Biogeochemistry of manganese- and iron-rich sediments in Toolik Lake,Alaska |
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Authors: | Jeffrey C Cornwell George W Kipphut |
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Institution: | (1) Horn Point Environmental Laboratory, University of Maryland CEES, 21613-0775 Cambridge, MD, USA;(2) Institute of Marine Science, University of Alaska-Fairbanks, 99775-1080 Fairbanks, AK, USA;(3) Present address: Center for Reservoir Research, Murray State University, 42071 Murray, KY, USA |
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Abstract: | The sediments within Toolik Lake in arctic Alaska are characterized by extremely low rates of organic matter sedimentation
and unusually high concentrations of iron and manganese. Pore water and solid phase measurements of iron, manganese, trace
metals, carbon, nitrogen, phosphorus, and sulfur are consistent with the hypothesis that the reduction of organic matter by
iron and manganese is the most important biogeochemical reaction within the sediment. Very low rates of dissolved oxygen consumption
by the sediments result in an oxidizing environment at the sediment-water interface. This results in high retention of upwardly-diffusing
iron and manganese and the formation of metal-enriched sediment. Phosphate in sediment pore waters is strongly adsorbed by
the metal-enriched phases. Consequently, fluxes of phosphorus from the sediments to overlying waters are very small and contribute
to the oligotrophic nature of the Toolik Lake aquatic system. Toolik Lake contains an unusual type of lacustrine sediment,
and in many ways the sediments are similar to those found in oligotrophic oceanic environments. |
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Keywords: | arctic lakes trace metals lake sediments manganese iron phosphorus sediment-water flux diagenesis Toolik Lake |
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