The eco-geochemical characteristics of germanium and its relationship with the genuine medicinal material Scutellaria baicalensis in Chengde, Hebei Province

The investigation of the relationship between the growth of genuine medicinal materials and eco-geochemical conditions is of great significance for the scientific development and standardization of traditional Chinese medicine. The geochemical background characteristics of Ge element in different geological formations and spatial scales were clarified in the regional scale of Luanhe River Basin and two Chinese herbal medicine planting demonstration areas of Jingoutun and Wudaoling. A multivariate statistical analysis method was used to analyze the eco-geochemical characteristics of germanium and its relationship with the genuine medicinal material Scutellaria baicalensis combined with mass transfer coefficient, chemical index of alteration, residual factor and bioconcentration factor. The results indicate that the average content of Ge element in the surface soil of Luanhe River Basin is 1.336 mg·kg^-1, and the content of Ge element in 43.54% of soil samples was generally categorized as belonging to rich to abundant level, while the average content of Ge element in the surface soil of Jingoutun and Wudaoling area is 1.352 mg·kg^-1 and 1.268 mg·kg^-1. The Ge element content of different geological formations and surface soil is significantly related to the TFe₂O₃ content, and the iron-bearing minerals in the soil have an adsorption effect on the Ge element. The soil-regolith-rock samples with higher degree of weathering and maturity tend to have higher Ge content. The weathering degree and soil maturity of Jingoutun area is higher than that of Wudaoling area as well as the enrichment of Ge element. The mass transfer coefficient based on Nb of Ge element is similar to that of TFe₂O₃, V, Ti, Co, P, Pb, Cu, Zn, Al₂O₃, SiO₂, K₂O and Na₂O. The ratio of Si/Ge changes significantly during the weathering process, which shows an antagonistic effect. The Ge element is mainly derived from the fracture of silicate mineral lattice and metal sulfide minerals released during their weathering process. The average bioconcentration factors of Ge element in Scutellaria baicalensis of Jingoutun and Wudaoling are 0.014 and 0.020 respectively. The root of Scutellaria baicalensis shows an obvious synergistic effect on the absorption of Fe and Ge in soil. The soil pH values have an important impact on the speciation and bioavailability of Ge element. The rich Fe, P and Sr values in the regional soil provide favorable conditions for the growth of high-quality Scutellaria baicalensis. The soil with abundant Fe group element content, slightly alkaline pH values and sand texture with better air permeability is suitable for the cultivation and growth of authentic Scutellaria baicalensis.