『Abstract
Rates of ebullition and composition of bubbles were measured
along a nutrient-enriched segment of the South Platte River below
Denver, Colorado. Ebullition was widespread in the South Platte
up to 81 km downstream from Denver. Ebullitive fluxes of 0.44
and 0.29 g N m-2 d-1 were recorded at two
sites downstream of Denver and represented 6-16% of the diffusive
N2 efflux from this region. These data indicate
that not accounting for ebullitive N2 losses
can, at some locations, lead to a considerable underestimation
of denitrification rates using the open-channel (gas exchange)
method. Gas bubbles often were>98% N2; methane
dominated in a few organic-rich areas. Rates of ebullition related
significantly to variations in temperature and dissolved organic
carbon. Ebullition was not observed in four tributaries of the
South Platte River, despite their moderate to high concentrations
of nitrate and dissolved organic carbon. The data demonstrate
that ebullition can contribute significantly to N2
effluxes in running waters exhibiting high rates of denitrification.
Keywords: Denitrification; Ebullition; Nitrogen; Bubbles; South
Platte River』
Introduction
Methods
Site description
Environmental variables
Gas concentrations
Ebullition rates
Results
Discussion
Acknowledgements
References