Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient
<p>Redox-stratified water columns are a prevalent feature of the Earth's history, and ongoing environmental changes tend to promote a resurgence of such settings. Studying modern redox-stratified environments has improved our understanding of biogeochemical processes and element cycling i...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-06-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/2347/2023/bg-20-2347-2023.pdf |
| _version_ | 1827919902071062528 |
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| author | R. Havas C. Thomazo C. Thomazo M. Iniesto D. Jézéquel D. Jézéquel D. Moreira R. Tavera J. Caumartin E. Muller P. López-García K. Benzerara |
| author_facet | R. Havas C. Thomazo C. Thomazo M. Iniesto D. Jézéquel D. Jézéquel D. Moreira R. Tavera J. Caumartin E. Muller P. López-García K. Benzerara |
| author_sort | R. Havas |
| collection | DOAJ |
| description | <p>Redox-stratified water columns are a prevalent feature of the Earth's
history, and ongoing environmental changes tend to promote a resurgence of
such settings. Studying modern redox-stratified environments has improved
our understanding of biogeochemical processes and element cycling in such
water columns. These settings are associated with peculiar carbon
biogeochemical cycling, owing to a layered distribution of biological
processes in relation to oxidant availability. Metabolisms from distinct
biogeochemical layers are diverse and may differently imprint the
sedimentological record. Paired carbon isotope compositions of organic
matter and carbonates, which are commonly used to characterize these
ecological dynamics, can thus vary from one stratified environment to
another. Changes in the organic/inorganic carbon sources and mass balance
can further complicate the isotopic message in stratified environments.
Better understanding of these multifaceted carbon isotope signals requires
further evaluation of how the processes occurring in redox-stratified water
columns are transferred to the sediments. We therefore characterized and
compared the isotopic signatures of dissolved inorganic carbon (DIC),
carbonate, and organic matter reservoirs at different depths in the water
column and upper sediments of four stratified Mexican lakes that follow a
gradient of alkalinity and salinity. Comparing these systems shows strong
diversity in the carbon isotope signals of the water column and sediments.
Differences in inorganic carbon isotope signatures arise primarily from the
size of the DIC reservoir, buffering the expression of redox-dependent
biological processes as alkalinity increases. Combining this isotopic
dataset with water column physicochemical parameters allows us to identify
oxygenic photosynthesis and aerobic respiration in the four lakes studied,
while anoxygenic photosynthesis is evidenced in only two of them.
Sedimentary organic matter does not originate from the same water column
layers in the four lakes, highlighting the ecological variability that can
stem from different stratified water columns and how it is transferred or
not to the sedimentary record. The least alkaline lake shows higher
isotopic
variability and signatures typical of methanogenesis in the sediment
porewaters. This metabolism, however, does not leave diagnostic isotopic
signatures in the sedimentary archives (organic matter and carbonates),
underlining the fact that even when alkalinity does not strongly buffer the
inorganic carbon reservoir, a comprehensive picture of the active
biogeochemical carbon cycling is not necessarily transferred to the
geological record.</p> |
| first_indexed | 2024-03-13T04:05:06Z |
| format | Article |
| id | doaj.art-4085b909945840cbb6c88709b77af39a |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-03-13T04:05:06Z |
| publishDate | 2023-06-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-4085b909945840cbb6c88709b77af39a2023-06-21T07:22:28ZengCopernicus PublicationsBiogeosciences1726-41701726-41892023-06-01202347236710.5194/bg-20-2347-2023Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradientR. Havas0C. Thomazo1C. Thomazo2M. Iniesto3D. Jézéquel4D. Jézéquel5D. Moreira6R. Tavera7J. Caumartin8E. Muller9P. López-García10K. Benzerara11Biogéosciences, CNRS, Université Bourgogne Franche-Comté, 21000 Dijon, FranceBiogéosciences, CNRS, Université Bourgogne Franche-Comté, 21000 Dijon, FranceInstitut Universitaire de France, 75005 Paris, FranceEcologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, 91190 Gif-sur-Yvette, FranceIPGP, CNRS, Université de Paris Cité, 75005 Paris, FranceUMR CARRTEL, INRAE and USMB, 74200 Thonon-les-Bains, FranceEcologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, 91190 Gif-sur-Yvette, FranceDepartamento de Ecología y Recursos Naturales, Universidad Nacional Autónoma de México, Mexico City, MéxicoInstitut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), CNRS, Muséum National d'Histoire Naturelle, Sorbonne Université, 75005 Paris, FranceInstitut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), CNRS, Muséum National d'Histoire Naturelle, Sorbonne Université, 75005 Paris, FranceEcologie Systématique Evolution, CNRS, Université Paris-Saclay, AgroParisTech, 91190 Gif-sur-Yvette, FranceInstitut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), CNRS, Muséum National d'Histoire Naturelle, Sorbonne Université, 75005 Paris, France<p>Redox-stratified water columns are a prevalent feature of the Earth's history, and ongoing environmental changes tend to promote a resurgence of such settings. Studying modern redox-stratified environments has improved our understanding of biogeochemical processes and element cycling in such water columns. These settings are associated with peculiar carbon biogeochemical cycling, owing to a layered distribution of biological processes in relation to oxidant availability. Metabolisms from distinct biogeochemical layers are diverse and may differently imprint the sedimentological record. Paired carbon isotope compositions of organic matter and carbonates, which are commonly used to characterize these ecological dynamics, can thus vary from one stratified environment to another. Changes in the organic/inorganic carbon sources and mass balance can further complicate the isotopic message in stratified environments. Better understanding of these multifaceted carbon isotope signals requires further evaluation of how the processes occurring in redox-stratified water columns are transferred to the sediments. We therefore characterized and compared the isotopic signatures of dissolved inorganic carbon (DIC), carbonate, and organic matter reservoirs at different depths in the water column and upper sediments of four stratified Mexican lakes that follow a gradient of alkalinity and salinity. Comparing these systems shows strong diversity in the carbon isotope signals of the water column and sediments. Differences in inorganic carbon isotope signatures arise primarily from the size of the DIC reservoir, buffering the expression of redox-dependent biological processes as alkalinity increases. Combining this isotopic dataset with water column physicochemical parameters allows us to identify oxygenic photosynthesis and aerobic respiration in the four lakes studied, while anoxygenic photosynthesis is evidenced in only two of them. Sedimentary organic matter does not originate from the same water column layers in the four lakes, highlighting the ecological variability that can stem from different stratified water columns and how it is transferred or not to the sedimentary record. The least alkaline lake shows higher isotopic variability and signatures typical of methanogenesis in the sediment porewaters. This metabolism, however, does not leave diagnostic isotopic signatures in the sedimentary archives (organic matter and carbonates), underlining the fact that even when alkalinity does not strongly buffer the inorganic carbon reservoir, a comprehensive picture of the active biogeochemical carbon cycling is not necessarily transferred to the geological record.</p>https://bg.copernicus.org/articles/20/2347/2023/bg-20-2347-2023.pdf |
| spellingShingle | R. Havas C. Thomazo C. Thomazo M. Iniesto D. Jézéquel D. Jézéquel D. Moreira R. Tavera J. Caumartin E. Muller P. López-García K. Benzerara Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient Biogeosciences |
| title | Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient |
| title_full | Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient |
| title_fullStr | Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient |
| title_full_unstemmed | Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient |
| title_short | Biogeochemical processes captured by carbon isotopes in redox-stratified water columns: a comparative study of four modern stratified lakes along an alkalinity gradient |
| title_sort | biogeochemical processes captured by carbon isotopes in redox stratified water columns a comparative study of four modern stratified lakes along an alkalinity gradient |
| url | https://bg.copernicus.org/articles/20/2347/2023/bg-20-2347-2023.pdf |
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