Hydroxyl Radicals in Marine Sediments

University Of Connecticut, Storrs CT

Investigators

Abstract

OCE-0526358 The burial of organic matter (OM) in sediments on geological time scales plays an important role in controlling atmospheric oxygen concentrations. Multiple mechanisms controlling OM burial in sediments have been proposed and the scientific discussion is controversial. One proposed mechanism is that formation of small, highly-reactive, oxygen-containing species, such as hydrogen peroxide and hydroxyl radicals, may be important in degradation of sorbed OM under oxic conditions. No studies have shown the presence of reactive oxygen species in sediments, but theoretical arguments suggest that the abiotic formation of hydroxyl radicals from hydrogen peroxide and Fe2+ through the Fenton reaction may be substantial in coastal sediments. In this project, researchers at the University of Connecticut will address the following hypotheses by studying the occurrence of hydroxyl radicals in sediment with and without seasonal anoxia (two geographical locations): 1. Hydroxyl radicals and hydrogen peroxide are formed in abiotic reactions affected by sediment redox conditions. 2. Hydroxyl radicals and hydrogen peroxide have substantial formation rates in coastal sediments and the formation rates and steady-sate concentrations vary with season. 3. Hydroxyl radicals and hydrogen peroxide can be formed in microbially-mediated reactions and the formation rates and steady-sate concentrations depend on redox conditions, season, and hydrogen-peroxide-removing enzyme activity. Four different methods for quantification of hydroxyl radical formation rates will be evaluated to arrive at the best method to use in the heterogeneous sediment environment. This project has a number of educational broader impacts. The scientific investigation will be carried out by an Hispanic predoctoral graduate student as part of a collaboration and exchange program with the Universidad Autonoma de Baja California. Additionally, the research team has established contact with an organization called Project Oceanology, with whom they can recruit high school science teachers in need of science credit for their continued teaching accreditation. The high school teachers will participate in the cruises within the main project, with the aim that they will take back an understanding of how scientific research is carried out to their classrooms. The team also plans to produce a CD with photographs and lesson plans for the participating teachers to use.