Factors affecting B/Ca ratios in synthetic aragonite

M. Holcomb, T. M. DeCarlo, G. A. Gaetani, M. McCulloch

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)
199 Downloads (Pure)

Abstract

Measurements of B/Ca ratios in marine carbonates have been suggested to record seawater carbonate chemistry, however experimental calibration of such proxies based on inorganic partitioning remains limited. Here we conducted a series of synthetic aragonite precipitation experiments to evaluate the factors influencing the partitioning of B/Ca between aragonite and seawater. Our results indicate that the B/Ca ratio of synthetic aragonites depends primarily on the relative concentrations of borate and carbonate ions in the solution from which the aragonite precipitates; not on bicarbonate concentration as has been previously suggested. The influence of temperature was not significant over the range investigated (20-40 °C), however, partitioning may be influenced by saturation state (and/or growth rate). Based on our experimental results, we suggest that aragonite B/Ca ratios can be utilized as a proxy of [CO3 2-]. Boron isotopic composition (δ11B) is an established pH proxy, thus B/Ca and δ11B together allow the full carbonate chemistry of the solution from which the aragonite precipitated to be calculated. To the extent that aragonite precipitation by marine organisms is affected by seawater chemistry, B/Ca may also prove useful in reconstructing seawater chemistry. A simplified boron purification protocol based on amberlite resin and the organic buffer TRIS is also described.

Original languageEnglish
Pages (from-to)67-76
Number of pages10
JournalChemical Geology
Volume437
DOIs
Publication statusPublished - 25 Oct 2016

Fingerprint

Dive into the research topics of 'Factors affecting B/Ca ratios in synthetic aragonite'. Together they form a unique fingerprint.

Cite this