Trace and major element incorporation into amorphous calcium carbonate (ACC) precipitated from seawater

TY - JOUR

T1 - Trace and major element incorporation into amorphous calcium carbonate (ACC) precipitated from seawater

AU - Evans, David

AU - Gray, William R.

AU - Rae, James W.B.

AU - Greenop, Rosanna

AU - Webb, Paul B.

AU - Penkman, Kirsty

AU - Kröger, Roland

AU - Allison, Nicola

N1 - © 2020 Elsevier Ltd. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

PY - 2020/12/1

Y1 - 2020/12/1

N2 - Amorphous calcium carbonate (ACC) has been identified or inferred to exist in many groups of marine organisms that produce biominerals widely used as geochemical archives (e.g. foraminifera, molluscs, echinoderms). However, little is known about trace element incorporation into ACC, and thus it is not understood how precipitation through an ACC precursor might impact the fidelity of climate proxies and biomineralisation models built on the skeletal geochemistry of these marine calcifiers. To address this, we investigated the incorporation of Li, B, Na, Mg, Mn, Sr, Ba, and U into inorganic amorphous calcium magnesium carbonates precipitated from seawater under a variety of different carbonate chemistries, Mg/Ca ratios, and in the presence of aspartic and glutamic acid, two of the most common intracrystalline amino acids found in foraminifera and corals. ACC is highly enriched in most of these trace elements relative to the crystalline carbonates yet similar in some respects in terms of the factors influencing trace element partitioning. For example, ACC B/Ca is sensitive to the carbonate system, whilst Mg/Ca and Sr/Ca are largely a function of their respective ratio in seawater. In general, we find that most of the variance in the distribution coefficients of the other trace elements can be explained by some combination of the seawater carbonate chemistry and the seawater or ACC Mg/Ca ratio.

AB - Amorphous calcium carbonate (ACC) has been identified or inferred to exist in many groups of marine organisms that produce biominerals widely used as geochemical archives (e.g. foraminifera, molluscs, echinoderms). However, little is known about trace element incorporation into ACC, and thus it is not understood how precipitation through an ACC precursor might impact the fidelity of climate proxies and biomineralisation models built on the skeletal geochemistry of these marine calcifiers. To address this, we investigated the incorporation of Li, B, Na, Mg, Mn, Sr, Ba, and U into inorganic amorphous calcium magnesium carbonates precipitated from seawater under a variety of different carbonate chemistries, Mg/Ca ratios, and in the presence of aspartic and glutamic acid, two of the most common intracrystalline amino acids found in foraminifera and corals. ACC is highly enriched in most of these trace elements relative to the crystalline carbonates yet similar in some respects in terms of the factors influencing trace element partitioning. For example, ACC B/Ca is sensitive to the carbonate system, whilst Mg/Ca and Sr/Ca are largely a function of their respective ratio in seawater. In general, we find that most of the variance in the distribution coefficients of the other trace elements can be explained by some combination of the seawater carbonate chemistry and the seawater or ACC Mg/Ca ratio.

KW - ACC

KW - amorphous calcium carbonate

KW - biomineralisation

KW - CaCO3

KW - trace element

UR - http://www.scopus.com/inward/record.url?scp=85091750263&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2020.08.034

DO - 10.1016/j.gca.2020.08.034

M3 - Article

AN - SCOPUS:85091750263

SN - 0016-7037

VL - 290

SP - 293

EP - 311

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

ER -