Atmospheric [14C]CO2 variations in Japan during 1982-1999 based on 14C measurements of rice grains

C-14 in rice grains is a useful tracer of atmospheric C-14(CO2). C-14 measurement in rice grains for 17 years during 1982-1999 reveals the following. There is negative correlation between Delta C-14 and the population densities of localities in Japan. Under-populated areas in the northern area of Japan and Okinawa remained clean in the 1990s. The C-14(CO2) decline rates at those areas are near to that of Shauinsland. A latitudinal effect due to Chinese nuclear tests is observed in 1982. Small Seuss effects is observed at the middle latitudes in East Asia after 1995. (c) 2005 Published by Elsevier Ltd.