Chemical and Biological Characteristics of Thermally and Chemically Disturbed Soil in Northwestern North Dakota

Abstract

Thermal desorption (TD) remediates hydrocarbon-contaminated soil by heating the soil (200 to 500 °C) to volatilize the hydrocarbons, effectively removing the contaminant from the soil. If the soil is then used for agricultural production, reclamation success can be determined by quantifying aspects of soil health. Cation exchange capacity (CEC), cation selectivity and Gibbs free energy (ΔGex) of TD-treated and untreated soil were compared. Although CEC and ΔGex differed, cation selectivities were not altered suggesting that alternative fertility management to retain previous soil productivity may not be needed. From field plots, N-transforming genes were lowered in contaminated and TD-treated soils as compared to non-contaminated soil, but the addition of surface soil (1:1 blends) increased N-cycling genes to levels reported in the literature. Thermal desorption may not alter soil chemical as much as biological metrics, but blending treated or contaminated soils with native surface soils can enhance soil function and, ultimately, productivity.