Nitrogen removal by microbial processes in aquatic systems

Spatial and temporal variation in denitrification and in the denitrifier community in a boreal lake

We investigated the spatial and temporal variation in denitrification rates (isotopepairing technique, IPT) and in the denitrifier community (examination of gene nirK by denaturinggradient gel electrophoresis [DGGE] of microbial DNA) in the sediments of a boreal, clear-water, eutrophic lake using samples collected from shallow littoral, deep littoral and shallow profundal sediments during early summer, mid-summer, autumn and winter. The measured denitrification rates (44 to 613 μmol N m−2 d−1) are among the lowest ever reported from lacustrine sediments. Denitri fi - cation rates varied both spatially and temporally, being highest in the profundal zone during midsummer and in the littoral z…