Key Laboratory for Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agricultural, Chinese Academy of Sciences, Changsha, 410125, China.
College of Resources and Environment, Hunan Agricultural University, Changsha, 410128, China.
Environ Sci Pollut Res Int. 2018 Jan;25(2):1147-1156. doi: 10.1007/s11356-017-0495-z. Epub 2017 Oct 27.
Soil amendments, such as biochar, have been used to enhance the immobilization of heavy metals in contaminated soil. A pot experiment was conducted to immobilize the available cadmium (Cd) and lead (Pb) in soil using peanut shell biochar (PBC) and wheat straw biochar (WBC), and to observe the accumulation of these heavy metals in rice (Oryza sativa L.). The application of PBC and WBC led to significantly higher pH, soil organic carbon (SOC), and cation exchange capacity (CEC) in paddy soil, while the content of MgCl-extractable Cd and Pb was lower than that of untreated soil. MgCl-extractable Cd and Pb showed significant negative correlations with pH, SOC, and CEC (p < 0.01). The application of 5% biochar to contaminated paddy soil led to reductions of 40.4-45.7 and 68.6-79.0%, respectively, in the content of MgCl-extractable Cd and Pb. PBC more effectively immobilized Cd and Pb than WBC. Sequential chemical extractions revealed that biochar induced the transformation of the acid-soluble fraction of Cd to oxidizable and residual fractions, and the acid-soluble fraction of Pb to reducible and residual fractions. PBC and WBC clearly inhibited the uptake and accumulation of Cd and Pb in rice plants. Specially, when compared to the corresponding concentrations in rice grown in control soils, 5% PBC addition lowered Cd and Pb concentrations in grains by 22.9 and 12.2%, respectively, while WBC addition lowered them by 29.1 and 15.0%, respectively. Compared to Pb content, Cd content was reduced to a greater extent in grain by PBC and WBC. These results suggest that biochar application is effective for immobilizing Cd and Pb in contaminated paddy soil, and reduces their bioavailability in rice. Biochar could be used as a soil amendment for the remediation of soils contaminated with heavy metals.
土壤改良剂，如生物炭，已被用于增强污染土壤中重金属的固定化。进行了一项盆栽实验，使用花生壳生物炭（PBC）和小麦秸秆生物炭（WBC）来固定土壤中有效态的镉（Cd）和铅（Pb），并观察这些重金属在水稻（Oryza sativa L.）中的积累。PBC 和 WBC 的应用导致稻田土壤的 pH 值、土壤有机碳（SOC）和阳离子交换量（CEC）显著升高，而 MgCl 提取的 Cd 和 Pb 含量低于未处理土壤。MgCl 提取的 Cd 和 Pb 与 pH 值、SOC 和 CEC 呈显著负相关（p<0.01）。将 5%的生物炭应用于污染稻田土壤，分别使 MgCl 提取的 Cd 和 Pb 含量降低了 40.4-45.7%和 68.6-79.0%。PBC 比 WBC 更有效地固定 Cd 和 Pb。连续化学提取表明，生物炭诱导了 Cd 的酸溶部分向可氧化和残留部分以及 Pb 的酸溶部分向可还原和残留部分的转化。PBC 和 WBC 明显抑制了 Cd 和 Pb 在水稻植株中的吸收和积累。特别是与对照土壤中生长的水稻相对应的浓度相比，添加 5%的 PBC 分别使稻谷中 Cd 和 Pb 的浓度降低了 22.9%和 12.2%，而添加 WBC 则使它们分别降低了 29.1%和 15.0%。与 Pb 含量相比，PBC 和 WBC 使稻谷中的 Cd 含量降低得更多。这些结果表明，生物炭的应用有效地固定了污染稻田土壤中的 Cd 和 Pb，降低了它们在水稻中的生物可利用性。生物炭可用作修复重金属污染土壤的土壤改良剂。
