Cl. Schiller et Dr. Hastie, EXCHANGE OF NITROUS-OXIDE WITHIN THE HUDSON-BAY LOWLAND, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 99(D1), 1994, pp. 1573-1588
The source strength of atmospheric trace gases from natural ecosystems
must be quantified in order to assess the effect of such inputs on th
e background tropospheric chemistry. A static chamber technique and a
gas exchange technique were used to determine the emissions of nitrous
oxide from five sites within the Hudson Bay Lowland, as part of the N
orthern Wetland Study. Two mechanisms, one diffusive and the other epi
sodic, were found likely to be responsible for the emissions of nitrou
s oxide. The annual diffusive flux ranged from -3.8 mg(N2O)/m(2) in a
treed bog to 7.9 mg(N2O)/m(2) in an open fen. The addition of the epis
odic flux, increased this range to -2.1 mg(N2O)/m(2) and 18.5 mg(N2O)/
m(2) respectively. These episodic emission occurred in from 2.5% to 16
.7% of the samples during the late summer peak emission period. Since
the gas exchange rate could not detect the episodic emissions, it was
found to be a poor method for water emission rate determination within
the wetland. LANDSAT-Thermatic Mapper (TM) imagery was used to scale
the emissions, from the chamber level to an integrated average over th
e entire Hudson Bay Lowland. The total emission rate of N2O from the H
udson Bay Lowland, was determined to be 1.2 Gg(N2O)/year, of which 80%
was attributed to episodic emissions.