Hydrogeochemical processes and groundwater vulnerability in Yucatán Peninsula cenotes: Insights from Rare Earth...

Groundwater vulnerability in the Yucatán Peninsula was evaluated using Rare Earth Elements and Yttrium (REY) data from 60 cenotes, combined with NASC-normalized patterns, Hierarchical Cluster Analysis (HCA), and Principal Component Analysis (PCA), to investigate water-rock interactions and redox-sensitive processes. Fractionation trends across hydrochemical facies (Ca-Mg-HCO₃, NaCl, Ca-Mg-SO₄, and mixed types) revealed distinct geochemical signatures associated with groundwater evolution. Redox-sensitive anomalies-such as negative Ce anomalies (0.75-1.12) linked to oxidative scavenging and positive Eu anomalies (1.32-1.55) indicating reducing conditions -highlighted key controls on REY mobility-. PCA identified carbonate dissolution, evaporite weathering, and marine inputs as primary geochemical drivers. Results obtained of the DRASTIC model (index range: 110-140) shows high vulnerability zones in karstic regions, where anthropogenic inputs alter REY complexation and redox balance. These findings demonstrate the utility of REY as sensitive tracers of hydrogeochemical processes and support their integration into groundwater vulnerability assessments in tropical karst environments.