Insightful knowledge of geochemical processes controlling fluoride (F) mobility is fundamental to understand
the occurrence of elevated F in groundwater. Principal component analysis (PCA) was applied to explore
the dominating factors in the F geochemistry in Shanxi and Inner Mongolia, two severely F-affected
areas in China. Field sampling results of 111 tubewells showed that 26.1% of drinking water wells, with F
concentrations in the range 0.3–5.6 mg/L, exceeded WHO standards of 1.5 mg/L. PCA with 16 geochemical
parameters demonstrated that F occurrence in Shanxi could be the result of mineral weathering and
water–rock interactions in the aquifer. Groundwater F concentrations increased with TDS in Shanxi, but
not in Inner Mongolia. In agreement with our PCA, the occurrence of F in Inner Mongolia may be attributed
to multiple processes including agriculture and mining activities, and water–rock interaction processes in the
aquifer. Calcium is the scavenger of fluoride in Shanxi and Inner Mongolia. The results of this study further
our understanding of the similarities and differences in the F occurrence and mobility at various locations