Boron has two naturally occuring stable isotopes - 10B and 11B. The 11B/10B ratio in marine carbonate (such as the shells of foraminifer) is set by the pH of the water in which the carbonate grew. Whilst the pH proxy is growing in popularity we continue its ground truthing and pursue analytical developments that exploit the latest technologies.
boron isotope geochemistry
plasma on the neptune mc-icpms - as hot as the surface of the sun!
Culturing foraminifera G. ruber at the IUI in Israel (image credit: Michael Henehan, Yale)
It was recognised in the early 1990's that the boron isotopic composition of marine carbonates, such as foraminifera and coral, was determined largely by ocean pH (Hemming and Hanson, 1992).
The development of the boron isotope-pH proxy rapidly followed and has occured hand-in-hand with advances in analytical techniques.
Because boron has only two isotopes, getting the required analytical precision is therefore difficult.
Gavin and his group has been at the forefront of using the latest generation of mass spectrometers (multi-collector inductively coupled plasma mass spectrometers, MC-ICPMS for short) to make the tricky boron isotope measurements for the past decade (e.g. see Foster, 2008 and Foster et al., 2013).
We continue to make analytical developments and are currently exploring a number of novel systems to aid in the measurement and preparation (e.g. ESI's prepFAST) and micro-analysis (e.g. laser ablation) of samples .
Along side these analytical efforts, we are also exploring the groundtruthing of the proxy with culture experiments (growing coral and foraminifera at different pH) and laboratory experiments with inorganic calcite/aragonite.
Our ultimate aim is to make boron isotope measurements routine and strengthen the theoretical and experimental basis of the d11B-pH proxy.
Recent Publications
Whiteford, R., Heaton, T. J., Henehan, M. J., Anagnostou, E., Jurikova, H., Foster, G. L., and Rae, J. W. B., 2024, Reconstruction of Cenozoic δ11Bsw Using a Gaussian Process: Paleoceanography and Paleoclimatology, v. 39, no. 6, p. e2023PA004769, https://doi.org/10.1029/2023PA004769
de la Vega, E., Chalk, T. B., Hain, M. P., Wilding, M. R., Casey, D., Gledhill, R., Luo, C., Wilson, P. A., and Foster, G. L., 2023, Orbital CO2 reconstruction using boron isotopes during the late Pleistocene, an assessment of accuracy: Climate of the Past, v. 19, no. 12, p. 2493-2510. https://doi.org/10.5194/cp-19-2493-2023
Henehan, M.J., Klein-Gebbinck, C.D., Wymans, J.V.B., Hain, M.P., Rae, J.W.B., Honisch, B., Foster, G.L., Sang-Tae, K. (2022) No ion is an island: Multiple ions influence boron incorporation into CaCO3, Geochimica et Cosmochimica Acta, 318, 510-530, https://doi.org/10.1016/j.gca.2021.12.011
Joseph A. Stewart, Russell D. Day, Steven J. Christopher, John R. Kucklick, Louise Bordier, Thomas B. Chalk, Arnaud Dapoigny, Eric Douville, Gavin L. Foster, William R. Gray, Rosanna Greenop, Marcus Gutjahr, Freya Hemsing, Michael J. Henehan, Philip Holdship, Yu-Te Hsieh, Ana Kolevica, Yen-Po Lin, Elaine M. Mawbey, James W. B. Rae, Laura F. Robinson, Rachael Shuttleworth, Chen-Feng You, Shuang Zhang (2020) NIST RM 8301 Boron Isotopes in Marine Carbonate (Simulated Coral and Foraminifera Solutions): Interlaboratory d11B and trace metal ratio value assignment, Geostandards and Geoanalytical Research, https://doi.org/10.1111/ggr.12363
Gutjahr, M., Bordier, L., Douville, E., Farmer, J., Foster, G. L., Hathorne, E. C., Hönisch, B., Lemarchand, D., Louvat, P., Mcculloch, M., Noireaux, J., Pallavicini, N., Rae, J. W. B., Rodushkin, I., Roux, P., Stewart, J. A., Thil, F., & You, C. (2020). Sub‐Permil interlaboratory consistency for solution‐based boron isotope analyses on marine carbonates. Geostandards and Geoanalytical Research. https://doi.org/10.1111/ggr.12364
Donald, H.K., Foster, G.L., Frohberg, N., Swann, G., Poulton, A.J., Moore, C.M., Humphreys, M.P. (2020) The pH dependency of the boron isotopic composition of diatom opal (Thalassoiosira weissflogii), Biogeosciences, Biogeosciences, 17, 2825–2837, 2020, https://doi.org/10.5194/bg-17-2825-2020
de la Vega, E., Foster, G.L., Martinez-Boti, M.A., Anagnostou, E., Field, P.M., Kim, M.H., Watson, P. Wilson, P. (2020) Automation of boron chromotographic purification for d11B analysis of coral aragonite, Rapid Communications in Mass Spectrometry, 34:e8762, doi:10.1002/rcm.8762
Badger, M.P.S, Chalk, T.B., Foster, G.L., Bown, P.R., Gibbs, S.J., Sexton, P.F., Schmidt, D.N., Palike, H., Mackensen, A., Pancost, R.D. (2019) Insensitivity of alkenone carbon isotopes to atmospheric CO2 at low to moderate CO2 levels, Climate of the Past, 15, 539-554, https://doi.org/10.5194/cp-15-539-2019
Anagnostou, E., Williams, B., Westfield, I., Foster, G.L., Ries, J.B. (2019) Calibration of the pH-d11B and temperature-Mg/Li proxies in long-lived high-latitude crustose coralline red alga Clathromorphum compactum via controlled laboratory experiments, Geochimica et Cosmochimica Acta, 254, 142-155, https://doi.org/10.1016/j.gca.2019.03.015
Standish, C.D., Chalk, T.B., Babila, T.L., Milton, J.A., Palmer, M.R., Foster, G.L. (2019) The effect of matrix interferences in situ boron isotope analysis by laser ablation MC-ICP-MS, Rapid Communications in Mass Spectrometry, https://doi.org/10.1002/rcm.8432
Hain, M.P., Foster, G.L., CHalk, T.B. (2018) Robust constraints on past climate forcing by CO2 from novel boron isotope proxy systematics, Paleoceanography and Paleoclimatology, 33, doi:10.1029/2018PA003362.
Donald, H. K., Ries, J. B., Stewart, J. A., Fowell, S. E., & Foster, G. L. (2017). Boron isotope sensitivity to seawater pH change in a species of Neogoniolithon coralline red alga. Geochimica et Cosmochimica Acta, 217, 240-253. DOI: 10.1016/j.gca.2017.08.021
Greenop, R., Foster, G.L., Sosdian, S.M., Hain, M.P., Oliver, K.I.C., Goodwin, P., Chalk, T.B., Lear, C.H., Wilson, P.A. (2017) A record of Neogene seawater δ11B reconstructed from paired δ11B analyses on benthic and planktic foraminifera, Climate of the Past,13, 149-170(doi:10.5194/cp-13-149-2017).
Foster, G.L., and Rae, J.W.B (2016) Reconstructing ocean pH with boron isotopes in foraminifera. Annual Review of Earth and Planetary Sciences, 44, 207-237 (doi:10.1146/annurev-earth-060115-012226)
Martin, P., Goodkin, N. F., Stewart, J.A., Foster, G.L., Sikes, E.L., White, H.K., Hennige, S., Roberts, J.M. (2016) Deep-sea coral d13C: A tool to reconstruct the difference between seawater pH and d11B-derived calcification site pH. Geophysical Research Letters, 43, 299-308 (doi:10.1002/2015GL066494).
Edgar, Kirsty M., Anagnostou, Eleni, Pearson, Paul N. and Foster, Gavin L. (2015) Assessing the impact of diagenesis on δ11B, δ13C, δ18O, Sr/Ca and B/Ca values in fossil planktic foraminiferal calcite. Geochimica et Cosmochimica Acta (doi:10.1016/j.gca.2015.06.018).
Foster, Gavin L., Hönisch, Bärbel, Paris, Guillaume, Dwyer, Gary S., Rae, James W.B., Elliott, Tim, Gaillardet, Jérôme, Hemming, N. Gary, Louvat, Pascale and Vengosh, Avner (2013) Interlaboratory comparison of boron isotope analyses of boric acid, seawater and marine CaCO3 by MC-ICPMS and NTIMS. Chemical Geology, 358, 1-14. (doi:10.1016/j.chemgeo.2013.08.027).
Henehan, Michael J., Rae, James W. B., Foster, Gavin L., Erez, Jonathan, Prentice, Katherine C., Kucera, Michal, Bostock, Helen C., Martínez-Botí, M.A., Milton, J.A., Wilson, P.A., Marshall, Brittney J. and Elliott, Timothy (2013) Calibration of the boron isotope proxy in the planktonic foraminifera Globigerinoides ruber for use in palaeo-CO2 reconstruction. Earth and Planetary Science Letters, 364, 111-122. (doi:10.1016/j.epsl.2012.12.029).
