An explainable machine learning and PMF framework with SHAP-informed source prioritization for tracing water quality degradation in a large river basin - Xingnian Ren; Ailian Li; Xiufeng Shi; Shanshan Guo; Weishan Hu; Wanping Zhang; Xi Weng; Mingkun Guo; Qingsong Chen; Dongdong Gao; Han Zhang (Journal of Environmental Chemical Engineering, 2026)