Dark Formation of Hydroxyl Radical in Arctic Soil and Surface Waters

作者：Page Sarah E; Kling George W; Sander Michael; Harrold Katherine H; Logan J Robert; McNeill Kristopher^*; Cory Rose M

来源：Environmental Science & Technology, 2013, 47(22): 12860-12867.

DOI：10.1021/es4033265

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

• 出版日期2013-11-19