Details
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 415-430 |
| Seitenumfang | 16 |
| Fachzeitschrift | BIOGEOSCIENCES |
| Jahrgang | 14 |
| Ausgabenummer | 2 |
| Publikationsstatus | Veröffentlicht - 26 Jan. 2017 |
Abstract
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 for reconstructing changes in past surface ocean pH. As B(OH)-4 is substituted into the biogenic calcite lattice in place of CO2-3 , and both borate and carbonate ions are more abundant at higher pH, it was suggested early on that B = Ca ratios in biogenic calcite may serve as a proxy for [CO2-3 ]. Although several recent studies have shown that a direct connection of B = Ca to carbonate system parameters may be masked by other environmental factors in the field, there is ample evidence for a mechanistic relationship between B= Ca and carbonate system parameters. Here, we focus on investigating the primary relationship to develop a mechanistic understanding of boron uptake. Differentiating between the effects of pH and [CO2-3 ] is problematic, as they co-vary closely in natural systems, so the major control on boron incorporation remains unclear. To deconvolve the effects of pH and [CO2-3 ] and to investigate their impact on the B= Ca ratio and δ11B, we conducted culture experiments with the planktonic foraminifer Orbulina universa in manipulated culture media: Constant pH (8.05), but changing [CO2-3 ] (238, 286 and 534 μmol kg-1 CO2-3 ) and at constant [CO2-3 ] (276±19.5 μmol kg-1) and varying pH (7.7, 7.9 and 8.05). Measurements of the isotopic composition of boron and the B = Ca ratio were performed simultaneously using a femtosecond laser ablation system coupled to a MC-ICP-MS (multiple-collector inductively coupled plasma mass spectrometer). Our results show that, as expected, δ11B is controlled by pH but it is also modulated by [CO2-3 ]. On the other hand, the B= Ca ratio is driven by [HCO-3 ], independently of pH. This suggests that B= Ca ratios in foraminiferal calcite can possibly be used as a second, independent, proxy for complete paleo-carbonate system reconstructions. This is discussed in light of recent literature demonstrating that the primary relationship between B= Ca and [HCO-3 ] can be obscured by other environmental parameters.
ASJC Scopus Sachgebiete
- Agrar- und Biowissenschaften (insg.)
- Ökologie, Evolution, Verhaltenswissenschaften und Systematik
- Erdkunde und Planetologie (insg.)
- Erdoberflächenprozesse
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in: BIOGEOSCIENCES, Jahrgang 14, Nr. 2, 26.01.2017, S. 415-430.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Decoupled carbonate chemistry controls on the incorporation of boron into Orbulina universa
AU - Howes, Ella L.
AU - Kaczmarek, Karina
AU - Raitzsch, Markus
AU - Mewes, Antje
AU - Bijma, Nienke
AU - Horn, Ingo
AU - Misra, Sambuddha
AU - Gattuso, Jean Pierre
AU - Bijma, Jelle
N1 - Copyright: Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017/1/26
Y1 - 2017/1/26
N2 - 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 for reconstructing changes in past surface ocean pH. As B(OH)-4 is substituted into the biogenic calcite lattice in place of CO2-3 , and both borate and carbonate ions are more abundant at higher pH, it was suggested early on that B = Ca ratios in biogenic calcite may serve as a proxy for [CO2-3 ]. Although several recent studies have shown that a direct connection of B = Ca to carbonate system parameters may be masked by other environmental factors in the field, there is ample evidence for a mechanistic relationship between B= Ca and carbonate system parameters. Here, we focus on investigating the primary relationship to develop a mechanistic understanding of boron uptake. Differentiating between the effects of pH and [CO2-3 ] is problematic, as they co-vary closely in natural systems, so the major control on boron incorporation remains unclear. To deconvolve the effects of pH and [CO2-3 ] and to investigate their impact on the B= Ca ratio and δ11B, we conducted culture experiments with the planktonic foraminifer Orbulina universa in manipulated culture media: Constant pH (8.05), but changing [CO2-3 ] (238, 286 and 534 μmol kg-1 CO2-3 ) and at constant [CO2-3 ] (276±19.5 μmol kg-1) and varying pH (7.7, 7.9 and 8.05). Measurements of the isotopic composition of boron and the B = Ca ratio were performed simultaneously using a femtosecond laser ablation system coupled to a MC-ICP-MS (multiple-collector inductively coupled plasma mass spectrometer). Our results show that, as expected, δ11B is controlled by pH but it is also modulated by [CO2-3 ]. On the other hand, the B= Ca ratio is driven by [HCO-3 ], independently of pH. This suggests that B= Ca ratios in foraminiferal calcite can possibly be used as a second, independent, proxy for complete paleo-carbonate system reconstructions. This is discussed in light of recent literature demonstrating that the primary relationship between B= Ca and [HCO-3 ] can be obscured by other environmental parameters.
AB - 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 for reconstructing changes in past surface ocean pH. As B(OH)-4 is substituted into the biogenic calcite lattice in place of CO2-3 , and both borate and carbonate ions are more abundant at higher pH, it was suggested early on that B = Ca ratios in biogenic calcite may serve as a proxy for [CO2-3 ]. Although several recent studies have shown that a direct connection of B = Ca to carbonate system parameters may be masked by other environmental factors in the field, there is ample evidence for a mechanistic relationship between B= Ca and carbonate system parameters. Here, we focus on investigating the primary relationship to develop a mechanistic understanding of boron uptake. Differentiating between the effects of pH and [CO2-3 ] is problematic, as they co-vary closely in natural systems, so the major control on boron incorporation remains unclear. To deconvolve the effects of pH and [CO2-3 ] and to investigate their impact on the B= Ca ratio and δ11B, we conducted culture experiments with the planktonic foraminifer Orbulina universa in manipulated culture media: Constant pH (8.05), but changing [CO2-3 ] (238, 286 and 534 μmol kg-1 CO2-3 ) and at constant [CO2-3 ] (276±19.5 μmol kg-1) and varying pH (7.7, 7.9 and 8.05). Measurements of the isotopic composition of boron and the B = Ca ratio were performed simultaneously using a femtosecond laser ablation system coupled to a MC-ICP-MS (multiple-collector inductively coupled plasma mass spectrometer). Our results show that, as expected, δ11B is controlled by pH but it is also modulated by [CO2-3 ]. On the other hand, the B= Ca ratio is driven by [HCO-3 ], independently of pH. This suggests that B= Ca ratios in foraminiferal calcite can possibly be used as a second, independent, proxy for complete paleo-carbonate system reconstructions. This is discussed in light of recent literature demonstrating that the primary relationship between B= Ca and [HCO-3 ] can be obscured by other environmental parameters.
UR - http://www.scopus.com/inward/record.url?scp=85010831474&partnerID=8YFLogxK
U2 - 10.5194/bg-14-415-2017
DO - 10.5194/bg-14-415-2017
M3 - Article
AN - SCOPUS:85010831474
VL - 14
SP - 415
EP - 430
JO - BIOGEOSCIENCES
JF - BIOGEOSCIENCES
SN - 1726-4170
IS - 2
ER -