EVALUATING DIRECT AND INDIRECT pCO₂ MEASUREMENTS IN ESTUARINE ENVIRONMENTS

EVALUATING DIRECT AND INDIRECT pCO₂ MEASUREMENTS IN ESTUARINE ENVIRONMENTS. Estuaries are dynamic systems globally characterized as sources of CO₂ to the atmosphere. However, they present large spatial-temporal variability in both pCO₂ and FCO₂. Increased CO₂ emissions turns imperative to obtain continuous and accurate measurements of pCO₂ in air and water to monitor FCO₂ in these sensitive and complex environments. Currently, direct measurements of pCO₂ and estimates of FCO₂ in estuarine regions are still scarce and frequently the indirect pCO₂ estimates are used that consists of measurements from at least two other parameters of the carbonate system: total alkalinity, dissolved inorganic carbon or pH. In this work, we evaluated recent direct and indirect measurements of pCO₂ in the Jaguaribe River estuary-CE. This study provides a critical analysis of the data obtained through the two main methods mostly used to estimate pCO₂, presenting the challenges towards greater consistency in obtaining data for a better understanding of the carbonate system in estuarine waters. We highlight the potential for continuous pCO₂ measurements and long-term monitoring in coastal environments, contributing to improve knowledge of regional CO₂ exchanges and to elucidate the role of estuaries in the global carbon cycle.

Keywords:
carbon dioxide fluxes; estuaries; carbonate system; pCO₂; total alkalinity; pH