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As propriedades hidrográficas e químicas das massas de água foram analisadas no estreito de Bransfield, uma bacia semi-isolada localizada ao norte da Península Antártica, no Oceano Austral. Os dados foram obtidos pelo Grupo de Oceanografia de Altas Latitudes(GOAL) nos cruzeiros consecutivos dos verões de 2015 até 2018, como parte das atividades executadas pelo projeto NAUTILUS. Nossos objetivos foram(i) quantificar o dióxido de carbono(CO2),associado a atividades antropogênicas(Cant),nas massas de água das bacias central e leste do estreito de Bransfield,e(ii) determinar o estado de acidificaçãodas águas da área de estudo. Baseados no método TrOCA(Tracer combining Oxygen, inorganic Carbon, and total Alkalinity),estimamos uma concentração média de Cantde 51 µmol kg1nas duas bacias, sendoligeiramente maior na bacia central(53 µmol kg1) quena bacia leste(49 µmol kg1).Os resultados indicaram que a ventilação recente das bacias profundas do estreito insere quantidades consideráveis de Cantna região,principalmente através da advecção da Água de Plataforma de Alta Salinidadeoriundado marde Weddell. Além disso, a profundidade média do horizonte de saturação da aragonita é ~ 200 m mais raso na bacia central que na leste. A intrusão de Cantno estreito de Bransfield pode mudar rapidamente o estado de acidificação do oceano devido aos intensos processos de mistura de massas de água We analyzed the hydrographic and chemical properties of the water masses in the Bransfield Strait, a semi-enclosed basin located in the Northern Antarctic Peninsula, Southern Ocean. The dataset analyzed was sampled by the Brazilian High Latitude Oceanography Group(GOAL) between four consecutive summer cruises from 2015 to 2018, as part of the activities executed by the NAUTILUS project. Our aims were(i):to quantify the carbon dioxide(CO2) associated with anthropogenic activities(Cant) in the water masses of the central and eastern basins, and(ii) to determine the ocean acidification state on the study region. Based on the Tracer combining Oxygen, inorganic Carbon, and total Alkalinity(TrOCA) approach, we estimated an averaged Cantconcentration of 51 µmol kg1in the Bransfield Strait, which is slightly higher in the central basin(53 µmol kg1) than the eastern basin(49 µmol kg1).The results indicated that recent ventilation of the Bransfield Strait deep basins brings considerable amounts of Cant, mainly through the advection of High Salinity Shelf Water coming from the Weddell Sea continental shelf. In addition, the averaged depth of aragonite saturation horizon is ~200 m shallower in the central than the eastern basin of the Bransfield Strait. Thus, the Cantintrusion in the Bransfield Strait can rapid change the ocean acidification state due intense water masses mixing process.

The AZORES-I cruise was conducted in August 1998, spanning the length of three latitudinal large-scale sections at 22, 28 and 32ºW. The oceanic carbon system was oversampled by measuring total alkalinity, total inorganic carbon and pH. It is thus possible to estimate anthropogenic CO2 (CANT) and to investigate its relationship with the main water masses that are present. C CANT is calculated using the latest back-calculation techniques: φCTº and TrOCA methods. Although the two approaches produce similar vertical distributions, the results of the TrOCA method show higher CANT variability and produce higher inventories than those of the φCTº method. The large proportion of Mediterranean Water found in the northern part of the study area is the main cause of the observed increase northwards of C CANT inventories. Changes in C CANT inventories between 1981 and 2004 are evaluated using data from the TTO-NAS, OACES-93 and METEOR-60/5 cruises. According to the φCTº and TrOCA approaches, the average long-term rates of C CANT inventory change are 1.32±0.11 mol C m-2 y-1 (P=0.008) and 1.18±0.16 mol C m-2 y-1 (P=0.018), respectively. During the 1993-1998 a significant increase in the C CANT storage rate was detected by the φCTº method. It is thought that this stems directly from the enhanced Labrador Seawater formation after the increased advection observed at the time., La campaña de macro-escala Azores I se desarrolló durante el mes de agosto de 1998 y consta de tres secciones meridionales centradas en 22, 28 y 32ºW. El sobre-muestreo realizado del sistema del carbónico, con medidas de alcalinidad total, carbono inorgánico total y pH, ha permitido el cálculo del CO2 antropogénico (CANT) e investigar su distribución en las masas de agua presentes. El CANT se calculó mediante las últimas técnicas de retro-cálculo disponibles: los métodos φCTº y TrOCA. A pesar de que ambos procedimientos producen distribuciones verticales similares, los resultados del método TrOCA indican mayores inventarios y variabilidad de CANT que los estimados por el método φCTº. La elevada proporción de agua mediterránea presente al norte de la región estudiada es la causa principal del aumento hacia el norte de los inventarios de CANT. Las tasas de cambio en los inventarios de CANT entre 1981 y 2004 se han evaluado utilizando datos de las campañas TTO-NAS, OACES-93 y METEOR-60/5. Según los métodos φCTº y TrOCA, las tasas de cambio promedio a largo plazo del inventario de CANT en esta zona son de 1.32±0.11 mol C m -2 y-1 (p-valor=0.008) y de 1.18±0.16 mol C m-2 y-2 (p-valor=0.018), respectivamente. Durante el periodo 1993-1998 el método φCTº detecta un aumento significativo de la tasa de acumulación de CANT provocado posiblemente por las elevadas tasas de formación de agua de Labrador, derivadas del aumento de la advección observada en dicho periodo.

[EN] The AZORES-I cruise was conducted in August 1998, spanning the length of three latitudinal large-scale sections at 22, 28 and 32ºW. The oceanic carbon system was oversampled by measuring total alkalinity, total inorganic carbon and pH. It is thus possible to estimate anthropogenic CO2 (CANT) and to investigate its relationship with the main water masses that are present. C CANT is calculated using the latest back-calculation techniques: φCTº and TrOCA methods. Although the two approaches produce similar vertical distributions, the results of the TrOCA method show higher CANT variability and produce higher inventories than those of the φCTº method. The large proportion of Mediterranean Water found in the northern part of the study area is the main cause of the observed increase northwards of C CANT inventories. Changes in C CANT inventories between 1981 and 2004 are evaluated using data from the TTO-NAS, OACES-93 and METEOR-60/5 cruises. According to the φCTº and TrOCA approaches, the average long-term rates of C CANT inventory change are 1.32±0.11 mol C m-2 y-1 (P=0.008) and 1.18±0.16 mol C m-2 y-1 (P=0.018), respectively. During the 1993-1998 a significant increase in the C CANT storage rate was detected by the φCTº method. It is thought that this stems directly from the enhanced Labrador Seawater formation after the increased advection observed at the time., [ES] CO2 antropogénico en la región de las Azores. – La campaña de macro-escala Azores I se desarrolló durante el mes de agosto de 1998 y consta de tres secciones meridionales centradas en 22, 28 y 32ºW. El sobre-muestreo realizado del sistema del carbónico, con medidas de alcalinidad total, carbono inorgánico total y pH, ha permitido el cálculo del CO2 antropogénico (CANT) e investigar su distribución en las masas de agua presentes. El CANT se calculó mediante las últimas técnicas de retro-cálculo disponibles: los métodos jCTº y TrOCA. A pesar de que ambos procedimientos producen distribuciones verticales similares, los resultados del método TrOCA indican mayores inventarios y variabilidad de CANT que los estimados por el método jCTº. La elevada proporción de agua mediterránea presente al norte de la región estudiada es la causa principal del aumento hacia el norte de los inventarios de CANT. Las tasas de cambio en los inventarios de CANT entre 1981 y 2004 se han evaluado utilizando datos de las campañas TTO-NAS, OACES-93 y METEOR-60/5. Según los métodos jCTº y TrOCA, las tasas de cambio promedio a largo plazo del inventario de CANT en esta zona son de 1.32±0.11 mol C m-2 y-1 (p-valor=0.008) y de 1.18±0.16 mol C m-2 y-1 (p-valor=0.018), respectivamente. Durante el periodo 1993-1998 el método jCTº detecta un aumento significativo de la tasa de acumulación de CANT provocado posiblemente por las elevadas tasas de formación de agua de Labrador, derivadas del aumento de la advección observada en dicho periodo., This work was developed and funded by the European Commission within the 6th Framework Programme (EU FP6 CARBOOCAN Integrated Project, Contract no. 511176), MEC (CTM2006–27116–E/MAR), CAIBEX Project (CTM2007-66408-C02) and by the Xunta de Galicia within the INCITE framework (M4AO project PGIDIT07PXB402153PR). Marcos Vázquez-Rodríguez is funded by the Consejo Superior de Investigaciones Científicas (CSIC) I3P pre-doctoral grant programme REF.: I3P-BPD2005.