Autor(es)

Millo, Christian ; Kujawski, Rita Stasevskas ; de Mello e Sousa, Silvia Helena ; Grizon, Anna ; Oudin, Elisa ; Berbel, Glaucia Bueno Benedetti ; Bertrand, Guillaume ; Chiozzini, Vitor Gonsalez ; Braga, Elisabete de Santis

• Tipo de documento: Artigo Científico
• Fonte: Ocean and Coastal Research; v. 72, p. 15-pg., 2024-01-01.

Resumo

The carbon isotope composition of Dissolved Inorganic Carbon (delta C-13(DIC)) is a useful tool to study the carbon budget in estuarine settings. Here we present the first set of delta C-13(DIC) data from the Canan & eacute;ia-Iguape Estuarine Complex (S & atilde;o Paulo, Brazil), a changing environment undergoing freshening at a rate of the order of 770 m(3) s(-1). We measured delta C-13(DIC) values of water at 15 stations distributed across the area, both during neap and spring tide, in May 2015 and April 2017. The spatio-temporal variability of delta C-13(DIC) suggests a conservative mixing of two water endmembers, freshwater with delta C-13(DIC) = -10 parts per thousand (V-PDB) and seawater with delta C-13(DIC) = +2.0 parts per thousand (V-PDB). Linear regression of delta C-13(DIC) vs. salinity predicts the delta C-13(DIC) values of open ocean surface water from the nearby Santos Basin and suggests that the freshwater and seawater endmembers mix at 1:1 proportion in the estuarine complex. Mixing was the dominant process governing the behavior of delta C-13(DIC) values, whereas photosynthesis, degradation of organic matter, and CO2 uptake or outgassing did not play a significant role. In particular, phytoplankton production had no impact on delta C-13(DIC), suggesting that the ecosystem was exempt from eutrophication. Long-term freshening in the NE sector of the estuary did not significantly impact the delta C-13 values of DIC. These results underline the need for long-term measurements of delta C-13(DIC) in the study area to contribute to the understanding of the evolution of the estuarine complex, whose freshening trend could be enhanced by extreme precipitation events linked to climate change. (AU)

• Processo FAPESP: 16/03381-3 - Evolução dos depósitos de contornitos no Quaternário superior e sua interação com massas de água na Bacia de Santos, Atlântico Sudoeste.
• Beneficiário: Silvia Helena de Mello e Sousa
• Modalidade de apoio: Auxílio à Pesquisa - Regular