Aquatic Sciences Meeting, Albuquerque 2001

CS39 Trace Metal Limitation of Biogeochemistry

Date: Tuesday, February 13, 2001, Time: 12:15:00 PM

Location: Dona Ana

Carrasco, G, G, Old Dominion University, Norfolk, USA, gcarrasc@odu.edu

Donat, J, R, Old Dominion University, Norfolk, USA, jdonat@odu.edu

CONCENTRATIONS, COMPLEXATION AND SPECIATION OF ZINC AND CADMIUM IN THE WESTERN SOUTH AND EQUATORIAL ATLANTIC OCEAN

We determined Zn and Cd concentrations, complexation and speciation in water column samples collected on the 1996 IOC Baseline Contaminant Survey. Zn and Cd complexation were determined using DPASV at a thin mercury film/rotating glassy carbon disk electrode, and speciation was calculated from the DPASV results using the MINEQL speciation program. Vertical profiles of total dissolved (0.22um-filtered) Zn (TDZn) and Cd (TDCd) showed nutrient-type profiles at open ocean stations; however, near the mouth of the Amazon high concentrations were found at the surface. In most surface samples at least two ligand classes were detected for each metal, whose conditional stability constants (log K') averaged 10.3 and 8.5 for Zn, and 10.7 and 9.0, for Cd, respectively. Interestingly no organic complexing ligands were found for Cd near the Amazon delta. The influence of these organic ligands on the speciation and bioavailability of Zn and Cd will be presented.

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Aquatic Sciences Meeting, Albuquerque 2001

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