| Nutrient-deficient, acidic soil from Resolution Island, Nunavut was contaminated with petroleum hydrocarbons during operations from 1954-1973 at a former radar station. Two mesocosm tanks containing ∼200 kg hydrocarbon-contaminated Resolution Island soil each were exposed to a seasonal freezing profile designed to simulate in situ ground conditions after the summer landfarming season. Soil from one tank was treated with 100.0 mg N kg-1 soil and 2.0 g CaCO3 kg-1 soil, while the second mesocosm remained untreated. Aliphatic nC10-nC16 hydrocarbon biodegradation was enhanced by soil treatments after an initial acclimation period, which corresponded to Actinomycetales and Rhodanobacter population growth from 2.4ºC to -2.1ºC. These Actinomycetales and Rhodanobacter populations probably represented hydrocarbonoclastic K-strategists and hydrocarbon metabolite-utilizing r-strategists, respectively. Additionally, a novel indigenous archaeal community was related to Thaumachaeota ammonia oxidizers but not associated with hydrocarbon biodegradation. Two diazotrophic Burkholderia isolates from the soil also degraded 14C-naphthalene and/or 14C-phenanthrene at -5°C. |
