Dark formation of hydroxyl radical in arctic soil and surface waters

Sarah E. Page, George W. Kling, Michael Sander, Katherine H. Harrold, J. Robert Logan, Kristopher McNeill, Rose M. Cory

Research output: Contribution to journalArticlepeer-review

82 Scopus citations

Abstract

Hydroxyl radical (•OH) is a highly reactive and unselective oxidant in atmospheric and aquatic systems. Current understanding limits the role of DOM-produced •OH as an oxidant in carbon cycling mainly to sunlit environments where •OH is produced photochemically, but a recent laboratory study proposed a sunlight-independent pathway in which •OH forms during oxidation of reduced aquatic dissolved organic matter (DOM) and iron. Here we demonstrate this non-photochemical pathway for •OH formation in natural aquatic environments. Across a gradient from dry upland to wet lowland habitats, •OH formation rates increase with increasing concentrations of DOM and reduced iron, with highest •OH formation predicted at oxic-anoxic boundaries in soil and surface waters. Comparison of measured vs expected electron release from reduced moieties suggests that both DOM and iron contribute to •OH formation. At landscape scales, abiotic DOM oxidation by this dark •OH pathway may be as important to carbon cycling as bacterial oxidation of DOM in arctic surface waters.

Original languageEnglish (US)
Pages (from-to)12860-12867
Number of pages8
JournalEnvironmental Science and Technology
Volume47
Issue number22
DOIs
StatePublished - Nov 19 2013

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