Environmental Background 14C Levels in Japan in 1990s.

Carbon-14 transfer into rice plants from a continuous atmospheric source: observations and model predictions

“…3). This suggests that in 1993, the background 14 C concentrations in this area were actually higher than those reported by Fuma et al (2002), which were estimated from wines made from grapes cultivated in several prefectures and unknown places in Japan. We, therefore, decided to use the observed concentrations at the ST-N site as the background concentrations for the area, and defined the excess 14 CO 2 concentration at a given site (i.e.…”

“…3, together with the background level of 14 C in Japan (Fuma et al, 2002). The figure demonstrates that the 14 CO 2 concentrations at ST-N, a control site 14.6 km westnorthwest of the main source, were almost at background levels.…”

“…5, together with the background level of 14 C in Japan (Fuma et al, 2002). In the 1991 samples, there was no remarkable 14 C enhancement above the background level, although the TRP presumably had released some amount of 14 C into the atmosphere since the commencement of operations in 1977.…”

“…diameter at the outlet and stack gas temperature and exhaust velocity), and hourly meteorological data. Also provided were the annual average background 14 C levels in Japan (Fuma et al, 2002) and information on the growth of rice plants. Modellers were asked to predict: (1) monthly mean 14 C concentrations in air at four monitoring locations (ST-1-ST-3 and ST-N) from May to October (i.e.…”

Accelerator mass spectrometry analysis of background 14C-concentrations in human blood: aiming at reference data for further microdosing studies

“…The 14 Cconcentration present in the atmosphere is only because of cosmic radiation, with a measured concentration of 1.2 parts per trillion [1]. The 14 C-content in the blood depends on the 14 C-content level in the atmosphere, which has been largely affected by the detonation of atomic bombs and the amount of CO 2 that is derived from fossil-fuel combustion [21,22]. To determine the predose background, AMS has been used to measure the 14 C-content in the plasma.…”