Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling
To keep global warming below 1.5°C, technologies that remove carbon from the atmosphere will be needed. Ocean artificial upwelling of nutrient-rich water stimulates primary productivity and could enhance the biological carbon pump for natural CO2 removal. Its potential may depend on the Si availabil...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2023-07-01
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| Series: | Frontiers in Marine Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmars.2023.1181351/full |
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| author | Moritz Baumann Silvan Urs Goldenberg Jan Taucher Mar Fernández-Méndez Joaquin Ortiz Jacqueline Haussmann Ulf Riebesell |
| author_facet | Moritz Baumann Silvan Urs Goldenberg Jan Taucher Mar Fernández-Méndez Joaquin Ortiz Jacqueline Haussmann Ulf Riebesell |
| author_sort | Moritz Baumann |
| collection | DOAJ |
| description | To keep global warming below 1.5°C, technologies that remove carbon from the atmosphere will be needed. Ocean artificial upwelling of nutrient-rich water stimulates primary productivity and could enhance the biological carbon pump for natural CO2 removal. Its potential may depend on the Si availability in the upwelled water, which regulates the abundance of diatoms that are key carbon exporters. In a mesocosm experiment, we tested the effect of nutrient composition (Si relative to N) in artificially upwelled waters on export quantity and quality in a subtropical oligotrophic environment. Upwelling led to a doubling of exported particulate matter and increased C:N ratios to well beyond Redfield (9.5 to 11.1). High Si availability stimulated this carbon over-consumption further, resulting in a temporary ~5-fold increase in POC export and ~30% increase in C:N ratios compared to Si-scarce upwelling. Whilst the biogenic Si ballast of the export flux increased more than 3.5-fold over the Si:N gradient, these heavier particles did not sink faster. On the contrary, sinking velocity decreased considerably under high Si:N, most likely due to reduced particle size. Respiration rates remained similar across all treatments indicating that biogenic Si did not protect particles against microbial degradation. Si availability thus influenced key processes of the biological carbon pump in counteracting ways by increasing the export magnitude and associated C:N ratios but decreasing the efficiency of carbon transfer to depth. These opposing effects need to be considered when evaluating the potential of artificial upwelling as negative emission technology. |
| first_indexed | 2024-03-13T01:13:05Z |
| format | Article |
| id | doaj.art-d987cf59554749e78e427508806d3b69 |
| institution | Directory Open Access Journal |
| issn | 2296-7745 |
| language | English |
| last_indexed | 2024-03-13T01:13:05Z |
| publishDate | 2023-07-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj.art-d987cf59554749e78e427508806d3b692023-07-05T17:23:19ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452023-07-011010.3389/fmars.2023.11813511181351Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwellingMoritz Baumann0Silvan Urs Goldenberg1Jan Taucher2Mar Fernández-Méndez3Joaquin Ortiz4Jacqueline Haussmann5Ulf Riebesell6Biological Oceanography, GEOMAR Helmholtz Centre for Ocean Research, Kiel, GermanyBiological Oceanography, GEOMAR Helmholtz Centre for Ocean Research, Kiel, GermanyBiological Oceanography, GEOMAR Helmholtz Centre for Ocean Research, Kiel, GermanyBiosciences, Polar Biological Oceanography, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, GermanyBiological Oceanography, GEOMAR Helmholtz Centre for Ocean Research, Kiel, GermanyBiological Oceanography, GEOMAR Helmholtz Centre for Ocean Research, Kiel, GermanyBiological Oceanography, GEOMAR Helmholtz Centre for Ocean Research, Kiel, GermanyTo keep global warming below 1.5°C, technologies that remove carbon from the atmosphere will be needed. Ocean artificial upwelling of nutrient-rich water stimulates primary productivity and could enhance the biological carbon pump for natural CO2 removal. Its potential may depend on the Si availability in the upwelled water, which regulates the abundance of diatoms that are key carbon exporters. In a mesocosm experiment, we tested the effect of nutrient composition (Si relative to N) in artificially upwelled waters on export quantity and quality in a subtropical oligotrophic environment. Upwelling led to a doubling of exported particulate matter and increased C:N ratios to well beyond Redfield (9.5 to 11.1). High Si availability stimulated this carbon over-consumption further, resulting in a temporary ~5-fold increase in POC export and ~30% increase in C:N ratios compared to Si-scarce upwelling. Whilst the biogenic Si ballast of the export flux increased more than 3.5-fold over the Si:N gradient, these heavier particles did not sink faster. On the contrary, sinking velocity decreased considerably under high Si:N, most likely due to reduced particle size. Respiration rates remained similar across all treatments indicating that biogenic Si did not protect particles against microbial degradation. Si availability thus influenced key processes of the biological carbon pump in counteracting ways by increasing the export magnitude and associated C:N ratios but decreasing the efficiency of carbon transfer to depth. These opposing effects need to be considered when evaluating the potential of artificial upwelling as negative emission technology.https://www.frontiersin.org/articles/10.3389/fmars.2023.1181351/fullartificial upwellingbiological carbon pumpparticulate matter exportsinking velocityremineralization ratecarbon sequestration |
| spellingShingle | Moritz Baumann Silvan Urs Goldenberg Jan Taucher Mar Fernández-Méndez Joaquin Ortiz Jacqueline Haussmann Ulf Riebesell Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling Frontiers in Marine Science artificial upwelling biological carbon pump particulate matter export sinking velocity remineralization rate carbon sequestration |
| title | Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling |
| title_full | Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling |
| title_fullStr | Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling |
| title_full_unstemmed | Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling |
| title_short | Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling |
| title_sort | counteracting effects of nutrient composition si n on export flux under artificial upwelling |
| topic | artificial upwelling biological carbon pump particulate matter export sinking velocity remineralization rate carbon sequestration |
| url | https://www.frontiersin.org/articles/10.3389/fmars.2023.1181351/full |
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