Complex behavior of petroleum hydrocarbons in vadose zone: A holistic analysis using unsaturated soil columns

Seongnam An, Heesoo Woo, Sang Hyun Kim, Seong Taek Yun, Jaeshik Chung, Seunghak Lee

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


The migration of petroleum hydrocarbons in vadose zone involves complex coupled processes such as downward displacement and natural attenuation. Despite its significance in determining groundwater vulnerability to petroleum contamination and optimizing the remedial strategy, it has not been comprehensively studied in terms of overall processes under field-relevant conditions. In this study, a series of unsaturated soil column experiments were conducted by simulating subsurface diesel contamination within a vadose zone using different soil textures at different soil bulk densities and initial diesel concentrations, while partly exposing them to simulated precipitation. The results showed that the soil column with less fine fraction was favorable for the downward migration of diesel but unfavorable for its natural degradation. However, precipitation complicated the relative conductivities of multiple fluids (water, air, and diesel) through the pore network, therby decreasing diesel migration and degradation. For example, the downward migration of diesel in the SL column decreased by 8.4% under precipitation, while the overall attenuation rate dropped to almost 0.24% of its original state. Lowering bulk density (from 1.5 to 1.23 g/cm3), however, could enhance the attenuation rate presumably due to the secured void space for the incoming fluids. A high initial concentration of diesel (2%; w/w) inhibited its natural attenuation, while its influence on its vertical propagation after the precipitation was not significant. The present findings provide a mechanistic basis for approximating the behavior of petroleum hydrocarbons in a random vadose zone.

Original languageEnglish
Article number138417
Publication statusPublished - 2023 Jun

Bibliographical note

Funding Information:
This study was supported by the Korea Environment Industry & Technology Institute ( KEITI ) through the Subsurface Environment Management ( SEM ) Project ( 2018002440006 , 2020002440002 , and 2021002470004 ) funded by the Korea Ministry of Environment ( MOE ) and National Research Foundation of Korea ( NRF ) through the “Climate Change Impact Minimizing Technology Program” funded by the Korean Ministry of Science and ICT ( MSIT ) ( 2020M3H5A1080712 ). The authors also acknowledge the support from the Future Research Program ( 2E32442 ) funded by the Korea Institute of Science and Technology ( KIST ). S. Lee was partly supported by the KU-KIST Graduate School Project.

Publisher Copyright:
© 2023 The Authors


  • Diesel
  • Infiltration
  • Natural attenuation
  • Pore network
  • Soil texture

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • General Chemistry
  • Pollution
  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis


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