The ocean’s role in the greenhouse gas dynamics has been on the radar of scientists for the last decades for better understanding and thus forecasting the future conditions, due to increasing, mainly, carbon dioxide (CO₂) atmospheric concentrations. Compared to open ocean regions, coastal waters show more variability, and these complex systems are harder to predict, mainly due to its interactions with land, human activity and coastal ecosystems. The Brazilian “Amazônia Azul” (combination of Brazil’s Exclusive Economic Zone and Continental Shelf) still has limited amount of carbon data available, mostly due to the lack of sufficient studies with spatial and temporal coverage with a common standardized methodology. Besides that, the Amazon river plays an important role as source of CO₂ in the flooded areas of the river and as a sink of CO₂ in the river plume, with influence in the western tropical Atlantic. To improve the understanding of the dynamics in “Amazonia Azul” and to increase data coverage, we implemented in 2022 an autonomous measuring system in the first Brazilian ship of opportunity (SOOP) line. The line is operating between Santos and Manaus (1300 km up in the Amazon river), measuring continuously temperature, salinity, dissolved oxygen, CO₂ in the surface water. Here we present the first data set spanning from the inland Amazon river to the offshore coastal waters of Brazil. The data show the sharp gradient between riverine and coastal waters and the resulting over- and undersaturation for CO_2.

Primary Presenter: Carlos Musetti de Assis, GEOMAR (cmusetti@geomar.de)

Authors:

Arne Körtzinger,  GEOMAR Helmholtz Centre for Ocean Research Kiel  (akortzinger@geomar.de)

Tobias Steinhoff,  GEOMAR Helmholtz Centre for Ocean Research Kiel  (tsteinhoff@geomar.de)

Leticia Cotrim da Cunha, Rio de Janeiro State University  (lcotrim@uerj.br)

Raquel Renó de Oliveira, Rio de Janeiro State University  (oliveira.raquel_3@posgraduacao.uerj.br)