Relationship between Carbon-14 Concentrations in Tree-ring Cellulose and Atmospheric CO₂

Abstract

Concentrations of organically-bound 14 C in the tree-ring cellulose of a Japanese Cedar (Cryptomeria japonica) grown in a rural region of Kanazawa, Ishikawa prefecture, Japan (36.5°N, 136.7°E), were measured for the ring-years from 1989 to 1998 to study relationship between 14 C concentrations in tree-ring cellulose and atmospheric CO 2 in a narrow region. An interesting result in comparing our data of tree-ring cellulose with those of atmospheric CO 2 is that the 14 C concentration in tree-ring cellulose was close to the corresponding average from mid-June to early September of 14 C concentrations in atmospheric CO 2. Furthermore, the 14 C concentrations in tree-ring cellulose were found to be merely influenced by the drastic decrease of 14 C concentrations in atmospheric CO 2 in winter, which might be caused by air pollution from the Asian continent and additional local fossil fuel contribution. These results suggest that the 14 C concentration in tree-ring cellulose for a given growing year reflects the 14 C concentrations of atmospheric CO 2 during the warm summer months.

Cosmic ray event in 994 C.E. recorded in radiocarbon from Danish oak

“…The annual rings consist of earlywood (EW) and latewood (LW), which are produced early and late in the growing season, respectively [Speer, 2010]. Studies of modern Δ 14 C values in earlywood and latewood fractions from gymnosperms, in particular, cedar [Yamada et al, 2008;Rakowski et al, 2010] and pine trees [Sheng et al, 2016], suggest that both fractions are consistent with the average atmospheric Δ 14 C value of the warm summer months (May-September) during the year of formation.…”

“…Oak, on the other hand, used by Usoskin et al [2013] and Rakowski et al [2015], is a ring-porous angiosperm (also called hardwood or deciduous tree) [Ladefoged, 1952;Speer, 2010]. Studies of modern Δ 14 C values in earlywood and latewood fractions from gymnosperms, in particular, cedar [Yamada et al, 2008;Rakowski et al, 2010] and pine trees [Sheng et al, 2016], suggest that both fractions are consistent with the average atmospheric Δ 14 C value of the warm summer months (May-September) during the year of formation. The cell types forming gymnosperms are generally simpler than the cell types in angiosperms.…”