Old Dominion University
Production and Decomposition of Hydrogen Peroxide by Marine Phytoplankton
Abstract
dc:description.abstract<p>H<sub>2</sub>0<sub>2</sub> in seawater has complicated sources and sinks. The relative importance of biological regulation of H<sub>2</sub>0<sub>2</sub> compared to other processes is not well understood. In addition, environmental factors affecting the biological regulation of H202 are largely unknown. Marine phytoplankton was examined for the kinetics of the production and decomposition of H<sub>2</sub>0<sub>2</sub> in the dark. Effects of varying environmental factors such as light, temperature, salinity, nutrients, amino acids, trace metals and growth phase, were examined. H<sub>2</sub>0<sub>2</sub> was determined with the scopoletin-fluorescence decay method.</p> <p>Five out of 11 species produced H<sub>2</sub>0<sub>2</sub>, while all of the 11 species decomposed H<sub>2</sub>0<sub>2</sub>. The relative significance of these species for producing H<sub>2</sub>0<sub>2</sub> decreased in the order of <em>Pleurochrysis carterae > Isochrysis galbana > Dunaliella tertiolecta > Tetraselmis levis > Emiliania huxley</em>i, and for decomposing it in the order of Synechococcus sp. = Skeletonema costatum » <em>Tetraselmis levis > Chaetoceros flexosus > Chaetoceros simplex > Isochrysis galbana > Thalassiosira oceanica > Amphidinium carterae > Pleurochrysis carterae ></em> Emiliania huxleyi > Dunaliella tertiolecta. Coccoid or unialgal cells showed a tendency to produce H<sub>2</sub>0<sub>2</sub>, whereas diatoms in chains were more likely to decompose H<sub>2</sub>0<sub>2</sub>. Both the production and decomposition of H<sub>2</sub>0<sub>2</sub> by these algae followed pseudo-first order reactions. The pseudo-first order rate constants related linearly to algal biomass. The biologically-mediated production and decomposition of H<sub>2</sub>0<sub>2</sub> showed reaction rate constants (k) ranging from 0.0017 to 0.0072 (fig chl-a'L'^ ^hr'1 for the production of H202 and from 0.0242 to 0.0002 (μg chl-a •L<sup>'1</sup>)'hr'<sup>1</sup> for the decomposition of H<sub>2</sub>0<sub>2</sub>. The studies on the rate kinetics suggested that marine phytoplankton regulates the H<sub>2</sub>0<sub>2</sub> budget in surface oceans by mediating primarily decomposition of H<sub>2</sub>0<sub>2</sub> rather than production of H<sub>2</sub>0<sub>2</sub>.</p> <p>The biological regulation of H<sub>2</sub>0<sub>2</sub> was not strongly affected by physical environmental factors such as light, temperature and salinity. Among the tested factors, amino acids were the most influential factor enhancing the production of H<sub>2</sub>0<sub>2</sub>. Inorganic nitrogen-limited conditions stimulated phytoplankton to produce more H<sub>2</sub>0<sub>2</sub> per unit biomass. The production of H<sub>2</sub>0<sub>2</sub> may be a result of amino acid utilization by nitrogen-starved phytoplankton. However, decomposition of H<sub>2</sub>0<sub>2</sub> was not affected by the addition of amino acids. Nutrient effects on the decomposition rate constants were much more profound in coastal species than in oligotrophic species. In general, the biological production of H<sub>2</sub>0<sub>2</sub> was small compared to photochemical production but could be significant in nitrogen-limited conditions whereas biological decomposition of H<sub>2</sub>0<sub>2</sub> was more important than other removal processes. The results of pure culture studies generally agreed with the results of the field studies. The oligotrophic Sargasso seawater showed biological production of H<sub>2</sub>0<sub>2</sub> whereas the mesotrophic coastal water displayed predominantly decomposition of H<sub>2</sub>0<sub>2</sub>. Biological production of H<sub>2</sub>0<sub>2</sub> could occur mostly in inorganic nitrogen-limited conditions by a limited number of species whereas biological decomposition of H<sub>2</sub>0<sub>2</sub> could remove H<sub>2</sub>0<sub>2</sub> from most coastal waters by a large number of species. This study implied that nitrogen dynamics as well as phytoplankton species composition and their abundance are necessary to understand biological roles in H<sub>2</sub>0<sub>2</sub> budget. The regulation of H<sub>2</sub>0<sub>2</sub> by phytoplankton may also be related to the speciation of trace metals in ambient waters because of strong oxidizing/reducing properties of H<sub>2</sub>0<sub>2</sub>.</p>
Degree
thesis:*- 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 and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Kim, Dong-Beom
- Contributors dc:contributor
-
- William M. Dunstan
- George T. F. Wong
- Anthony J. Provenzano, Jr.
- Frank E. Scully, Jr.
Subjects
dc:subject × 5Rights
dc:rights- 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>
Identifiers
dc:identifier.*- Repository record dc:identifier
- https://digitalcommons.odu.edu/oeas_etds/129
- OAI identifier oai:identifier
- oai:digitalcommons.odu.edu:oeas_etds-1134