Autonomous buoy station at a carbon measurement supersite: integrated monitoring of the freshwater ecosystem and greenhouse gas fluxes

Abstract

This paper presents the experience of deploying an autonomous buoy station (ABS) for high-frequency real-time monitoring of water quality parameters and dissolved greenhouse gases (CH₄ and CO₂) at the Volga Carbon Supersite (Kuibyshev Reservoir, Russia). Lowland reservoirs are important sources of greenhouse gases, yet their contribution to regional carbon budgets remains constrained by the lack of continuous, synchronized observations. To the best of our knowledge, for the first time in Russia, a YSI EXO2s multiparameter sonde was integrated with direct in situ sensors for methane (METS) and carbon dioxide (AMT) on a single autonomous platform based on the Daowan buoy. The developed hardware-software architecture includes 4G data transmission, a multithreaded Python TCP server, and long-term storage in PostgreSQL with the TimescaleDB extension, enabling data synchronization at 4‑minute resolution. Interactive monitoring and visualization were implemented using Grafana. During the deployment period from July to October 2025, the system collected approximately 35,000 records, providing a detailed assessment of diurnal and seasonal dynamics. The results revealed short-term peaks in dissolved methane concentrations, potentially associated with episodic ebullition events, which are typically missed by discrete sampling methods. Integration of the ABS with eddy covariance systems and floating chambers enables cross-verification of flux data and the calibration of regional bio-optical and emission models. The proposed ABS architecture and technical solutions serve as a reference design for the development of integrated greenhouse gas monitoring networks on inland water bodies.