The Biogeochemistry of Hydrogen Sulfide in the Open Ocean

<p>Hydrogen sulfide is a poorly quantified component of the global sulfur cycle. In seawater, its dissolved species (dissolved sulfide) can react with trace metals to form dissolved complexes and insoluble compounds. Therefore, the study of dissolved° sulfide in the open ocean can yield a better understanding of the biogeochemical cycles of sulfur and trace metals.</p> <p>The biogeochemical cycling of dissolved sulfide was examined using specially developed sampling and analytical methods. In the western North Atlantic and central Equatorial Pacific Oceans, total dissolved sulfide concentrations ranged from /L; they were highest, in the mixed layer and decreased with depth. The depth distribution and the rate of carbonyl sulfide (OCS) hydrolysis to hydrogen sulfide under oceanographic condition were determined because of their importance for the cycling of dissolved sulfide. Depth profiles of OCS show near-surface enrichment up to 150 pmol/1, and depletion at depth. These profiles suggest <em>in situ</em> OCS production, perhaps by organic matter regeneration. A budget was constructed to quantify the sources and sinks of dissolved sulfide in the Sargasso Sea mixed layer. The rate of dissolved sulfide production was 5.43 pmol/L/h (OCS hydrolysis + air/sea exchange), a.ncl the removal rate was 115.2 pmol/1/h (oxidation+ particulate sinking). Similarities in profiles of dissolved sulfide and chlorophyll a or <em>Synechococcus sp</em>., and results from recent phytoplankton culture studies, also suggest its production by phytoplankton; this source is necessary to balance the dissolved sulfide budget.</p> <p>The conditional formation constant of Cu(HS)⁺ was determined under oceanographic conditions and is 10^{9.1± 0.6}. The speciation of dissolved sulfide was computed with this constant and literature thermodynamic data using a multiequilibrium model. The calculation predicts that 80% of dissolved sulfide is uncomplexed in the mixed layer, while over 90% is complexed by zinc and copper below the pycnocline. Because dissolved sulfide is rapidly cycled and interact.s with Irace met.a.ls, future studies should continue to quantify, under oceanographic conditions, its the interactions with trace meta.ls, and its rat.e of product.ion by phytoplankton.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ocean & Earth Sciences

Year dc:date.available

1993

Author dc:creator

• Radford-Knoery, Joël

Contributors dc:contributor

• Gregory A. Cutter
• G. Wong
• Eileen Hofmann
• William Landing

• Synechococcus
• Chlorophyll
• Phytoplankton
• Hydrogen sulfide
• Biogeochemistry
• Oceanography

Statement dc:rights

• <p>In Copyright. URI: <a href="http://rightsstatements.org/vocab/InC/1.0/">http://rightsstatements.org/vocab/InC/1.0/</a> This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).</p>

Repository record dc:identifier

https://digitalcommons.odu.edu/oeas_etds/156

OAI identifier oai:identifier

oai:digitalcommons.odu.edu:oeas_etds-1152