Spatial variations in biosphere ⁸⁷ Sr/ ⁸⁶ Sr in Britain

Abstract

Strontium isotopes are a powerful tool for investigating the geographical origins of people and animals but assignment of provenance requires reference maps and databases. This paper presents a map of strontium isotope variations across Britain for use in archaeological and other studies, and is produced by direct measurement of strontium isotope compositions of biosphere components, predominantly plants. The map characterizes the biosphere signature of specific lithologies: a technique that is applicable worldwide. Marine-derived strontium, from both rainwater and coastal sea-splash and spray, is an important contribution to the British biosphere, particularly on the western seaboard, which is subject to high rainfall and prevailing westerly winds. Supplementary material: Methods, full data table, and full-size version of Figure 1b are available at http://www.geolsoc.org.uk/SUP18388 .

Bioavailable 87Sr/86Sr in different environmental samples — Effects of anthropogenic contamination and implications for isoscapes in past migration studies

“…However, in those studies, the soil-exchangeable cations were obtained using various chemical reagents, which hampers direct comparison with our results -here we simply used MilliQ water. Nonetheless, Evans and Tatham (2004) Sr/ 86 Sr. Evans et al (2010) found that the 87 Sr/ 86 Sr recorded by snail shells appears to be shifted towards that of rainwater. Furthermore, land snails also incorporate significant amounts of soil carbonates into their diet -up to 40% (Yanes et al, 2008).…”

“…However, the fact that 87 Sr/ 86 Sr of the intra-site ground vegetation is lower than that of the corresponding tree leaves reflects the overall lower 87 Sr/ 86 Sr found in top soils, which seems to occur regardless of the nature of the geological substrate. Although vegetation samples have been used as Sr isotope biosphere proxy (Evans et al, 2010;Kusaka et al, 2011), the constantly less radiogenic 87 Sr/ 86 Sr found in ground vegetation needs to be better understood. In particular, one must determine which type of plant, ground vegetation or tree leaves, yields the most reliable estimate of the bioavailable 87 Sr/ 86 Sr entering the food chain today and in the past.…”

“…Different environmental samples have been put forward to assess the spatial variability in the bioavailable 87 Sr/ 86 Sr. These include surface water, soil leachates, vegetation and snail shells (Evans et al, 2010;Hodell et al, 2004;Nafplioti, 2011;Price et al, 2002;Sillen et al, 1998). However, industrial/anthropogenic activities, such as the use of fertilizers, might have influenced the Sr isotope ratios of modern ecosystems (Böhlke and Horan, 2000;Christian et al, 2011;Tichomirowa et al, 2010;West et al, 2009), which would then be inappropriate for interpreting 87 Sr/ 86 Sr data of archeological specimens.…”

On the hoof: exploring the supply of animals to the Roman legionary fortress at Caerleon using strontium (87Sr/86Sr) isotope analysis

“…In addition, interpretation is hindered by the relatively coarse biosphere maps that are generally available. The work by Evans et al (2010) has greatly improved the situation in Britain, but biosphere mapping remains far from comprehensive.…”

“…Enamel samples were cleaned with high-purity (99%) acetone followed by deionised water (DI H 2 O, > 17 MΩ) and dried down. Plant samples were washed in DI water, dried and crushed to tea leaf consistency following Evans et al (2010). Samples were then weighed into clean perfluoroalkoxy (PFA) vials.…”