Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela
Ten years of monthly observations of the δ15N of sinking particulate nitrogen (δ15N-PN (in ‰ versus atmospheric N2)=[(15N/14N)sample/(15N/14N)standard)-1]1000) in the Cariaco Basin, Venezuela, confirm that the basin's bottom sediments store information about nitrogen dynamics related to seasona...
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ftunisfloridatam:oai:digitalcommons.usf.edu:msc_facpub-2113 2023-05-15T17:35:38+02:00 Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela Montes, Enrique Thunell, R. Muller-Karger, Frank E Lorenzoni, Laura Tappa, E. Troccoli, L. Astor, Y. Varela, R. 2013-01-01T08:00:00Z https://digitalcommons.usf.edu/msc_facpub/1056 https://doi.org/10.1016/j.dsr2.2013.01.006 unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/msc_facpub/1056 doi:10.1016/j.dsr2.2013.01.006 Marine Science Faculty Publications Cariaco Basin Climate variability Nitrogen fixation Nitrogen isotopes Sediment traps Sinking particulate organic matter article 2013 ftunisfloridatam https://doi.org/10.1016/j.dsr2.2013.01.006 2021-10-09T07:51:46Z Ten years of monthly observations of the δ15N of sinking particulate nitrogen (δ15N-PN (in ‰ versus atmospheric N2)=[(15N/14N)sample/(15N/14N)standard)-1]1000) in the Cariaco Basin, Venezuela, confirm that the basin's bottom sediments store information about nitrogen dynamics related to seasonal and interannual variability in regional surface ocean processes. During the upwelling period of the southern Caribbean Sea (February-April), the δ15N-PN is similar to that of the thermocline nitrate (~3.5‰). This nitrate is imported into the Cariaco Basin with Subtropical Underwater (SUW), which wells up near the coast. Thus, particles generated by phytoplankton photosynthesis during this productive period bear a sub-tropical North Atlantic isotopic imprint of N2 fixation (low compared to the global average of nitrate δ15N≈5‰). During the non-upwelling period when surface waters are stratified (September-November), the δ15N-PN is also 3.5-4.0‰, and reflects a mixture of local N2 fixation within the mixed layer, inputs of terrigenous organic matter and SUW nitrate consumption by phytoplankton below the mixed layer, which most likely exerts the strongest control on the δ15N-PN signal during this time. In the transition periods of May-July and December-January, the δ15N-PN increases to 4.5-6.5‰. This coincides with maxima of continental material fluxes (terrestrial PON δ15N is >6‰) into the Cariaco Basin. The δ15N signal in the sediments of the Cariaco Basin thus provides information about the relative strength of the local coastal upwelling, the relative input of continental material via river runoff, and local N2 fixation. The findings contribute to interpretations of the basin's paleoclimatic nitrogen cycle variations based on observations of the sedimentary δ15N record at this location. Article in Journal/Newspaper North Atlantic Digital Commons University of South Florida (USF) Deep Sea Research Part II: Topical Studies in Oceanography 93 96 107 |
institution |
Open Polar |
collection |
Digital Commons University of South Florida (USF) |
op_collection_id |
ftunisfloridatam |
language |
unknown |
topic |
Cariaco Basin Climate variability Nitrogen fixation Nitrogen isotopes Sediment traps Sinking particulate organic matter |
spellingShingle |
Cariaco Basin Climate variability Nitrogen fixation Nitrogen isotopes Sediment traps Sinking particulate organic matter Montes, Enrique Thunell, R. Muller-Karger, Frank E Lorenzoni, Laura Tappa, E. Troccoli, L. Astor, Y. Varela, R. Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela |
topic_facet |
Cariaco Basin Climate variability Nitrogen fixation Nitrogen isotopes Sediment traps Sinking particulate organic matter |
description |
Ten years of monthly observations of the δ15N of sinking particulate nitrogen (δ15N-PN (in ‰ versus atmospheric N2)=[(15N/14N)sample/(15N/14N)standard)-1]1000) in the Cariaco Basin, Venezuela, confirm that the basin's bottom sediments store information about nitrogen dynamics related to seasonal and interannual variability in regional surface ocean processes. During the upwelling period of the southern Caribbean Sea (February-April), the δ15N-PN is similar to that of the thermocline nitrate (~3.5‰). This nitrate is imported into the Cariaco Basin with Subtropical Underwater (SUW), which wells up near the coast. Thus, particles generated by phytoplankton photosynthesis during this productive period bear a sub-tropical North Atlantic isotopic imprint of N2 fixation (low compared to the global average of nitrate δ15N≈5‰). During the non-upwelling period when surface waters are stratified (September-November), the δ15N-PN is also 3.5-4.0‰, and reflects a mixture of local N2 fixation within the mixed layer, inputs of terrigenous organic matter and SUW nitrate consumption by phytoplankton below the mixed layer, which most likely exerts the strongest control on the δ15N-PN signal during this time. In the transition periods of May-July and December-January, the δ15N-PN increases to 4.5-6.5‰. This coincides with maxima of continental material fluxes (terrestrial PON δ15N is >6‰) into the Cariaco Basin. The δ15N signal in the sediments of the Cariaco Basin thus provides information about the relative strength of the local coastal upwelling, the relative input of continental material via river runoff, and local N2 fixation. The findings contribute to interpretations of the basin's paleoclimatic nitrogen cycle variations based on observations of the sedimentary δ15N record at this location. |
format |
Article in Journal/Newspaper |
author |
Montes, Enrique Thunell, R. Muller-Karger, Frank E Lorenzoni, Laura Tappa, E. Troccoli, L. Astor, Y. Varela, R. |
author_facet |
Montes, Enrique Thunell, R. Muller-Karger, Frank E Lorenzoni, Laura Tappa, E. Troccoli, L. Astor, Y. Varela, R. |
author_sort |
Montes, Enrique |
title |
Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela |
title_short |
Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela |
title_full |
Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela |
title_fullStr |
Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela |
title_full_unstemmed |
Sources of Δ15N Variability in Sinking Particulate Nitrogen in the Cariaco Basin, Venezuela |
title_sort |
sources of δ15n variability in sinking particulate nitrogen in the cariaco basin, venezuela |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2013 |
url |
https://digitalcommons.usf.edu/msc_facpub/1056 https://doi.org/10.1016/j.dsr2.2013.01.006 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Marine Science Faculty Publications |
op_relation |
https://digitalcommons.usf.edu/msc_facpub/1056 doi:10.1016/j.dsr2.2013.01.006 |
op_doi |
https://doi.org/10.1016/j.dsr2.2013.01.006 |
container_title |
Deep Sea Research Part II: Topical Studies in Oceanography |
container_volume |
93 |
container_start_page |
96 |
op_container_end_page |
107 |
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1766134846476779520 |