Nutrient and temperature interactions in bioremediation of petroleum-contaminated cryic soil

A factorial study was performed using a sandy, petroleum-contaminated subsoil from Fort Wainwright, Alaska, to examine the effect of temperature, moisture content, nutrient levels, and diesel range organic (DRO) concentration on microbial activity at a cold climate bioremediation site. In soils with 500 mg/kg of DRO, soil heating and nutrient addition slightly increased biodegradation rates, implying a substrate limitation. With 8100 mg/kg of DRO, soil warming increased the microbial activity, suggesting that low soil temperature was the main factor limiting biodegradation rates at this site. Maximum microbial activity was achieved at ~ 21°C, with little or no additional increase at 31°C. Heating the soil to 41°C decreased biodegradation rates. Addition of nitrogen and phosphorus to soil heated at > 1°C increased biodegradation. Soil nitrogen concentration was the more essential factor in maximizing biodegradation rates.