PIE LTER 30-min interval of radon at two sites in the Plum Island Estuary in year 2023.

Radon time-series measurements were conducted in the Plum Island Estuary to characterize short-term variability in groundwater and porewater-associated tracers. Radon concentrations were recorded at 30-minute intervals over 24-hour tidal cycles at two sites: RO (Rowley House) on the Rowley River and MR (Middle Bridge) on the Parker River. At the RO site, measurements were collected during three campaigns spanning different seasons: June 6–7, July 22–23, and October 8–9, 2023. At the MR site, measurements were conducted during a single campaign from July 22–23, 2023. These high-frequency observations capture tidal and diurnal variability in radon dynamics across both rivers and seasonal conditions within the estuary.