleted pH dropped 8.3 7.5. Contrary iron, being solubilized reduced layers can penetrate strata metastable form due slow oxidation kinetics; when redoxcline moves upwards Mn 2+ is enriched waters. maximum controlled phase properties similar MnCO 3 (rhodochrosite). Bottom enrichment could traced originate excess within top cm sediment.