Figure 3

The relationship between microbial communities based on the 16S rRNA amplicon datasets and environmental parameters in the groundwater samples were collected from the three sites in November and December 2021 and in January 2022. Panel a shows the results of nonmetric multidimensional scaling (NMDS) analysis using all environmental factors listed in Table 1. Panel b shows the result of distance-based redundancy analysis (dbRDA), where environmental factors adopted were pH and ORP, and concentrations of HCO₃⁻, DOC, SS, T-P, NO₃-N and SO₄²⁻, showing low collinearity (Table 3). Green, yellow and red circles indicate the microbial communities at sites 1, 2 and 3, respectively.