Using the Surface Energy Balance As an Indicator of Success in Soil Reclamation.

The resurgence of oil and gas development in the Northern Great Plains in the past decade has increased the exposure of historically agricultural land to contamination by petroleum hydrocarbons. Successful management of these soils must include not only contaminant reduction, remediation, but it must also provide a pathway for returning remediated soil to agronomic use, reclamation. Ex situ thermal desorption (TD) is a thermal remediation technique that can quickly and reliably reduce petroleum hydrocarbon concentrations, but it also alters some soil characteristics. Determining the surface energy balance may be a useful technique for assessing the viability of soil reuse of following TD because it can offer insight into soil heat and evaporative fluxes. This study assessed surface energy balance using a micro-Bowen ratio system over native non-contaminated soil, TD-treated soil, and a 1:1 mixture of native soil and TD-treated soil. Despite changes in soil color and amount of litter cover, net radiation was consistent among the three treatments. The soil heat flux varied among treatments, wherein the TD-treated soil showed greater extremes in daily fluctuation, which is likely associated with the reduction of organic matter. Notably, mixing native topsoil with TD-treated soil seemed to mitigate this effect. Further, both the latent and sensible heat fluxes were consistent among treatments throughout the duration of the study, which suggests that evaporative fluxes may not be significantly altered by TD. These findings indicate that changes in soil temperature dynamics and water balances of these TD-treated soils may not be severe and might be mitigated by mixing them with native topsoil.