Total mercury, methylmercury concentrations and environmental characterization of spring water, porewater, and seawater from Es Port Bay, Cabrera Island

First release of the Cabrera mercury and submarine groundwater discharge dataset. This dataset contains physicochemical, hydrological (SGD fluxes), biogeochemical, optical, microbial, and mercury concentrations data 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 (Ra-224), dissolved nutrients (NO₂⁻, NO₃⁻, NH₄⁺, PO₄³⁻, SiO₄, and TDN), dissolved organic carbon, FDOM components, CDOM absorption parameters, total prockaryotic abundance, High Nucleic Acid prokaryote concentration, and Heterotrophic activity. The dataset also includes dissolved Hg and MeHg flux estimates calculated for the studied area of Es Port Bay. This dataset supports the assessment of groundwater-derived mercury and methylmercury inputs to Es Port Bay and the interpretation of their links with hydrological connectivity, organic matter composition, nutrient availability, and microbial activity in a protected Mediterranean karstic coastal environment.本数据集为卡布雷拉岛汞与海底地下水排泄（Submarine Groundwater Discharge, SGD）数据集的首次发布版本。本数据集包含2022年夏季与2023年冬季，在西地中海巴利阿里群岛卡布雷拉岛埃斯波特湾采集的泉水、孔隙水与海水的理化、水文（SGD通量）、生物地球化学、光学、微生物学及汞浓度数据。 数据集涵盖总溶解汞、溶解态甲基汞，以及甲基汞占总汞的百分比数据，同时包含用于表征海底地下水排泄及相关生物地球化学梯度的环境变量。上述环境变量包括温度、盐度、pH值、溶解氧、氧化还原电位、总碱度、放射性同位素示踪剂（Ra-224）、溶解态营养盐（NO₂⁻、NO₃⁻、NH₄⁺、PO₄³⁻、SiO₄及总溶解氮（Total Dissolved Nitrogen, TDN））、溶解态有机碳、荧光溶解有机质（Fluorescent Dissolved Organic Matter, FDOM）组分、有色溶解有机质（Colored Dissolved Organic Matter, CDOM）吸收参数、总原核生物丰度、高核酸原核生物浓度以及异养活性。 本数据集还包含针对埃斯波特湾研究区域估算的溶解态汞（Mercury, Hg）与甲基汞（Methylmercury, MeHg）通量数据。 本数据集可用于评估地下水输入埃斯波特湾的汞与甲基汞通量，并助力解析受保护地中海喀斯特海岸环境中，二者与水文连通性、有机质组成、营养盐有效性及微生物活动之间的关联。