The effect of growth rate on uranium partitioning between individual calcite crystals and fluid

Jeremy M. Weremeichik, Rinat I. Gabitov, Bruno M.J. Thien, Aleksey Sadekov

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Elemental to calcium ratios in calcium carbonate minerals are used to study environmental conditions. In particular, uranium to calcium ratio (U/Ca) has been proposed as a proxy for seawater carbonate ion concentration (CO3 2 −) and seawater pH. This work is focused on the evaluation of growth rate and its effect on uranium partitioning between calcite and fluid. We grew inorganic calcite (by diffusion of CO2) isothermally from NH4Cl-CaCl2 doped with uranium. The growth rate of calcite (crystal extension rate, V) was monitored by sequentially spiking calcite-precipitating fluids with rare earth element (REE) dopants. The REE was analyzed with secondary ion mass spectrometry (SIMS) at spots matching those where U/Ca was determined. Partition coefficient KU = (U/Ca)calcite / (U/Ca)fluid increases with increasing growth rate (V). Specifically, KU increases from 0.02 to 0.06 when V increases from 0.01 to 0.14 nm/s and remains nearly constant at faster rates. Numerical simulations using the growth entrapment model (GEM) and unified uptake kinetics model (UUKM) were undertaken to explain KU-V relationship in the recent data on calcite.

Original languageEnglish
Pages (from-to)145-153
Number of pages9
JournalChemical Geology
Volume450
DOIs
Publication statusPublished - 5 Feb 2017
Externally publishedYes

Fingerprint

Uranium
Calcium Carbonate
uranium
calcite
partitioning
crystal
Crystals
Fluids
fluid
Rare earth elements
Seawater
rare earth element
calcium
seawater
Carbonate minerals
ion
Calcium
calcium carbonate
partition coefficient
Carbonates

Cite this

Weremeichik, Jeremy M. ; Gabitov, Rinat I. ; Thien, Bruno M.J. ; Sadekov, Aleksey. / The effect of growth rate on uranium partitioning between individual calcite crystals and fluid. In: Chemical Geology. 2017 ; Vol. 450. pp. 145-153.
@article{2f1a610d53cf4c9ca5f94bcf754b7d07,
title = "The effect of growth rate on uranium partitioning between individual calcite crystals and fluid",
abstract = "Elemental to calcium ratios in calcium carbonate minerals are used to study environmental conditions. In particular, uranium to calcium ratio (U/Ca) has been proposed as a proxy for seawater carbonate ion concentration (CO3 2 −) and seawater pH. This work is focused on the evaluation of growth rate and its effect on uranium partitioning between calcite and fluid. We grew inorganic calcite (by diffusion of CO2) isothermally from NH4Cl-CaCl2 doped with uranium. The growth rate of calcite (crystal extension rate, V) was monitored by sequentially spiking calcite-precipitating fluids with rare earth element (REE) dopants. The REE was analyzed with secondary ion mass spectrometry (SIMS) at spots matching those where U/Ca was determined. Partition coefficient KU = (U/Ca)calcite / (U/Ca)fluid increases with increasing growth rate (V). Specifically, KU increases from 0.02 to 0.06 when V increases from 0.01 to 0.14 nm/s and remains nearly constant at faster rates. Numerical simulations using the growth entrapment model (GEM) and unified uptake kinetics model (UUKM) were undertaken to explain KU-V relationship in the recent data on calcite.",
keywords = "Calcite, Disequilibrium, Growth rate, Partition coefficient, SIMS, Uranium",
author = "Weremeichik, {Jeremy M.} and Gabitov, {Rinat I.} and Thien, {Bruno M.J.} and Aleksey Sadekov",
year = "2017",
month = "2",
day = "5",
doi = "10.1016/j.chemgeo.2016.12.026",
language = "English",
volume = "450",
pages = "145--153",
journal = "Chemical Geology",
issn = "0009-2541",
publisher = "Pergamon",

}

The effect of growth rate on uranium partitioning between individual calcite crystals and fluid. / Weremeichik, Jeremy M.; Gabitov, Rinat I.; Thien, Bruno M.J.; Sadekov, Aleksey.

In: Chemical Geology, Vol. 450, 05.02.2017, p. 145-153.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The effect of growth rate on uranium partitioning between individual calcite crystals and fluid

AU - Weremeichik, Jeremy M.

AU - Gabitov, Rinat I.

AU - Thien, Bruno M.J.

AU - Sadekov, Aleksey

PY - 2017/2/5

Y1 - 2017/2/5

N2 - Elemental to calcium ratios in calcium carbonate minerals are used to study environmental conditions. In particular, uranium to calcium ratio (U/Ca) has been proposed as a proxy for seawater carbonate ion concentration (CO3 2 −) and seawater pH. This work is focused on the evaluation of growth rate and its effect on uranium partitioning between calcite and fluid. We grew inorganic calcite (by diffusion of CO2) isothermally from NH4Cl-CaCl2 doped with uranium. The growth rate of calcite (crystal extension rate, V) was monitored by sequentially spiking calcite-precipitating fluids with rare earth element (REE) dopants. The REE was analyzed with secondary ion mass spectrometry (SIMS) at spots matching those where U/Ca was determined. Partition coefficient KU = (U/Ca)calcite / (U/Ca)fluid increases with increasing growth rate (V). Specifically, KU increases from 0.02 to 0.06 when V increases from 0.01 to 0.14 nm/s and remains nearly constant at faster rates. Numerical simulations using the growth entrapment model (GEM) and unified uptake kinetics model (UUKM) were undertaken to explain KU-V relationship in the recent data on calcite.

AB - Elemental to calcium ratios in calcium carbonate minerals are used to study environmental conditions. In particular, uranium to calcium ratio (U/Ca) has been proposed as a proxy for seawater carbonate ion concentration (CO3 2 −) and seawater pH. This work is focused on the evaluation of growth rate and its effect on uranium partitioning between calcite and fluid. We grew inorganic calcite (by diffusion of CO2) isothermally from NH4Cl-CaCl2 doped with uranium. The growth rate of calcite (crystal extension rate, V) was monitored by sequentially spiking calcite-precipitating fluids with rare earth element (REE) dopants. The REE was analyzed with secondary ion mass spectrometry (SIMS) at spots matching those where U/Ca was determined. Partition coefficient KU = (U/Ca)calcite / (U/Ca)fluid increases with increasing growth rate (V). Specifically, KU increases from 0.02 to 0.06 when V increases from 0.01 to 0.14 nm/s and remains nearly constant at faster rates. Numerical simulations using the growth entrapment model (GEM) and unified uptake kinetics model (UUKM) were undertaken to explain KU-V relationship in the recent data on calcite.

KW - Calcite

KW - Disequilibrium

KW - Growth rate

KW - Partition coefficient

KW - SIMS

KW - Uranium

UR - http://www.scopus.com/inward/record.url?scp=85009343305&partnerID=8YFLogxK

U2 - 10.1016/j.chemgeo.2016.12.026

DO - 10.1016/j.chemgeo.2016.12.026

M3 - Article

VL - 450

SP - 145

EP - 153

JO - Chemical Geology

JF - Chemical Geology

SN - 0009-2541

ER -