This work investigates the mechanisms determining Cr speciation and availability in two different soils polluted with two chromium sources (an industrial sludge, highly polluted with Cr, and Cr(VI) solution) and the influence of these parameters on the recovery of the soil functions related with biological quality and plant growth. The experiment was carried out in greenhouse conditions using 36 pots of 17 kg for the growth of Silene vulgaris for 21 months. Logistic Regression Model using Lasso estimator shows that soil organic matter (SOM) and pH control Cr availability in studied soils. In soils treated with the sludge, X ray Absorption spectroscopy showed that Cr was present as Cr(III), biological quality indicators increased and plants were able to grow. However, in soils polluted with Cr(VI), Cr availability was significantly different in the two soils. In the alkaline and poor in organic matter soil, 12% of Cr(VI) remained in the soil leading to the decrease of soil quality indicators and the total inhibition of plant growth. In the neutral soil, Cr(VI) was totally reduced to Cr(III) by soil organic matter (SOM), quality indicators were not affected and plants grown properly. Infrared Spectroscopy showed that different functional groups reacted with Cr in the two soils. This study highlights the importance to understand the mechanisms underlaying Cr redox and adsorption reactions in Cr polluted soils as they determine the potential recovery of the functions related with biological quality indicators and plant growth. The methodology proposed allows this study in complex soil samples at realistic concentrations and may be useful for risk assessment and for the planning of managing strategies in Cr polluted soils.

这项工作调查了确定在两种不同的土壤中被两种铬源（工业污泥，高铬和六价铬溶液污染）的铬形态和有效性的机理，以及这些参数对相关土壤功能恢复的影响。具有生物质量和植物生长。该实验在温室条件下进行，使用36盆17公斤的菜豆生长持续21个月。使用拉索估计量的Logistic回归模型表明，研究土壤中的土壤有机质（SOM）和pH值可控制铬的有效性。在污泥处理过的土壤中，X射线吸收光谱法表明Cr以Cr（III）的形式存在，生物质量指标提高并且植物能够生长。但是，在被Cr（VI）污染的土壤中，两种土壤中Cr的利用率显着不同。在碱性和有机质较差的土壤中，土壤中残留了12％的Cr（VI），这导致土壤质量指标下降并完全抑制了植物的生长。在中性土壤中，土壤有机质（SOM）将Cr（VI）完全还原为Cr（III），质量指标没有受到影响，并且植物生长正常。红外光谱表明，两种土壤中不同的官能团与Cr反应。这项研究强调了理解铬污染土壤中铬氧化还原和吸附反应的基础的重要性，因为它们确定了与生物质量指标和植物生长有关的功能的潜在恢复。所提出的方法使这项研究能够在实际浓度的复杂土壤样品中进行，并且可能对风险评估和铬污染土壤管理策略的规划很有用。