Moisture-corrected portable XRF survey of post-eruption soils at Sileri Crater, Dieng Volcanic Complex (August–September 2025)

This dataset contains field portable X-ray fluorescence (pXRF) measurements of surface soils collected around Sileri Crater, Dieng Volcanic Complex, Central Java, Indonesia, eight months after the 18 December 2024 phreatic eruption. Sampling took place during the dry, post-harvest season in August-September 2025 to maximize surface stability and safety. Five radial transects (W, NE, N, E, S) were laid from the crater rim with 2 m spacing near the vent, extending to 20-40 m depending on terrain and access. In total, 81 points were screened. Measurements were acquired in situ using a Thermo Scientific Niton XL3t (Soil Mode). Each location was analyzed in triplicate (210 s per read). Surfaces were cleared of vegetation and coarse fragments, then covered with 6 μm Mylar. For each point a grab sample was taken to determine moisture content gravimetrically. All reported concentrations include a dry-basis correction using the site-specific gravimetric factor. Instrument performance was checked routinely with a SiO2 procedural blank and NIST SRM 2711a (Montana II Soil). Acceptance criteria were: blank responses below LOD for target analytes and SRM recoveries within 80-120 percent for As and Pb. Triplicate precision is reported as relative standard deviation. Method detection limits (MDL) per transect were estimated as three times the standard deviation of the ten lowest As readings. Primary analyte of interest is arsenic (As). Ancillary elements reported by the Soil Mode are included where signal quality and QA/QC permit. Methods summary Instrument: Thermo Scientific Niton XL3t, Soil Mode, 210 s per read, 3 replicates per point. Surface prep: clear fines and vegetation, Mylar film on measurement spot. QA/QC: SiO2 blank, NIST SRM 2711a, replicate RSD tracking, MDL = 3σ of low-end data per transect. Data processing: inverse-variance weighting for triplicates, dry-basis conversion with F, no substitution for <LOD. Geographic and temporal coverage Location: Sileri Crater, Dieng Volcanic Complex, Central Java, Indonesia. Dates: August-September 2025 (8 months post-eruption). Funding: National Research and Innovation Agency (BRIN), RIIM Invitasi Strategis Ekspedisi Geologi Darat di Pulau Jawa Tahun 2025 - Indonesia Endowment Fund for Education (LPDP) RISPRO. Keywords: portable XRF; pXRF; arsenic; hydrothermal; phreatic eruption; Dieng; Sileri Crater; moisture correction; gravimetric factor; environmental geochemistry Intended use and limitations: The dataset is intended for rapid post-eruption screening and spatial analysis of trace elements at the soil surface. Values are field screening results corrected to a dry basis. For regulatory decisions that require confirmatory laboratory analysis, pair with ICP-MS or aqua regia digestion where appropriate. Recommended citation: Wijaya, J. H., Shoedarto, R. M., Maria, R., & Nurohman, H. (2025). Moisture-corrected portable XRF survey of post-eruption soils at Sileri Crater, Dieng Volcanic Complex (Aug-Sep 2025) [Data set]. Zenodo. Version 1.0.