Date of Award

Fall 1987

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean & Earth Sciences

Program/Concentration

Oceanography

Committee Director

Gregory A. Cutter

Committee Member

David J. Burdige

Committee Member

Larry P. Atkinson

Call Number for Print

Special Collections LD4331.O35K72

Abstract

Sulfide in the surface ocean has been recently considered as a source of hydrogen sulfide gas in the marine boundary layer. This "oxic" sulfide may also be important as a ligand in trace metal complexation. In the absence of actual data, the existence of sulfide in the ocean mixed layer remains speculative. The purpose of this study was to develop a sensitive technique (having picomolar detection limits) for the determination of sulfide in seawater, and to investigate the distribution of sulfide in the surface ocean.

In order to assess the abundance and distribution of sulfide in surface waters, samples were collected during two field investigations in the shelf and slope waters of the western Atlantic Ocean. Sulfide determinations were made using gas chromatography and photoionization detection. Sulfide was complexed with zinc and preconcentrated via filtration onto a 0.4 μm Nuclepore filter. The sulfide on the filter was then volatilized via acidification and detected as H2s. A direct technique, where sulfide is liberated as H2s following acidification of the water sample, served to intercalibrate the zinc-sulfide technique.

Generally, sulfide concentrations were in the pico- to nanomolar range, the highest values (around 1 nmol/L) occurring during the summer field study off the coast of Virginia. The field investigations also indicate that sulfide varies both temporally and spatially.

Possible mechanisms which might affect the existence of sulfide in the mixed layer are the hydrolysis of carbonyl sulfide (HS- production) and sulfide oxidation. A model based on this production/removal process predicts sulfide variability different than that observed in the field. Thus, other production and removal mechanisms need to be considered.

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DOI

10.25777/4pgt-0452

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