Low-cost open-source H₂S monitoring system for coastal Sargassum decomposition

Hydrogen sulfide (H₂S) emissions associated with decaying sargassum mats in coastal regions represents both an environmental and occupational health risk, underscoring the need for H₂S sensors capable of storing information over time. Commercial detectors with such features involve a costly investment for coastal workers and field monitoring, highlighting the necessity for low-cost alternatives. In this study we address this issue through the assembling, calibrating and field testing of 15 custom-built H₂S sensors, while also generating open-source hardware and software material to ensure reproducibility. A calibration protocol was implemented under controlled laboratory conditions using an experimental chamber and a certified honeywell reference sensor. Each device underwent three independent regression trials and mean calibration parameters demonstrated strong linearity and duplicability. Field deployments were conducted in Puerto Morelos, Mexico where the sensors monitored both shoreline conditions and the exposure of workers engaged in handling and cleaning decomposed sargassum.