Laboratory measurements of atmospheric hydrogen uptake from soils under controlled moisture and temperature conditions across 11 temperate and tropical sites in the UK, Malaysia and Sri Lanka

Soils were collected from 11 temperate and tropical sites in the United Kingdom, Malaysia and Sri Lanka, representing a range of land uses and physicochemical characteristics. Samples were air-dried, homogenised and sieved (2 mm) prior to laboratory incubation. Atmospheric hydrogen (H2) fluxes were measured under controlled moisture and temperature conditions using static chambers and analysis via an Agilent 8890 gas chromatograph with a pulsed discharge helium ionisation detector (GC-PDHID). Associated soil properties, including bulk density, soil particle density, pH, texture, soil organic carbon and dissolved organic carbon, were measured using standard laboratory methods. Fluxes were calculated from changes in chamber headspace H2 concentration over time and combined with environmental and soil property data to create the final dataset. Quality assurance included calibration against certified H2 standards during each analytical run, routine inspection of chromatograms, exclusion of measurements with poor instrument performance or unsuccessful integrations, and reporting of upper and lower uncertainty estimates for each flux measurement. No interpolation or gap-filling was applied. Final data processing and quality control were undertaken using custom R-based analysis workflows.