• Radiocarbon Activity Variation in Dated Tree Rings Grown in Mackenzie Delta

      Fan, C. Y.; Tie-Mei, Chen; Si-Xun, Y.; Kai-Mei, Dai (American Journal of Science, 1986-01-01)
      We measured the Delta-14C values in 57 rings (from AD 1824 to 1880) of a white spruce grown in Mackenzie Delta (68 degrees N, 130 degrees W), as part of our continuing study of the Delta-14C variation related to solar activities. The values exhibit a 10 per mil fluctuation with an 11-year periodicity anti-correlated with the solar activity cycle. We also measured the Delta-14C values in 6 rings (from AD 1940 to 1945). The abnormally high value in the 1943 ring may be due to two large solar flares occurring in 1942.