Kernwaffen-induziertes Radiocarbon (14C) und die Liegezeitbestimmung von menschlichen Skelettresten

In forensic osteology the determination of time since death is regularly problematic in cases of isolated human skeletal remains. Up to now only a discrimination between pre- and post-1950 was possible using the radioactive decay of radiocarbon (14C). Attempts to differenciate the time span after 1950 failed because the physiology of bone formation, modeling and remodeling had not been regarded sufficiently. In this dissertation a model is presented (FORCADA: FOrensic RadioCArbon DAting) by which measured 14C concentrations of bone collagen and bone fat may be processed and interpreted. Beside the variable 14C values of the atmosphere between 1865 and 2028 the model includes the attained age and the sex of an individual. Moreover, the model is based on two parameters. The first includes the skeletal mass development up to age 21 (females) and 31 (males). The second includes an additional, lifelong and constant 14C exchange in the living tissues. For collagen this exchange amounts to 1 to 6 % and for fat to 20 to 66 %. Linear regressions of 74 bone samples yielded an adjusted R² of 98 %, and for 71 of them (96 %) the difference between measured value and value calculated by FORCADA did not exceed the fourth standard deviation of the measurement. Conclusion: Now a well differenciated time since death determination may be done for the time after 1950, particularly when the 14C content of the metabolically slow bone collagen (retention time > 16 y) and of the metabolically fast fat (rentention time < 5 y) are combined. However, in forensic routine only intervals of time since death can be given because the age at death cannot diagnose to a single year