Natural vs Unnatural Sources of Soil Chemical Compounds

This research project aimed to distinguish between soil impacts caused by petroleum facility operations and those occurring naturally within the central mixedwood natural subregion of Alberta at Pelican Lake. The study compiled and analyzed soil chemistry, vegetation type, wildfire history, and hydrological conditions to better understand how biogenic and anthropogenic parameters of concern interact. Work included mapping sites with naturally elevated levels of toluene, petroleum hydrocarbon (PHC) fractions F3 and F4, naphthalene, and phenanthrene, and creating a GIS layer linked to a tabular dataset for use in remediation planning, pre-disturbance assessments, and facility siting. By identifying natural sources of salinity, petroleum compounds, and metals, the project seeks to reduce unnecessary remediation and improve site planning efficiency.

Results showed that wetland types such as larch, black spruce, and wet shrub had higher levels of boron, selenium, toluene, and PHC fractions F3 and F4 than upland sites, with 73% of the study area classified as wet and influenced by flooding. Wildfires, which have affected 36% of the area since 1940, were linked to elevated PHC fractions, PAHs, and toluene. Organic soils, dominating 71% of the study area, had lower pH values and higher concentrations of several parameters of concern compared to mineral soils, which contained no elevated toluene or PHC fraction F3. The findings emphasize that certain hydrocarbons and metals can occur naturally under specific site conditions, highlighting the need for targeted sampling strategies, refined predictive modeling, and analytical methods capable of accurately detecting contaminants in organic soils.