Effects of light rare earth tailings on the germination and growth of Brassica chinensis L. in northern China

This study investigates the effect of light rare earth tailings on the growth of Brassica chinensis L. in northern China. A pot experiment was conducted by mixing commercial peat soil with tailings in a mixing ratio of 0 (CK), 25 %, 50 %, 75 %, and 100 %, respectively. By measuring the growth and physiological indicators of Brassica chinensis L. at different growth stages, the Biomarker Response Index (BRI) and the second-generation Integrated Biomarker Response Index (IBRv2) were calculated and the enrichment and translocation of seven light rare earth elements from the tailings to Brassica chinensis L. were analyzed. Results showed that Brassica chinensis L. exhibited certain tolerance to the tailings, with the optimal mixing ratio of 75 %. Both BRI and IBRv2 provided references for remediation conditions, with IBRv2 being superior, and the seedling stage (40 d) being more suitable for predicting remediation conditions than 60 d. The root system of Brassica chinensis L. showed stronger enrichment capacity of light rare earth elements than that in its aboveground parts. Its enrichment content increased with rising tailings mixing ratio, with the accumulation of Ce, La, and Nd exceeding 1000 mg/kg. This study provides theoretical references for screening phytoremediation conditions, evaluating remediation effects, and applying leafy vegetables as remediation plants.