Xi Kun-Fang, Hu Wei-Fei, Li De-Chang, Jiang Shun-Feng, Jiang Hong
Department of Applied Chemistry, University of Science and Technology of China, Hefei 230026, China.
Department of Applied Chemistry, University of Science and Technology of China, Hefei 230026, China.
Sci Total Environ. 2021 Jul 1;776:145921. doi: 10.1016/j.scitotenv.2021.145921. Epub 2021 Feb 19.
Pyrolysis, as a convenient and fast technology, has been proved to be promising in the remediation of oil-contaminated soil. However, little is known about the dissolved organic matter (DOM) associated with pyrolyzed oil-contaminated soil and its environmental impact. Herein, optical spectroscopic techniques (i.e., absorbance and fluorescence) were adopted to reveal the relationship between the pyrolysis temperature and the characteristics of the DOM and the associated phytotoxicity. Results show that one of the main factors determining the properties and phytotoxicity of DOM leached from the pyrolyzed soil is the critical temperature (approximately 325 °C) during pyrolysis. When the temperature was lower than 325 °C, more types and quantities of DOM, mainly fulvic acid-like substances, were desorbed from the soil with the temperature, which have little effect on wheat growth. However, when the temperature was in the range of 325-550 °C, the type and quantity of DOM increased first and then decreased as the temperature increased, during which the organic matter in the soil decomposed. The wheat growth was first inhibited and then promoted. Finally, the correlation between the spectral indices of DOM with the phytotoxicity suggested that fluorescent components identified by parallel factor analysis were positively correlated with phytotoxicity. This study indicates the pyrolytic remediation of oil-contaminated soil should avoid some critical temperature ranges.
热解作为一种便捷快速的技术，已被证明在修复石油污染土壤方面具有广阔前景。然而，对于与热解后的石油污染土壤相关的溶解有机物（DOM）及其环境影响却知之甚少。在此，采用光学光谱技术（即吸光度和荧光）来揭示热解温度与DOM特性及相关植物毒性之间的关系。结果表明，决定从热解土壤中淋溶出的DOM性质和植物毒性的主要因素之一是热解过程中的临界温度（约325℃）。当温度低于325℃时，更多种类和数量的DOM（主要是类富里酸物质）随温度从土壤中解吸出来，对小麦生长影响较小。然而，当温度在325 - 550℃范围内时，DOM的种类和数量随温度升高先增加后减少，在此期间土壤中的有机物发生分解。小麦生长先是受到抑制，随后得到促进。最后，DOM光谱指数与植物毒性之间的相关性表明，通过平行因子分析识别出的荧光成分与植物毒性呈正相关。本研究表明，石油污染土壤的热解修复应避免一些临界温度范围。
