Table of Contents Author Guidelines Submit a Manuscript
Geofluids
Volume 2018 (2018), Article ID 2141878, 11 pages
https://doi.org/10.1155/2018/2141878
Research Article

Field Reaction Experiments of Carbonate Minerals in Spring Waters: Natural Analogue of Geologic CO2 Storage

1Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan
2Department of Earth Science, Tohoku University, Sendai, Miyagi, Japan

Correspondence should be addressed to Masao Sorai

Received 22 September 2017; Revised 8 January 2018; Accepted 15 January 2018; Published 12 February 2018

Academic Editor: Marco Petitta

Copyright © 2018 Masao Sorai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

To diminish the uncertainty of the mineral trapping rate during geologic CO2 storage, the growth rate of carbonate minerals was measured in CO2-containing spring waters, which can be regarded as a natural analogue of geologic CO2 storage. The authors’ approach, using nanoscale analysis of seed crystal surfaces after immersion into spring waters, enables rapid and accurate measurement of mineral reaction rates. The results show that calcite growth rates in spring waters were lower by 1–3 orders than the values given in a database of laboratory experiment results. We verified the traditional paradigm that Mg2+ controls carbonate reaction kinetics. An increase of the Mg/Ca ratio to around 5 by adding Mg2+ to spring waters markedly reduced the calcite growth rate. However, even if effects of Mg2+ and flow rate are considered, we were unable to explain satisfactorily the difference of the calcite growth rates between those of spring waters and laboratory experiments. Therefore, other factors might also be related to the slow growth rate in nature. The present results, including the fact such that neither dolomite nor magnesite was formed even at the high Mg/Ca ratio, are expected to provide an important constraint to overestimation of the mineral trapping rate.