Balloons take to sky for volcanic gas study
Volcanic gases erupting from Kilauea's Halemaumau vent were measured and tracked with high-altitude balloons this summer for the first time.
The results show that sulfur dioxide gas eventually forms airborne droplets of sulfuric acid that are even more harmful to lungs than the original gas.
The National Science Foundation funded the venture from a program for high-risk experimental work, said Adam Durant, an adjunct geological sciences faculty member at Michigan Technological University.
"We didn't know if we were going to be able to track volcanic emissions, and we didn't know if we would be able to retrieve the balloons," Durant said in a telephone interview from Iceland, where he was presenting the research results.
Both goals were met, and the scientists hope to obtain funding for a scaled-up project with more flights and advanced instruments, he said.
Jeff Sutton, Hawaiian Volcano Observatory staff geochemist, said these novel measurements will complement the observatory's ground-based readings.
The scientists, wearing goggles and breathing masks, launched two meteorological balloons at the vent in July in coordination with the U.S. Geological Survey and the National Park Service.
Keola Awong of the park service conducted a blessing before the first flight at the rim of the caldera. The scientists also left flowers as a gift to Pele, the volcano goddess.
One balloon rose 8,250 feet, then crashed in an ohia forest.
"We had a GPS location and drove as close as we could to it," said Durant. "We bushwhacked through the forest and found the balloon."
The second rose to 11,500 feet and landed in a macadamia orchard.
The data was transferred by satellite to collaborator Paul Voss, an atmospheric scientist at Smith College in Massachusetts. Voss flew the balloons by satellite link using Google Earth for flight visualization and while communicating with the Federal Aviation Administration, Durant said.
The balloons, 6 to 8 feet tall when inflated, can fly for days, but the FAA restricted the flights in Hawaii to 5 1/2 hours, he said. The balloons were equipped with high-tech sensors to measure the temperature, composition and water content of gases as they followed the plumes.
Winds carried them up the slopes of Mauna Loa to the Ocean View subdivision downwind from the volcano on the west side of the island, then toward Kona, Durant said. Sulfur dioxide was detected in Ocean View several hours after the gas erupted from the volcano, he said.
Initial findings suggest most of the sulfur dioxide in the plume converts to sulfate aerosol about one hour after it is spewed from the volcano -- and that causes haze, Durant said.
"What we're showing is, it's not necessarily sulfur dioxide that's a hazard to health, but the small particles that the gas converts into. ...
"Sulfuric acid droplets are very, very small," he added. "They irritate the lining of the lungs."
Durant conducted the experiment with colleague Matt Watson, also a Michigan Tech adjunct faculty member. Both are now doing postdoctoral work at the University of Bristol in the United Kingdom.
"It's a challenging task they were trying to do -- to chase the plume down," Sutton said. "They're looking at relative amounts of each gas in the plume and at concentrations at places distant from the vent. What Adam is trying to do is refine the understanding of how long that conversion process takes. That will be a useful contribution if they're actually able to do that."