Researcher looks to Antartica for key to understanding global climate

Dr. Mark Altabet, a professor at the School for Marine Sciences and Technology at the University of Massachusetts Dartmouth, is looking southwards for research opportunities in his field of marine biogeochemistry.

March 5, 2003 

University of Massachusetts Dartmouth researcher looks to Antartica for key to understanding global climate 

Dr. Mark Altabet, a professor at the School for Marine Sciences and Technology at the University of Massachusetts Dartmouth, is looking southwards for research opportunities in his field of marine biogeochemistry. As a specialist in measuring ratios of different forms, known as stable isotopes of nitrogen and carbon, Altabet is a member of a large research team working in the Ross Sea in the Southern Ocean off Antarctica. Nitrogen and carbon play key roles in the life cycles of organisms, as well as global climate cycles. 

Biogeochemists such as Altabet investigate the three components of the term, bio (life), geo (earth), and chemistry (molecules and reactions). Altabet and Dr. David Timothy, a post-doctoral researcher in Altabet's SMAST lab, are analyzing samples taken during Timothy's trip to the Ross Sea last winter. They are members of the Southern Ocean Iron Experiment (SOFeX), a project involving almost two dozen international laboratories. 

The School for Marine Sciences and Technology at UMass Dartmouth is based at the SMAST laboratory on the New Bedford harbor. Professor Brian Rothschild is director of the SMAST graduate school and facility, which is also the headquarters of the Massachusetts Marine Fisheries Institute. In addition, Rothschild is dean of the five-campus University of Massachusetts Intercampus Graduate School of Marine Sciences and Technolog of which the SMAST graduate school is a part. UMass is the state's leading educational institution dedicated to the study of marine sciences and associated technologies. 

"Projects like this are driven by a huge global requirement to understand the biology of the ocean. The terrestrial budget [of carbon dioxide] is fairly well understood, but the ocean budget is not nearly as well understood," says SMAST Director Brian Rothschild. 

Basing their work on the "iron hypothesis," which was developed at the Moss Landing Marine Laboratory at the University of Southern California, the SOFeX team "fertilized" a section of sea with iron. The iron hypothesis proposes that the nutrient-rich cold waters of the Southern Ocean are relatively unproductive biologically because of a lack of trace elements, such as iron. An increase in the iron supply would increase phytoplankton productivity and thus remove carbon dioxide from the atmosphere. 

To test the iron hypothesis in as realistic a setting as possible, SOFeX scientists added iron to seawater in the experimental area. Crew on three research vessels then collected samples inside and outside of the designated area. The physical structure of the surrounding ocean, chemical changes in nutrient and trace metals, and the abundance and activity of phytoplankton and zooplankton were assessed during SOFeX. 

Back at Altabet's lab, ratios of nitrogen and carbon isotopes are being measured using a highprecision instrument called a mass spectrometer; the results provide information on the biogeochemical reactions underway in the ocean's water. The analysis is ongoing, but early results are promising and show substantial changes in nitrogen and carbon stable isotopic ratios. 

"Understanding the past environmental variations as well as pivotal modern processes in key regions is critical to our ability to predict the future," says Altabet. The questions he is trying to answer are: "How did nitrogen and carbon isotopic signatures change in the past," and, "Where does the carbon in organic matter go?" 

Altabet's work is supported by grants from the National Science Foundation ($175,000) and the U.S. Department of Energy (DOE) ($120,000). The DOE funds Altabet's research because it may prove useful in understanding the problem of global warming. Phytoplankton utilize carbon dioxide during photosynthesis, much like trees and houseplants. Phytoplankton draw from, and thereby lower, carbon dioxide levels in the ocean's water. Carbon dioxide in the air above the water's surface is then absorbed as a replacement, creating a lower load of atmospheric carbon dioxide. Since high levels of atmospheric carbon dioxide are linked to global warming, phytoplankton could potentially play a role in curbing it. 

However, Altabet cautions that cultivating phytoplankton may not be a good idea if future research shows that it upsets ecological balances. For Altabet, this is yet another hypothesis in need of testing by a biogeochemist. 

This article was written by Elizabeth Lehr for the News & Publications Office 


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