TITLE:
Quantitative Source Apportionment and Spatial Differentiation of Soil Heavy Metals in Farmland Soils of the Huize Mining Area, Southwest China
AUTHORS:
Jingyi Chen, Shipi Peng, Ao Li, Zhiwen Yang, Jiacheng Shu, Li Bao
KEYWORDS:
Huize Mining Area, Soil Heavy Metals, Spatial Distribution, PMF Model, Source Apportionment, Driving Mechanism
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.7,
July
27,
2026
ABSTRACT: Mining and smelting activities are predominant anthropogenic drivers of soil heavy metal accumulation in farmland ecosystems, posing pronounced threats to agricultural food safety and public health in mineral-rich regions of southwest China. To systematically characterize contamination status, resolve spatial distribution patterns, and quantitatively apportion pollution sources of soil heavy metals in the Huize mining area of Yunnan Province, this study investigated 28.6 km2 of arable farmland as the study domain. A total of 50 topsoil (0 - 20 cm) samples were collected to determine concentrations of five heavy metals (As, Cu, Zn, Pb, Cd) and soil pH. Coupled with multi-source geospatial datasets (10 m-resolution DEM, county-level GDP grid, long-term meteorological records, and population density), spatial distribution patterns were mapped via ordinary Kriging interpolation in ArcGIS 10.6. The Positive Matrix Factorization (PMF 5.0) model and geographical detector method were jointly applied to identify pollution sources, quantify their contribution rates, and disentangle the driving mechanisms of natural conditions and anthropogenic activities on heavy metal spatial differentiation. Results showed varying degrees of heavy metal accumulation across the study area. Cadmium (mean 0.34 mg/kg) exceeded the risk screening value of GB 15618–2018 at 2.0% of sampling sites, while As, Cu, Zn and Pb mean concentrations remained below the Yunnan provincial soil background values. Heavy metals exhibited significant spatial clustering, with high-concentration zones concentrated in the core mining district and its surrounding 5 km buffer. Four primary pollution sources were quantified: industrial emissions (38.2%), agricultural activities (27.5%), natural background (22.3%), and traffic pollution (12.0%). Industrial emissions contributed 50.8% and 45.5% to Cd and Pb accumulation, respectively. Population density and annual precipitation exerted dominant effects on spatial differentiation, and multi-factor interactions significantly amplified spatial heterogeneity. This study provides quantitative evidence for targeted pollution prevention, precise remediation, and sustainable agricultural management in mining-affected karst regions.