The diurnal cycle of <i>p</i>CO<sub>2</sub> in the coastal region of the Baltic Sea
<p>The direction and magnitude of carbon dioxide fluxes between the atmosphere and the sea are regulated by the gradient in the partial pressure of carbon dioxide (<span class="inline-formula"><i>p</i>CO<sub>2</sub></span>) across the air–sea inter...
Guardado en:
| Autores principales: | , , , , , , , , |
|---|---|
| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
Copernicus Publications
2021
|
| Materias: | |
| Acceso en línea: | https://doaj.org/article/4862e8d835544ff0a108191efe990eff |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| Sumario: | <p>The direction and magnitude of carbon dioxide fluxes between the atmosphere and the sea are regulated by the gradient in the partial pressure of carbon dioxide (<span class="inline-formula"><i>p</i>CO<sub>2</sub></span>) across the air–sea interface. Typically, observations of <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> at the sea surface are carried out by using research vessels and ships of opportunity, which usually do not resolve the diurnal cycle of <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> at a given location. This study evaluates the magnitude and driving processes of the diurnal cycle of <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> in a coastal region of the Baltic Sea. We present <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> data from July 2018 to June 2019 measured in the vicinity of the island of Utö at the outer edge of the Archipelago Sea, and quantify the relevant physical, biological, and chemical processes controlling <span class="inline-formula"><i>p</i>CO<sub>2</sub></span>. The highest monthly median of diurnal <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> variability (31 <span class="inline-formula">µatm</span>) was observed in August and predominantly driven by biological processes. Biological fixation and mineralization of carbon led to sinusoidal diurnal <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> variations, with a maximum in the morning and a minimum in the afternoon. Compared with the biological carbon transformations, the impacts of air–sea fluxes and temperature changes on <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> were small, with their contributions to the monthly medians of diurnal <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> variability being up to 12 and 5 <span class="inline-formula">µ</span>atm, respectively. During upwelling events, short-term <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> variability (up to 500 <span class="inline-formula">µ</span>atm within a day) largely exceeded the usual diurnal cycle. If the net annual air–sea flux of carbon dioxide at our study site and for the sampled period is calculated based on a data subset that consists of only one regular measurement per day, the bias in the net exchange depends on the sampling time and can amount up to <span class="inline-formula">±12</span> %. This finding highlights the importance of continuous surface <span class="inline-formula"><i>p</i>CO<sub>2</sub></span> measurements at fixed locations for the assessment of the short-term variability of the carbonate system and the correct determination of air–sea <span class="inline-formula">CO<sub>2</sub></span> fluxes.</p> |
|---|