Abstract

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⁻¹ and exchangeable = 1,120 mg kg⁻¹) 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⁻¹) 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.

Novelty statement: 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.

摘要

通常分别研究植物修复技术和土壤中市政污水污泥（SW）对重金属的稳定化。我们旨在验证将植物提取法和金属稳定化与SW结合使用在恢复高Pb含量（总量= 28,650 mg kg ^-1和可交换= 1,120 mg kg ^-1）的土壤中的潜力，并验证这两种技术对土壤中Pb含量的关联（稳定化）。我们已经测试了五剂SW（0; 13.4; 26.7; 53.4; 106.8 Mg ha ^-1）和三种耕种条件（未耕种，黑燕麦和牧草萝卜）。在高Pb含量的土壤中施用SW有利于植物（茎和根）的营养和生长，并促进Pb吸收的增加，这是植物提取中的理想组合。施SW和植物栽培对土壤中Pb的稳定具有积极作用。证实了可交换部分的减少，以及在高岭石和菱镁矿边缘的内球沉淀和吸附的增加。SW和植物修复的组合使用非常有前途，应在中等重金属含量的土壤上进行测试。

新颖性声明：我们认为，该研究提供了一种更全面的方法来评估和回收被重金属高度污染的土壤。土壤中重金属的高毒性条件损害了植物的生长，并限制了植物修复的有效性。我们旨在验证将植物提取物和稳定剂与污水污泥一起使用在回收高Pb含量的土壤中的潜力，并验证这两种技术的结合对土壤中Pb组分的影响（稳定化）。通常，仅通过植物修复对总铅含量减少的简单评估不足以描述土壤去污的程度。理想的方法还在于确定铅的不同形式（例如：可溶；可交换；沉淀；与有机物络合；以及 铁和锰氧化物中的内球吸附；三水铝石和高岭石的内球吸附；回收技术之前和之后的土壤中的残留物），以获取可能迁移到更稳定的环境Pb馏分中。