Concentrations of 222Rn, CO2,
N2O and CH4 were measured in a cold-temperate northern
Japanese grassland soil during 1996 to compare the fluxes of CO2, N2O
and CH4 calculated by the 222Rn method and the static
chamber method and to estimate the source strengths of CO2 and N2O
in the soil using the 222Rn method. The 222Rn fluxes
ranged from 890 to 3400 dpm/m2/h
and the average was 1570±310 dpm/m2/h on sandy soil (50% sand). The
results of CO2, N2O and CH4
flux-measurements by the 222Rn method were in agreement with those
by the static chamber method within the observed range of error. The vertical
profiles of soil source
strengths of CO2
and N2O were also calculated from the concentration
gradients of 222Rn, CO2 and N2O to investigate
seasonal changes in the soil production rates of CO2
and N2O. The production rates of CO2 and N2O
varied significantly by season, averaging 1650±450 mgC/m3/h and
19±3.2 µgN/m3/h, respectively. These seasonal changes in the source
strengths of CO2 and N2O in the surface soil corresponded
with changes in fluxes of CO2 and N2O from the soil.
Author: Yongwon Kim and Noriyuki Tanaka (kimyw at iarc dot uaf dot edu)
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