Date of Award

Fall 2000

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

John R. Donat

Committee Member

Patricia A. Pleban

Committee Member

Gregory Cutter

Call Number for Print

Special Collections LD4331.C45 C657

Abstract

Presented here are the first data on copper complexation and speciation in the South Atlantic Ocean. Samples were collected at six vertical profile stations and along the surface (1m) transect during the 1996 IOC Baseline Contaminant Survey. Copper complexation measurements were made for the surface transect (1m) samples and three of the six vertical profile stations (1m - ~500m) using differential pulse anodic stripping voltammetry (DPASV) with a thin mercury film, rotating glassy carbon disk electrode (TMFRGCDE).

A strong organic copper complexing ligand (L1; log K' cuL1/cu2+ > 11. 8 ± 0 .4) was detected in 57% of all samples. [L1] ranged from 2.83nM in all samples in which it was detected. A weaker organic copper complexing ligand (L2; log K' cuL2/cu2+ = 10.3 ± 0.4) was detected in all samples and ranged from 0.66 to 11.48nM.

Copper speciation was dominated by organic complexation. [Cu2 +] in the surface samples was generally 2-3 orders of magnitude lower than [Cu]T due to organic complexation. In the upper 200m at the three vertical profile stations, [Cu2 +] was approximately one order of magnitude lower than it would have been in the absence of organic complexation. Organic complexation caused [Cu2 +] in the surface waters of the South Atlantic to be at or below the threshold level at which [Cu2 +] becomes toxic to many oceanic phytoplankton species.

Along the surface (1m) transect, the distribution of [L1] was similar to [chlorophyll a]. In the upper water column at the two open ocean stations (10 and Romanche), both [L1] and [L2] displayed depth profiles similar to [chlorophyll a], suggesting surface water sources for these ligands (in the open ocean) of recent biological origin.

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DOI

10.25777/bhpp-4d66

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