14C activity of Antarctic lichens

By the nuclear bomb tests during the 1950s and early 1960s, the radiocarbon content of the atmospheric CO, on the Southern Hemisphere rose within a few years from 98 to 162% of the standard recent value and then dropped to 122% (at the end of 1984). This rapid fluctuation was used to determine the lifetime of five species of lichens collected in the beginning of 1985 in the maritime Antarctic. Under the assumption that Lichens assimilate each year carbon at the same rate and that carbon once fixed at least in main branches never will be exchanged later on. The age of mature thalli of Caioplaco regalis, Ramalino tetebrata and Ustiea antarctica was determined to 32 years, while U, aurantiaco-atra and Himantormia lugubris
gave an age of ca. 38 years and ca. 60 years, respectively.

1950年代至1960年代初的核弹试验，使得南半球大气CO中的放射性碳含量在数年内从标准现代值的98%升至162%，随后于1984年末降至122%。这一快速波动被用于测定1985年初采集于南极海洋性地带的5种地衣的寿命。实验假设地衣每年以恒定速率同化碳，且至少在主枝中固定的碳后续不会再发生碳交换。经测定，Caioplaco regalis、Ramalino tetebrata及Ustiea antarctica的成熟地衣体年龄为32年，而U. aurantiaco-atra与Himantormia lugubris的成熟地衣体年龄分别约为38年和60年。