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Four Old Dominion University chemists lead a research team that has been awarded $465,000 by the National Science Foundation (NSF) for a sophisticated new study of dissolved organic matter (DOM) in seawater. The researchers propose to investigate the connections between DOM and the carbon cycle, which influences climate change.

Aron Stubbins, an assistant research professor in ODU's Department of Chemistry and Biochemistry, is principal investigator for the three-year grant. Other investigators from ODU are Patrick Hatcher, Batten Endowed Chair in Physical Sciences; Jingdong Mao, assistant professor of chemistry and biochemistry; and Kenneth Mopper, professor of chemistry and biochemistry.

The researchers' goal of providing the most in-depth analysis ever of DOM in seawater is made possible by instruments in ODU's 18-month-old College of Sciences Major Instrumentation Cluster (COSMIC), which Hatcher directs. Those instruments include a $1.3 million, ultra-high-resolution 12-Tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer.

Michael Perdue, a chemist and professor of earth and atmospheric sciences at Georgia Tech, is also an investigator on the NSF collaborative research grant.

The title of the grant, "Comprehensive Chemical Characterization of Marine Dissolved Organic Matter Using Efficient Isolation Coupled to Advanced Analytical Techniques," reflects a two-pronged effort.

First, the researchers will isolate DOM molecules using a new, highly efficient reverse osmosis and electrodialysis technique capable of isolating as much as 95 percent of DOM from a seawater sample. This is a major improvement over other current procedures, which can only collect 10-40 percent of DOM.

The second prong is the actual analysis of DOM. The proposal predicts that the "unparalleled power" of the ultra-high-resolution FT-ICR mass spectrometer and an advanced nuclear magnetic resonance (NMR) spectroscopy instrument in Hatcher's COSMIC lab will allow the researchers to read the "molecular messages" of marine DOM.

Those messages are important to our understanding of how DOM and dissolved organic carbon (DOC) arrives and is processed in seawater. DOM comes from decomposed plant and animal matter, both on land and from within the sea itself. As river water is carried to the sea, and then mixes through the oceans, it carries the molecular signals of all the environments it has passed through and all the life that has occurred within it. The DOM pool consists of millions of different molecules, each carrying information about its source, how it has been processed and, therefore, also about the journey of the water that carries it. The variety and multitude of DOM molecules bestows great information richness to these molecules and makes them extremely useful for scientists exploring the cycling of carbon and the mixing of waters in the oceans.

DOM accounts for almost all of the organic carbon in the oceans, making it a storehouse containing about the same amount of carbon as is present in atmospheric carbon dioxide (CO2). The amount of atmospheric CO2 is already rising at an alarming rate, and any change in DOM dynamics that results in more carbon being released into the atmosphere could hasten global warming. A thorough understanding of the Earth's carbon cycle is therefore required so that we can best predict and react to future climate disruption.

For their various tests, the researchers have chosen seawater sample collection sites in the North Pacific near Hawaii and off the west coast of Africa.

Stubbins, who is a first-time NSF investigator, has been at ODU since 2005. His doctorate in marine biogeochemistry is from the University of Newcastle-upon-Tyne in Great Britain. Since joining ODU, he has worked with Mopper and Hatcher, both of whom have participated in numerous NSF-supported research projects.

As manager of the project, Stubbins will take the leading role in fieldwork and coordinating laboratory analyses and data interpretation. Hatcher will oversee all FT-ICR mass spectrometer and NMR analyses. Mao will lead the NMR analyses. Mopper will help integrate the project goals and results, and oversee wet chemical DOM characterization.

Perdue at Georgia Tech will develop and build the reverse osmosis-electrodialysis system for the project and assist in chemical data interpretation.

This article was posted on: August 20, 2007

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