Table 3 Factor loadings of selected heavy metals in the borehole water samples during the monitoring period

0.274

0.351

− 0.684

− 0.568

− 0.063

0.955

0.864

− 0.466

0.718

− 0.092

− 0.510

− 0.009

0.662

− 0.357

0.855

− 0.355

0.897

0.031

− 0.596

0.079

0.889

− 0.238

0.902

0.097

− 0.316

0.609

− 0.715

− 0.538

0.052

0.881

0.546

0.680

− 0.135

− 0.815

0.866

0.127

0.690

0.596

− 0.350

0.864

0.707

− 0.305

2.490

1.662

3.157

2.215

2.821

1.579

35.568

23.750

45.093

31.648

40.300

22.559

35.568

59.318

45.093

76.741

40.300

62.859