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  • 1
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    Decoupled carbonate chemistry controls on the incorporation of boron into Orbulina universa. (2016)
    Copernicus
    Details
    Publication Date: 2016-05-12
    Description: In order to fully constrain paleo-carbonate systems, proxies for two out of seven parameters, plus temperature and salinity are required. The boron isotopic composition (δ11B) of planktonic foraminifera shells is a powerful tool to reconstruct changes in past surface ocean pH. As B(OH)4− is substituted into the biogenic calcite lattice in place of CO32−, it has been suggested that B/Ca ratios in biogenic calcite are a possible proxy for [CO32−]. However, differentiating between the effects of pH and [CO32−] is problematic, as they co-vary closely in natural systems, and so the major control on boron incorporation remains unclear. To deconvolve the effects of pH and [CO32−] on the B/Ca ratio and to test whether δ11B remains constant at constant pH, but under changing [CO32−] (pH 8.05 with 238, 285 and 532 µmol kg−1 CO32−) and vice versa, we decoupled pH and [CO32−] (276 ± 19.5 µmol kg−1 CO32− with pH 7.7, 7.9 and 8.05) and grew the planktonic foraminifer Orbulina universa in these manipulated culture media. Measurements of the isotope composition of boron and the B/Ca ratio were performed simultaneously using a femtosecond laser ablation system coupled to an MC ICP-MS. Results show that δ11B is controlled by pH and does not respond to changes in [CO32−]. On the other hand, the B/Ca ratio is driven by [HCO3−] independently of pH. This suggests that B/Ca ratios in foraminiferal calcite may be used as a second, independent, proxy for paleo-carbonate system reconstructions.
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 2
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    Impact of seawater Ca2+ on the calcification and calcite Mg/Ca of Amphistegina lessonii (2014)
    Copernicus
    Details
    Publication Date: 2014-12-16
    Description: Mg/Ca ratios in foraminiferal tests are routinely used as paleo temperature proxy, but on long timescales, also hold the potential to reconstruct past seawater Mg/Ca. Impact of both temperature and seawater Mg/Ca on Mg incorporation in foraminifera have been quantified by a number of studies. The underlying mechanism responsible for Mg incorporation in foraminiferal calcite and its sensitivity to environmental conditions, however, is not fully identified. A recently published biomineralization model (Nehrke et al., 2013) proposes a combination of transmembrane transport and seawater leakage or vacuolization to link calcite Mg/Ca to seawater Mg/Ca and explains inter-species variability in Mg/Ca ratios. To test the assumptions of this model, we conducted a culture study in which seawater Mg/Ca was manipulated by varying [Ca2+] and keeping [Mg2+] constant. Foraminiferal growth rates, test thickness and calcite Mg/Ca of newly formed chambers were analyzed. Results showed optimum growth rates and test thickness at Mg/Ca closest to that of ambient seawater. Calcite Mg/Ca is positively correlated to seawater Mg/Ca, indicating that not absolute seawater [Ca2+] and [Mg2+], but the telative ratio controls Mg/Ca in tests. These results demonstrate that the calcification process cannot be based only on seawater vacuolization, supporting the mixing model proposed by Nehrke et al. (2013). Here we, however, suggest a transmembrane transport fractionation that is not as strong as suggested by Nehrke et al. (2013).
    Print ISSN: 1810-6277
    Electronic ISSN: 1810-6285
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 3
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    Impact of seawater [Ca2+] on the calcification and calciteMg / Ca of Amphistegina lessonii (2015)
    Copernicus
    Details
    Publication Date: 2015-04-10
    Description: Mg / Ca ratios in foraminiferal tests are routinely used as paleotemperature proxies, but on long timescales, they also hold the potential to reconstruct past seawater Mg / Ca. The impact of both temperature and seawater Mg / Ca on Mg incorporation in Foraminifera has been quantified by a number of studies. The underlying mechanism responsible for Mg incorporation in foraminiferal calcite and its sensitivity to environmental conditions, however, has not been fully identified. A recently published biomineralization model (Nehrke et al., 2013) proposes a combination of transmembrane transport and seawater leakage or vacuolization to link calcite Mg / Ca to seawater Mg / Ca and explains inter-species variability in Mg / Ca ratios. To test the assumptions of this model, we conducted a culture study in which seawater Mg / Ca was manipulated by varying [Ca2+] and keeping [Mg2+] constant. Foraminiferal growth rates, test thickness and calcite Mg / Ca of newly formed chambers were analyzed. Results showed optimum growth rates and test thickness at Mg / Ca closest to that of ambient seawater. Calcite Mg / Ca is positively correlated to seawater Mg / Ca, indicating that it is not absolute seawater [Ca2+] and [Mg2+] but their ratio that controls Mg / Ca in tests. These results demonstrate that the calcification process cannot be based only on seawater vacuolization, supporting the mixing model proposed by Nehrke et al. (2013). Here, however, we suggest transmembrane transport fractionation that is not as strong as suggested by Nehrke et al. (2013).
    Print ISSN: 1726-4170
    Electronic ISSN: 1726-4189
    Topics: Biology , Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 4
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    Decoupled carbonate chemistry controls on the incorporation of boron into Orbulina universa (2017)
    PANGAEA
    In:  Supplement to: Howes, Ella L; Kaczmarek, Karina; Raitzsch, Markus; Mewes, A; Bijma, N; Horn, Ingo; Misra, Sambuddha; Gattuso, Jean-Pierre; Bijma, Jelle (2017): Decoupled carbonate chemistry controls on the incorporation of boron into Orbulina universa. Biogeosciences, 14(2), 415-430, https://doi.org/10.5194/bg-14-415-2017
    Details
    Publication Date: 2024-03-15
    Description: In order to fully constrain paleo-carbonate systems, proxies for two out of seven parameters, plus temperature and salinity are required. The boron isotopic composition (delta 11B) of planktonic foraminifera shells is a powerful tool to reconstruct changes in past surface ocean pH. As [B(OH)]4- is substituted into the biogenic calcite lattice in place of [CO3]2-, it has been suggested that B/Ca ratios in biogenic calcite are a possible proxy for [CO3]2-. However, differentiating between the effects of pH and [CO3]2- is problematic, as they co-vary closely in natural systems, and so the major control on boron incorporation remains unclear. To deconvolve the effects of pH and [CO3]2- on the B/Ca ratio and to test whether d11B remains constant at constant pH, but under changing [CO3]2- (pH 8.05 with 238, 285 and 532 µmol/kg [CO3]2-) and vice versa, we decoupled pH and [CO3]2- (276 +/- 19.5 µmol/kg [CO3]2- with pH 7.7, 7.9 and 8.05) and grew the planktonic foraminifer Orbulina universa in these manipulated culture media. Measurements of the isotope composition of boron and the B/Ca ratio were performed simultaneously using a femtosecond laser ablation system coupled to an MC ICP-MS. Results show that delta11B is controlled by pH and does not respond to changes in [CO3]2-. On the other hand, the B/Ca ratio is driven by [HCO3]- independently of pH. This suggests that B/Ca ratios in foraminiferal calcite may be used as a second, independent, proxy for paleo-carbonate system reconstructions.
    Keywords: Alkalinity, total; Alkalinity, total, standard deviation; Aragonite saturation state; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcite saturation state; Calculated using seacarb; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chromista; Coast and continental shelf; EXP; Experiment; Foraminifera; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Heterotrophic prokaryotes; Laboratory experiment; Mediterranean Sea; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Potentiometric; Potentiometric titration; Registration number of species; Salinity; Salinity, standard deviation; Single species; Species; Temperate; Temperature, standard deviation; Temperature, water; Type; Uniform resource locator/link to reference; Villefranche-2012; δ11B
    Type: Dataset
    Format: text/tab-separated-values, 1820 data points
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  • 5
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    Impact of seawater [Ca]2+ on the calcification and calcite Mg / Ca of Amphistegina lessonii (2015)
    In:  EPIC3Biogeosciences, 12, pp. 2153-2162, ISSN: 1726-4189
    Details
    Publication Date: 2015-04-13
    Description: Abstract. Mg= Ca ratios in foraminiferal tests are routinely used as paleotemperature proxies, but on long timescales, they also hold the potential to reconstruct past seawater Mg= Ca. The impact of both temperature and seawater Mg= Ca on Mg incorporation in Foraminifera has been quantified by a number of studies. The underlying mechanism responsible for Mg incorporation in foraminiferal calcite and its sensitivity to environmental conditions, however, has not been fully identified. A recently published biomineralization model (Nehrke et al., 2013) proposes a combination of transmembrane transport and seawater leakage or vacuolization to link calcite Mg= Ca to seawater Mg= Ca and explains interspecies variability in Mg= Ca ratios. To test the assumptions of this model, we conducted a culture study in which seawater Mg= Ca was manipulated by varying [Ca2C] and keeping [Mg2C] constant. Foraminiferal growth rates, test thickness and calcite Mg= Ca of newly formed chambers were analyzed. Results showed optimum growth rates and test thickness at Mg= Ca closest to that of ambient seawater. Calcite Mg= Ca is positively correlated to seawater Mg= Ca, indicating that it is not absolute seawater [Ca2C] and [Mg2C] but their ratio that controls Mg= Ca in tests. These results demonstrate that the calcification process cannot be based only on seawater vacuolization, supporting the mixing model proposed by Nehrke et al. (2013). Here, however, we suggest transmembrane transport fractionation that is not as strong as suggested by Nehrke et al. (2013).
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 6
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    Ba incorporation in benthic foraminifera (2017)
    In:  EPIC3Biogeosciences Discuss., pp. 1-35
    Details
    Publication Date: 2017-03-24
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , notRev
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