Changes in radiocarbon concentration in modern wood from Nagoya, central Japan

Abstract

Recently radiocarbon (14C) concentration in the atmospheric CO2 has decreased over time due to the exchange of CO2 between atmosphere and ocean, but also due to emission of 14C free-CO2 from burning fossil fuels. The second contribution, known as the Suess effect, can be observed in the highly industrialized and/or urban area. 14C concentrations in annual rings of a pine tree from the urban area in Nagoya, Japan, that grew over the last 24 years were measured with AMS to be remarkably lower than those observed in “clear air” of corresponding years at Schauinsland station in Germany. The measured data were used to estimate the rate of the fossil component in atmospheric CO2 that was derived from fossil fuel burning. Exponential and linear functions were fitted to the secular variations of 14C concentration in annual rings to calculate the decay constant and an average decreasing rate of 14C concentration. The result suggests that the use of annual rings of trees to obtain the secular variations of 14C concentration of atmospheric CO2 can be useful and efficient for environmental monitoring and modeling of the carbon distribution in local scale.