Extremely high alkalinity due to dissolution of Mg-rich phyllosilicate in the hemipelagic sediments of the Ulleung Basin (East/Japan Sea): stable Si isotopic evidence and reactive transport modeling.
Saved in:
| Title: | Extremely high alkalinity due to dissolution of Mg-rich phyllosilicate in the hemipelagic sediments of the Ulleung Basin (East/Japan Sea): stable Si isotopic evidence and reactive transport modeling. |
|---|---|
| Authors: | Huang, Tzu-Hao1 (AUTHOR) tzu-hao.huang@geo.su.se, Sun, Xiaole2,3 (AUTHOR), Kim, Ji-Hoon4 (AUTHOR), Mark, Chris5 (AUTHOR), Hong, Wei-Li1,3 (AUTHOR) wei-li.hong@geo.su.se |
| Source: | Geochimica et Cosmochimica Acta. Sep2025, Vol. 405, p132-147. 16p. |
| Subjects: | Alkalinity, Phyllosilicates, Silicate minerals, Reactive flow, Stable isotopes, Clay minerals |
| Abstract: | Marine silicate alteration includes the processes of lithogenic silicate (LSi) dissolution, clay formation, and biogenic silica dissolution. LSi dissolution consumes CO 2 and results in marine silicate weathering. Formation of cation-rich clay minerals produces CO 2 , which is known as reverse weathering. The net effects on carbon cycling of both processes are poorly constrained as the responsible silicate phases and controlling factors are unclear. We investigate the coupling between LSi dissolution and clay formation by analyzing stable Si isotopic signatures (δ30Si) of porewater and solid Si phases (reactive LSi, biogenic silica, and amorphous secondary Si phases) in two drill cores from the Ulleung Basin, East/Japan Sea. High porewater total alkalinity (up to 131 meq L−1) was measured, indicating net marine silicate weathering. Based on the elemental composition (Si, K, and Al) as well as δ30Si of the reactive LSi phase in sediments, phyllosilicates that are potentially mica group silicates are identified as the primary silicate group that sustains marine silicate weathering in the Ulleung Basin. Our reactive transport modeling supports such an inference and further reveals how early diagenetic reactions could affect the downcore occurrence and rates of LSi dissolution and clay formation. Predominant clay formation/reverse weathering in sulfate-reducing sediments is evident from the high δ30Si values in porewater. In the shallow methanogenesis zone, net marine silicate weathering due to phyllosilicate dissolution explains the observed high total alkalinity and low δ30Si in porewater. Nonetheless, we show that the rates of clay formation primarily control the level of porewater total alkalinity, even in the condition of net marine silicate weathering. Clay formation is strongly suppressed by the low porewater pH as a result of the active fermentation in the site with the highest rate of organic matter degradation. Deep in the methanogenesis zone, enrichment of dissolved aluminum from LSi dissolution counteracts the influence of pH on silicate alteration processes, thereby further limiting the extent of LSi dissolution, as supported by the downcore increasing of porewater δ30Si. Our results demonstrate that δ30Si in porewater reflects downcore variations in marine silicate alteration, with microbial processes and dissolved aluminum accumulation regulating the rates of LSi dissolution and clay formation. [ABSTRACT FROM AUTHOR] |
| Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
|---|---|
| Header | DbId: egs DbLabel: Engineering Source An: 187650098 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
| IllustrationInfo | |
| Items | – Name: Title Label: Title Group: Ti Data: Extremely high alkalinity due to dissolution of Mg-rich phyllosilicate in the hemipelagic sediments of the Ulleung Basin (East/Japan Sea): stable Si isotopic evidence and reactive transport modeling. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Huang%2C+Tzu-Hao%22">Huang, Tzu-Hao</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> tzu-hao.huang@geo.su.se</i><br /><searchLink fieldCode="AR" term="%22Sun%2C+Xiaole%22">Sun, Xiaole</searchLink><relatesTo>2,3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kim%2C+Ji-Hoon%22">Kim, Ji-Hoon</searchLink><relatesTo>4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Mark%2C+Chris%22">Mark, Chris</searchLink><relatesTo>5</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Hong%2C+Wei-Li%22">Hong, Wei-Li</searchLink><relatesTo>1,3</relatesTo> (AUTHOR)<i> wei-li.hong@geo.su.se</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Geochimica+et+Cosmochimica+Acta%22">Geochimica et Cosmochimica Acta</searchLink>. Sep2025, Vol. 405, p132-147. 16p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Alkalinity%22">Alkalinity</searchLink><br /><searchLink fieldCode="DE" term="%22Phyllosilicates%22">Phyllosilicates</searchLink><br /><searchLink fieldCode="DE" term="%22Silicate+minerals%22">Silicate minerals</searchLink><br /><searchLink fieldCode="DE" term="%22Reactive+flow%22">Reactive flow</searchLink><br /><searchLink fieldCode="DE" term="%22Stable+isotopes%22">Stable isotopes</searchLink><br /><searchLink fieldCode="DE" term="%22Clay+minerals%22">Clay minerals</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Marine silicate alteration includes the processes of lithogenic silicate (LSi) dissolution, clay formation, and biogenic silica dissolution. LSi dissolution consumes CO 2 and results in marine silicate weathering. Formation of cation-rich clay minerals produces CO 2 , which is known as reverse weathering. The net effects on carbon cycling of both processes are poorly constrained as the responsible silicate phases and controlling factors are unclear. We investigate the coupling between LSi dissolution and clay formation by analyzing stable Si isotopic signatures (δ30Si) of porewater and solid Si phases (reactive LSi, biogenic silica, and amorphous secondary Si phases) in two drill cores from the Ulleung Basin, East/Japan Sea. High porewater total alkalinity (up to 131 meq L−1) was measured, indicating net marine silicate weathering. Based on the elemental composition (Si, K, and Al) as well as δ30Si of the reactive LSi phase in sediments, phyllosilicates that are potentially mica group silicates are identified as the primary silicate group that sustains marine silicate weathering in the Ulleung Basin. Our reactive transport modeling supports such an inference and further reveals how early diagenetic reactions could affect the downcore occurrence and rates of LSi dissolution and clay formation. Predominant clay formation/reverse weathering in sulfate-reducing sediments is evident from the high δ30Si values in porewater. In the shallow methanogenesis zone, net marine silicate weathering due to phyllosilicate dissolution explains the observed high total alkalinity and low δ30Si in porewater. Nonetheless, we show that the rates of clay formation primarily control the level of porewater total alkalinity, even in the condition of net marine silicate weathering. Clay formation is strongly suppressed by the low porewater pH as a result of the active fermentation in the site with the highest rate of organic matter degradation. Deep in the methanogenesis zone, enrichment of dissolved aluminum from LSi dissolution counteracts the influence of pH on silicate alteration processes, thereby further limiting the extent of LSi dissolution, as supported by the downcore increasing of porewater δ30Si. Our results demonstrate that δ30Si in porewater reflects downcore variations in marine silicate alteration, with microbial processes and dissolved aluminum accumulation regulating the rates of LSi dissolution and clay formation. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Geochimica et Cosmochimica Acta is the property of Pergamon Press - An Imprint of Elsevier Science and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=egs&AN=187650098 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.gca.2025.07.022 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 16 StartPage: 132 Subjects: – SubjectFull: Alkalinity Type: general – SubjectFull: Phyllosilicates Type: general – SubjectFull: Silicate minerals Type: general – SubjectFull: Reactive flow Type: general – SubjectFull: Stable isotopes Type: general – SubjectFull: Clay minerals Type: general Titles: – TitleFull: Extremely high alkalinity due to dissolution of Mg-rich phyllosilicate in the hemipelagic sediments of the Ulleung Basin (East/Japan Sea): stable Si isotopic evidence and reactive transport modeling. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Huang, Tzu-Hao – PersonEntity: Name: NameFull: Sun, Xiaole – PersonEntity: Name: NameFull: Kim, Ji-Hoon – PersonEntity: Name: NameFull: Mark, Chris – PersonEntity: Name: NameFull: Hong, Wei-Li IsPartOfRelationships: – BibEntity: Dates: – D: 15 M: 09 Text: Sep2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 00167037 Numbering: – Type: volume Value: 405 Titles: – TitleFull: Geochimica et Cosmochimica Acta Type: main |
| ResultId | 1 |
