<p>This study integrates hydrochemical analysis with strontium isotope tracing to investigate strontium sources and enrichment mechanisms in the Xujiagou karst system, North China. Groundwater samples (<i>n</i> = 36) across exposed, covered, and buried area were analyzed for spatiotemporal Sr²⁺ concentrations variations and isotopic signatures. Results reveal distinct spatial zoning: Sr²⁺ concentrations increase from southwest recharge zones to northeast discharge zones, correlating with longer flow paths and enhanced groundwater-rock interaction. Temporally, dry season Sr²⁺ concentration was higher than wet season in 2018, but extreme rainfall in 2021 reversed this trend in confined zones due to accelerated carbonate dissolution. Strong Sr/Ca–Sr/Mg correlations (R²=0.45) confirm carbonate weathering as the primary strontium source. However, the ⁸⁷Sr/⁸⁶Sr ratios of samples exceeding typical carbonate values, coupled with elevated Cl⁻ and depressed Sr²⁺/(K⁺+Na⁺) in coal-mining areas, demonstrate significant anthropogenic inputs from agriculture and sewage. Through the analysis of different nitrate sources, it is found that the Sr²⁺ concentrations is influenced by manure and sewage, while the ⁸⁷Sr/⁸⁶Sr ratio is affected by fertilizers, further supporting the presence of diverse anthropogenic impacts. The research results show that karst groundwater in the Xujiagou Spring area has been contaminated to varying degrees by human activities. It is imperative to strengthen the protection of karst groundwater to ensure sustainable development of the regional economy, society, and ecology.</p>