Assessment of methane concentrations in estuarine regions on the coast of the state of São Paulo

Abstract

We evaluated concentrations of atmospheric CH4, which is considered one of the main gases causing global warming. We observed methane concentrations in the Cananéia-Iguape estuarine system on the southern coast of the state of São Paulo, Brazil and in the Santos estuary, Baixada Santista region, coast of the state of São Paulo, Brazil. The south coast region is widely studied as it presents very well-preserved fauna and flora and thus offers an important background on natural emissions. Data acquisition was carried out by a portable gas analyzer (LGR-ICOSTM GLA131), this equipment has a high sensitivity in detecting the gases under study and was placed on board the research vessels Albacora and Alpha Delphini owned by the Institute of Oceanography at the University of São Paulo in campaigns that were carried out between 2021 and 2023 in specific periods. The concentrations observed during the exploratory campaigns in the estuaries on the coast of the State of São Paulo (Iguape Cananéia Estuarine-Lagunar Complex and Santos Estuary) behaved as described in the literature, regions with greater anthropic impact present higher values of methane concentrations in the atmosphere, low-impact regions have lower methane concentrations.