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Geochemical Journal
Geochemical Journal An open access journal for geochemistry
Published for geochemistry community from Geochemical Society of Japan.

δ13C records of Japanese cedars from Yakushima Island and past atmospheric CO2

Hiroyuki Kitagawa, Eiji Matsumoto
Geochemical Journal, Vol. 27, No. 6, P. 397-402, 1993

ABSTRACT

δ13C records of annual growth rings of two Japanese cedars (Cryptomeria japonica) from Yakushima Island, southern Japan are presented for the past 200 years. Some portions of the short-term fluctuations in the δ13C records from the Japanese cedars are correlated with the variabilities of the ring-thickness index. Regressions between the ring-thickness indices and δ13C values were used to “correct” the δ13C records for local climate and environmental effects. These corrected δ13C records from the two Japanese cedars show a steady downward trend with time, but with pronounced short-term fluctuations superimposed on the trend. The overall δ13C fall from 1870 to the present is between 1.2–1.4‰, consistent with the δ13C records of atmospheric CO2 estimated from ice-core bubbles, which show a fall of 1.14 ± 0.15‰ from 1740 to the present (Friedli et al., 1986). The δ13C fall seems to be related to the increase in the concentration of atmospheric CO2 as a result of fossil fuel burning and deforestation. The corrected δ13C records show small increases at 1900 and 1950, which can not be explained satisfactorily at present.

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