Soil Science and Engineering Department, Federal University of Paraná State, Curitiba, Paraná, Brazil.
Int J Phytoremediation. 2021;23(3):328-335. doi: 10.1080/15226514.2020.1813077. Epub 2020 Sep 8.
Phytoremediation techniques and stabilization of heavy metals with municipal sewage sludge (SW) in soils are usually studied separately. We aimed to verify the potential of the combined use of phytoextraction method and metal stabilization with SW in the recovery of soil with high Pb content (total = 28,650 mg kg and exchangeable = 1,120 mg kg) and to verify the effect of the association of these two techniques on the Pb fractions in the soil (stabilization). We have tested five doses of SW (0; 13.4; 26.7; 53.4; 106.8 Mg ha) and three cultivation conditions (uncultivated, black oats and forage turnip). The SW application in soil with a high Pb content favored the nutrition and growth of the plants (shoots and roots) and promoted an increase in the Pb absorption, a desirable combination in phytoextraction. The SW application and the cultivation of plants had a positive effect on the stabilization of Pb in the soil. It was verified decrease of the exchangeable fraction and increase precipitated and adsorbed by inner-sphere at the edges of the kaolinite and gibbsite. The combined use of SW and phytoremediation is very promising and should be tested on soils with moderate levels of heavy metals. We believe that the study presents a more comprehensive methodology to assess and to recover soils highly contaminated with heavy metals. Conditions of the high toxicity of heavy metals in the soil compromise the growth of plants and limit the effectiveness of phytoremediation. We aimed to verify the potential of the combined use of phytoextraction and stabilization with sewage sludge in the recovery of soil with a high Pb content and to verify the effect of the association of these two techniques on the Pb fractions in the soil (stabilization). Often, the simple evaluation of the reduction in total Pb contents with phytoremediation is not sufficient to describe the magnitude of soil decontamination. The ideal is also to determine the different forms of Pb (such as: soluble; exchangeable; precipitate; complexed in organic matter; inner-sphere adsorption in Fe and Mn oxides; inner-sphere adsorption in gibbsite and kaolinite; residue) in soil before and after the recovery techniques to access the possible migration to more stable environmental Pb fractions.
修复技术和稳定重金属与城市污水污泥（SW）在土壤中通常分别进行研究。我们的目的是验证联合使用植物提取方法和 SW 稳定重金属在回收高 Pb 含量土壤（总= 28650mg/kg 和可交换= 1120mg/kg）中的潜力，并验证这两种技术的结合对土壤中 Pb 形态（稳定）的影响。我们已经测试了五种 SW 剂量（0；13.4；26.7；53.4；106.8 Mg/ha）和三种种植条件（未开垦、黑燕麦和饲料萝卜）。在高 Pb 含量的土壤中应用 SW 有利于植物（地上部分和根系）的营养和生长，并促进了 Pb 的吸收增加，这是植物提取中理想的组合。SW 的应用和植物的种植对 Pb 在土壤中的稳定化有积极影响。可交换态 Pb 比例的降低以及在高岭石和水铝石边缘的内圈吸附和沉淀得到证实。SW 和植物修复的联合使用非常有前景，应该在重金属含量中等的土壤上进行测试。我们认为，该研究提出了一种更全面的方法来评估和回收受重金属高度污染的土壤。土壤中重金属的高毒性条件会影响植物的生长，限制植物修复的有效性。我们的目的是验证联合使用植物提取和稳定化与污水污泥在回收高 Pb 含量土壤中的潜力，并验证这两种技术的结合对土壤中 Pb 形态（稳定）的影响。通常，仅通过植物修复来评估总 Pb 含量的降低不足以描述土壤脱污染的程度。理想的情况也是在回收技术前后确定土壤中不同形式的 Pb（例如：可溶；可交换；沉淀；与有机物络合；Fe 和 Mn 氧化物的内圈吸附；水铝石和高岭石的内圈吸附；残渣），以评估可能向更稳定的环境 Pb 形态迁移的情况。
