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The Manguruyú Zungaro jahu, endemic to the La Plata Basin, is one of the largest neotropical fish species whose life history is virtually unknown. The objectives of this study were to determine if Z. jahu is a large‐scale migratory species and to describe habitat use throughout ontogeny using the otolith Sr isotope (87Sr/86Sr) ratio. Surface water samples were collected in 2020 at four sites representing the main water courses of the Great Pantanal in Brazil (upper Paraguay, Cuiabá, São Lourenço and Vermelho rivers). Eighteen fish individuals were collected from the Paraná River (Argentina). New water 87Sr/86Sr data were incorporated into previously established statistical models to infer the fish habitat use through the otolith 87Sr/86Sr ratios. The water 87Sr/86Sr ratio of the upper Paraguay tributaries varied (0.7209 and 0.7229) and were the highest in the La Plata Basin. The dispersal area of Z. jahu was restricted to the surroundings of the confluence of the Paraná and Paraguay rivers. Fish showed chemical signatures compatible with those of the middle Paraná (88%), Paraguay‐Pilcomayo‐Bermejo (50%) and the lower/upper Paraná (66%). The discriminant analysis based on otolith core indicated natal origins from the middle Paraná (37%), upper Paraná (32%), and Paraguay sub‐basin (32%). The dispersal area of Z. jahu migrations could be restricted to the surroundings of the confluence of Paraná and Paraguay, which highlights the need to review regional fishing regulations, especially between latitudes 30°–34° S. [ABSTRACT FROM AUTHOR]

Peatlands provide a large panel of socio‐ecosystemic services such as biodiversity, water and carbon storage and amenities. Hydrological and geochemical interactions between peats and their surroundings are expected to be favoured in mountainous areas, which are nowadays increasingly sensitive to climate changes. In order to provide an integrated scheme of potential interactions, this study evaluates spatio‐temporal patterns of environmental tracers (87Sr/86Sr, δ18O/δ2H, elemental ratios) during high‐ and low‐flow periods in the largest peatland complex of the Jura Mountains (France). Systematically depleted δ18O/δ2H values in the deepest peat pore waters suggest contrasted dynamics and origins, both compatible with either preferential winter recharge or supply from adjacent high‐elevation areas. Combined with strontium isotopes (87Sr/86Sr), we show that these water fluxes are purveyors of solutes derived from water‐rock interactions, modified by mixing, evapotranspiration and dilution with local meteoric inputs. An end member mixing analysis of the peat pore water solute composition is consistent with a major contribution of carbonates from the regional Cretaceous limestone formations, located beneath fluvio‐glacial Quaternary deposits underlying the peat. This contribution implies a significant upward water flux from the underlying syncline that could reach a sufficient hydraulic head thanks to recharge from an adjacent regional anticline. These multiscale (anticline‐syncline, syncline‐peatland, peatland‐surface) constraints allow us to propose a relevant scheme for the hydrogeochemical functioning of the peatland, enabling an improved understanding of the current high socio‐ecosystemic value of the area, and the potential future evolution of the related services. [ABSTRACT FROM AUTHOR]

The potential use of Sr/Ca and Ba/Ca ratios in fish otolith, as a complement to 87Sr/86Sr to study movements of Prochilodus lineatus, was evaluated in the La Plata Basin (South America). Water ratios were obtained from samples collected during the high and low water seasons at 42 sites across the La Plata Basin. Elemental and isotopic ratios in water were measured by MC-ICP-MS, ICP-MS and ion chromatography, and obtained from available literature. Fish were caught from six different sites with different physiochemical features. Otolith core-to-edge Sr/Ca and Ba/Ca profiles were determined by LA-ICP-MS, while the otolith 87Sr/86Sr data set was taken from literature. The predictive classification by rivers according to water Sr/Ca, Ba/Ca and 87Sr/86Sr ratios (92.5%) was higher than that based solely on 87Sr/86Sr (58%), with classification that reached 100% for several rivers. Unlike Ba/Ca, a significant relationship (R2 = 0.94, p < 0.05) was found between otolith edge and water Sr/Ca, suggesting that this could be an efficient movement indicator for P. lineatus. The Sr/Ca ratio complemented the information provided by Sr isotopes and it was particularly useful in the northwest basin, where the isotopes alone do not allow differentiating between large rivers. [ABSTRACT FROM AUTHOR]

Strontium isotopes (87Sr/86Sr) were evaluated as a potential method for studying the geographical origin of populations and movements patterns of migratory fish from the La Plata Basin (Paraná, Uruguay and Bermejo Rivers and Río de la Plata Estuary, South America). Surface water samples were collected at 43 sites during austral summer and winter (2018) while, Surubí (Pseudoplatystoma corruscans), Patí (Luciopimelodus pati), dorado (Salminus brasiliensis) and sábalo (Prochilodus lineatus) fishes were collected at seven locations. Water 87Sr/86Sr ratio was analysed by MC‐ICP‐MS (N = 74) and otolith core‐to‐edge 87Sr/86Sr transects (N = 50) were measured by LAfs‐MC‐ICP‐MS. Several water bodies presented significantly different (p < 0.05) water 87Sr/86Sr values. A ~ 1:1 relationship was found between 87Sr/86Sr measured in edge otolith and water. Data provide novel perspectives about migratory behaviour for all species, such as potential cross‐border migrations between countries of more than 1,000 km recorded for L. pati, S. brasiliensis and P. lineatus. These species seem to move between the Paraná and Uruguay rivers, which imply using the delta or the estuary as a corridor between them. Discriminant analysis based on otolith core 87Sr/86Sr suggested that the four species studied originate in sub‐basins different from those that were collected and revelled the presence of several potential spawning/nursery areas. The otolith 87Sr/86Sr profiles also suggested movements between different environments such as reservoirs, large plain rivers, mountain streams, floodplain valleys and estuaries. These results show the potential of 87Sr/86Sr as a tool for tracking the life history of fishes, and depict for the first time a complex use of the La Plata basin by the fishes, providing new information for management plans at the regional level. [ABSTRACT FROM AUTHOR]

Graph: Supplementary file1 (XLSX 18 KB) Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s10641-023-01419-9. [Extracted from the article]

While barium (Ba) and strontium (Sr) stable isotopes are increasingly used as tracers of biogeochemical processes and paleo-proxies, the role of biotic processes on Ba and Sr isotope fractionation is poorly understood. Here, Ba and Sr stable isotope fractionations were studied in the laboratory using Gloeomargarita lithophora , a cyanobacterium that selectively hyperaccumulates Ba and Sr within intracellular amorphous carbonate biominerals. Our results show that lighter Ba and Sr isotopes are enriched in G. lithophora cells compared to the initial solution by –0.24‰ to –0.03‰ (δ137Ba) and –0.33‰ to –0.01‰ (δ88Sr) depending on the stage of the experiment. The fractionation of Ba and Sr isotopes is distinct in magnitude from that occurring during abiogenic and other known biogenic carbonate formation cases. Additionally, using a Rayleigh fractionation model, the fractionation factors of Ba and Sr isotopes between G. lithophora cells and the fluid (the growth medium), i.e., Δ137Ba (bac-sol) and Δ88Sr (bac-sol) , were equal to –0.25‰ and between –0.46‰ and –0.38‰, respectively. Interestingly, δ137Ba sol and δ88Sr sol decreased at the end of Ba and Sr uptake stages back towards their initial values, which caused departures from the Rayleigh fractionation model. This suggests the existence of a back reaction resulting in a Ba and Sr outflux from cells to the solution. Possible hypotheses for this back-reaction include dissolution of amorphous carbonate inclusions in response to cellular stress, or a first-order rate dependence of amorphous carbonate dissolution on the amount of Ba and Sr inside the cell. Our findings suggest that bacteria forming intracellular amorphous carbonates could introduce Ba and Sr isotope variability in environmental records, especially in environments where they thrive. Moreover, the enrichment of lighter isotopes of Ba and Sr during amorphous carbonate formation is consistent with that occurring during the formation of other biogenic carbonates but slightly differs in magnitude, opening a discussion about the possibility to use Δ137Ba (bac-sol) and Δ88Sr (bac-sol) as an indicator of intracellular amorphous carbonate biomineralization in the fossil rock record. Overall, this work highlights the complexity of the biological uptake of alkali-earth metals and stresses the overlooked role of bacteria forming intracellular amorphous carbonates in Ba and Sr biogeochemical cycles. [ABSTRACT FROM AUTHOR]

Abstract: Rivers continuously discharge dissolved material to the oceans. Dissolved compounds partially result from water–rock interactions, which produce a large range of water chemical and isotopic compositions. These waters are collected by rivers, that are commonly assumed to be well-mixed with regard to their different tributaries, as a result of turbulent dispersion. In this paper, we test this hypothesis on the Solimões River (at Manacapuru), the largest tributary of the Amazon River, by analyzing the sodium concentration and strontium isotopic composition of river water on a transverse section at different depths. High-precision measurements reveal lateral heterogeneities. This reflects poor mixing between two main river masses, that have distinct chemical and isotopic signatures, a hundred kilometers downstream from their confluence: the Solimões mainstream and the Purús River. Using sodium concentration data, the transverse dispersion coefficient is estimated for the studied Solimões reach (the Earth''s largest river on which such an estimate now exists), and is found to be 1.8±0.2m2/s. Comparison with previously reported data highlights the potential role of bed morphology and islands in the efficiency of lateral mixing in large rivers. We finally demonstrate that the characteristic length of lateral mixing downstream from confluences in large rivers is at least of several tens of kilometers. [Copyright &y& Elsevier]

Different approaches are used to study wood provenance, but most of them are based on tracers in wood that are generally controlled by climatic factors. The strontium isotopic ratio 87 Sr/ 86 Sr in trees and soils is related to the signature of the local bedrock. Despite being used in diverse archaeological studies, Sr isotopes have rarely been used to trace the provenance of archaeological wood and especially wood from shipwrecks. In addition, recent analytical advances have allowed the detection of mass-dependent fractionation of Sr isotopes during biogeochemical processes, as reflected in the variation of δ 88/86 Sr values between different environmental materials. The δ 88/86 Sr values could be used in conjunction with the 87 Sr/ 86 Sr isotope ratio to improve constraints on the sources of Sr in the archaeological materials being studied. This paper discusses the potential and limitations of using both of these Sr isotope ratios to trace the provenance of wood from shipwrecks. We review the 87 Sr/ 86 Sr and δ 88/86 Sr variations in rocks, waters, soils, plants and other living organisms and discuss how to determine the local Sr isotopic signature of potential sites. We also compile a list of known wood post mortem modifications in seawater. Possible implications in terms of the modification of the original Sr isotope ratios of wood during storage in seawater are illustrated through preliminary observations. This paper points out some limitations and perspectives for using Sr isotopes in provenancing wood from shipwrecks, and suggests future research to test and apply this approach for tracing the origin of archaeological wood. [ABSTRACT FROM AUTHOR]

In order to better understand how stable metal isotope signals in large rivers can be used to constrain present and past weathering, the seasonal riverine Mg Sr isotopic pattern in the middle Yellow River was systematically investigated based upon weekly collected samples for the whole year of 2013. The results demonstrate that Mg is mainly transported in the dissolved form (65%) in this river system and that 45% of the total dissolved Mg is transported during the monsoon seasons, with 2% exported over 4 days during a single storm event. Dissolved Mg in the middle Yellow River is dominantly derived from both silicate and carbonate (82–89%) in this semi-arid region, with limited evaporite contribution (∼7%). Lithological mixing is the first order control on riverine dissolved Mg and Sr isotopes, with a contribution from ∼40% carbonate dissolution and ∼ 60% from silicate dissolution in the dry seasons, and ∼ 50% carbonate and ∼ 50% silicate during the monsoon seasons according to δ26Mg signals. Furthermore, a significant role of prior calcite precipitation (PCP) can be quantified, which fractionates Mg isotopes by about 0.17‰ to 0.39‰ positively depending on the choice of elemental and isotope partition of Mg in secondary carbonates. Clay formation following the PCP further fractionates riverine Mg isotopes to the negative side. An ∼0.2‰ decrease of riverine Mg isotopes is attributable to (1) a single storm event causing carbonate dissolution and (2) delayed delivery of depleted waters to rivers (∼3 months after the storm event) because of subsurface hydrological circulation. Annually, the weighted average riverine δ26Mg (−1.05‰) in the middle Yellow River is identical to the global average (−1.09‰). Despite the significant impact of lithology on the riverine dissolved Mg isotope signature, the mixing proportions of different Mg sources remain virtually constant, even when there are huge contrast of temperature, hydrology, and precipitation seasonally along the year, providing a basis for dissolved δ26Mg response to climatic forcing on the continental scale. This means that significant changes in the sedimentary Mg isotope records would reflect extreme conditions in deep time. [ABSTRACT FROM AUTHOR]