Implications of Using Thermal Desorption to Remediate Contaminated Agricultural Soil: Physical Characteristics and Hydraulic Processes

• Published in: Journal of environmental quality Vol. 45; no. 4; pp. 1430 - 1436
• Main Authors: O'Brien, Peter L., DeSutter, Thomas M., Casey, Francis X. M., Derby, Nathan E., Wick, Abbey F.
• Format: Journal Article
• Language: English
• Published: United States The American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc 01.07.2016
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2015.12.0607

Given the recent increase in crude oil production in regions with predominantly agricultural economies, the determination of methods that remediate oil contamination and allow for the land to return to crop production is increasingly relevant. Ex situ thermal desorption (TD) is a technique used to remediate crude oil pollution that allows for reuse of treated soil, but the properties of that treated soil are unknown. The objectives of this research were to characterize TD‐treated soil and to describe implications in using TD to remediate agricultural soil. Native, noncontaminated topsoil and subsoil adjacent to an active remediation site were separately subjected to TD treatment at 350°C. Soil physical characteristics and hydraulic processes associated with agricultural productivity were assessed in the TD‐treated samples and compared with untreated samples. Soil organic carbon decreased more than 25% in both the TD‐treated topsoil and the subsoil, and total aggregation decreased by 20% in the topsoil but was unaffected in the subsoil. The alteration in these physical characteristics explains a 400% increase in saturated hydraulic conductivity in treated samples as well as a decrease in water retention at both field capacity and permanent wilting point. The changes in soil properties identified in this study suggest that TD‐treated soils may still be suitable for sustaining vegetation, although likely at a slightly diminished capacity when directly compared with untreated soils. Core Ideas Soil from a crude oil spill site was remediated using thermal desorption. Thermal desorption treatment reduced SOC, SSA, and aggregation. Changes to physical properties caused increased Ks and decreased water retention. Soils subjected to TD may be less effective in crop production than native soil. Adding organic amendments to TD‐treated soil may ameliorate some effects of TD.