Strontium isotope and multi-tracer insights into groundwater mixing and fluoride mobilization in the Luanhe River Delta, Northern China - Zhuo Zhang; Futian Liu; Sheming Chen; Jing Zhang; Wanjun Jiang; Hang Ning; Wengang Liu; Zhipeng Gao; Wengeng Cao; Huaming Guo (Applied Geochemistry, 2025)