I plan to start sampling rainfall for O18 and Deuterium analysis.  What
precautions are currently made to prevent evaporative enrichment?  Oil?  If
so what kind?  Silicone?  If so, what is a source and product name?

Thanks,
Paul

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Paul, We have used a Dow Corning silicone oil DC200 for this purpose.  We
tested its effectiveness for preventing evaporation and found it
effective. It did not introduce any isotope effects during contact
periods/conditions comparable to those encountered in the field.  Using a
glass separating funnel with stopcock allows convenient drainage from
below of collected rainwater without disturbing the silicone layer which
is then simply re-used.

Jeffrey Turner


 =============================================================================
   Dr Jeffrey Turner
   Centre for Groundwater Studies
   CSIRO Land and Water           Phone:  +61 (0)8 9 333 6314 (International:
   Private Bag                    Fax:    +61 (0)8 9 387 8211   Delete 0)
   PO Wembley WA 6014             E-mail:  [log in to unmask]
   Australia                      WWW:  http://www.clw.csiro.au

 =============================================================================



On Mon, 5 Apr 1999, Automatic digest processor wrote:

> Date:     Mon, 5 Apr 1999 00:02:59 -0400
> Reply-To: Stable Isotope Geochemistry <[log in to unmask]>
> Sender:   Stable Isotope Geochemistry <[log in to unmask]>
> From:     Automatic digest processor <[log in to unmask]>
> Subject:  ISOGEOCHEM Digest - 2 Apr 1999 to 4 Apr 1999 (#1999-31)
> To:       Recipients of ISOGEOCHEM digests <[log in to unmask]>
> MIME-Version: 1.0
>
> There is one message totalling 26 lines in this issue.
>
> Topics of the day:
>
>   1. Rainfall Sampling
>