It's well known that the hydrogen
and oxygen isotope ratios of precipitation correlate with climate and
global circulation patterns. In general the pattern is that the higher
the ambient temperature the higher the oxygen-18 and deuterium abundance
of the precipitation. The oxygen and hydrogen isotope ratios of tree ring
cellulose are ultimately derived from the oxygen and hydrogen isotope
ratios of plant available water which is closely correlated with that
of precipitation. If cellulose is well preserved, then it holds great
potential as a proxy for paleoclimate. Dr. Hope Jahren's ( John Hopkins
University ) laboratory and mine have analyzed tree ring cellulose from
samples in an arctic island approximately 50 million years old with some
interesting results. The isotopic signal of cellulose, however, is a mixed
signal and the challenge is to disentangle these signals. Dr. William
Anderson's ( Florida International University ) laboratory and mine have
developed a new technique towards this end. Once it is refined, we plan
to use it in determining water sources of the paleo samples as well as
in coastal plants.
Sample Publications
Jahren , H. and Sternberg, L. da S.L. Eocene Meridional
Weather Patterns Reflected in the Oxygen Isotopes of Arctic Fossil Wood.
GSA Today 12: 4-9. 2002.
Jahren, A. H. and Sternberg L. da
S. L. Humidity estimate for the middle Eocene Arctic rainf forest. Geology
31: 463-466. 2003.
Sternberg L. da S. L., Anderson W. and Morrison K. Separating soil and
leaf water 18O isotopic signals in plant stem cellulose. Geochimica
Cosmochimica Acta 67: 2561-2566. 2003
Sternberg L. da S. L., Pinzon M.
C., Anderson W. T. & Jahren A.H. Variation in oxygen isotope fractionation
during cellulose synthesis: intramolecular and biosynthetic effects.
Plant Cell and Environment
29: 1881-1889. 2006.
Sternberg L. da S. L., Pinzon M.
C., Vendramini P. F., Anderson W. T., Jahren A. H., Beuning C. Oxygen
isotope ratios of cellulose-derived Phenylglucosazone: an improved paleoclimate
indicator of environmental water and relative humidity. Geochimica
Cosmochimica Acta 71: 2463-2473(2007).
Jahren A. H., Sternberg L. da S.L.
Annual patterns within tree rings of the Arctic Middle Eocene (ca 45Ma):
Isotopic signatures of precipitation, relative humidity and deciduousness.
Geology
36: 99 -102 (2008).
Jahren A.H., Byrne M.C., Graham
H.V., Sternberg L da SL, Summons R.E. The environmental water of the
middle Eocene Arctic: Evidence from dD, d18O
and d13C within specific compounds. Palaeogeography,
Palaeoclimatology, Palaeoecology 271: 96-103 (2009).
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