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Changes in liquid water alter nutrient bioavailability and gas diffusion in frozen antarctic soils contaminated with petroleum hydrocarbons



Bioremediation has been used to remediate petroleum hydrocarbon (PHC)-contaminated sites in polar regions; however, limited knowledge exists in understanding how frozen conditions influence factors that regulate microbial activity. We hypothesized that increased liquid water (θliquid) would affect nutrient supply rates (NSR) and gas diffusion under frozen conditions. If true, management practices that increase θliquid should also increase bioremediation in polar soils by reducing nutrient and oxygen limitations. Influence of θliquid on NSR was determined using diesel-contaminated soil (0–8,000 mg kg−1) from Casey Station, Antarctica. The θliquid was altered between 0.007 and 0.035 cm3cm−3 by packing soil cores at different bulk densities. The nutrient supply rate of NHmath image and NOmath image, as well as gas diffusion coefficient, Ds, were measured at two temperatures, 21°C and −5°C, to correct for bulk density effects. Freezing decreased NSR of both NHmath image and NOmath image, with θliquid linked to nitrate and ammonia NSR in frozen soil. Similarly for Ds, decreases due to freezing were much more pronounced in soils with low θliquid compared to soils with higher θliquid contents. Additional studies are needed to determine the relationship between degradation rates and θliquid under frozen conditions. Environ. Toxicol. Chem. 2012;31:395–401. © 2011 SETAC

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