A global dataset of soil microplastics (2005–2026)

Abstract. Microplastics (<5 mm) pose persistent global ecological risks due to their ubiquitous environmental distribution and negligible biodegradability. Compared with marine and freshwater ecosystems, for which global-scale distribution datasets have been increasingly developed, soil microplastic research still lacks a unified dataset that can support cross-regional comparison and geospatial analysis. Existing syntheses are mostly limited to national or regional scales, and the few global compilations remain constrained by data volume, spatial coverage, or variable harmonization. To address this gap, we systematically compiled published records of soil microplastics worldwide from 2005 to 2026. The resulting database comprises 6,197 harmonized records from 4,901 sampling sites across 49 countries, nearly doubling the record-level evidence base compared with the largest soil-microplastic distribution or risk synthesis identified to date. To enable cross-study synthesis, we developed a standardized schema to harmonize microplastic abundance records, land-use classifications, polymer types, shape categories, and particle-size data. Notably, we implemented particle-size distribution models to correct and harmonize abundance data reported across heterogeneous size fractions. Analysis of the compiled data reveals a highly uneven geographic distribution of current records, with Asia accounting for 89% of records with abundance information and China contributing the largest share. Soil microplastic abundance showed strongly right-skewed distributions across land-use types, and abundance patterns differed markedly between quantification methods. Spectroscopy-based records showed significantly higher median abundance than visual-based records. Differences in particle size, shape, and polymer composition among land-use categories further indicate substantial heterogeneity in soil microplastic characteristics across terrestrial environments. This dataset is archived on the Zenodo platform at https://doi.org/10.5281/zenodo.20806151 (Wu et al., 2026). The standardized data foundation presented here is critical for initializing global monitoring networks and accurately modeling soil microplastic dynamics across the Earth system.