Accurate determination of /sup 13/C//sup 12/C in CO/sub 2/ of past atmospheres from /sup 13/C//sup 12/C in tree rings by removal of climatic interferences. Final technical progress report

Technical Report · Thu Jul 01 00:00:00 EDT 1982

OSTI ID:6782132

Long, A; Leavitt, S W

Analysis of delta/sup 13/C in tree rings offers the potential for reconstructing changes in delta/sup 13/C of atmospheric CO/sub 2/, which combined with /sup 14/C trends will be important in evaluating the past and present role of the biosphere as a net carbon dioxide source or sink. One problem with such tree-ring delta/sup 13/C records is that in addition to changes in atmospheric delta/sup 13/C, climatic factors may influence the isotopic composition of the rings. This study examines delta/sup 13/C in cellulose of five-year intervals of juniper tree rings. The sampling sites were near weather stations for which climate data are readily available. delta/sup 13/C vs winter climate relationships were derived from those sites not under the influence of local pollution sources. These relationships facilitated development of a delta/sup 13/C record from which climate effects have been factored out. The resulting 1930-1979 delta/sup 13/C reconstruction shows a pronounced delta/sup 13/C decrease from 1930 to 1960 and then a post-1960 flattening of the curve. We interpret this trend as representing an increasing role of biospheric CO/sub 2/ sinks relative to sources, although other interpretations may be possible within the limits of precision of data analysis. Research with this technique is continuing with pinyon pine and dendroclimatological reconstructions to verify these results and to develop a climate-free delta/sup 13/C chronology back to pre-industrial time.

• Research Organization: Arizona Univ., Tucson (USA)
• DOE Contract Number: AC02-81EV10687
• OSTI ID: 6782132
• Report Number(s): DOE/EV/10687-2; ON: DE82021975
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
CARBON 13
VARIATIONS
TREE RINGS
ISOTOPE RATIO
CARBON DIOXIDE
CLIMATES
CONIFERS
SINKS
TEMPERATURE EFFECTS
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON OXIDES
CHALCOGENIDES
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
NUCLEI
OXIDES
OXYGEN COMPOUNDS
PLANTS
STABLE ISOTOPES
510200* - Environment
Terrestrial- Chemicals Monitoring & Transport- (-1989)
500200 - Environment
Atmospheric- Chemicals Monitoring & Transport- (-1989)