I found many years ago when collecting sea water samples that the
bacterial community is very active and to get reliable C-13 and TCO2
values you had to quench the reaction immediately.  The most effective
was the injection of a few tenths of a cc of a saturated solution of
HgCl2.

You wrote:
>
>Torsten,
>A variation on Bill Patterson's suggestion is to introduce a small
amount
>of saturated HgCl2 into each vessel which you are going to collect
your
>samples in advance and then allowing them to dry  completely.  This
way you
>get the Hg and no worry of spilling any crystals.  Of course, if Hg is
some
>kind of problem...  Sterilization by UV?
>
>Hope life is treating  you and yours well in Tuebingen.
>
>Jim
>
> >Dear Isogeochemists
>>
>>We are interested in analyzing DIC from groundwaters by acidification
with
>>H3PO4. The water samples are commonly poisoned with HgCl2 for this
method.
>>Would anyone know if  there is an alternative to the HgCl2?
>>
>>Thanks in advance, greetings
>>
>>Torsten.
>>
>>------------------------------------
>>Torsten W. Vennemann
>>Institute for Geochemistry
>>University of Tuebingen
>>Wilhelmstr. 56
>>72074 Tuebingen
>>Germany
>>
>>Tel: (0)7071 29 74992
>>Fax: (0)7071 29 6870
>>----------------------------------
>
>
>Jim Burdett
>Cornell Laboratory for Stable Isotope Analysis
>125 Boyce Thompson Intitute
>Tower Rd.
>Ithaca NY  14853
>
>Telephone:  (607)  254-6732 (office), 254-1227 (prep lab), 254-1382
(mass
>specs)
>FAX:  (607)  254-1382
>





Dr. Peter Kroopnick
Fluor Daniel GTI
(aka Groundwater Technology Inc.)
19033 W. Valley Hwy.
Suite D-104
Kent, WA 98032

Phone  206-251-5441
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