Bioaccumulation and translocation characteristics of heavy metals in a soil and Scutellaria baicalensis system in Chengde Central Region

The heavy metal content in soil environment have an important impact on the quality and yield of Chinese medicinal plant-scutellaria baicalensis. A total of 355 soil samples,30 scutellaria baicalensis root samples were collected in two Chinese herbal medicine planting demonstration area of Chengde Central Region and analyzed for Mn, Zn, Cu, Cr, Co, Cd, Pb, Ni, Hg, V, As,Co, Sb, Soil organic matter(SOM)content and speciation of 8 heavy metals (Zn, Cu, Cr, Cd, Pb, Ni, Hg, V).The bioaccumulation and translocation characteristics of heavy metals in a soil-scutellaria baicalensis system was investigated based on descriptive statistical analysis, geological accumulative index, bioconcentration factors and migration factor combing with principal component and redundancy analysis. The results showed that the average accumulation index of surface soil in Jingoutun and Wudaoling area was generally categorized as no accumulation or moderate accumulation.The accumulation of Cu and Hg in the soil of Wudaoling area was higher, while other element lower than that in Jingoutun area.In comparison to China's soil environmental quality standard risk screening values (GB15618-2018), the over-standard rates of Cr、Cu and Cd in Wudaoling area were 2.82%,1.69% and 1.13%, and the over-standard rates of Cd, Cr and Ni in Jingoutun area and Zn and Hg content in Wudaoling area were 0.56%. The elemental content of Scutellaria baicalensis in Jingoutun area was higher than that in Wudaoling area expect Cu and the bioconcentration factor of Co and Cu elements in Wudaoling area is higher than that in Jingoutun area. The migration factor of Cd and Hg were relatively higher, and than the average value of Ni, Zn and Pb were relatively lower, while the bioavailability of Cu, Cr and As were the lowest. The Jingoutun area has lower pH value, higher SOM content in root soil and higher average BCF of As, Cd, Cr, Ni, Zn and Pb in the root of Scutellaria baicalensis than that in Wudaoling area. The soil pH and SOM content have an important impact on the bioavailability, bioaccumulation and translocation characteristics of heavy metals in a soil-scutellaria baicalensis system, while the Cd and Cu bioaccumulation were most affected by soil SOM content.