Potentially toxic elements (PTE), e.g. As, Sb, Cd, Cu, Pb, Zn, can severely impact soil element cycling, organic matter turnover and soil inhabiting microbiota. Very often this has dramatic consequences for plant growth and yield which are greatly restricted in PTE-contaminated soils. The use of innovative amendments to reduce the labile pool of such soil contaminants, can result as a feasible and sustainable strategy to improve the fertility and functionality of PTE-contaminated soils as well as to exploit these latter from an agronomic point of view. Water treatment residuals (WTR), red muds (RM), organic-based materials originating from the waste cycle, e.g. municipal solid waste compost (MSWC) and biochar (BCH), have emerged in the last decades as promising amendments. In this paper, we report a synthesis of the lessons learned from research carried out in the last 20 years on the use of the above-mentioned innovative amendments for the manipulation of soil fertility and functionality in PTE-contaminated soils. The amendments considered possess physico-chemical properties useful to reduce labile PTE in soil (e.g. alkaline pH, porosity, Fe/Al phases, specific functional groups and ionic composition among the others). In addition, they contain organic and inorganic nutrients which can contribute to improve the soil chemical, microbial and biochemical status. This is often reflected by a higher organic matter content in amended soils and/or an increase of the cation exchange capacity, available P and total N and/or dissolved organic C. As a result, soil microbial abundance, in particular heterotrophic fungi and bacteria, and enzyme activities (e.g. dehydrogenase, urease and β-glucosidase) are commonly enhanced in amended soils, while plant growth can be significantly stimulated. Overall, the obtained results suggest that the studied amendments can be used to reduce PTE bioavailability in polluted soils, improve soil microbial status and functionality, and enhance the productivity of different crops. This can offer a precious opportunity for the productive recovery of PTE-polluted soils.

Highlights
- Water treatment residuals, red muds, municipal solid waste compost and biochar can reduce labile PTE in contaminated soils.
- When used as amendments, WTR, RM, MSWC and BCH improve soil chemical fertility of PTE-polluted soils.
- WTR, RM, MSWC and BCH stimulate soil enzyme activity and heterotrophic bacterial abundance in PTE-polluted soils.
- WTR, RM, MSWC and BCH can be used as strategic amendments to enhance plant growth in environments polluted by PTE.

潜在有毒元素 (PTE)，例如。As、Sb、Cd、Cu、Pb、Zn 会严重影响土壤元素循环、有机质周转和土壤栖息微生物群。这通常会对植物生长和产量产生巨大影响，而这在 PTE 污染的土壤中受到极大限制。使用创新的改良剂来减少此类土壤污染物的不稳定池，可以作为一种可行且可持续的策略来提高受 PTE 污染的土壤的肥力和功能，并从农艺学的角度开发这些土壤。水处理残留物 (WTR)、赤泥 (RM)、源自废物循环的有机基材料，例如. 城市固体废物堆肥 (MSWC) 和生物炭 (BCH) 在过去几十年中作为有希望的修正而出现。在本文中，我们报告了过去 20 年中关于使用上述创新改良剂在 PTE 污染土壤中控制土壤肥力和功能的研究中吸取的经验教训。所考虑的改良剂具有有助于降低土壤中不稳定 PTE 的物理化学特性（例如. 碱性 pH、孔隙率、Fe/Al 相、特定官能团和离子组成等）。此外，它们含有有机和无机养分，有助于改善土壤化学、微生物和生化状况。这通常反映在改良土壤中更高的有机质含量和/或阳离子交换能力、有效磷和总氮和/或溶解有机碳的增加。 因此，土壤微生物丰度，特别是异养真菌和细菌, 和酶活性（例如脱氢酶、脲酶和 β-葡萄糖苷酶）通常在改良土壤中得到增强，而植物生长可以得到显着刺激。总体而言，获得的结果表明，所研究的改良剂可用于降低污染土壤中 PTE 的生物有效性，改善土壤微生物状况和功能，并提高不同作物的生产力。这可以为 PTE 污染土壤的生产性恢复提供宝贵的机会。

亮点
- 水处理残留物、赤泥、城市固体废物堆肥和生物炭可以降低受污染土壤中的不稳定 PTE。
- 当用作改良剂时，WTR、RM、MSWC 和 BCH 可提高 PTE 污染土壤的土壤化学肥力。
- WTR、RM、MSWC 和 BCH 刺激 PTE 污染土壤中的土壤酶活性和异养细菌丰度。
- WTR、RM、MSWC 和 BCH 可用作战略性修正，以促进受 PTE 污染的环境中的植物生长。