Hyporheic exchange and fulvic acid redox reactions in an alpine stream/wetland ecosystem, Colorado front range

Miller, M. P.; McKnight, D. M.; Cory, R. M.; Williams, M. W.; Runkel, R. L.

Abstract:

The influence of hyporheic zone interactions on the redox state of fulvic acids and other redox active species was investigated in an alpine stream and adjacent wetland, which is a more reducing environment. A tracer injection experiment using bromide (Br-) was conducted in the stream system. Simulations with a transport model showed that rates of exchange between the stream and hyporheic zone were rapid (?? ??? 10-3 s -1). Parallel factor analysis of fluorescence spectra was used to quantify the redox state of dissolved fulvic acids. The rate coefficient for oxidation of reduced fulvic acids (?? = 6.5 ?? 10-3 s -1) in the stream indicates that electron-transfer reactions occur over short time scales. The rate coefficients for decay of ammonium (?? = 1.2 ?? 10-3 s-1) and production of nitrate (?? = -1.0 ?? 10-3 s-1) were opposite in sign but almost equal in magnitude. Our results suggest that fulvic acids are involved in rapid electron-transfer processes in and near the stream channel and may be important in determining ecological energy flow at the catchment scale. ?? 2006 American Chemical Society.

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Article

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70028857

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Miller, M. P.; McKnight, D. M.; Cory, R. M.; Williams, M. W.; Runkel, R. L.

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5949

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English

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Environmental Science and Technology

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Hyporheic exchange and fulvic acid redox reactions in an alpine stream/wetland ecosystem, Colorado front range; 2006; Article; Journal; Environmental Science and Technology; Miller, M. P.; McKnight, D. M.; Cory, R. M.; Williams, M. W.; Runkel, R. L.