Impact of salinity and carbonate saturation on stable Sr isotopes (δ88/86Sr) in a lagoon-estuarine system

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dc.contributor.authorShao, YXen_AU
dc.contributor.authorFarkaš, Jen_AU
dc.contributor.authorMosely, LMen_AU
dc.contributor.authorTyler, JJen_AU
dc.contributor.authorWong, HKYen_AU
dc.contributor.authorChamberlayne, BKen_AU
dc.contributor.authorRaven, Men_AU
dc.contributor.authorSamanta, Men_AU
dc.contributor.authorHolmden, Cen_AU
dc.contributor.authorGillanders, BGen_AU
dc.contributor.authorKolevica, Aen_AU
dc.contributor.authorEisenhauer, Aen_AU
dc.date.accessioned2022-11-02T22:20:46Zen_AU
dc.date.available2022-11-02T22:20:46Zen_AU
dc.date.issued2021-01-15en_AU
dc.date.statistics2022-08-29en_AU
dc.description.abstractLocal carbonate cycling in lagoon-estuarine systems, involving processes such as inorganic and biogenic carbonate precipitation/dissolution, represents an important but poorly constrained component of the coastal carbon budget. This study investigates the sensitivity of stable Sr isotope tracer (δ88/86Sr) with respect to carbonate saturation and salinity of local waters in the Coorong, Lower Lakes and Murray Mouth (CLLMM) estuary in South Australia. The CLLMM has an extensive range of salinity from fresh to hypersaline (from ∼0 to over 100 PSU), with corresponding variations in water chemistry and major ion composition that in turn controls mineral saturation states, and thus CaCO3 precipitation/dissolution in local waters. Here we use the novel δ88/86Sr tracer in tandem with the more established radiogenic Sr isotope ratio (87Sr/86Sr), where the latter is a robust proxy for Sr sources and thus water provenance. We also produced a geochemical (PHREEQC) model of calcium carbonate (CaCO3) saturation changes across this unique lagoon-estuarine system. The results indicate a systematically increasing trend of δ88/86Sr (from ∼0.25‰ to ∼0.45‰) with increasing salinity and CaCO3 (aragonite, calcite) saturation indices of the coastal waters, which in turn suggest an overall control of carbonate dissolution/precipitation processes on the stable Sr isotope composition in the CLLMM system. This was further corroborated by Ca isotope data (δ44/40Ca) published previously on the same samples from the Coorong, as well as a quantitative simulation of local carbonate removal in the lagoon based on Rayleigh modelling and Sr isotope data. Overall, our results confirm that a coupled Sr isotope approach (combining 87Sr/86Sr and δ88/86Sr) can be used to constrain not only the main water sources (continental versus marine Sr) but also local CaCO3 dissolution/precipitation processes, and thus inorganic carbon and coastal carbonate cycling in the CLLMM system. Finally, this coupled δ88/86Sr and 87Sr/86Sr approach can be potentially applied to fossil carbonate archives to reconstruct paleo-hydrology and salinity changes in the CLLMM and/or other carbonate-producing coastal systems. © 2020 Elsevier Ltd.en_AU
dc.description.sponsorshipThis work was supported by the Project Coorong (HCHB – Healthy Coorong Healthy Basin program) and the Czech Science Foundation (GACR grant No. 17-18120S), and additional support from the Environment Institute of the University of Adelaide as well as an ARC Linkage project (LP160101353) are also acknowledged. This study is part of the Ph.D. research of YS, supported by an Adelaide Graduate Research Scholarship, ANSTO research portal (No. 11642), and funding from the CRC LEME Regolith Science Scholarship via Cooperative Research Centre for Landscape Environments and Mineral Exploration (CRC LEME) Regolith Science Scholarship.en_AU
dc.identifier.citationShao, Y., Farkaš, J., Mosley, L., Tyler, J., Wong, H., Chamberlayne, B., Raven, M., Samanta, M., Holmden, C., Gillanders, B. G., Kolevica, A. & Eisenhauer, A. (2021). Impact of salinity and carbonate saturation on stable Sr isotopes (δ88/86Sr) in a lagoon-estuarine system. Geochimica et Cosmochimica Acta, 293, 461-476. doi:10.1016/j.gca.2020.11.014en_AU
dc.identifier.issn0016-7037en_AU
dc.identifier.journaltitleGeochimica et Cosmochimica Actaen_AU
dc.identifier.pagination461-476en_AU
dc.identifier.urihttps://doi.org/10.1016/j.gca.2020.11.014en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/13956en_AU
dc.identifier.volume293en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectStable isotopesen_AU
dc.subjectCarbonatesen_AU
dc.subjectStrontiumen_AU
dc.subjectEstuariesen_AU
dc.subjectSalinityen_AU
dc.subjectWater chemistryen_AU
dc.titleImpact of salinity and carbonate saturation on stable Sr isotopes (δ88/86Sr) in a lagoon-estuarine systemen_AU
dc.typeJournal Articleen_AU
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