The 279-foot US Research Vessel, Knorr
University of Delaware marine scientists are now participating in a month-long international expedition funded by the National Science Foundation to explore the curious chemistry of the Black Sea, the world’s largest body of water containing poisonous hydrogen sulfide.
George Luther, a professor of oceanography at the UD College of Marine Studies, is one of the chief scientists representing the United States on the expedition. He and his graduate students are working aboard the 279-foot U.S. research vessel Knorr with teams from the University of Washington, Scripps Institution of Oceanography, and Skidaway Institute of Oceanography, as well as scientists from Turkey, Russia, and Ukraine.
On April 27, the expedition team docked at Sevastopol, Ukraine, on a goodwill visit with researchers and directors of the Marine Hydrophysical Institute, the Institute of Biology of the Southern Seas, and Moscow State University. The U.S. contingent presented each institute with a flag from the National Science Foundation during a tour of the research vessel Knorr.
The Black Sea occupies an area larger than California. Nearly 90% of the over 700-mile-long, mile-deep system is a zero-oxygen “dead zone” that supports only a few bacteria.
This oxygen-less zone is the result of natural and human factors. Due to the Black Sea’s nearly landlocked status, little mixing occurs between the surface waters, which receive major freshwater inputs from rivers, and the denser, saltier bottom waters that enter the system from the Mediterranean Sea through the narrow Bosporus.
This natural state is compounded by serious pollution problems generated by the over 160 million people who live in the 16 countries in the Black Sea’s watershed. While only six nations border the Black Sea, half of continental Europe drains into it through the Danube and other major rivers.
“Besides having a substantial zone where no oxygen exists and high levels of sulfides occur, the Black Sea has an unusual region known as the ‘suboxic zone’ that lies between its oxygen-rich surface waters and its oxygen-starved depths,” Luther says.
“This zone is of particular interest to us because it has both minimal oxygen and minimal sulfide concentrations. Typically, when the oxygen level increases in an aquatic system, the sulfide level decreases, and vice versa, but that’s not what happens here,” he notes. “And it’s a remarkably stable area, extending over a depth ranging from 20 to 50 meters.”
Luther and his team are using a solid-state microelectrode they invented that can verify the presence of the suboxic zone thanks to the sensor’s ability to measure oxygen and sulfide simultaneously. The gold-tipped probe, encased in a protective plastic sheath, is mounted in a pressure housing and deployed at various depths in the water column.
Previously, Luther has used this electrochemical analyzer to reveal the chemistry of marine systems ranging from deep-sea hydrothermal vents to several “deep hole” lagoons near Delaware’s Inland Bays where major fish kills have occurred.
Starting May 10, the scientists will be welcoming aboard two new crew members from Delaware for the expedition’s third and last leg. Hepsi Zsoldos and Lynn Scanlan, two teachers from Talley Middle School in Wilmington will be joining the team to assist with the research and provide a firsthand report of the team’s findings back to the classroom.
Zsoldos, who won Delaware’s first Governor’s Marine Science Teacher-of-the-Year Award in 2002, went to sea last October as a shipboard education coordinator for UD’s “Extreme 2002: Mission to the Abyss,” a 24-day expedition to explore hydrothermal vents over a mile deep in the Pacific Ocean.
During the past few months, in preparation for the Black Sea cruise, the teachers have worked with an after-school student club that has researched and developed “Kids Corner” Web pages on topics ranging from the water quality of the Black Sea to Turkish carpets.
To learn more about the research mission and to link over to Talley Middle School’s “Kids Corner,” visit UD’s Black Sea Web site at www.ocean.udel.edu/blacksea. The site was developed through a partnership involving Dr. Luther and his research team, the UD Marine Public Education Office, and Information Technologies – User Services.