Soil Treatment Towards Stress-Tolerant Bioremediation Strategy for Petroleum Hydrocarbon-Contaminated Soils in Cold Climates Using Zeolite as a Remediation Agent: A Preliminary Study

Petroleum hydrocarbon (PHC) contamination in soil environments in cold climates has been a significant concern in Canada. However, the ground in cold regions remains frozen or partially frozen for many months of the year, and seasonal temperature cycles significantly affect field monitoring, management and remediation practices. Current remedial strategies and on-site activities, regardless of the type of remediation technology, have been considered effective only during short summers (e.g., 2–4 months per year) due to the colder climate, slower contaminant degradation rates, and limited accessibility to remote areas during the freezing months. Nonetheless, we have consistently observed the meaningful extension of hydrocarbon biodegradation activity in freezing and frozen contaminated soils. This study suggests that our soil treatment specialized for stress-tolerant biostimulation in seasonally freezing and thawing PHC-contaminated soils is effective at sub-zero temperatures. We used analcime zeolite, a natural clay mineral, to retain unfrozen liquid water, immobilize nutrients and hydrocarbons (substrate), and provide unfrozen water-insulated pores, surface areas and microsites in partially frozen and frozen PHC-contaminated soils. Amending PHC-contaminated soils with zeolite retains unfrozen liquid water and changes the soil freezing characteristic curve (SFCC) of the soils. We also showed the excellent compatibility of the Canadian analcime zeolite with amendments of conventional inorganic nutrients and carbon-based soil amendments for enhancing indigenous microbial populations in field-aged, PHC-contaminated soils at low temperatures (10 °C).