The trace metal composition of suspended particles in the oceanic water column near Bermuda (original) (raw)

1992, Earth and Planetary Science Letters

Trace metal partitioning between seawater and particles, both suspended and sinking, must be determined to understand and model oceanic trace metal scavenging processes. In order to improve the oceanic particulate trace metal data base, a new in-situ pump was developed and deployed to collect suspended particles from 0-4000 m in the Sargasso Sea near Bermuda. These particles were analyzed for AI, Fe, Mn, Co, Zn, Cu, Ni, Cd and Pb; major particulate carrier phases were estimated from Ca, opaline Si, and P. Cd is the only trace element of this group with a particulate maximum in near-surface waters. The other metals have low particulate concentrations (mol/l) in near-surface waters, and increase with depth into the upper thermocline. Particulate A1 and Fe are then uniform with depth below about 1000 m until increasing in the bottom nepheloid layer. The remaining elements (Mn, Co, Zn, Cu, Ni and Pb) decrease from the mid-thermocline values to lower and relatively uniform concentrations in deep waters, The similarities among the vertical profiles for these metals suggest that authigenic Mn oxides influence their uptake from the dissolved pool, although an important or dominant role for other host phases, specifically particulate organic matter, is not ruled out by the data.