Formation of environmentally persistent free radicals during the transformation of anthracene in different soils: Roles of soil characteristics and ambient conditions

• Published in: Journal of hazardous materials Vol. 362; pp. 214 - 223
• Main Authors: Jia, Hanzhong, Zhao, Song, Shi, Yafang, Fan, Xiaoyun, Wang, Tiecheng
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.01.2019
• Subjects: Anthracene; Environmentally persistent free radicals; Polycyclic aromatic hydrocarbons; Soil; Soil; Anthracene; Polycyclic aromatic hydrocarbons; Environmentally persistent free radicals
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2018.08.056

[Display omitted] •PAH-type EPFRs formation depend on the soil characteristics and reaction conditions.•Abiotic transformation of anthracene is highly correlated with Fe content in soils.•Soil organic carbon could inhibits PAHs degradation and stabilize the formed EPFRs.•Relatively high RH inhibits the PAHs transformation and EPFRs formation in soils.•Photolysis not only accelerates the EPFRs formation but also quenches the radicals. Transformation of PAHs, i.e., anthracene, and production of environmentally persistent free radicals (EPFRs) on seven types of representative soils were investigated, focusing on the influences of soil characteristics and ambient conditions on these reactions. The transformation rate of anthracene exhibits the order of red earth > yellow earth > latosol ∼ fluvo-aquic soil > brown earth > chernozem > calcic brown soil, which is positively correlated with Fe content in soils. Afterwards, batch reactions on pure representatives of soil minerals, including Fe2O3, Fe3O4, FeOOH, and MnO2, demonstrate that anthracene is prone to mineral-promoted transformation. The presence of higher amount of organic carbon lower the transformation rate of anthracene, whereas the formed EPFRs can be stabilized for a longer time. Subsequent experiments associated with the influences of environmental conditions on mineral-promoted reactions suggest that both anthracene transformation and EPFRs generation readily occur under dry condition. Light irradiation not only promotes the formation of EPFRs, but also greatly accelerates the decay of EPFRs and the 1/e lifetime decreases from 5 to 20 d in dark to approximately 1 d. Meanwhile, the anoxic condition is favorable for the persistence of EPFRs. The obtained results suggested the potential environmental risks association with EPFRs in PAHs-contaminated soils.