<p>High-arsenic groundwater in the middle-lower Yellow River Basin, widely used for agriculture, poses significant carcinogenic risks, yet its environmental characteristics and sources remain unclear. This study characterized shallow high-arsenic groundwater (As &gt; 10&#xa0;µg·L^− 1), quantified population-specific health risks, and identified sources using PCA-PMF. Elevated As concentrations were observed in alluvial fan frontal swales and Yellow River burst fan sediments (20–45&#xa0;m depth), reaching 128&#xa0;µg·L^− 1, with 40.8% of samples exceeding the WHO guideline. HCO₃-Ca and HCO₃-Ca·Na dominated the water types, and weakly alkaline reducing conditions with high HCO₃⁻ facilitatesd As enrichment alongside Fe²⁺ and NH₄⁺ release. The alluvial fan frontal swales (Zone A) exhibited the highest proportional high-risk coverage (&gt; 90%). PCA-PMF identified three main sources: reductive dissolution of iron oxides (35.5%), competitive adsorption of HCO₃⁻ via water-rock interaction (48.8%), and agricultural fertilizers (15.7%), with reductive dissolution contributing &gt; 60% in high-risk zones. These findings clarify the environmental characterization and health risks on shallow high-arsenic groundwater and support targeted risk management and mitigation strategies. Environmental Characterization and Health Risks of Shallow High-Arsenic Groundwater with PCA-PMF Source Apportionment: Middle-Lower Yellow River Plain Case Study.</p> Graphical abstract <p></p>