Dear Sergey and Jochen,

thank you very much for your helpful messages!
The CaCO3 dust content is really a problem, because the mentioned ice 
cave is situated in a karstic area and there are whitish layers in the 
ice block with a visible CaCO3 content. So if we try to extract the CO2 
from the ice, then we have to do it at low temperature (below freezing 
point).
But beside the extraction of CO2 we have other problem as well. We made 
a hand borer, and with this hand-borer we could get ice core. But this 
ice core was consideralbe longer than the depth of the hole, becaue the 
ice core was cracked into many pieces. In this way we lose the majority 
of the trapped CO2. So we would need a better hand borer and I would 
appreciate very much to get a description of a good hand borer for the 
above purpose. We have a very talanted technitian and he could make it 
according to the description.

Best regards
István

Jochen Schmitt wrote:

>Dear Istvan and others,
>Sergey's review concerning ice core analysis on 13C of CO2 is really nice and he is right in stating that a 
>wet extraction is no option.
> In fact, a wet extraction under vacuum with melting the ice is possible for just the CO2 concentration. 
>Kawamura et al. did this for an Antarctic ice core (see references below) and got similar results to the 
>Vostok record, but with some spikes and offsets within the record. 
>Since ice from Antarctica is so clean, the few "extra" ppm CO2 contribution resulting from the reaction of 
>carbonates with acid is relatively small (depending how accurate you need the data). But this argument is 
>only valid for CO2 concentration not for d13C. Considering an isotopic mass balance a few ppm CO2 from 
>carbonates do have a large impact on the isotopic signal. 
>Consequently, don't try it with a wet extraction if you want good and interpretable isotope data from your 
>ice cave. 
>Additionally, I want to add to the literature Sergey has provided...
>Good luck with your cave ice! 
>
>Jochen
>
>
>1. Kawamura K, Nakazawa T, Aoki S, Sugawara S, Fujii Y, Watanabe O. Atmospheric CO2 variations 
>over the last three glacial-interglacial climatic cycles deduced from the Dome Fuji deep ice core, Antarctica 
>using a wet extraction technique. Tellus B 2003; 55: 126.
>
>2. Leuenberger MC, Eyer M, Nyfeler P, Stauffer B, Stocker TF. High-resolution  13C measurement on 
>ancient air extracted from less than 10 cm3 of ice. Tellus 2003; 55B: 138.
>
>3. Tschumi J, Stauffer B. Reconstructing past atmospheric CO2 concentration based on ice-core 
>analyses: open questions due to in situ production of CO2 in the ice. Journal of Glaciology 2000; 46: 45.
>
>
>-------------------------------------------------------------------------
>Jochen Schmitt
>Alfred Wegener Institute for Polar and Marine Research
>Am Alten Hafen 26
>D-27568 Bremerhaven
>Germany
>-------------------------------------------------------------------------
>Building D, room: 3410
>phone: 0049-(0)471-4831-1345
>fax:      0049-(0)471-4831-1149
>email: [log in to unmask]
>
>  
>

-- 
-------------------------------------------------------------------------
Dr. FÓRIZS István ......... Istvan FORIZS Ph.D.
Magyar Tudományos Akadémia, Geokémiai Kutatóintézet
Institute for Geochemical Research, Hungarian Academy of Sciences
Cím/Address: H-1112 Budapest, Budaörsi út 45.   Hungary
Tel./Phone: (36-1)-309-2600/ mellék/extension 1151
Fax: (36-1)-319-3137
Http://www.geokemia.hu/people/forizs_hu.html
-------------------------------------------------------------------------