Normalized 14C activity ratios (F14C) of an African baobab (Adansonia digitata) tree from Oman

Calender dating and annual character of the baobab's growth rings was confirmed by matching of highly resolved data of normalized 14C activity ratios (F14C) with the bomb peak.

Normalized 14C activity ratio (F14C) data was determined at ETH Zürich, Dep. of Earth Sciences, Labor für Ionenstrahlphysik (LIP) and was obtained from cellulose extracted with a base-acid-base-acid-bleaching procedure after (Němec et al., 2010). Cellulose samples were graphitized using an Automated Graphitization Equipment (AGE III) coupled to an elemental analyzer (EA: Vario MICRO cube; Wacker et al., 2010). Once graphitized, the samples were immediately pressed into targets to minimize their interaction with air and their 14C content was measured with a MICADAS mass spectrometer (Wacker et al., 2010a). With intention to minimize possible carry-over effects from the implementation of previous years' non-structural carbohydrates into the current year's wood cellulose, the samples for dating were selected from the last third of each growth ring structure and comprised fibres and vessels while steering clear of terminal parenchyma bands (TPB)which usually complete each Baobab tree ring. 5 individual TPBs were analyzed for 1960-1963 (n = 4) and for 2005. In addition, intra-tree-ring F14C analysis was performed on the tree rings of 1962 (6 samples) and 1963 (8 samples).