Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang, 550025, China; College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, China.
College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, China.
Chemosphere. 2023 Sep;334:138938. doi: 10.1016/j.chemosphere.2023.138938. Epub 2023 May 12.
The remediation of heavy metals contaminated soils is of great significance for reducing their risk to human health. Here, pristine pinewood sawdust biochar (BC) and phosphate-functionalized biochar (PBC) were conducted to investigate their immobilization performance towards lead (Pb) and cadmium (Cd) in arable soils severely polluted by Pb (9240.5 mg kg) and Cd (10.71 mg kg) and microbial response in soils. Compared to pristine BC (2.6-12.1%), PBC was more effective in immobilizing Pb and Cd with an immobilization effectiveness of 45.2-96.2% after incubation of 60 days. Moreover, the labile Pb and Cd in soils were transformed to more stable species after addition of PBC, reducing their bioavailability. The immobilization mechanisms of Pb and Cd by PBC were mainly to facilitate the formation of stable phosphate precipitates e.g., Cd(PO), Cd(PO)OH, CdH(PO)‧4HO, and pyromorphite-type minerals. Further, PBC increased pH, organic matter, cation exchange capacity, and available nutrients (phosphorus and potassium) in soils. High-throughput sequencing analysis of 16 S rRNA genes indicated that the diversity and composition of bacterial community responded to PBC addition due to PBC-induced changes in soil physicochemical properties, increasing the relative abundance of beneficial bacteria (e.g., Brevundimonas, Bacillus, and norank_f__chitinophagaceae) in the treated soils. What's more, these beneficial bacteria could not only facilitate Pb and Cd immobilization but also alter nutrient biogeochemical transformation (nitrogen and iron) in co-contaminated soils. Overall, PBC could be a promising material for immobilization of Pb and Cd and the simultaneous enhancement of soil quality and available nutrients in co-contaminated mining soils.
受铅（9240.5 mg kg）和镉（10.71 mg kg）污染的耕地土壤中，原状松木屑生物炭（BC）和磷酸化生物炭（PBC）对重金属铅和镉的固定性能及其对土壤微生物的响应。与原状 BC（2.6-12.1%）相比，PBC 更有效地固定 Pb 和 Cd，在 60 天的培养后，固定效率为 45.2-96.2%。此外，添加 PBC 后，土壤中不稳定的 Pb 和 Cd 转化为更稳定的形态，降低了它们的生物可利用性。PBC 固定 Pb 和 Cd 的机制主要是促进稳定的磷酸盐沉淀的形成，如 Cd(PO)、Cd(PO)OH、CdH(PO)‧4HO 和磷锌矿型矿物。此外，PBC 增加了土壤的 pH 值、有机质、阳离子交换能力和有效养分（磷和钾）。16S rRNA 基因高通量测序分析表明，由于 PBC 诱导的土壤理化性质变化，细菌群落的多样性和组成对 PBC 的添加有响应，增加了处理土壤中有益细菌（如 Brevundimonas、Bacillus 和 norank_f__chitinophagaceae）的相对丰度。更重要的是，这些有益细菌不仅可以促进 Pb 和 Cd 的固定，还可以改变 co 污染土壤中养分的生物地球化学转化（氮和铁）。总之，PBC 可以作为一种很有前途的材料，用于固定 Pb 和 Cd，同时提高 co 污染矿区土壤的质量和有效养分。
