Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement
<p>This study contributes to the inaugural exploration of non-equilibrated ocean alkalinity enhancement (OAE). Total alkalinity (TA) was manipulated, with silicate- and calcium-based <span class="inline-formula">Δ</span>TA gradients ranging from 0 to 600 <span class=&q...
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Copernicus Publications
2024-12-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/21/5707/2024/bg-21-5707-2024.pdf |
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| author | L. Marín-Samper J. Arístegui N. Hernández-Hernández U. Riebesell |
| author_facet | L. Marín-Samper J. Arístegui N. Hernández-Hernández U. Riebesell |
| author_sort | L. Marín-Samper |
| collection | DOAJ |
| description | <p>This study contributes to the inaugural exploration of non-equilibrated ocean alkalinity enhancement (OAE). Total alkalinity (TA) was manipulated, with silicate- and calcium-based <span class="inline-formula">Δ</span>TA gradients ranging from 0 to 600 <span class="inline-formula">µ</span>mol L<span class="inline-formula"><sup>−1</sup></span>, without prior CO<span class="inline-formula"><sub>2</sub></span> sequestration, under natural conditions and at a mesocosm scale (<span class="inline-formula">∼</span> 60 m<span class="inline-formula"><sup>3</sup></span>). This manipulation led to a sustained increase in pH and a decrease in <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> throughout the experiment, as full natural equilibration through sea–air gas exchange did not occur. Implemented in a neritic system under post-bloom conditions, a midway mixing event was simulated. After the inorganic nutrient addition, mild delays in bloom formation were observed. These delays were related to, though not directly proportional to, the <span class="inline-formula">Δ</span>TA gradient, as indicated by the gross production (GP), net community production (NCP), and chlorophyll <span class="inline-formula"><i>a</i></span> (Chl <span class="inline-formula"><i>a</i></span>) concentrations. Notably, the delay was more pronounced for the calcium treatment set compared to the silicate one, with the low-TA treatments exhibiting earlier responses than the high-TA ones. This delay is likely due to the previously documented species-specific negative relationships between high pH/low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> conditions and phytoplankton growth rates. This study underscores the need for further investigation into the implications of these response patterns in terms of trophic transfer and seasonal suitability. Moreover, it is anticipated that a greater delay in bloom formation would be evident with a larger non-equilibrated TA gradient, highlighting the importance of exploring variations in TA thresholds for a comprehensive understanding of OAE's impacts.</p> |
| format | Article |
| id | doaj-art-42e68cabec4f4ae0a71a23d78299d904 |
| institution | OA Journals |
| issn | 1726-4170 1726-4189 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj-art-42e68cabec4f4ae0a71a23d78299d9042025-08-20T02:34:47ZengCopernicus PublicationsBiogeosciences1726-41701726-41892024-12-01215707572410.5194/bg-21-5707-2024Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancementL. Marín-Samper0J. Arístegui1N. Hernández-Hernández2U. Riebesell3Instituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, 35017 Telde, SpainInstituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, 35017 Telde, SpainInstituto de Oceanografía y Cambio Global, Universidad de Las Palmas de Gran Canaria, 35017 Telde, SpainGEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany<p>This study contributes to the inaugural exploration of non-equilibrated ocean alkalinity enhancement (OAE). Total alkalinity (TA) was manipulated, with silicate- and calcium-based <span class="inline-formula">Δ</span>TA gradients ranging from 0 to 600 <span class="inline-formula">µ</span>mol L<span class="inline-formula"><sup>−1</sup></span>, without prior CO<span class="inline-formula"><sub>2</sub></span> sequestration, under natural conditions and at a mesocosm scale (<span class="inline-formula">∼</span> 60 m<span class="inline-formula"><sup>3</sup></span>). This manipulation led to a sustained increase in pH and a decrease in <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> throughout the experiment, as full natural equilibration through sea–air gas exchange did not occur. Implemented in a neritic system under post-bloom conditions, a midway mixing event was simulated. After the inorganic nutrient addition, mild delays in bloom formation were observed. These delays were related to, though not directly proportional to, the <span class="inline-formula">Δ</span>TA gradient, as indicated by the gross production (GP), net community production (NCP), and chlorophyll <span class="inline-formula"><i>a</i></span> (Chl <span class="inline-formula"><i>a</i></span>) concentrations. Notably, the delay was more pronounced for the calcium treatment set compared to the silicate one, with the low-TA treatments exhibiting earlier responses than the high-TA ones. This delay is likely due to the previously documented species-specific negative relationships between high pH/low <span class="inline-formula"><i>p</i></span>CO<span class="inline-formula"><sub>2</sub></span> conditions and phytoplankton growth rates. This study underscores the need for further investigation into the implications of these response patterns in terms of trophic transfer and seasonal suitability. Moreover, it is anticipated that a greater delay in bloom formation would be evident with a larger non-equilibrated TA gradient, highlighting the importance of exploring variations in TA thresholds for a comprehensive understanding of OAE's impacts.</p>https://bg.copernicus.org/articles/21/5707/2024/bg-21-5707-2024.pdf |
| spellingShingle | L. Marín-Samper J. Arístegui N. Hernández-Hernández U. Riebesell Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement Biogeosciences |
| title | Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement |
| title_full | Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement |
| title_fullStr | Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement |
| title_full_unstemmed | Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement |
| title_short | Responses of microbial metabolic rates to non-equilibrated silicate- versus calcium-based ocean alkalinity enhancement |
| title_sort | responses of microbial metabolic rates to non equilibrated silicate versus calcium based ocean alkalinity enhancement |
| url | https://bg.copernicus.org/articles/21/5707/2024/bg-21-5707-2024.pdf |
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