Biological Soil Health Indicators in Highly Disturbed Soils.

One approach to remediate hydrocarbon contaminated soil is thermal desorption (TD), which involves heating the soil at high temperatures (200 to 500°C) to volatilize the hydrocarbons, effectively removing the contaminant from the soil, but after such drastic treatment, soil biological diversity and functions are likely to be altered.  Soil enzyme activities are a measure of the soil microbial activity, which respond rapidly to changes caused by both natural and anthropogenic factors, and are directly related to nutrient cycles and transformations.  The objectives of this study analyzed the activities of N cycling enzymes (ammonium oxidation, nitrate reductase and urease) and the quantification of important N transforming organisms in oil-contaminated soil, TD-treated soil, non-contaminated soil, and 1:1 blends with and without compost.  Results indicate that nitrogen transforming microorganisms, measured by enzymes and gene quantification, were reduced in contaminated and TD-treated soil as compared to non-contaminated soil.  Results of this study will offer information on whether TD remediation has applications for returning oil-contaminated soil back to agricultural production by considering soil microbial processes.  Additionally, results will suggest the viability of TD as a remediation strategy in cropland and impacts on long-term nutrient cycling.