Trends of /sup 13/C//sup 12/C ratios in pinyon tree rings of the American Southwest and the global carbon cycle
An accurate atmospheric /sup 13/C//sup 12/C chronology can provide important constraints to models of the global carbon cycle. Trees accumulate carbon from atmospheric CO/sub 2/ into growth rings and offer potential for /sup 13/C//sup 12/C reconstructions, but results have not been reproducible. This paper presents delta/sup 13/C curves from 5 sites, representing 20 pinyon (Pinus edulis) trees, where cores of 4 trees from each site have been pooled into a composite sample. Isotopic analysis of cellulose in 5-yr ring groups produces curves with a general trend of decreasing delta/sup 13/C after 1800, but with pronounced short-term fluctuations superimposed upon the trend. Evidence indicates the fluctuations are strongly related to moisture availability (drought). A mean curve of the 5 delta/sup 13/C chronologies from which the fossil-fuel component is subtracted suggests a substantial biospheric CO/sub 2/ contribution to the atmosphere since 1800.
- Research Organization:
- Univ. of Wisconsin-Parkside, Kenosha
- OSTI ID:
- 6174629
- Journal Information:
- Radiocarbon; (United States), Vol. 28:2A
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
CARBON 12
ISOTOPE RATIO
CARBON 13
CARBON CYCLE
MATHEMATICAL MODELS
TREE RINGS
ISOTOPE DATING
CARBON DIOXIDE
GLOBAL ASPECTS
PINES
AGE ESTIMATION
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXIDES
CHALCOGENIDES
CONIFERS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLANTS
STABLE ISOTOPES
TREES
580100* - Geology & Hydrology- (-1989)
510101 - Environment
Terrestrial- Basic Studies- Radiometric Techniques- (-1989)