Estimation of residual coal tar saturation in soils
Year: 2026
Type: article
Abstract: Coal tars are viscous polycyclic aromatic hydrocarbon (PAH)-rich nonaqueous phase liquids (NAPLs) that persist as subsurface contaminants at former manufactured gas plant (MGP) sites. Accurate determination of residual coal tar saturation ( S Tr ) in soils is essential for estimating tar mass, predicting long-term source longevity, and designing cost-effective remediation strategies. However, limited S Tr data exist for natural soils, and no predictive framework currently relates S Tr to measurable tar and soil properties. In this study, coal tars and soils from nine former MGP sites were comprehensively characterized to identify key factors governing tar entrapment. Two-phase (water-tar) column experiments using paired and unpaired tar-soil combinations were conducted to determine S Tr , employing a nonreactive tracer approach to overcome challenges associated with viscous tars and small tar-water density differences. Measured S Tr values ranged from 7.70% to 22.6%, and were strongly influenced by soil texture, porosity, carbon content, and tar viscosity. Using the combined dataset, linear and nonlinear regression models (e.g., r 2 = 0.84 for a linear model incorporating soil carbon content, median grain size, tar viscosity and tar-water interfacial tension) were developed to provide a practical, cost-effective tool for estimating S Tr at MGP sites without labor-intensive column testing.
Source: Journal of Hazardous Materials
Authors: Lingjun Kong, Peng-Fei Yan, Kurt D. Pennell
Institutions: FMC (United States), Brown University
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: hybrid
Estimated APC paid: $4,340
OpenAlex ID: W7171669542