Red coralline algae assessed as marine pH proxies using ¹¹B MAS NMR

M. Cusack (1) , N.A. Kamenos (1) , C. Rollion-Bard (2) , G. Tricot (3)

1 Glasgow School Geogr. & Earth Science
2 IPGP - Institut de Physique du Globe de Paris
3 LASIRE - Laboratoire Avancé de Spectroscopie pour les Intéractions la Réactivité et l'Environnement - UMR 8516

Reconstructing pH from biogenic carbonates using boron isotopic compositions relies on the assumption that only borate, and no boric acid, is present. Red coralline algae are frequently used in palaeoenvironmental reconstruction due to their widespread distribution and regular banding frequency. Prior to undertaking pH reconstructions using red coralline algae we tested the boron composition of the red coralline alga Lithothamnion glaciale using high field NMR. In bulk analysed samples, thirty percent of boron was present as boric acid. We suggest that prior to reconstructing pH using coralline algae 1) species-specific boron compositions and 2) within-skeleton special distributions of boron are determined for multiple species. This will enable site selective boron analyses to be conducted validating coralline algae as palaeo-pH proxies based on boron isotopic compositions.

Domaines: Chimie théorique et/ou physique

M. Cusack, N.A. Kamenos, C. Rollion-Bard, G. Tricot. Red coralline algae assessed as marine pH proxies using ¹¹B MAS NMR. Scientific Reports, 2015, 5, pp.8175-1 - 8175-3. ⟨10.1038/srep08175⟩. ⟨hal-01168275⟩