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Sediment-water interface nitrogen transformations in Missisquoi Bay, Lake Champlain (Québec): potential impacts on cyanobacteria community structure
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Mark J. Mccarthy David F. Bird W. S. Gardner
Congrès 2008 Les causes et les conséquences de la prolifération et de la toxicité des cyanobactéries.

Nitrogen transformations at the sediment-water interface were evaluated in Missisquoi Bay, Lake Champlain, using sediment core incubations and stable isotopes. Sampling occurred in June and Aug 2007. Potential denitrification (DNF) rates at two sites ranged from 160 to 560 µmol N m-2 h-1. Higher DNF rates versus net N2 fluxes suggest that denitrifiers may be limited by substrate, a surprising result given the high water column NO3- concentrations (up to 78 µM) in most cases. Sediment-water interface N2 fixation rate estimates determined from isotope pairing cannot account for this difference. Dissimilatory NO3- reduction to NH4+ (DNRA) was observed at the …

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