Inference of past atmospheric delta/sup 13/C and P/sub CO/sub 2// from /sup 13/C//sup 12/C measurements in tree rings

Thesis/Dissertation · Fri Jan 01 00:00:00 EST 1982

OSTI ID:6051477

Leavitt, S W

Carbon dioxide release from fossil-fuel burning is significant enough that we may soon experience perceptible changes in climate with important human consequences. An accurate reconstruction of past /sup 13/C//sup 12/C ratios of atmospheric CO/sub 2/ may provide key constraints on the historical activity of the biosphere as CO/sub 2/ source or sink. Tree rings appear to be a repository of this information but there is much noise in the collection of previous reconstructions, presumably associated with site selection, radial variability, choice of representative wood chemical constituent, and subtle effects of climate on fractionation. This study attempts to avoid these pitfalls and develop a 50-yr delta/sup 13/C/sub ATM/ record from juniper trees (genus Juniperus), in fact, by taking advantage of the influence of climate on fractionation. Trees were harvested from suitable sites in close proximity to weather stations with monthly records of temperature and precipitation. The most useful relationships for at most 7 of the 10 sites were delta/sup 13/C with December temperature or precipitation, because the coefficients were nearly constant from one interval to the next and the intercepts differed. Local pollution effects are believed responsible for the three anomalous sites. The separation of these regression lines of different intervals is interpreted as the response of the trees to the changing delta/sup 13/C of atmospheric CO/sub 2/ so that delta/sup 13/C/sub ATM/ curves are constructed from this spacing. The shape of the best-fit reconstruction suggests the biosphere has acted as CO/sub 2/ source to about 1965 and may now be a net sink.

• Research Organization: Arizona Univ., Tucson (USA)
• OSTI ID: 6051477
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CARBON 13
ISOTOPE RATIO
CARBON 14
CARBON DIOXIDE
ENVIRONMENTAL EFFECTS
ATMOSPHERIC PRECIPITATIONS
CARBON SINKS
CLIMATES
DOSE-RESPONSE RELATIONSHIPS
PARTIAL PRESSURE
TREE RINGS
TREES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXIDES
CHALCOGENIDES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLANTS
RADIOISOTOPES
SINKS
STABLE ISOTOPES
YEARS LIVING RADIOISOTOPES
500200* - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)