Accumulation, transformation and immobilization of atmospheric mercury in karst soil–water systems revealed by Hg isotope signatures

These datasets contain the original measurements of mercury (Hg) concentrations and stable isotopic compositions (δ²⁰²Hg, Δ¹⁹⁹Hg, Δ²⁰⁰Hg, Δ²⁰¹Hg), together with major/trace element concentrations and soil physicochemical properties, from a comprehensive field study on Hg cycling in a karst catchment in Southwest China. The soil dataset (Soil.xlsx) provides vertical profile (0–100 cm) data of total Hg, soil organic matter, pH, elemental abundances (Al, Ca, Fe, K, Mg, Mn, Na, Si, Ti), soil bulk density, and Hg isotope signatures, collected from four land-use types (shrub, forage, maize, walnut) at three slope positions with multiple replicates. The water dataset (Water_data_all.xlsx) includes total and dissolved Hg concentrations, dissolved organic carbon (DOC), Hg isotope ratios, and a suite of trace elements for rainfall, throughfall, surface runoff, subsurface flow, and epikarst water, sampled over a 16‑month period (August 2024 – November 2025) that spans a full hydrological year. These data underpin the findings presented in the associated publication, which elucidates the accumulation, transformation, and immobilization of atmospheric Hg in karst soil–water systems. The datasets are valuable for constraining Hg biogeochemical processes in carbonate terrains and for evaluating the vulnerability of karst groundwater to atmospheric Hg contamination under changing land use and climate conditions.