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Bioweathering of Egyptian Nubian sandstone and Theban limestone: three months insight by experimental incubation

Anna Potysz

Anna Potysz

University of Wroclaw, Faculty of Earth Sciences and Environmental Management, Institute of Geological SciencesWrocław, Poland
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Potysz, Anna
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Amr Osman

Amr Osman

Sohag University, Faculty of Archaeology, Conservation of Antiquities DepartmentSohag, Egypt
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Osman, Amr
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Wojciech Bartz

Wojciech Bartz

University of Wroclaw, Faculty of Earth Sciences and Environmental Management, Institute of Geological SciencesWrocław, Poland
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Bartz, Wojciech
  
Dec 13, 2024
Bioweathering of Egyptian Nubian sandstone and Theban limestone: three months insight by experimental incubation's Cover Image
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Article Category: Original Paper
Published Online: Dec 13, 2024
Page range: 60 - 79
Received: Jul 04, 2024
Accepted: Nov 07, 2024
DOI: https://doi.org/10.2478/mipo-2024-0006
Keywords
© 2024 Anna Potysz et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1.

A map showing the locations of sampling sites, where Nubian sandstone S1-S6 (A) and Theban limestone (B) have been collected.
A map showing the locations of sampling sites, where Nubian sandstone S1-S6 (A) and Theban limestone (B) have been collected.

Figure 2.

Flowchart presenting experimental approach undertaken to decipher stone weathering.
Flowchart presenting experimental approach undertaken to decipher stone weathering.

Figure 3.

Microphotographs of Nubian sandstone (S3, S6) taken in plane-polarized (left column) and cross-polarized light (right column).
Microphotographs of Nubian sandstone (S3, S6) taken in plane-polarized (left column) and cross-polarized light (right column).

Figure 4.

Results of X-ray diffraction and thermal analysis of Theban limestone (TL) and Nubian sandstone (S3, S6). Mineral abbreviations: cal-calcite, qz-quartz, kln-kaolinite, hl-halite, afs-alkali feldspar, zrn-zircon, gth-goethite, hem-hematite, mag-magnetite, gp-gypsum, lpc-lepidocrocite (Warr, 2021); dh-dehydration, dxo-dehydroxylation.
Results of X-ray diffraction and thermal analysis of Theban limestone (TL) and Nubian sandstone (S3, S6). Mineral abbreviations: cal-calcite, qz-quartz, kln-kaolinite, hl-halite, afs-alkali feldspar, zrn-zircon, gth-goethite, hem-hematite, mag-magnetite, gp-gypsum, lpc-lepidocrocite (Warr, 2021); dh-dehydration, dxo-dehydroxylation.

Figure 5.

BSE images and EDS spectra of Nubian sandstone (S3, S6) and Theban limestone (TL) before leaching experiment. 1 – euhedral dolomite; 2 – bioclast; 3 – Fe-bearing phases encrusting bioclast; 4, 9 – alkali feldspar; 5 – quartz; 6, 10 – Fe-bearing phases in matrix; 7, 11 – kaolinite; 8 – magnetite.
BSE images and EDS spectra of Nubian sandstone (S3, S6) and Theban limestone (TL) before leaching experiment. 1 – euhedral dolomite; 2 – bioclast; 3 – Fe-bearing phases encrusting bioclast; 4, 9 – alkali feldspar; 5 – quartz; 6, 10 – Fe-bearing phases in matrix; 7, 11 – kaolinite; 8 – magnetite.

Figure 6.

BSE images and EDS spectra of Nubian sandstone (S3, S6) and Theban limestone (TL) after leaching experiment. 1 – bioclast; 2 – bioclast covered with biofilm, 3 – euhedral dolomite; 4 – quartz and biofilm; 5 – syntaxial quartz overgrowths; 6 – bacteria on kaolinite aggregate; 7 – kaolinite aggregate; 8 – magnetite; 9, 11 – Fe-bearing phases; 10 – single kaolinite flake.
BSE images and EDS spectra of Nubian sandstone (S3, S6) and Theban limestone (TL) after leaching experiment. 1 – bioclast; 2 – bioclast covered with biofilm, 3 – euhedral dolomite; 4 – quartz and biofilm; 5 – syntaxial quartz overgrowths; 6 – bacteria on kaolinite aggregate; 7 – kaolinite aggregate; 8 – magnetite; 9, 11 – Fe-bearing phases; 10 – single kaolinite flake.

Figure 7.

Microphotographs of Theban limestone (TL) taken in plane-polarized (left column) and cross-polarized light (right column).
Microphotographs of Theban limestone (TL) taken in plane-polarized (left column) and cross-polarized light (right column).

Figure 8.

Evolution of elements leaching from studied sandstones throughout the experiment (BAC: growth medium with bacteria filtered at <0.22 μm; MED: sterile growth medium; H2O: sterile water). Error bars present standard deviation of the replicate values.
Evolution of elements leaching from studied sandstones throughout the experiment (BAC: growth medium with bacteria filtered at <0.22 μm; MED: sterile growth medium; H2O: sterile water). Error bars present standard deviation of the replicate values.

Figure 9.

Evolution of elements leaching from studied limestone throughout the experiment (BAC: growth medium with bacteria filtered at <0.22 μm; MED: sterile growth medium; H2O: sterile water). Error bars present standard deviation of the replicate values.
Evolution of elements leaching from studied limestone throughout the experiment (BAC: growth medium with bacteria filtered at <0.22 μm; MED: sterile growth medium; H2O: sterile water). Error bars present standard deviation of the replicate values.

Specific conditions set in the incubation experiments_

Incubation Name Characteristics of the constituents Presence of bacteria Initial pH Final pH S3 Final pH S6 Final pH TL Siderophore concentration Proxy
Ultrapure water WAT none - 5.6 8.7 8.6 8.1 - Neutral unaggressive conditions
Growth medium MED Inorganic, organic (succinic acid) - 7.0 7.8 7.8 8.0 - Chemical weathering
Growth medium with bacteria Pseudomonas fluorescens BAC Inorganic, organic (succinic acid, microbially-derived compounds including siderophore) + 7.0 8.7 9.1 9.2 S3: 45.2 μM L−1S6: 75.5 μM L−1TL: 90.6 μM L−1 Biotic weathering

Chemical composition of the studied samples_

[Wt. %] Sandstone S3 Sandstone S6 Limestone TL
SiO2 92.57 85.67 7.08
Al2O3 3.12 0.96 0.54
Fe2O3 1.18 7.94 0.33
MgO 0.07 0.11 0.51
CaO 0.07 1.56 50.22
Na2O 0.07 0.13 0.15
K2O 0.87 0.19 0.08
TiO2 0.84 0.18 0.03
LOI 1.0 3.1 40.7
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