Biogeochemical response to widespread anoxia in the past ocean
Oxygen is a key element for life on earth. Oxygen concentrations in the ocean vary greatly in space and time. These changes are regulated by various physical and biogeochemical processes, such as primary productivity, sea surface temperatures and ocean circulation. In the geological past, several pe...
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ftunivutrecht:oai:dspace.library.uu.nl:1874/307365 2023-07-23T04:20:29+02:00 Biogeochemical response to widespread anoxia in the past ocean Ruvalcaba Baroni, I. UU-F&M: Ocean biochemistry of the mid-Cretaceous: reconstructing the nutrient-biosphere-climate-link Geochemistry Slomp, Caroline Middelburg, Jack 2015-02-06 image/pdf https://dspace.library.uu.nl/handle/1874/307365 en eng UU Dept. of Earth Sciences https://dspace.library.uu.nl/handle/1874/307365 info:eu-repo/semantics/OpenAccess Oceanic Anoxic Event phosphorus nitrogen carbon proto-North Atlanitc ocean circulation Dissertation 2015 ftunivutrecht 2023-07-02T01:12:41Z Oxygen is a key element for life on earth. Oxygen concentrations in the ocean vary greatly in space and time. These changes are regulated by various physical and biogeochemical processes, such as primary productivity, sea surface temperatures and ocean circulation. In the geological past, several periods of widespread anoxia have been identified. These are typically accompanied with major perturbations of the cycles of carbon, phosphorus (P) and nitrogen (N). These are registered in the geological records and can be used to study Earth’s past environmental conditions. Our knowledge of the biogeochemical response to long-term deoxygenation in the ocean is still limited. This study focuses on the biogeochemistry in the ocean during a well-demarcated anoxic event that occurred in the mid-Cretaceous (94 Ma ago), when atmospheric CO2 levels were higher than at present. This event lasted approximately 550 kys and is termed Oceanic Anoxic Event 2 (OAE2). Most available geological records for OAE2 are from the North Atlantic, which during the mid-Cretaceous was a semi-enclosed deep basin (i.e. proto-North Atlantic) with a restricted connection to the Pacific and Tethys Ocean. In this research, a multi-box ocean model describing the cycles of water, carbon, oxygen, N and P of the proto-North Atlantic is built to better understand the key mechanisms involved in the development of widespread anoxia during OAE2. Because our knowledge of spatial variability in bottom-water conditions in the northern open ocean of the proto-North Atlantic is limited, proxy data from several deep-sea sites in the northern proto-North Atlantic were collected. Proxy data strongly suggest that, during OAE2, bottom waters in the entire deep proto-North Atlantic were anoxic and that the ocean circulation in the basin was restricted. Moreover, the N isotopic composition (δ15N) of organic matter buried in sediments in samples treated with acid led to selective removal of N compounds and thus should not be used to describe N dynamics in past ... Doctoral or Postdoctoral Thesis North Atlantic Utrecht University Repository Pacific |
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English |
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Oceanic Anoxic Event phosphorus nitrogen carbon proto-North Atlanitc ocean circulation |
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Oceanic Anoxic Event phosphorus nitrogen carbon proto-North Atlanitc ocean circulation Ruvalcaba Baroni, I. Biogeochemical response to widespread anoxia in the past ocean |
topic_facet |
Oceanic Anoxic Event phosphorus nitrogen carbon proto-North Atlanitc ocean circulation |
description |
Oxygen is a key element for life on earth. Oxygen concentrations in the ocean vary greatly in space and time. These changes are regulated by various physical and biogeochemical processes, such as primary productivity, sea surface temperatures and ocean circulation. In the geological past, several periods of widespread anoxia have been identified. These are typically accompanied with major perturbations of the cycles of carbon, phosphorus (P) and nitrogen (N). These are registered in the geological records and can be used to study Earth’s past environmental conditions. Our knowledge of the biogeochemical response to long-term deoxygenation in the ocean is still limited. This study focuses on the biogeochemistry in the ocean during a well-demarcated anoxic event that occurred in the mid-Cretaceous (94 Ma ago), when atmospheric CO2 levels were higher than at present. This event lasted approximately 550 kys and is termed Oceanic Anoxic Event 2 (OAE2). Most available geological records for OAE2 are from the North Atlantic, which during the mid-Cretaceous was a semi-enclosed deep basin (i.e. proto-North Atlantic) with a restricted connection to the Pacific and Tethys Ocean. In this research, a multi-box ocean model describing the cycles of water, carbon, oxygen, N and P of the proto-North Atlantic is built to better understand the key mechanisms involved in the development of widespread anoxia during OAE2. Because our knowledge of spatial variability in bottom-water conditions in the northern open ocean of the proto-North Atlantic is limited, proxy data from several deep-sea sites in the northern proto-North Atlantic were collected. Proxy data strongly suggest that, during OAE2, bottom waters in the entire deep proto-North Atlantic were anoxic and that the ocean circulation in the basin was restricted. Moreover, the N isotopic composition (δ15N) of organic matter buried in sediments in samples treated with acid led to selective removal of N compounds and thus should not be used to describe N dynamics in past ... |
author2 |
UU-F&M: Ocean biochemistry of the mid-Cretaceous: reconstructing the nutrient-biosphere-climate-link Geochemistry Slomp, Caroline Middelburg, Jack |
format |
Doctoral or Postdoctoral Thesis |
author |
Ruvalcaba Baroni, I. |
author_facet |
Ruvalcaba Baroni, I. |
author_sort |
Ruvalcaba Baroni, I. |
title |
Biogeochemical response to widespread anoxia in the past ocean |
title_short |
Biogeochemical response to widespread anoxia in the past ocean |
title_full |
Biogeochemical response to widespread anoxia in the past ocean |
title_fullStr |
Biogeochemical response to widespread anoxia in the past ocean |
title_full_unstemmed |
Biogeochemical response to widespread anoxia in the past ocean |
title_sort |
biogeochemical response to widespread anoxia in the past ocean |
publisher |
UU Dept. of Earth Sciences |
publishDate |
2015 |
url |
https://dspace.library.uu.nl/handle/1874/307365 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://dspace.library.uu.nl/handle/1874/307365 |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1772184861614800896 |