Stable isotope data acquired by the DS procedure cannot detect such effects because the data reduction assumes that the natural isotope fractionation is adequately described by a single kinetic mass fractionation curve, which connects sample and starting material (Siebert et al. [ 31]).
The large size of the positive anomalies reported for Gd in some river waters, therefore, rules out any possibility that they result from natural REE fractionation (Kualaksi and Bau 2007).
The light elements, hydrogen, carbon, nitrogen and oxygen to mention a few, are therefore especially susceptible to natural isotopic fractionation, while much less physical differences are observed for the heavier elements.
The natural mass fractionation, δ13C, was measured with a VG OPTIMA dual inlet mass spectrometer.
In the putative skull of St. Birgitta, the measured natural mass fractionation δ13C is −18,5‰ (Table 1).
The reservoir effect can be evaluated by the measured natural mass fractionation of the stable isotope δ13C, which in skull A is −18.5 ‰ (Table 1).
Most studies concerning physiological and natural N fractionation have involved plants grown with NO3- as the only N source.
