Recently we have been using the oxygen isotope ratios of a cellulose
derivative (Phenylglucosazone, see Sternberg et al. (2007) Geochimica
Cosmochimica Acta 71: 2463-2473) as a proxy for environmental water.
This oxygen isotope ratio of the derivative is much more fateful to the
oxygen isotope ratio of environmental waters. We have done a tree ring
sequence with very promising results. However, we need more tree ring
sequences to confirm the validity of this method. Here is what we need:
A tree ring sequence (7 or more years) having more than 25mg of
cellulose per annual ring (It would be easier if you have extracted the
cellulose already). Each of the year must have a recorded annual
amount-weighed average oxygen isotope ratios of precipitation. If you
would like to contribute to this effort, please contact me directly.