Title: Early diagenesis of cadmium and cobalt in sediments of the Laurentian Trough
Abstract: The depth distributions of hydroxylamine/acetic acid-extractable Co and Cd were determined in box-cores from a series of stations along the 1200 Km length of the Laurentian Trough. These were compared with the concentrations of total Co and Cd and the distributions of extractable Mn and Fe in the cores, as well as with the total Cd concentrations in sedimenting particles collected with a sediment trap. The results indicate a strongly contrasting behaviour of the two elements during early diagenesis, consistent with their respective chemistries and particle-associations. Cobalt occurs mainly in a non-reactive form and is buried with the accumulating sediments. A mobile component of Co is associated with Mn- and Fehydroxides and, like these compounds, follows a redox-sensitive pattern of dissolution in the reducing zone of the sediment—vertical migration—enrichment by precipitation in the oxidized surface layer—and redistribution along the bottom in paniculate form. Paniculate Cd arrives at the sediment surface bound to biogenic material, is rapidly solubilized during aerobic degradation of the organic matter, and migrates vertically both into the reducing zone of the sediments where it precipitates, and back into the water column where it may be recycled through biological processes. In an estuary, Co will be concentrated in the oxidized layer of the sediments and tend to migrate landward, while Cd will be most abundant in sediments underlying regions where plankton production is high relative to dilution by terrigenous particles.
Publication Year: 1986
Publication Date: 1986-05-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 86
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