Zinc isotopes from archaeological bones provide reliable tropic level information for marine mammals

In marine ecology, dietary interpretations of faunal assemblages often rely on nitrogen isotopes as the main or only applicable trophic level tracer. We investigate the geographic variability and trophic level isotopic discrimination factors of bone zinc 66Zn/64Zn ratios (δ66Zn value) and compared it to collagen nitrogen and carbon stable isotope (δ15N and δ13C) values. Focusing on ringed seals (Pusa hispida) and polar bears (Ursus maritimus) from multiple Arctic archaeological sites, we investigate trophic interactions between predator and prey over a broad geographic area. All proxies show variability among sites, influenced by the regional food web baselines. However, δ66Zn shows a significantly higher homogeneity among different sites. We observe a clear trophic spacing for δ15N and δ66Zn values in all locations, yet δ66Zn analysis allows a more direct dietary comparability between spatially and temporally distinct locations than what is possible by δ15N and δ13C analysis alone. When combining all three proxies, a more detailed and refined dietary analysis is possible.

Determining sedimentary material sources in a Brazilian urban lake using Zn stable isotope compositions of bottom sediments: a preliminary study

Zinc isotopes ratios provide qualitative and quantitative information about contributions from different Zn sources in the environment. Here we present the results of a preliminary study to identify the main sources controlling Zn isotope signatures of sediments from Lake Paranoá (Brazil), an urban water reservoir. The Zn isotope ratios were measured by MC-ICP-MS and expressed as δ66/64Zn notation relative to the JMC 3-0749-L solution. The studied sediments showed a narrow isotopic range (+0.00 to +0.13 ‰; n = 10) similar to that reported for intensely weathered soils worldwide (from -0.4 to +0.2‰). The geoaccumulation index (Igeo) also suggests low or negligible influence of Zn anthropogenic source. This research provides a baseline assessment of the Zn isotopes signatures in lake sedimentary environments under the influence of these weathered soils.

Advantages of zinc isotopes as a new dietary proxy in marine ecology

In marine ecology, dietary interpretations of faunal assemblages often rely on nitrogen isotopes as the main or only applicable trophic level tracer. We investigate geographic variability and trophic level isotopic discrimination factors of a new tracer, bone 66Zn/64Zn ratios (δ66Zn value), and compared it to collagen nitrogen and carbon stable isotope (δ15N and δ13C) values. Focusing on ringed seals (Pusa hispida) and polar bears (Ursus maritimus) from multiple Arctic archaeological sites, we investigate trophic interactions between predator and prey over a broad geographic area. All proxies show variability among sites, influenced by the regional food web baselines. However, δ66Zn shows a significantly higher homogeneity among different sites. We observe a clear trophic spacing for δ15N and δ66Zn values in all locations, yet δ66Zn may more reliably record trophic levels between U. maritimus and prey species than δ15N. δ66Zn analysis allows a more direct dietary comparability between spatially and temporally distinct locations than what is possible by δ15N and δ13C analysis alone. When combining all three proxies a more detailed and refined dietary analysis is possible.

An isotopic and trace element investigation of gossans from Troodos ophiolite, Cyprus

<p>The Troodos ophiolite is widely accepted to be a fragment of Mesozoic oceanic crust, which uplifted during Alpine orogeny, due to the collision of Eurasia and Africa (Gass and Masson-Smith, 1963; Vibetti, 1993; Adamides, 2011; Antivachis, 2015). It belongs to supra-subduction ophiolites, which probably set up during subduction initiation associated with back-arc spreading (Pearce, 1975; Rautenschlein et al., 1985; Pearce and Robinson, 2010; Martin et al., 2019). The Troodos ophiolite is mentioned to be one of the most well studied and well-preserved ophiolitic sequences (Moores and Vine, 1971; Benn and Laurent, 1987; Patten et al., 2017), presenting significant Cyprus-type sulphide deposits (Constantinou and Govett, 1973; Adamides, 2014).</p><p>Cyprus-type deposits are generally, considered as mafic type volcanogenic massive sulfide deposits (VMS), mainly rich in copper and subsidiary zinc, with average grade of 1.3 ± 1.1% Cu and 0.8 ± 0.4% Zn (Hannington et al., 1998; Barie and Hannington, 1999; Patten et al., 2016). VMS deposits are formed in the sea floor, along mid-ocean ridges, by the circulation of high temperature hydrothermal fluids, which their source is seawater (Gillis and Robinson, 1988; Richards et al., 1989; Patten et al., 2017; Martin et al., 2019). In many different regions along the Troodos ophiolite, the VMS deposits are covered by thick, Fe oxides enriched gossans (Bear, 1960; Herzig et al., 1991). In general, those can be formed, when the VMS deposits are exposed to weathering and oxidizing conditions (Herzig et al., 1991), but still the conditions for their formation are debated. The studied gossans from Troodos ophiolite are variegated due to the presence of white silica, red hematite and yellow jarosite. Gossans are always a very interesting part of the ophiolitic sequence from an economic point of view, as they present not only significant amount of extractible copper and zinc, but also, gold and silver (Bear, 1960; Herzig et al., 1991).</p><p>We aim to examine the major and trace elements of gossans, which have been collected from different mines (West Apliki, Skouriotissa and Agrokipia mines) of Troodos ophiolite, and define their enrichment or depletion in copper and zinc, by coupling copper and zinc stable non-traditional isotopes. We combined copper with zinc isotopes in a very novel and original approach in order to give information about the conditions prevailing in the system of interest. As many authors mentioned before, supergene enriched environments are the best places to examine the behavior of Cu isotope fractionation under the weathering conditions of ore deposits (Mathur et al., 2008). On the other hand, Zn isotopes are not redox sensitive, but pH-sensitive (Pons, 2016). By coupling them, it can bring light in understanding the way, the nature of fluids that led to gossans formation and their enrichment in copper and zinc in different locations of Troodos ophiolite.</p>

Zinc isotopes in Late Pleistocene fossil teeth from a Southeast Asian cave setting preserve paleodietary information

Stable carbon and nitrogen isotope ratios of collagen from bone and dentin have frequently been used for dietary reconstruction, but this method is limited by protein preservation. Isotopes of the trace element zinc (Zn) in bioapatite constitute a promising proxy to infer dietary information from extant and extinct vertebrates. The66Zn/64Zn ratio (expressed as δ66Zn value) shows an enrichment of the heavy isotope in mammals along each trophic step. However, preservation of diet-related δ66Zn values in fossil teeth has not been assessed yet. Here, we analyzed enamel of fossil teeth from the Late Pleistocene (38.4–13.5 ka) mammalian assemblage of the Tam Hay Marklot (THM) cave in northeastern Laos, to reconstruct the food web and assess the preservation of original δ66Zn values. Distinct enamel δ66Zn values of the fossil taxa (δ66Zncarnivore< δ66Znomnivore< δ66Znherbivore) according to their expected feeding habits were observed, with a trophic carnivore-herbivore spacing of +0.60‰ and omnivores having intermediate values. Zn and trace element concentration profiles similar to those of modern teeth also indicate minimal impact of diagenesis on the enamel. While further work is needed to explore preservation for settings with different taphonomic conditions, the diet-related δ66Zn values in fossil enamel from THM cave suggest an excellent long-term preservation potential, even under tropical conditions that are well known to be adverse for collagen preservation. Zinc isotopes could thus provide a new tool to assess the diet of fossil hominins and associated fauna, as well as trophic relationships in past food webs.