Geochemical characteristics of fluorine (F) in mainland China's pedosphere: On the basis of the China Geochemical Baselines project

The China Geochemical Baseline (CGB) project (2008–2013) obtained harmonious geochemical baseline data covering all of China, and provided reliable data for 76 elements including F from 3382 top and 3380 deep soil samples. This paper described the statistical and spatial distribution of fluorine (F) throughout China. F concentration ranged from 63 to 9364 μg/g in top soil and ˂ 52 to 9346 μg/g in deep soil. The median concentration of F, which is deemed to be the geochemical baseline in top and deep samples are 488 μg/g and 456 μg/g respectively. The mean concentration of F in top and deep soil samples are 506 μg/g and 482 μg/g respectively. Low F concentrations areas are linearly distributed from northeastern to southwestern China, and high F concentrations areas are distributed in northwestern, northern China and karst area. The anomalous centres of F are exactly correlated with F mineralization. This distribution pattern of F in pedosphere is influenced by minealizations, lithology background, geomorphic landscapes, drainage basins and soil types. Generally, fluorine-bearing rocks provide a reliable source of F in pedosphere, and the geochemical behavior of F determines its ability to migrate in different media.