Department of Chemistry
University of Otago
PO Box 56, Dunedin
New Zealand

Tel: +64-3-4797908
Fax: +64-3-4797906
email: chemistry@otago.ac.nz

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• Research graduates 2000–present
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Steve Rusak, MSc (2004)

Thesis Title:

Hydrogen peroxide in natural aquatic systems

Supervisor:

Dr. Barrie Peake

Thesis Abstract:

Hydrogen peroxide is often a product of sunlight-driven photochemical reactions in natural waters. Naturally occurring concentrations of H2O2 in most surface waters are between 1 x 10-8 and 1 x 10-6 moles per litre (10 and 1000 nM), and can change dramatically over short temporal and spatial scales. These varying concentrations are related to several factors, including levels of solar radiation, the concentration of chromophoric dissolved organic matter (CDOM), and the activity of peroxide-degrading enzymes in the water. In practical terms, an understanding of the factors that determine H2O2 concentrations will help us to better predict the dynamics of some biological processes, the degradation of dissolved organic compounds, and the fate of pollutants in natural waters.

In this thesis, formation and decomposition pathways that govern hydrogen peroxide concentrations in natural waters are reviewed, and some factors related to distributions of H2O2 in surface water are discussed. Several methods for measuring concentrations of H2O2 in natural waters are considered, and a new method for measuring H2O2 by means of flow injection analysis (FIA) is described. Concentrations of H2O2 in the Water of Leith at 2:00 pm are reported for most days in September, October and November 2003. The concentrations generally increased as the southern summer solstice approached. Measurements of solar ultraviolet-B radiation are also reported for the same time period. A kinetic-type model is used to describe the H2O2 concentrations in terms of the radiation measurements, but the model residuals are large. Reasons for the large residuals are discussed, along with speculations on the ecological effects of H2O2 in natural waters.

Life since MSc

 

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