We did some soil gas sampling back in 1991-92 in Bill Reeburgh's lab and
the following is how we sampled. We had advice from H. Dorr and Munnich and
I believe we obtained the tedlar bags from them. Saturated soils obviously
don't work as they clogg the tube. Hope this helps. Valerie Barber

Soil gas concentration profiles were collected adjacent to the chamber by
sampling at discrete depth intervals.  Perforated steel-alloy tube probes
(1/6" O.D. and 1/8" I.D.) were inserted into the ground at predetermined
depths and attached to a battery-powered diaphragm pump (pumping rate of
1.5 l min-1).  The soil air (200-300 cc), was pumped directly into 1 l
TedlarTM bags equipped with septum and tube/valve fittings.  This volume is
equivalent to  that which would occupy a sphere of radius of 4-5 cm, based
on an average soil porosity of 50%  (Whalen et al., 1992)  and symmetrical
sampling of soil air.  A potential problem exists if a channeling effect
were to occur along the length of the probe.  The effect would be a
dilution of the depth being sampled by soil air from shallower depth
strata.  There are no indications that this was a problem.  The probe had
to be pounded into the ground (some were left out for the season) and as a
result was seated securely and firmly in the soil.

>Dear listmembers
>We are initiating a program of measuring 13C in soil CO2 and are
>looking for an easy and inexpensive method of
>collecting/concentrating CO2 from soil gas in the field. If some of
>you have experiences we would be glad to here about it.
>Thanks in advance
>Bjorn Buchardt


Valerie Barber
Institute of Marine Science
O'Neill 200
University of Alaska Fairbanks
Fairbanks, AK 99775
work phone (907) 474-7899
fax (907) 474-7204