Environmentally persistent free radicals (EPFRs) are emerging contaminants of increasing concern due to their toxicity for life and ecosystems, yet their formation, behavior and fate are poorly known. In particular, there is actually no knowledge on the formation of those radicals during the thermal treatment of soils containing polycyclic aromatic hydrocarbons. Such knowledge is important because thermal treatment is a remediation method used to decontaminate soils by removing and degrading PAHs. Here, we studied the formation of radicals in three types of cultivated soils, bauxite soil, fluvo-aquic soil and chernozem soil, artificially contaminated by benzo[a]pyrene, during thermal treatment from 100 to 200 °C for 1 h, using electron paramagnetic resonance. Results show spins densities of radicals up to of 2.079 × 10¹⁷ spins/g for bauxite soil, 1.481 × 10¹⁷ spins/g for fluvo-aquic soil and 8.592 × 10¹⁶ spins/g for chernozem soil at 175 °C. The formed radicals exhibited multiple decays during their observable time and the shortest 1/e lifetimes of radicals up to 757.58 h. These findings are strengthened by EPFR-induction of reactive oxygen species (ROS), O₂^·− and ^·OH, which increased in concentrations from 100 to 200 °C. Overall, our results demonstrates for the first time that thermal treatment of PAHs-contaminated soils induces the formation of EPFRs and suggests that thermal treatment might not be a fully clean remediation method for soils as thermal treatment creates new contaminants.

由于其对生命和生态系统的毒性，环境持久性自由基（EPFR）是正在引起人们日益关注的污染物，但其形成，行为和命运却鲜为人知。特别地，实际上不知道在热处理含有多环芳族烃的土壤期间那些自由基的形成。这些知识很重要，因为热处理是用于通过去除和降解多环芳烃来净化土壤的补救方法。在这里，我们研究了在100至200°C热处理1 h的过程中，使用电子对三种类型的耕种土壤中自由基的形成过程，这些土壤分别是被苯并[a] re人工污染的铝土矿，潮铝土和黑钙土。顺磁共振。结果显示自由基的自旋密度高达2.079×10 ¹⁷铝土矿在175°C时为1.481×10 ¹⁷旋转/克，潮黑土为8.592×10 ¹⁶旋转/克。所形成的自由基在其可观察的时间内表现出多次衰变，并且自由基的最短1 / e寿命长达757.58 h。EPFR诱导活性氧（ROS），O ₂ ^·-和^· OH的浓度增加了这些发现，其浓度从100升高到200°C。总体而言，我们的结果首次证明了受PAHs污染的土壤的热处理会诱导EPFR的形成，并表明热处理可能不是一种完全清洁的土壤修复方法，因为热处理会产生新的污染物。