Observation of the dissolution process of Globigerina bulloides tests (planktic foraminifera) by X-ray microcomputed tomography

Shinya Iwasaki, Katsunori Kimoto, Osamu Sasaki, Harumasa Kano, Makio C. Honda, Yusuke Okazaki

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

We performed a 9 day dissolution experiment with tests of the planktic foraminifer Globigerina bulloides at pH 6.7 ± 0.1 in water undersaturated with respect to calcite. The initial stage of the dissolution process, which is not recognizable from the surface structure of the tests, was quantitatively evaluated by X-ray microcomputed tomography (XMCT). XMCT revealed three distinct test structures: early-developed calcite formed during the juvenile stage of G. bulloides, an inner calcite layer, and an outer calcite layer. The test ultrastructure was observed by scanning electron microscopy, and CT number evaluated the density distribution in the test. The early-developed calcite and inner calcite layer had low CT numbers (500-1300; low density, porous) and were sensitive to dissolution, whereas the outer calcite layer had high CT numbers (<1300; high density) and resisted dissolution. Both the modes and the frequencies of the CT numbers decreased with progress of dissolution. Changes in the CT number histogram with progress of dissolution were quantified in terms of the percentage of calcite volume accounted for by low-density calcite (% Low-CT-number calcite). A clear linear relationship (R2 = 0.87) between % Low-CT-number calcite and % Test weight loss was found. This relationship indicates that the amount of test dissolution can be estimated from the distribution of CT numbers. We propose that XMCT measurements will be useful for quantitatively estimating the amount of carbonate loss from foraminiferal tests by dissolution.

Original languageEnglish
Pages (from-to)317-331
Number of pages15
JournalPaleoceanography
Volume30
Issue number4
DOIs
Publication statusPublished - Apr 1 2015

Fingerprint

foraminifera
tomography
calcite
dissolution
test
ultrastructure
histogram
scanning electron microscopy
carbonate

All Science Journal Classification (ASJC) codes

  • Oceanography
  • Palaeontology

Cite this

Observation of the dissolution process of Globigerina bulloides tests (planktic foraminifera) by X-ray microcomputed tomography. / Iwasaki, Shinya; Kimoto, Katsunori; Sasaki, Osamu; Kano, Harumasa; Honda, Makio C.; Okazaki, Yusuke.

In: Paleoceanography, Vol. 30, No. 4, 01.04.2015, p. 317-331.

Research output: Contribution to journalArticle

Iwasaki, Shinya ; Kimoto, Katsunori ; Sasaki, Osamu ; Kano, Harumasa ; Honda, Makio C. ; Okazaki, Yusuke. / Observation of the dissolution process of Globigerina bulloides tests (planktic foraminifera) by X-ray microcomputed tomography. In: Paleoceanography. 2015 ; Vol. 30, No. 4. pp. 317-331.
@article{96c2db4ffaf94f6cb7d01be61626ed0b,
title = "Observation of the dissolution process of Globigerina bulloides tests (planktic foraminifera) by X-ray microcomputed tomography",
abstract = "We performed a 9 day dissolution experiment with tests of the planktic foraminifer Globigerina bulloides at pH 6.7 ± 0.1 in water undersaturated with respect to calcite. The initial stage of the dissolution process, which is not recognizable from the surface structure of the tests, was quantitatively evaluated by X-ray microcomputed tomography (XMCT). XMCT revealed three distinct test structures: early-developed calcite formed during the juvenile stage of G. bulloides, an inner calcite layer, and an outer calcite layer. The test ultrastructure was observed by scanning electron microscopy, and CT number evaluated the density distribution in the test. The early-developed calcite and inner calcite layer had low CT numbers (500-1300; low density, porous) and were sensitive to dissolution, whereas the outer calcite layer had high CT numbers (<1300; high density) and resisted dissolution. Both the modes and the frequencies of the CT numbers decreased with progress of dissolution. Changes in the CT number histogram with progress of dissolution were quantified in terms of the percentage of calcite volume accounted for by low-density calcite ({\%} Low-CT-number calcite). A clear linear relationship (R2 = 0.87) between {\%} Low-CT-number calcite and {\%} Test weight loss was found. This relationship indicates that the amount of test dissolution can be estimated from the distribution of CT numbers. We propose that XMCT measurements will be useful for quantitatively estimating the amount of carbonate loss from foraminiferal tests by dissolution.",
author = "Shinya Iwasaki and Katsunori Kimoto and Osamu Sasaki and Harumasa Kano and Honda, {Makio C.} and Yusuke Okazaki",
year = "2015",
month = "4",
day = "1",
doi = "10.1002/2014PA002639",
language = "English",
volume = "30",
pages = "317--331",
journal = "Paleoceanography and Paleoclimatology",
issn = "2572-4517",
publisher = "American Geophysical Union",
number = "4",

}

TY - JOUR

T1 - Observation of the dissolution process of Globigerina bulloides tests (planktic foraminifera) by X-ray microcomputed tomography

AU - Iwasaki, Shinya

AU - Kimoto, Katsunori

AU - Sasaki, Osamu

AU - Kano, Harumasa

AU - Honda, Makio C.

AU - Okazaki, Yusuke

PY - 2015/4/1

Y1 - 2015/4/1

N2 - We performed a 9 day dissolution experiment with tests of the planktic foraminifer Globigerina bulloides at pH 6.7 ± 0.1 in water undersaturated with respect to calcite. The initial stage of the dissolution process, which is not recognizable from the surface structure of the tests, was quantitatively evaluated by X-ray microcomputed tomography (XMCT). XMCT revealed three distinct test structures: early-developed calcite formed during the juvenile stage of G. bulloides, an inner calcite layer, and an outer calcite layer. The test ultrastructure was observed by scanning electron microscopy, and CT number evaluated the density distribution in the test. The early-developed calcite and inner calcite layer had low CT numbers (500-1300; low density, porous) and were sensitive to dissolution, whereas the outer calcite layer had high CT numbers (<1300; high density) and resisted dissolution. Both the modes and the frequencies of the CT numbers decreased with progress of dissolution. Changes in the CT number histogram with progress of dissolution were quantified in terms of the percentage of calcite volume accounted for by low-density calcite (% Low-CT-number calcite). A clear linear relationship (R2 = 0.87) between % Low-CT-number calcite and % Test weight loss was found. This relationship indicates that the amount of test dissolution can be estimated from the distribution of CT numbers. We propose that XMCT measurements will be useful for quantitatively estimating the amount of carbonate loss from foraminiferal tests by dissolution.

AB - We performed a 9 day dissolution experiment with tests of the planktic foraminifer Globigerina bulloides at pH 6.7 ± 0.1 in water undersaturated with respect to calcite. The initial stage of the dissolution process, which is not recognizable from the surface structure of the tests, was quantitatively evaluated by X-ray microcomputed tomography (XMCT). XMCT revealed three distinct test structures: early-developed calcite formed during the juvenile stage of G. bulloides, an inner calcite layer, and an outer calcite layer. The test ultrastructure was observed by scanning electron microscopy, and CT number evaluated the density distribution in the test. The early-developed calcite and inner calcite layer had low CT numbers (500-1300; low density, porous) and were sensitive to dissolution, whereas the outer calcite layer had high CT numbers (<1300; high density) and resisted dissolution. Both the modes and the frequencies of the CT numbers decreased with progress of dissolution. Changes in the CT number histogram with progress of dissolution were quantified in terms of the percentage of calcite volume accounted for by low-density calcite (% Low-CT-number calcite). A clear linear relationship (R2 = 0.87) between % Low-CT-number calcite and % Test weight loss was found. This relationship indicates that the amount of test dissolution can be estimated from the distribution of CT numbers. We propose that XMCT measurements will be useful for quantitatively estimating the amount of carbonate loss from foraminiferal tests by dissolution.

UR - http://www.scopus.com/inward/record.url?scp=84929166947&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84929166947&partnerID=8YFLogxK

U2 - 10.1002/2014PA002639

DO - 10.1002/2014PA002639

M3 - Article

AN - SCOPUS:84929166947

VL - 30

SP - 317

EP - 331

JO - Paleoceanography and Paleoclimatology

JF - Paleoceanography and Paleoclimatology

SN - 2572-4517

IS - 4

ER -