This manuscript presents an inventory of the carbonate system from the main water masses comprising the marine current system on Brazil’s northeast coast (South Atlantic Ocean). For this purpose, four transects were conducted with an approximate length of 357 km (each one) through the platform and continental slope of the Sergipe–Alagoas sedimentary basin. Water samples were then collected in vertical profiles measuring from 5 to 1,799 meters depth, totaling 34 stations. Total alkalinity, calcium, and total boron were obtained analytically from these samples and by relationships with salinity. Speciation and concentration of the carbonate system were obtained by means of thermodynamic modeling. The results revealed that the empirical models used to calculate the concentrations of TA, calcium and total boron showed relevant variation when compared to the analytical values (TA: 5.0–6.5%; Ca: 0.4–4.8%; BT: 7.0–18.9%). However, the speciation and concentration of the carbonate system (CA, DIC, CO32−, CO2(aq), ΩCalc, and ΩArag) obtained from the empirical values of TA, calcium and total boron did not differ significantly from those obtained analytically (0.0–6.1%). On the other hand, the parameters of pH, HCO3‐, CO3(aq)2‐, CO2(aq), ρCO2, ΩCalc, and ΩArag varied significantly within the different water masses (p < 0.05). This study supports and encourages acidification monitoring projects in the South Atlantic Ocean, based on modeling the carbonate system parameters generated in real-time.

The quantitative assessment of the carbonate system represents one of the biggest challenges toward the "Sustainable Development Goals" defined by the United Nations in 2015. In this sense, the present study investigated the Spatio-temporal dynamics of the carbonate system and the effects of the El Niño and La Niña phenomena over the Cabo Frio upwelling area. The physical characterization of the site was carried out through data on wind speed and sea surface temperature. Water samples were also collected during the oceanographic cruise onboard the Diadorim R/V (Research Vessel). From these samples, the parameters of absolute and practical salinity, density, pH, total alkalinity, carbonate, calcite, aragonite, bicarbonate dissolved inorganic carbon, carbon dioxide, partial pressure of carbon, calcium, and total boron were obtained. The highest average concentration of bicarbonate in S1 (2018 µmol/kg) seems to contribute to the dissolved inorganic carbon values (2203 µmol/kg). The values of calcite saturation state, aragonite saturation state, and carbonate were higher on the surface of each station (calcite saturation state = 4.80–5.48; aragonite saturation state = 3.10–3.63, and carbonate = 189–216 µmol/kg). The mean values of pH were similar in the day/night samples (7.96/7.97). The whole carbonate system was calculated through thermodynamic modeling with the Marine Chemical Analysis (AQM) program loaded with the results of the following parameters: temperature, salinity, total alkalinity, and pH parameters. This manuscript presents original data on the carbonate system and the "acidification" process influenced by the Cabo Frio upwelling, which directly depends on the El Niño and La Niña phenomena oscillations in the sea surface temperature.

The quantitative assessment of the carbonate system represents one of the biggest challenges toward the "Sustainable Development Goals" defined by the United Nations in 2015. In this sense, the present study investigated the Spatio-temporal dynamics of the carbonate system and the effects of the phenoms ENOS and ENSO over the Cabo Frio upwelling area. The physical characterization of the site was carried out through data on wind speed and sea surface temperature (SST). Water samples were also collected during the oceanographic cruise onboard the Diadorim Oceanographic Research Vessel. From these samples, the parameters of absolute and practical salinity, density, pH, total alkalinity, carbonate, calcite, aragonite, \(C{O}_{3}^{2-}\), \(HC{O}_{3}^{-}\), dissolved inorganic carbon, carbon dioxide, partial pressure of carbon, calcium, and total boron were obtained. After the physical-chemical survey described above, the same parameters were calculated through thermodynamic modeling with the Marine Chemical Analysis (AQM) software loaded with temperature, salinity, TA, and pH parameters. This manuscript presents original data on the carbonate system and the "acidification" process influenced by the Cabo Frio upwelling, which directly depends on the El Niño and La Niña phenomena oscillations in the sea surface temperature (SST).

The quantitative assessment of the carbonate system represents one of the biggest challenges defined by the United Nations in 2015 toward the "Sustainable Development Goals" (SDGs). In this sense, the present study investigated the Spatio-temporal dynamics of the carbonate system and the effects of the phenoms ENOS and ENSO over the Cabo Frio upwelling area. The physical characterization of the site was carried out through wind speed and sea surface temperature (SST) data. Water samples were collected during the oceanographic cruise onboard the Diadorim R/V (Research Vessel). From these samples, the parameters of absolute and practical salinity, density, pH, total alkalinity, carbonate, calcite, aragonite, CO32-, HCO3-, dissolved inorganic carbon, carbon dioxide, partial pressure of carbon, calcium, and total boron were obtained. After the physical-chemical survey, the same parameters were calculated through thermodynamic modeling with the Marine Chemical Analysis (AQM) software loaded with the results of the following parameters: temperature, salinity, TA, and pH parameters. This manuscript presents original data on the carbonate system and the "acidification" process influenced by the Cabo Frio upwelling, which directly depends on the El Niño and La Niña phenomena oscillations in the sea surface temperature (SST).

The quantitative assessment of the carbonate system represents one of the biggest challenges toward the "Sustainable Development Goals" defined by the United Nations in 2015. In this sense, the present study investigated the Spatio-temporal dynamics of the carbonate system and the effects of the phenoms ENOS and ENSO over the Cabo Frio upwelling area. The physical characterization of the site was carried out through data on wind speed and sea surface temperature (SST). Water samples were also collected during the oceanographic cruise onboard the Diadorim R/V (Research Vessel). From these samples, the parameters of absolute and practical salinity, density, pH, total alkalinity, carbonate, calcite, aragonite, \(C{O}_{3}^{2-}\), \(HC{O}_{3}^{-}\), dissolved inorganic carbon, carbon dioxide, partial pressure of carbon, calcium, and total boron were obtained. After the physical-chemical survey, the same parameters were calculated through thermodynamic modeling with the Marine Chemical Analysis (AQM) software loaded with the results of the following parameters: temperature, salinity, TA, and pH parameters. This manuscript presents an original data on the carbonate system and the "acidification" process influenced by the Cabo Frio upwelling, which directly depends on the El Niño and La Niña phenomena oscillations in the sea surface temperature (SST).