Mae Gustin and airborne mercury

Mae Gustin

Mae Gustin was working on her latest paper, and she found that she had to get up periodically, take a deep breath and walk around a little.

Gustin, an environmental scientist at CABNR, was working on a paper reviewing methods to measure airborne mercury, and her findings were supporting those reported in previous work. What her data showed was that the equipment that has been used for years to measure gaseous oxidized mercury (GOM) in the atmosphere wasn't accurate. And she was finding that it wasn't off by just a little. It was off by at least 50 percent or more.

Scientists worry about airborne mercury because when it falls to the ground, microorganisms can transform it into a toxic, organic form that can infiltrate the environment and harm wildlife and people. The residents of Minamata, Japan suffered birth defects and other diseases as a result of eating seafood contaminated by highly toxic wastewater in Minamata Bay. Although most of the mercury in the air is elemental mercury that remains largely inert, the rest is the reactive type of mercury (GOM) that can be converted into methylmercury and get into the food chain. GOM is hard to measure, and researchers have suspected for years that the instrument currently used (Tekran) was underreporting what was there.

To investigate this Gustin and her team at UNR set up an experiment at the Main Station Field Laboratory to compare the existing measurement approach with alternative methods. Data were collected using Tekran systems, University of Miami laser-induced fluorescence, a University of Washington Detector for Oxidized Mercury, a University of Houston mercury instrument, and a filter-based system that Gustin herself is developing. The team took a series of samples, pulling those samples from the same tube, and, in one case, spiking the incoming air with known quantities of reactive mercury.

The results showed that the old method of measuring airborne mercury was off. Based on the findings collected at the Main Station, GOM concentrations in the air were two to three times higher than previously reported.

"That's a huge statement," Gustin says. "Gaseous oxidized mercury is water soluble and that's what ends up in ecosystems. And there's a lot more of it than we thought."

According to the trade journal "Chemical and Engineering News," other researchers familiar with Gustin's work suggest that scientists have to find a better way of measuring GOM. Alexandra Steffen, a chemist at Environment Canada, a government agency, told the journal that she thinks the results fortify past doubts about the existing method of measuring GOM, while another researcher, at McGill University in Canada, said researchers will have to develop methods to characterize all the different reactive species.

"It's very stressful to be telling the world that the equipment we've relied on for the last 15 years doesn't work," Gustin said. "It's a little overwhelming."

Mercury collection installation at UNR's Main Station Field Lab, Reno, Nevada.Gustin, considered one of the world's foremost experts on airborne mercury, has already been an author on three papers published that conclude that the Tekran GOM measuring device measurements are off. Not only did her own research show that the Tekran device caught only about 30 percent of the measurable mercury in the air, but she also carefully documented all the other times in other researchers' studies where the device produced "conflicting and uncertain" measurements.

"I wanted everything laid out there and what I found just reinforced my own findings: The GOM measurement method currently used does not work," Gustin said.

Before you start thinking that this is a minor development that might interest a small cadre of scientists around the world, consider this: In October, 92 countries signed a United Nations treaty, called the Minamata Convention on Mercury, designed to control and prevent mercury poisoning like the kind that afflicted the residents of Minamata in Japan in the 1950s.

What's more, the finding that certain types of airborne mercury measurements have been woefully underreported for years suggests that mercury contamination in the environment may be of more concern than anyone thought. This could have a major impact on industries that are known to produce airborne mercury, such as the mining industry. It could have an effect on both gold and zinc mines that have mercury naturally occurring in the ore. This also means that small-scale artisanal mining that often uses mercury to extract gold needs to be curtailed. Coal fired power plants could also be affected.

"There is nothing minor about this," Gustin says of her findings. "This is huge."

Is our world a lot more toxic than we thought?

"As a person, that's what it says to me," Gustin says. Gustin is also studying ozone now. Although she insists she is not an ozone expert, she does know that ozone can convert gaseous elemental mercury into GOM, and what her research is showing is that ozone levels in Nevada are climbing.

Others have also reported increasing ozone concentrations using data collected at national parks across the Western United States. Gustin is collaborating with NASA and the National Oceanic and Atmospheric Administration, who are keenly interested in her research in Nevada.

"That's another reason why I'm spending so much time writing these papers," she says. "We can't sit on this."