Publikationsdatum:
2024-03-15
Beschreibung:
Lithium has proven a powerful tracer of weathering processes and chemical seawater evolution. Skeletal components of marine calcifying organisms, and in particular brachiopods, present promising archives of Li signatures. However, Li incorporation mechanisms and potential influence from biological processes or environmental conditions require a careful assessment. In order to constrain Li systematics in brachiopod shells, we present Li concentrations and isotope compositions for 11 calcitic brachiopod species collected from six different geographic regions, paralleled with data from culturing experiments where brachiopods were grown under varying environmental conditions and seawater chemistry (pH–pCO2, temperature, Mg/Ca ratio). The recent brachiopod specimens collected across different temperate and polar environments showed broadly consistent δ7Li values ranging from 25.2 to 28.1‰ (with mean δ7Li of 26.9 ± 1.5‰), irrespective of taxonomic rank, indicating that incorporation of Li isotopes into brachiopod shells is not strongly affected by vital effects related to differences among species. This results in Δ7Licalcite–seawater values (per mil difference in 7Li/6Li between brachiopod calcite shell and seawater) from −2.9‰ to −5.8‰ (with mean Δ7Licalcite–seawater value of −3.6‰), which is larger than the Δ7Licalcite–seawater values calculated based on data from planktonic foraminifera (~0‰ to ~−4‰). This range of values is further supported by results from brachiopods cultured experimentally. Under controlled culturing conditions simulating the natural marine environment, the Δ7Licalcite–seawater for Magellania venosa was −2.5‰ and not affected by an increase in temperature from 10 to 16 °C. In contrast, a decrease in Mg/Ca (or Li/Ca) ratio of seawater by addition of CaCl2 as well as elevated pCO2, and hence low-pH conditions, resulted in an increased Δ7Licalcite-seawater up to −4.6‰. Collectively, our results indicate that brachiopods represent valuable archives and provide an envelope for robust Li-based reconstruction of seawater evolution over the Phanerozoic.
Schlagwort(e):
Alkalinity, total; Animalia; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate; Bicarbonate ion; Biomass/Abundance/Elemental composition; Brachiopoda; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Coast and continental shelf; Comau_Fjord; Containers and aquaria (20-1000 L or 〈 1 m**2); EXP; Experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Laboratory experiment; Lithium; Magellania venosa; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Registration number of species; Salinity; Sample ID; Single species; South Pacific; Species; Temperate; Temperature, water; Type; Uniform resource locator/link to reference; δ7Li; δ7Li, standard deviation
Materialart:
Dataset
Format:
text/tab-separated-values, 699 data points
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