College of Geography and Environmental Science, Guizhou Normal University, Guiyang, 550025, China.
The State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, Guiyang, 550025, China.
Sci Rep. 2021 Nov 19;11(1):22542. doi: 10.1038/s41598-021-01685-6.
Study on the form partitioning and content of heavy metals in soil particles with different sizes is crucial for preventing and controlling heavy metals pollution, but few studies regard soil contaminated by heavy metals as a homogeneous body. In this study (Fig. 1), goat manure, lime and phosphate were used to stabilize exogenous lead (Pb). These soil passivators' differential effects on total Pb and Pb with different chemical forms in soil particles of different sizes as well as Pb immobilization in soil were investigated. By passivation experiment in laboratory for 45 days, the passivation effect of the single and combined application treatments on exogenous Pb and partitioning characteristics were analyzed and compared. The characterization method of fine sand microstructure and mineral composition analysis was used. The results showed that the single application of P5 and combined application of LP5 had optimum passivation efficiency. The content of DTPA-Pb was reduced with P5 by 65.27% and the percentage of available Pb decreased significantly in soil particles of the four sizes. The content of TCLP-Pb and available Pb (weak acid extraction and reducible Pb) significantly decreased by 71.60 and 25.12% respectively after the application of LP5 in the original soil. Furthermore, most of the total Pb was enriched in coarse sand and clay, while its content was lower in fine sand and silt. The combined application treatment of GL5 significantly increased the content of weak acid extractable and reducible Pb in fine sand, silty sand and clay. Through SEM and XRD analysis, it was found that the diffraction peak of P5 treatment groups might be related to the formation of insoluble Pb that contained compounds, which were mainly mineral components, including quartz, feldspar and mica, and LP showed a big potential in the study on passivation of heavy metal Pb-contaminated soil in the natural environment. In conclusion, further studies on the different dosage and metal-contamination levels as well as different combination forms of passivators should be considered under natural conditions, the selection of suitable passivators according to soil texture is of great significance for remediation of Pb-contaminated soil.
研究不同粒径土壤颗粒中重金属的形态分配和含量对于防治重金属污染至关重要，但很少有研究将重金属污染土壤视为均一体。本研究（图 1）采用羊粪、石灰和磷酸盐稳定外源铅（Pb）。研究了这些土壤钝化剂对不同粒径土壤颗粒中总 Pb 和不同化学形态 Pb 以及 Pb 在土壤中固定化的差异效应。通过 45 天的实验室钝化实验，分析比较了单一和组合应用处理对外源 Pb 的钝化效果及分配特征。采用细砂微观结构特征和矿物组成分析的表征方法。结果表明，P5 单一应用和 LP5 组合应用具有最佳的钝化效果。P5 处理使 DTPA-Pb 含量降低了 65.27%，四种粒径土壤中有效 Pb 含量显著降低。原土中 LP5 应用后，TCLP-Pb 和有效 Pb（弱酸提取和可还原 Pb）含量分别显著降低 71.60%和 25.12%。此外，大部分总 Pb 富集在粗砂和粘土中，而在细砂和粉砂中含量较低。GL5 的组合应用处理显著增加了细砂、粉砂和粘土中弱酸可提取和可还原 Pb 的含量。通过 SEM 和 XRD 分析，发现 P5 处理组的衍射峰可能与形成不溶性 Pb 化合物有关，这些化合物主要是矿物成分，包括石英、长石和云母，LP 在外源重金属 Pb 污染土壤的自然环境钝化研究中具有很大的应用潜力。综上所述，应在自然条件下考虑不同剂量和金属污染水平以及不同钝化剂的组合形式，根据土壤质地选择合适的钝化剂对 Pb 污染土壤的修复具有重要意义。
