Pyrite-induced hydroxyl radical formation and its effect on nucleic acids

Corey A Cohn¹^,5 , Steffen Mueller² , Eckard Wimmer² , Nicole Leifer³ , Steven Greenbaum³ , Daniel R Strongin⁴^,5 and Martin AA Schoonen¹^,5

¹Department of Geosciences, Stony Brook University, Stony Brook, NY 11794, USA

²Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11794-2100, USA

³Department of Physics, Hunter College, New York, NY 10021, USA

⁴Department of Chemistry, Beury Hall 201, 1901 N. 13th Street, Temple University, Philadelphia, PA 19122, USA

⁵Center for Environmental Molecular Science, Stony Brook University, Stony Brook, Stony Brook, NY 11794-2100, USA

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Geochemical Transactions 2006, 7:3doi:10.1186/1467-4866-7-3


Published:	4 April 2006

Abstract

Background

Pyrite, the most abundant metal sulphide on Earth, is known to spontaneously form hydrogen peroxide when exposed to water. In this study the hypothesis that pyrite-induced hydrogen peroxide is transformed to hydroxyl radicals is tested.

Results

Using a combination of electron spin resonance (ESR) spin-trapping techniques and scavenging reactions involving nucleic acids, the formation of hydroxyl radicals in pyrite/aqueous suspensions is demonstrated. The addition of EDTA to pyrite slurries inhibits the hydrogen peroxide-to-hydroxyl radical conversion, but does not inhibit the formation of hydrogen peroxide. Given the stability of EDTA chelation with both ferrous and ferric iron, this suggests that the addition of the EDTA prevents the transformation by chelation of dissolved iron species.

Conclusion

While the exact mechanism or mechanisms of the hydrogen peroxide-to-hydroxyl radical conversion cannot be resolved on the basis of the experiments reported in this study, it is clear that the pyrite surface promotes the reaction. The formation of hydroxyl radicals is significant because they react nearly instantaneously with most organic molecules. This suggests that the presence of pyrite in natural, engineered, or physiological aqueous systems may induce the transformation of a wide range of organic molecules. This finding has implications for the role pyrite may play in aquatic environments and raises the question whether inhalation of pyrite dust contributes to the development of lung diseases.