Mercury and methylmercury concentrations, fluxes, and environmental characterization of submarine groundwater discharge in Es Port Bay, Cabrera Island (Mediterranean Sea)

This dataset contains total mercury and methylmercury concentrations, as well as physicochemical, hydrological, and biogeochemical parameters from spring water, porewater, and seawater collected in Es Port Bay, Cabrera Island, Balearic Islands, western Mediterranean Sea, during summer 2022 and winter 2023. The dataset includes total dissolved mercury, dissolved methylmercury, and the percentage of methylmercury relative to total mercury, together with environmental variables used to characterize submarine groundwater discharge and associated biogeochemical gradients. These variables include temperature, salinity, pH, dissolved oxygen, oxidation-reduction potential, total alkalinity, radionuclide tracers such as ²²⁴Ra, dissolved nutrients, dissolved organic carbon, fluorescent dissolved organic matter components, CDOM absorption parameters, prokaryotic abundance, HNA bacterial abundance, and heterotrophic activity. The dataset also includes SGD fluxes and Hg-derived SGD fluxes calculated for the studied area of Es Port Bay in Cabrera Island.