Actinide isotope analysis and trace element composition of bones of prehistoric animals and humans by inductively coupled plasma mass spectrometry (ICP-MS)
Аннотация
Abstract Inductively coupled plasma mass spectrometry (ICP-MS) has been used for analysis of the bones of archanthropus, ancient bear, southern mammoths, dinosaurs, as well as soils collected in various parts of Uzbekistan. The concentrations of 64 elements have been detected including thorium and uranium for which isotope compositions were also analysed. The comparison of the ICP-MS data with the results we obtained earlier for some bones using instrumental neutron activation analysis (INAA) is presented. The concentrations of 234, 235, 238 U are up to two orders of magnitude elevated compared to the soils (e.g. 238 U in south mammoth bone—130.1 mg/kg, and that of soil is only 1.6 mg/kg). The levels of 236 U, and 239, 240, 242, 244 Pu isotopes (possible neutron capture products of 235 U and 238 U) correspond to a count rate of blank samples. In addition, the isotope analysis confirms the uranium in the bones and surrounding soils is natural (the average determined for all samples uranium ratios 235 U/ 238 U = 0.0071 ± 0.0003 (2-sigma errors). The concentration of 230Th (which is the part of 234 U and 238 U decay chain) is also elevated in the bones compared to the surrounding soils, however, the concentrations of stable 232 Th largely correspond to those of the soil. The excess uranium detected in bones is most probably due to the preferential accumulation from soil, and not to the paleo diet.