Vapor-phase biodegradation and natural attenuation of petroleum VOCs in the unsaturated zone: A microcosm study

作     者：Sun, Yue Liu, Yanbo Yue, Gangsen Cao, Jinhui Li, Chong Ma, Jie 

作者机构：State Key Laboratory of Heavy Oil Processing Beijing Key Lab of Oil & Gas Pollution Control China University of Petroleum-Beijing Beijing102249 China 

出 版 物：《Chemosphere》 (Chemosphere)

年 卷 期：2023年第336卷第1期

页      面：139275页

核心收录：

学科分类：0820[工学-石油与天然气工程] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 0817[工学-化学工程与技术] 08[工学] 0807[工学-动力工程及工程热物理] 0703[理学-化学] 0836[工学-生物工程] 0814[工学-土木工程] 

基　　金：The authors thank the financial support from National Natural Science Foundation of China (21878332  42177042) and Science Foundation of China University of Petroleum-Beijing (2462022QNXZ006  2462022YXZZ011) 

主　　题：Biodegradation 

摘      要：Traditional natural attenuation studies focus on aqueous process in the saturated zone while vapor-phase biodegradation and natural attenuation in the unsaturated zone received much less attention. This study used microcosm experiments to explore the vapor-phase biodegradation and natural attenuation of 23 petroleum VOCs in the unsaturated zone including 7 monoaromatic hydrocarbons, 6 n-alkanes, 4 cycloalkanes, 3 alkylcycloalkanes and 3 fuel ethers. We found that monoaromatic hydrocarbon vapors were easily attenuated with significantly high first-order attenuation rates (9.48 d−1-43.20 d−1) in live yellow earth, of which toluene and benzene had the highest rates (43.20 d−1 and 28.32 d−1, respectively). The 13 aliphatic hydrocarbons and 3 fuel ethers all have relatively low attenuation rates (−1) in live soil and negligible biodegradation contribution. We explored the effects of soil types (black soil, yellow earth, lateritic red earth and quartz sand), soil moisture (2, 5, 10, and 17 wt%) contents and temperatures (4, 15, 25, 35 and 45 °C) on the vapor attenuation. Results showed that increasing soil organic matter (SOM) content, silt content, porosity and soil microorganism numbers enhanced contaminant attenuation and remediation efficiency. Increasing moisture content reduced the apparent first-order biodegradation rates of monoaromatic hydrocarbon vapors. The vapor-phase biodegradation had optimal temperature (∼25 °C in yellow earth) and increasing or decreasing temperature slowed down biodegradation rate. Overall, this study enhanced our understanding of vapor-phase biodegradation and natural attenuation of petroleum VOCs in the unsaturated zone, which is critical for the long-term management and remediation of petroleum contaminated site. © 2023 Elsevier Ltd