Source-risk-driver analysis of heavy metal pollution in karst soils: An integrated assessment in eastern Yunnan, China

• Study develops "Source-Risk-Driver" (SRD) to analyze SMP contamination via source identification, risk assessment, driver prioritization. • Cd identified as primary pollutant in karst soils (natural-human sources). • Hybrid sources (natural weathering + agriculture/industry) drive karst soil pollution. • Natural-Agricultural activities contribute 77% of ecological risks in karst soils. • Spatial risk patterns tied to metal levels, GDP gradients, and climate stressors. The fragile karst ecosystems in eastern Yunnan are confronting severe challenges from soil metallic pollutants (SMPs). This study innovatively constructs a “Source-Risk-Driver” (SRD) framework to systematically unravel the dynamics of SMP contamination through three dimensions: source identification, risk quantification, and driver prioritization. By integrating pollution indices, positive matrix factorization (PMF), and Geodetector models, a multidimensional analysis was conducted on six SMPs in the region. Key findings include: (1) SMPs originate from the interplay between karst geological processes (e.g., carbonate weathering) and anthropogenic activities (agricultural inputs, industrial emissions, and transportation). PMF source apportionment revealed that 17.9% of the pollution load stems from agro-natural synergistic sources. (2) The Natural-Agricultural Composite Source dominated ecological risks (contribution rate: 77.17%), primarily driven by cadmium. (3) Geodetector quantification identified SMP concentration gradients, socioeconomic pressures (GDP and population density), and climatic stressors (temperature and evapotranspiration) as the primary drivers of risk spatial differentiation. The SRD framework elucidates, for the first time, the cascading linkages from pollution sources to risk manifestation and their socio-environmental drivers in karst regions. This provides a theoretical basis for implementing source-oriented control strategies (e.g., prioritizing agro-natural synergistic source management) and establishing cross-sectoral governance frameworks (e.g., reconciling mineral exploitation with ecological conservation policies).