Absence of Saharan dust influence on the strontium isotope ratios on modern trees from the Bahamas and Turks and Caicos Islands

Abstract

We report on strontium (87Sr/86Sr) isotope results from 91 modern trees growing on the Bahamas and Turks and Caicos Islands. The average87Sr/86Sr ratio of 0.709169±0.000010 is consistent with the late Quaternary limestone of the islands and with the modern ocean value. The absence of any detectable influence of87Sr-enriched Saharan dust is notable, given the known contribution of this material to both past and recent soils of the Caribbean. Our results indicate that the impact of Saharan dust to the modern biosphere of the Bahamian archipelago is at least an order of magnitude less than modeled in currently available strontium isoscapes for the circum-Caribbean. We suggest that the bioavailability of Sr in Saharan dust may be considerably less than previously thought. Nevertheless, further work could usefully be carried out in the Bahamian archipelago on plants with different rooting depths, growing on different soil types and on limestone of different ages. Our results have particular relevance for the refinement of existing strontium isoscapes and the archaeological provenience of artifacts, animals, and people in the circum-Caribbean.

The zooarchaeology and isotopic ecology of the Bahamian hutia (Geocapromys ingrahami): Evidence for pre-Columbian anthropogenic management

“…Saharan dust 87 Sr/ 86 Sr is mostly between 0.715 and 0.718 [76] and thus much higher (more radiogenic) than any of the seawater precipitated carbonate rocks that dominate The Bahamas geology. However, Schulting et al [77] conducted an extensive strontium isotope study of modern trees from The Bahamas and the Turks & Caicos Islands and the data were all within the strontium range of modern seawater (see also [78, 79]). Carbonate rocks naturally contain very high Sr concentrations and apparently, the Saharan dust strontium contribution is not significant enough to affect the strontium isotopic compositions of the local soils and plants.…”

Towards a biologically available strontium isotope baseline for Ireland

“…The results demonstrated spatial variation in biologically available strontium, supporting their use as an effective tool for provenance studies in Ireland, but they were incomplete in coverage. Therefore, to construct a map of biologically available strontium for Ireland, we collected and analysed a series of georeferenced modern plants, following the strategy of similar studies elsewhere (Evans et al, 2009(Evans et al, , 2010Copeland et al, 2010Copeland et al, , 2011Hartman and Richards, 2014;Laffoon et al, 2012;Schulting et al, 2018). Here, we combine previously published and new measurements on plants within a GIS-based spatial model to create the first baseline of the biologically available strontium isotope ratios for the island of Ireland.…”

87Sr/86Sr and 14C evidence for peccary (Tayassuidae) introduction challenges accepted historical interpretation of the 1657 Ligon map of Barbados

“…This study provides evidence for a previously unrecognized peccary introduction to Barbados and indicates the presence of this animal on the island in the 17 th or 18 th century. Along with this new record of human-assisted introduction, our results expand bioavailable Sr data for Barbados and contribute to ongoing efforts to map the West Indian Sr isoscape [22, 25, 34, 51, 54, 55, 57]. Further investigation is required to determine the species, timing, source, and number of animals involved in peccary translocation, and the size and persistence of the population on the island.…”

“…The degree to which exogenous aerosols influence bioavailable Sr for Barbados thus requires further empirical assessment. Notably, Schulting et al [57] demonstrated an insignificant effect for Saharan dust on bioavailable Sr in the Bahamas, contrary to Bataille et al’s [55] model predictions.…”

“…In the West Indies, 87 Sr /86 Sr analysis has been applied to understand patterns of human and animal movement between islands and the continent [22, 24, 25, 49–53] and reconstruct exchange networks through the sourcing of wood and animal-tooth artifacts [34, 35, 54]. Modelling and empirical studies conducted in the last decade have produced a more robust understanding of the 87 Sr /86 Sr isoscape of the islands and South American circum-Caribbean [22, 51, 54, 55], with recent efforts expanded to include multi-isotopic approaches [25, 34, 52] and evaluation of Sr inputs from African dust transport, notably from Saharan and Bodélé Depression sources, to the Caribbean [56, 57] (see also [58–60]).…”