Underestimated Airborne Mercury Levels

A study finds the methods scientists typically use to monitor airborne mercury underestimate the levels of a reactive form of the metal. About 95% of the mercury in air is elemental mercury. The rest consists of more reactive but hard to detect mercury(II) compounds, such as mercuric chloride, says Mae S. Gustin, an environmental scientist at the University of Nevada, Reno. Environmental scientists worry about reactive mercury species because when they fall to Earth, microorganisms can transform them into methylmercury, which is toxic and harmful to wildlife and people. The standard detection method uses a potassium chloride-coated quartz surface to trap reactive mercury compounds. The new technique measures total and elemental airborne mercury levels via atomic fluorescence spectroscopy and determines the amount of reactive species from the difference. On the basis of an experiment comparing both methods, Gustin concludes that reactive mercury concentrations in air could be two to three times as much as previously reported (Environ. Sci. Technol., DOI: 10.1021/es3039104).