On site bioremediation of hydrocarbon-contaminated Arctic tundra soils in inoculated biopiles

There is a need to develop technology to allow the remediation of soil in polar regions that have been contaminated by hydrocarbon fuel spills. Bioremediation is potentially useful for this purpose, but has not been well demonstrated in polar regions. We investigated biopiles for on-site bioremediation of soil contaminated with Arctic diesel fuel in two independent small-scale field experiments at different sites on the Arctic tundra. The results were highly consistent with one another. In biopiles at both sites, extensive hydrocarbon removal occurred after one summer. After 1 year in treatments with optimal conditions, total petroleum hydrocarbons were reduced from 196 to below 10 mg per kg of soil at one site, and from 2,109 to 195 mg per kg of soil at the other site. Addition of ammonium chloride and sodium phosphate greatly stimulated hydrocarbon removal and indicates that biodegradation was the primary mechanism by which this was achieved. Inoculation with cold-adapted, mixed microbial cultures further stimulated hydrocarbon removal during the summer immediately following inoculation. At one site, soil temperature was monitored during the summer season, and a clear plastic cover increased biopile soil temperature, measured as degree-day accumulation, by 30-49%. Our results show that on-site bioremediation of fuel-contaminated soil at Arctic tundra sites is feasible.