AEROBIC DEGRADATION OF ORGANIC-MATTER AND THE MOBILITY OF CU, CD, NI, PB, ZN, FE AND MN IN MARINE SEDIMENT SLURRIES

Results of aerobic degradation of organic matter have been studied with respect to the dissolved and particulate partition of the metals Cu, Cd, Ni, Pb, Zn, Fe and Mn in sediment slurries in the laboratory (100% air saturated, pH 7.8, temperature 14°C). The rate of degradation was monitored by oxygen consumption and production of inorganic nitrogen compounds. The dissolved Cu and Ni concentrations show a strong relationship with the content of dissolved organic carbon (DOC), indicating their complexed state in solution. Cd and Cu are released by degradation of particulate organic carbon (POC). Per mol POC degraded, 1.8×10-5 mol Cu and 2×10-6 mol Cd are released into solution. The concentration of Pb in solution remains constant; Pb released by degradation of POC is probably precipitated as a salt or oxide, which governs the constant concentration in solution. Sequential extraction data revealed an increasing mobility during the time of the experiment especially for Cu and Cd, but also for the other metals with the exception of Ni. © 1990.