We do observe the same phenomenon you have described with regard to hydrogen and oxygen isotope ratios in blood samples from human subjects.
Our baseline hydrogen values (delta VSMOW) from human subjects vary from -45permil to -15per mil while our tap water is measured at -85permil.
Our oxygen values (delta VSMOW) from human subjects vary from -11per mil to -2 permil while our tap water is measured at -9 permil.
We are also interested to hear other list members' input on the above.
Food is an important source of H and O to the body water, as is atmospheric O2 through metabolism. In general, I would expect the opposite of the pattern you describe below...body water d18O should be relatively heavy due to metabolic (+23.5‰) and dietary (ca. +10‰ and greater) contributions, whereas the d2H should be not too dissimilar from drinking water (plant and animal tissue d2H is only moderately 2H-enriched relative to environmental water).
There is a lot of published work on 18O in body water, for a good example w/ some synthesis see Bryant and Froelich, GCA: 59, 4523-4537, 1995.
Podlesak and colleagues have also published some relevant data in the latest issue of GCA: 72, 19-35, 2008.
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of H.A.J. Meijer
Sent: Friday, December 14, 2007 10:53 AM
To: [log in to unmask]
Subject: [ISOGEOCHEM] 2H and 18O values for "blood" water and body tissue
My estimate for the isotope values for blood (that is the water
component) in humans and animals would be that it has to be pretty
close to the local (drinking) water. It is possibly slightly enriched
due to evaporation processes in the body as well as in the open water
available in nature for animals to drink, but not by more than a few
In the "bakground" samples we process for doubly labelled water
studies, however, relatively high values for 2H occur regularly,
sometimes higher than + 50 o/oo. 18O is always in the local natural
range that I expect.
Is this an artefact, i.e. contamination by memory effects in the lab,
or in the field, or during sample storage (samples are being stored
in flame-off capilaries)?. If so, why does it never happen for 18O?
Or is it real? We know that the hydrogen in body water interacts with
H in tissue to some extent, but can tissue be that highly enriched in
2H? And if so, why is it so variable?
Is there any experience with "blood water" isotopes in fields where
people do not use enriched water as well, f.i. in forensics?
Thanks on forehand for helping!
Prof. dr. Harro A.J. Meijer
Centrum voor IsotopenOnderzoek (CIO), Rijksuniversiteit Groningen
Nijenborgh 4, 9747 AG Groningen, Netherlands
tel +31-50-3634760 fax +31-50-3634738