Microbially-mediated formation of Ca-Fe carbonates during dissimilatory ferrihydrite reduction:Implications for the origin of sedimentary ankerite

Deng LIU ¹Jinpeng CAO ²Shanshan YANG ²Yating YIN ²Pengcong WANG ³Dominic PAPINEAU ⁴Hongmei WANG ¹Xuan QIU ³Genming LUO ³Zongmin ZHU ³Fengping WANG⁵

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作者信息

1. State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,China;School of Environmental Studies,China University of Geosciences,Wuhan 430074,China
2. School of Environmental Studies,China University of Geosciences,Wuhan 430074,China
3. State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,China
4. State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,China;London Centre for Nanotechnology,University College London,London WC1H 0AH,UK;Department of Earth Sciences,University College London,London WC1E 6BT,UK;Center for Planetary Sciences,University College London and Birkbeck College London,London WC1E 6BT,UK
5. State Key Laboratory of Microbial Metabolism,State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China
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Abstract

The origin of sedimentary dolomite has become a long-standing problem in the Earth Sciences.Some carbonate minerals like ankerite have the same crystal structure as dolomite,hence their genesis may provide clues to help solving the dolomite problem.The purpose of this study was to probe whether microbial activity can be involved in the formation of ankerite.Bio-carbonation experiments associated with microbial iron reduction were performed in batch systems with various concentrations of Ca2+(0-20 mmol/L),with a marine iron-reducing bacterium Shewanella piezotolerans WP3 as the reaction mediator,and with lactate and ferrihydrite as the respective electron donor and acceptor.Our biomineralization data showed that Ca-amendments expedited microbially-mediated ferrihydrite reduction by enhancing the adhesion between WP3 cells and ferrihydrite particles.After bioreduction,siderite occurred as the principal secondary mineral in the Ca-free systems.Instead,Ca-Fe carbonates were formed when Ca2+ions were present.The CaCO3 content of microbially-induced Ca-Fe carbonates was positively correlated with the initial Ca2+concentration.The Ca-Fe carbonate phase produced in the 20 mmol/L Ca-amended biosystems had a chemical formula of Ca0.8Fe1.2(CO3)2,which is close to the theoretical composition of ankerite.This ankerite-like phase was nanometric in size and spherical,Ca-Fe disordered,and structurally defective.Our simulated diagenesis ex-periments further demonstrated that the resulting ankerite-like phase could be converted into ordered ankerite under hydro-thermal conditions.We introduced the term"proto-ankerite"to define the Ca-Fe phases that possess near-ankerite stoichiometry but disordered cation arrangement.On the basis of the present study,we proposed herein that microbial activity is an important contributor to the genesis of sedimentary ankerite by providing the metastable Ca-Fe carbonate precursors.

Key words

Ankerite/Proto-ankerite/Microbial iron reduction/Dolomite problem/Mineral transformation

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基金项目

National Natural Science Foundation of China(42272046)

National Natural Science Foundation of China(42293292)

National Natural Science Foundation of China(42072336)

National Key R&D Program of China(2022YFF0800304)

111 Project(BP0820004)

出版年

2024

中国科学:地球科学(英文版)

中国科学院

中国科学:地球科学(英文版)

影响因子：1.002

ISSN：1674-7313

参考文献量2

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