User Manual
In order to measure the difference in
concentration used to calculate flux,
the eosFD has two internal chambers
where gas is exchanged with the
atmosphere - the Soil Cavity and the
Atmospheric Cavity. Gases emitted
from the soil surface flow into the
bottom of the eosFD and accumulate in
the Soil Cavity. This gas is exchanged
with the atmosphere through two of the
membrane covered windows near the
bottom of the eosFD. The other two
windows lead to the Atmospheric
Cavity, which encircles the inner Soil
Cavity, but is isolated from direct
exposure to soil gas.
When the measurement cycle occurs,
samples from these two cavities are
drawn (via internal pump) to the NDIR
CO
2
sensor for analysis, before being
returned to the original cavity. These
measurements are used to calculate
the difference in concentration, ∆C.
For more information:
Risk, D., Nickerson, N., Creelman, C., McArthur, G., Owens, J., 2011. Forced diffusion
soil flux: a new technique for continuous monitoring of soil gas efflux. Agric. For. Meteorol. 151, 1622–1631.
5
m
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