14C in aerosols:what F14C value to use for contemporary carbon

Information about the source of carbonaceous aerosols can be obtained by measuring the C/C ratio (leading to a FC value) in aerosol samples. C is a naturally occurring radionuclide with a half-life of 5730 years. Thus carbon in aerosols from sources of fossil origin (such as coal and oil, which are several million years old) will be free from C, since all C has decayed. On the other hand, contemporary carbon (found in aerosols originating e.g. from combustion of biomass) has a concentration of C which may be estimated from the atmospheric concentration. Measurement of the C/C ratio is performed by accelerator mass spectrometry (AMS). What FC value to use for contemporary carbon is complicated by at least two factors, both related to human activities: bomb-C and C from the nuclear industry.

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