Bomb-pulse 14C analysis combined with 13C and 15N measurements in blood serum from residents of Malmö, Sweden

Abstract

The 14C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of 14C bomb-pulse dating. The difference between the date estimated using the Calibomb software and sampling date varied between −3 ± 0.4 and +0.2 ± 0.5 years. The average age deviation of all samples was −1.5 ± 0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the 14C date has been evaluated using stable isotope δ13C and δ15N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ13C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ13C and the age deviation. No significant correlation was found between the age deviation and the δ15N values of any dietary group. No influence of sex or year of birth was found on neither the 14C nor the δ13C and δ15N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ15N in the samples. The consumption of high δ15N-valued fish and birds can be responsible for this clustering.

Potential Influence of Diet on Bomb-Pulse Dating of Human Plaque Samples

“…Bomb-pulse dating of human tissue typically uses clean-air atmospheric 14 CO 2 data as a reference. However, as reported by Georgiadou and Stenström (2010) and Georgiadou et al (2013), it is important to be aware that the diet of the subjects might affect the results. Carbon in terrestrial foodstuffs generally contains a higher concentration of 14 C than marine foodstuffs.…”

“…Analysis of isotope fractionation of stable carbon and nitrogen isotopes ( 13 C and  15 N) using isotope ratio mass spectrometry (IRMS) can provide information on the diet of a subject (DeNiro and Epstein 1981;Tieszen 1983;Schoeller et al 1986;Gearing 1991;Minagawa 1992;O'Connell 1996;Vanderklift and Ponsard 2003;Nash et al 2012;Georgiadou et al 2013). In bomb-pulse dating, this information can be valuable to detect extreme dietary conditions that might influence the 14 C date obtained from atmospheric calibration data (Georgiadou et al 2013). Isotope fractionation arises during chemical and physical reactions due to the difference in mass between the different isotopes of an element (Schoeller 1999).…”

“…In a study by Georgiadou et al (2013), 60 human blood serum samples collected in 1978 from Swedish subjects with known dietary habits were bomb-pulse dated with the aim of estimating the accuracy of the technique. The difference (±1) between the date estimated by bomb-pulse dating and the sampling date varied between -3 ± 0.4 and +0.2 ± 0.5 yr. On average, the bomb-pulse dates obtained were 1.5 ± 0.7 yr older than the sampling dates.…”

“…It was concluded that this effect could probably be attributed to the delay between production and consumption of foodstuffs. In addition to 14 C measurements, stable isotope analyses revealed information about the diet of the subjects, who were either omnivores, vegetarians, or lacto-ovo vegetarians (Georgiadou et al 2013). Marine foodstuffs present both high  15 N and  13 C values ( Figure 1) as well as lower 14 C (F 14 C) values (Reimer et al 2004) compared to terrestrial foodstuffs.…”

Sealed-Glass-Tube Combustion of µg-Sized Aerosol Samples

“…The CO 2 was cryogenically transferred from the tube cracker to the reference cell through 1/4 and 3/8 tubing (between 60 and 100 cm) for quantification and then back to the reduction reactor (see Genberg et al 2010). This method has proven satisfactory for other samples such as blood serum and atherosclerotic plaques as well as standards such as sugar, oxalic acid, and charcoal (Georgiadou et al 2013). However, this method led to considerable variation in the yield for aerosol samples.…”