Advanced multivariate analysis to assess remediation of hydrocarbons in soils

Abstract

Accurate monitoring of degradation levels in soils is essential in order to understand and achieve complete degradation of petroleum hydrocarbons in contaminated soils. We aimed to develop the use of multivariate methods for the monitoring of biodegradation of diesel in soils and to determine if diesel contaminated soils could be remediated to a chemical composition similar to that of an uncontaminated soil. An incubation experiment was set up with three contrasting soil types. Each soil was exposed to diesel at varying stages of degradation and then analysed for key hydrocarbons throughout 161 days of incubation. Hydrocarbon distributions were analysed by Principal Coordinate Analysis and similar samples grouped by cluster analysis. Variation and differences between samples were determined using permutational multivariate analysis of variance. It was found that all soils followed trajectories approaching the chemical composition of the unpolluted soil. Some contaminated soils were no longer significantly different to that of uncontaminated soil after 161 days of incubation. The use of cluster analysis allows the assignment of a percentage chemical similarity of a diesel contaminated soil to an uncontaminated soil sample. This will aid in the monitoring of hydrocarbon contaminated sites and the establishment of potential endpoints for successful remediation.

Natural attenuation of legacy hydrocarbon spills in pristine soils is feasible despite difficult environmental conditions in the monsoon tropics

“…In our previous work on similar soils in nearby Barrow Island in Western Australia, and in other sites in the Kimberley, we have shown how low concentrations of soil nutrient (particularly nitrogen and phosphorus) restrict hydrocarbon degradation and alter the soil microbial communities (Lin et al, 2014;Tibbett et al, 2011). However, these were shortterm, ex-situ microcosm studies and, to date, there is a paucity of knowledge on the longerterm effect of terrestrial hydrocarbon spills on microbial communities in-situ in environments with naturally low nutrient concentrations that also experience high annual temperatures and monsoonal rainfall.…”