Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
J Hazard Mater. 2021 Jun 5;411:125129. doi: 10.1016/j.jhazmat.2021.125129. Epub 2021 Jan 14.
Thermal treatment can not only efficiently remove volatile pollutants but also distinctly alter the speciation of organic carbon (C) and the behaviors of residual pollutants in contaminated soils. Here we examined the distribution and bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in industrially contaminated site soils affected by thermal treatment (temperature ranging of 105-650 ℃) using synchrotron-based infrared microspectroscopy and n-butanol extraction (a mild solvent extractant). In the pristine soils, the sequestration and distribution of PAHs were simultaneously controlled by aromatic C, aliphatic C and clay minerals. Desorption efficiency of PAHs was substantially increased with increasing temperature, whereas the residual PAHs were strongly immobilized within their binding sites evidenced by their dramatically decreased bioaccessibility. Aliphatic and carboxylic C were gradually decomposed and/or carbonized with increasing temperature. In contrast, aromatic C remained relatively recalcitrant during the thermal treatment and was the key controlling factor for the desorption of residual PAHs in the soils with either thermal treatment or n-butanol extraction. This study is the first to visualize the changes in the binding sites and bioaccessibility of PAHs induced by thermal treatment, which have important implications for understanding the sequestration mechanisms of organic pollutants in soil and optimizing the remediation technique.
热处理不仅可以有效地去除挥发性污染物，而且可以明显改变有机碳（C）的形态和污染土壤中残留污染物的行为。在这里，我们使用同步辐射红外微光谱和正丁醇萃取（一种温和的溶剂萃取剂）研究了受热处理（温度范围为 105-650℃）影响的工业污染场地土壤中多环芳烃（PAHs）的分布和生物可利用性。在原始土壤中，PAHs 的赋存和分布同时受到芳族 C、脂肪族 C 和粘土矿物的控制。随着温度的升高，PAHs 的解吸效率显著增加，而残留的 PAHs 则由于其生物可利用性急剧下降而被强烈固定在其结合位上。随着温度的升高，脂肪族和羧酸 C 逐渐分解和/或碳化。相比之下，芳族 C 在热处理过程中仍然相对稳定，是土壤中残留 PAHs 解吸的关键控制因素，无论是经过热处理还是正丁醇萃取。本研究首次可视化了热处理引起的 PAHs 结合位点和生物可利用性的变化，这对于理解土壤中有机污染物的固存机制和优化修复技术具有重要意义。
