Passaúna Reservoir Continuous pCO₂ and Dissolved Oxygen Monitoring Dataset (June–October 2024)

This dataset contains high-frequency measurements of dissolved carbon dioxide (pCO₂) and dissolved oxygen (DO) collected in the Passaúna Reservoir (Paraná, Brazil, 25°30'43.5"S 49°22'09.4"W) between June and October 2024 during three field campaigns totaling 78 days of continuous monitoring. Dissolved pCO₂ was measured using a custom low-cost monitoring platform consisting of a marble-type gas–water equilibrator coupled to a SenseAir K30 nondispersive infrared (NDIR) sensor and a microcontroller-based data acquisition system. Dissolved oxygen was measured concurrently using a miniDOT optical dissolved oxygen logger (Precision Measurement Engineering, PME). The dataset includes timestamped measurements of pCO₂, dissolved oxygen concentration and water temperature. The monitoring system was deployed on a floating photovoltaic platform and operated autonomously throughout the study period. The data were collected to evaluate temporal variability in carbon dynamics, air–water CO₂ departure, and ecosystem metabolism in a subtropical reservoir, while also supporting the validation of a low-cost, energy-efficient platform for long-term autonomous pCO₂ monitoring. These data support the manuscript: “A Microcontroller-Based, Low-Cost Platform for Continuous pCO₂ Measurements in Lakes and Reservoirs.”