Bioavailable soil and rock strontium isotope data from Israel

Strontium isotope ratios (87Sr = 86Sr) of biogenic material such as bones and teeth reflect the local sources of strontium ingested as food and drink during their formation. This has led to the use of strontium isotope ratios as a geochemical tracer in a wide range of fields including archaeology, ecology, food studies and forensic sciences. In order to utilise strontium as a geochemical tracer, baseline data of bioavailable 87Sr = 86Sr in the region of interest are required, and a growing number of studies have developed reference maps for this purpose in various geographic regions, and over varying scales. This study presents a new data set of bioavailable strontium isotope ratios from rock and soil samples across Israel, as well as from sediment layers from seven key archaeological sites. This data set may be viewed and accessed both in an Open Science Framework repository (https://doi.org/10.17605/OSF.IO/XKJ5Y, Moffat et al., 2020) or via the IRHUM (Isotopic Reconstruction of Human Migration) database.

TC1725 - A Proposed Chalcopyrite Reference Material for LA-MC-ICP-MS Sulfur Isotope Determination

Sulfur isotope is an important geochemical tracer in diverse fields of geosciences. Controlling the accuracy and precision of microanalysis of sulfur isotope requires well-characterized reference materials with matrices similar to...

Bioavailable soil and rock strontium isotope data from Israel

Strontium isotope ratios (87Sr ∕ 86Sr) of biogenic material such as bones and teeth reflect the local sources of strontium ingested as food and drink during their formation. This has led to the use of strontium isotope ratios as a geochemical tracer in a wide range of fields including archaeology, ecology, food studies and forensic sciences. In order to utilise strontium as a geochemical tracer, baseline data of bioavailable 87Sr ∕ 86Sr in the region of interest are required, and a growing number of studies have developed reference maps for this purpose in various geographic regions, and over varying scales. This study presents a new data set of bioavailable strontium isotope ratios from rock and soil samples across Israel, as well as from sediment layers from seven key archaeological sites. This data set may be viewed and accessed both in an Open Science Framework repository (https://doi.org/10.17605/OSF.IO/XKJ5Y, Moffat et al., 2020) or via the IRHUM (Isotopic Reconstruction of Human Migration) database.

Bioavailable Soil and Rock Strontium Isotope Data from Israel

Strontium isotope ratios (87Sr/86Sr) of biogenic carbonates such as bones and teeth reflect the local sources of strontium ingested as food and drink during their formation. This has led to the use of strontium isotope ratios as a geochemical tracer in a wide range of fields including archaeology, ecology, food studies and forensic sciences. In order to utilise strontium as a geochemical tracer, baseline data of bioavailable 87Sr/86Sr in the region of interest is required, and a growing number of studies have developed reference maps for this purpose in various geographic regions, and over varying scales. This study presents a new data set of bioavailable strontium isotope ratios across Israel, from rock and soil samples. This data set may be viewed and accessed both in an Open Science Framework repository (doi:10.17605/OSF.IO/XKJ5Y (Moffat et al., 2020)) or via the IRHUM (Isotopic Reconstruction of Human Migration) database (Willmes et al. 2014).

Low recycling efficiency of boron into the deep mantle

<p>Boron is a distinctly crustal element in that it is strongly enriched in the surface reservoirs, such as continental crust, seawater, sediments, serpentinites and altered oceanic crust, relative to the mantle. These B-enriched reservoirs are also isotopically very distinct from the regular depleted upper mantle (d<sup>11</sup>B = -7.1 ±0.9 ‰ [10.1016/j.gca.2017.03.028]). This has encouraged the idea that boron could be an ideal tracer for subducted surface materials in the deep mantle in the form of isotopically anomalous recycled components in ocean island basalts (OIB) and enriched MORB. Yet, the potential of a geochemical tracer of this type is weakened by its extraction from the slab at the onset of subduction by dewatering and metamorphic dehydration, because this process depletes the recycled components in fluid-mobile elements. As such, this “subduction barrier” diminishes the deep recycling efficiency of incompatible, fluid-mobile tracers like B.</p><p>This study focuses on the B abundances and B isotopic compositions of glasses and melt inclusions that show low Cl/K ratios and are thought to represent the uncontaminated mantle signal from the HIMU (Tuvalu and Mangaia), EM1 (Pitcairn) and EM2 (Samoa) sources. Strikingly, all samples are depleted in boron by a factor of approximately 1.5 to 4 relative to non-fluid-mobile elements of similar incompatibility (e.g. LREE, P, Be). This negative boron anomaly is ubiquitous in OIB and is consistent with the results of previous studies [10.1016/0016-7037(95)00402-5; 10.1016/j.epsl.2018.12.005]. It also mirrors their characteristic negative Pb anomaly. These anomalies show that the mantle sources of OIB are depleted in B (and Pb) relative to non-fluid-mobile elements of similar incompatibility and relative to the MORB-source mantle. This is best explained by the presence in the OIB sources of recycled components that are enriched in all incompatible elements except for the fluid-mobile B (and Pb). The fluid mobile elements must have been preferentially extracted in the subduction barrier and returned to the surface on the short path via arc magmas. Arc magmas consistently show a general enrichment in isotopically heavy boron [10.1007/978-3-319-64666-4_9] with positive B anomalies.</p><p>Despite of the low recycling efficiency of boron into the convecting mantle, OIB still have B isotope signatures that are distinct from those of MORB. Previous studies have reported OIB signatures slightly lighter than MORB and the primitive mantle [10.1016/j.epsl.2018.12.005]. However, our study exclusively finds isotopically heavy B with a range in d<sup>11</sup>B from MORB-like values (-8.6 ±2.0 ‰) up to -2.5 ±1.5‰ for EM1 and HIMU lavas. The total OIB range is small but significant, and is consistent with the deep recycling of material that is strongly depleted in boron, but isotopically distinct (with isotopically heavy B in the case of our EM1 and HIMU samples). The B depletion combined with the B isotopic anomaly in OIB shows that B is efficiently (but not quantitatively) removed from the slab during subduction, and that isotopically distinct mantle domains are thus produced. The subduction barrier for boron increases its strength as a tracer in arcs, but it diminishes its potential as a tracer of deep mantle recycling.</p>

Arctic freshwater fluxes: sources, tracer budgets and inconsistencies

The traditionally divergent perspectives of the Arctic Ocean freshwater budget provided by control volume-based and geochemical tracer-based approaches are reconciled, and the sources of inter-approach inconsistencies identified, by comparing both methodologies using an observational data set of the circulation and water mass properties at the basin's boundary in summer 2005. The control volume-based and geochemical estimates of the Arctic Ocean (liquid) freshwater fluxes are 147 ± 42 mSv (1 Sv = 106 m3 s−1) and 140 ± 67 mSv, respectively, and are thus in agreement. Examination of meteoric, sea ice and seawater contributions to the freshwater fluxes reveals near equivalence of the net freshwater flux out of the Arctic and the meteoric source to the basin, and a close balance between the transport of solid sea ice and ice-derived meltwater out of the Arctic and the freshwater deficit in the seawater from which the sea ice has been frozen out. Inconsistencies between the two approaches are shown to stem from the distinction between "Atlantic" and "Pacific" waters based on tracers in geochemical tracer-based calculations. The definition of Pacific waters is found to be particularly problematic, because of the non-conservative nature of the inorganic nutrients underpinning that definition, as well as the low salinity characterising waters entering the Arctic through Bering Strait - which makes them difficult to isolate from meteoric sources.

The effect of pH, organic ligand chemistry and mineralogy on the sorption of beryllium over time

Environmental contextBeryllium is a toxic environmental contaminant but has many industrial and scientific applications. Our work explores the effects of soil composition on beryllium retention, focussing on organic matter, mineralogy and pH and concludes that phosphorus and sulfur oxides in addition to soil acidity are strong controls on beryllium mobility. These results aid in future predictions regarding the fate of beryllium in the environment. AbstractUnderstanding the chemical controls on beryllium sorption is fundamental when assessing its mobility as a pollutant and interpreting its concentration as a geochemical tracer of erosion, weathering and landscape surface stability. In order to evaluate the interactions of beryllium with soil- and aquatic-related materials, we selected model organic compounds and minerals to perform sorption experiments. The retention of beryllium by each of these compounds and minerals was evaluated over a pH range of 3–6 and at various equilibration times to determine which conditions allowed the greatest retention of beryllium. We conclude that most beryllium sorption occurred within 24h for both organic and mineral materials. However, equilibration required longer periods of time and was dependent on the solution pH and sorbent material. The pH exhibited a strong control on beryllium sorption with distribution coefficient (Kd) values increasing non-linearly with increasing pH. A system with a pH of 6 is likely to retain 79–2270% more beryllium than the same system at a pH of 4. Phosphonate retained the greatest amount of beryllium, with Kd values 2–30× greater than all other materials tested at a pH of 6. Therefore, soils containing larger amounts of phosphorus-bearing minerals could result in greater retention of beryllium relative to phosphorus-limited soils. Overall, soil composition, with an emphasis on phosphorus oxide content and pH, is an important property to consider when evaluating the capacity of a system to retain beryllium.