Bioaccumulation and Translocation of Cadmium in Rapeseed in High Cadmium-Contaminated Regions: A Case Study of You County, Hunan Province
Cadmium (Cd) contamination of agricultural soils poses significant economic and health risks. While extensive research has focused on Cd accumulation in staple crops like rice, data on oilseed crops remain scarce, hindering safety assessments of edible oils and oilseed meals. This study investigated Cd accumulation and translocation in rapeseed (Brassica napus) grown in You County, Hunan Province, a region severely contaminated with Cd. Rhizosphere soil and plant tissues (roots, stems, seeds) were collected and analyzed for Cd concentrations. Results showed that approximately 71% of rhizosphere soil samples exceeded the agricultural soil pollution risk screening value for Cd, indicating high ecological risk. Cd concentrations in roots and stems were (0.49 ± 0.39) mg·kg⁻¹ and (0.54 ± 0.31) mg·kg⁻¹, respectively, comparable to or higher than soil Cd levels (0.51 ± 0.31) mg·kg⁻¹, with elevated bioaccumulation and translocation factors. This suggests that improper disposal of rapeseed roots and stems, such as returning them to fields or burning, could lead to secondary Cd pollution. In contrast, Cd bioaccumulation and translocation factors in seeds were less than 1, and Cd concentrations in seeds, oil, and oilseed meals were relatively low. Comparative analysis with sesame, camellia oleifera, and peanut indicated that rapeseed-derived oil and meal contain lower Cd levels, positioning rapeseed as a promising low-Cd-accumulating edible oil crop for cultivation in Cd-contaminated areas.