Fig. 2

Microbial α-diversity of aquifer samples from uncontaminated wells (UC), low-contaminated wells (LC), mid-contaminated wells (MC), and high-contaminated wells (HC). Diversity metrics are represented as follows: A taxonomic diversity, B phylogenetic diversity, and C functional diversity, calculated by richness; and D taxonomic diversity, E phylogenetic diversity, and F functional diversity, calculated by the Shannon index. Statistical differences between groups were assessed using ANOVA followed by a post hoc test, with a significance threshold set at p < 0.05. Letters indicate significant differences between groups