Bill:

I analyzed several thousand deep lysimeter waters on our Gas bench for
13DIC for my MS (Karberg et al. 2005, Oecologia 142:296-306).  I used a gas
evolution technique modified from:

Atekwana and Krishnamurthy (1998) J Hydrol 205:265-278, and
Andrews and Schlesinger (2001) Glob Biogeochem Cycles 15(1):149-162

Very simply put, we prefilled a LabCo exetainer (#738W: NOTE: Use the right
exetainer, some time ago I talked with the LabCO folks and different
containers contain different coatings, some of which react with acid: We
ended up with a mess when we used hte Labco #438B)  with 0.25 microliters
of 85% phosphoric acid, capped them, and then evacuated them with high
guage needle attatched to a vacuum pump.  Then we went out to the field,
and as soon as we pulled soil water from a lysimeter or well, we would
inject 1.5 ml of the solution into the exetainer with a sterilized,
disposable syringe.  We then ran them on the gas bench at room temperature.
The only caveat is that about a thousand or so samples and you will need to
replace the first nafion water trap in the gas bench.

Other than that, the rest of the details escape me, though I am happy to
chat off-line.

Cheers,

Noah
___________________________
Noah J Karberg, Ecologist
USDA Forest Service
North Central Research Station
410 MacInnes Drive
Houghton, MI 49931
(906) 482-6303 ext 21



             Bill Showers
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Hi all,

Can anyone direct me to a reference (or give some advice) on using the gas
bench to analyze DIC in ground waters? I have a student who would like to
make some measurements this summer, but we have not tried this on the gas
bench and would prefer not to reinvent the wheel.

Thanks,
Bill



William J. Showers
Dept of Marine, Earth & Atm Sciences
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