|Mobility of Cu, Cd, Ni, Pb, Zn, Fe and Mn in marine sediment slurries under anaerobic conditions and at 20% air saturation|
Gerringa, L.J.A. (1991). Mobility of Cu, Cd, Ni, Pb, Zn, Fe and Mn in marine sediment slurries under anaerobic conditions and at 20% air saturation. Neth. J. Sea Res. 27(2): 145-156
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
Marine sediment slurries were incubated in the laboratory at constant temperature and pH and at controlled oxygen concentrations (0% and 12 to 40% air saturation) to study the effects of the degradation of organic matter on the mobility of trace metals. Under anaerobic conditions, sulphate reduction and reduction of Fe(hydr)oxides occurred. Mn species were reduced within 24 h after the onset of anaerobic conditions. Mobilization of metals by reduction of Mn oxides was not observed. After 2 weeks the dissolved-Mn concentration decreased. The total dissolved-sulphide concentration was probably limited by the precipitation of FeS. Soluble Cu and Cd sulphides could not be formed at the relatively low sulphide concentration. In the sediment Cd, Cu, Pb and Zn were more strongly bound under anaerobic conditions than under aerobic conditions and their species changed quickly (within 1 to 4 d) upon aeration to fractions that were easily extractable (Na-acetate, pH=5; Na-dodecylsulphate, pH=8). At 20% air saturation, aerobic degradation, nitrate reduction and reduction of Fe(hydr)oxides occurred. Mn species were completely reduced; only part of the Fe(III) species were reduced when compared with anaerobic conditions. The concentration of dissolved Mn decreased after 2 weeks. Dissolved Cu could not be detected at 20% air saturation, in contrast to dissolved Ni. Although Ni was in general unreactive because its speciation in the sediment did not change with changing O2 concentrations, a very small fraction (0.2%) was highly reactive.