Effects of biochar on phytotoxicity and translocation of polybrominated diphenyl ethers in Ni/Fe bimetallic nanoparticle-treated soil

In this study, soil culture experiments were conducted to explore the effects of biochar-supported Ni/Fe nanoparticles on the accumulation and translocation of polybrominated diphenyl ethers (PBDEs) in soil-plant system and its phytotoxicity to Brassica chinensis. Compared with those in BDE209 contaminated soils (S1) and Ni/Fe nanoparticle-treated soil (S3), the plant biomass, root, and shoot lengths in biochar-supported Ni/Fe nanoparticle-treated soil (S4) were increased by 23 mg, 1.35 cm, and 2.08 cm and 27.2 mg, 1.75 cm, and 2.52 cm, respectively, suggesting that the phytotoxicity in S4 treatment was significantly decreased. Moreover, in all treatments, the contents of BDE209, the total PBDEs, Ni, and Fe in sample plant tissues of S4 were the lowest. In addition, the superoxide dismutase, peroxidase, and catalase activities in S4 treatment were found to decrease by 33.8, 47.2, and 24.1%, respectively, compared to those in S3. Results also showed that biochar addition not only reduced the uptake of PBDEs and heavy metals but also effectively improve soil fertility and reduce the leachability of Ni and Fe caused by Ni/Fe. Finally, the translocation factors (TFs) of PBDEs in four treatments followed the orders as S1 > S3 > S4 > S2, indicating that biochar has an inhibition effects on PBDE translocation in the plants. In summary, all of the results suggested that the phytotoxicity, translocation of PBDEs, and the negative effects caused by neat Ni/Fe nanoparticles in B. chinensis were decreased as a result of the effects of the biochar.