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 (α ≈ 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 (λ = 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 (λ = 1.2 × 10-3 s-1) and production of nitrate (λ = −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.
Citation Information
Publication Year | 2006 |
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Title | Hyporheic exchange and fulvic acid redox reactions in an alpine stream/wetland ecosystem, Colorado front range |
DOI | 10.1021/es060635j |
Authors | Matthew P. Miller, Diane M. McKnight, R.M. Cory, Mark W. Williams, Robert L. Runkel |
Publication Type | Article |
Publication Subtype | Journal Article |
Series Title | Environmental Science & Technology |
Index ID | 70028857 |
Record Source | USGS Publications Warehouse |
USGS Organization | Colorado Water Science Center; Toxic Substances Hydrology Program |