Exploring the CO<sub>2</sub> fugacity along the east coast of South America aboard the schooner <i>Tara</i>
<p>The air–sea CO<span class="inline-formula"><sub>2</sub></span> flux in the coastal ocean is a critical component of the global carbon budget, yet it remains poorly understood due to limited data, the many sources and sinks of carbon, and their complex inter...
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| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Earth System Science Data |
| Online Access: | https://essd.copernicus.org/articles/17/3583/2025/essd-17-3583-2025.pdf |
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| Summary: | <p>The air–sea CO<span class="inline-formula"><sub>2</sub></span> flux in the coastal ocean is a critical component of the global carbon budget, yet it remains poorly understood due to limited data, the many sources and sinks of carbon, and their complex interactions. In August–November 2021, the <i>Tara</i> schooner collected over 14 000 km of CO<span class="inline-formula"><sub>2</sub></span> fugacity (<span class="inline-formula"><i>f</i></span>CO<span class="inline-formula"><sub>2</sub></span>) measurements along the coast of South America, including in the Amazon River–ocean continuum (<span class="uri">https://doi.org/10.5281/zenodo.13790064</span>, Olivier et al., 2024a). The Amazon River and its oceanic plume exhibit complex interactions under the combined influence of many processes such as tides and bathymetry. Observations revealed a wide range of <span class="inline-formula"><i>f</i></span>CO<span class="inline-formula"><sub>2</sub></span> values, from up to 3000 <span class="inline-formula">µ</span>atm in the river to a minimum of 42 <span class="inline-formula">µ</span>atm downstream of the plume, where values were notably lower than atmospheric levels. South of the estuary, the <span class="inline-formula"><i>f</i></span>CO<span class="inline-formula"><sub>2</sub></span> of the North Brazil Current waters (0–9° S) exceeds 400 <span class="inline-formula">µ</span>atm, while along the Brazil Current (10–30° S), <span class="inline-formula"><i>f</i></span>CO<span class="inline-formula"><sub>2</sub></span> is around 400 <span class="inline-formula">µ</span>atm and decreases with temperature and distance from the Equator. Due to its high variability in the coastal environment, in the dataset salinity emerged as the primary driver of <span class="inline-formula"><i>f</i></span>CO<span class="inline-formula"><sub>2</sub></span> variability across this dynamic region. Despite strong variability, comparison with discrete samples of other carbonate parameters showed a mean difference of 2 <span class="inline-formula">µ</span>atm, within the range of uncertainties of the chemical formulas used for comparison. This dataset provides critical insights into the under-sampled region of the Brazilian coast, improving our understanding of coastal <span class="inline-formula"><i>f</i></span>CO<span class="inline-formula"><sub>2</sub></span> dynamics and their role in the global carbon budget.</p> |
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| ISSN: | 1866-3508 1866-3516 |