Understanding how particulate organic carbon (POC) moves from the surface waters to the depths of the world's oceans and how it is transformed to dissolved organic carbon is the focus of an $827,710 award from the National Science Foundation (NSF) to GSO chemical oceanographer Dr. S. Bradley Moran and collaborators Drs. Adrian Burd of Georgia Institute of Technology in Atlanta and George Jackson of Texas A&M University in College Station.
Moran and his team will conduct field and modeling studies to assess and improve the current methods of tracing the sinking flux of POC from the upper ocean. A major focus of the work will be on an isotope of the radioactive element thorium (Th-234) that is used to estimate the magnitude and variability of the export flux of POC. Although more than a decade of research has been conducted on the use of Th-234 to measure the flux of POC, Moran and co-workers recently reported that current estimates can be quite variable, by a factor of 2-10 times.
The scientific team will experiment with new and existing measurements of Th-234, combined with POC and specific organic compounds in the upper ocean to test the validity of their assessments, given the chemical, physical, and biological differences that exist in different parts of the world.
"This research bears on a number of national and international carbon cycle research programs, will involve extensive scientific collaboration, and contribute to the education of undergraduate and graduate students," said Moran.
The researchers will collect samples from three study sites characterized by distinct differences in food-web structure and particle sinking fluxes. The sites include the Mediterranean Sea, the western Arctic Ocean, and the northwest Atlantic Ocean. Once the field observations are complete, computer models will be developed that will provide accurate information on the mechanisms of estimating upper ocean POC export flux using thorium-234.
A resident of Kingston, Moran received a B.Sc. in chemistry from Concordia University in Montreal, Quebec, Canada, and a Ph.D. in chemical oceanography from Dalhousie University in Halifax, Nova Scotia, Canada. His research at GSO, where he is a professor of oceanography, focuses on radionuclides as tracers of scavenging and particle cycling, marine colloids, solid-solution interactions of trace metals in seawater, coastal groundwater input, and natural and artificial radionuclides in Arctic rivers and ocean basins.
The URI Graduate School of Oceanography is one of the country's largest marine science education programs, and one of the world's foremost marine research institutions. Founded in 1961 in Narragansett, RI, GSO serves a community of scientists who are researching the causes of and solutions to such problems as acid rain, harmful algal blooms, global warming, air and water pollution, oil spills, overfishing, and coastal erosion. GSO is home to the Coastal Institute, the Coastal Resources Center, Rhode Island Sea Grant, the Institute for Archaeological Oceanography, and the National Sea Grant Library.