In situ biodegradation of petroleum hydrocarbons in frozen arctic soils

In this in situ study performed at a hydrocarbon contaminated site at Longyearbyen, Spitsbergen, temperatures down to 6.6 m and soil gas composition of O2, CO2 and VOC at depths of 0.7, 2.0 and 3.5 m at the plume site (B) and the less contaminated site (R) were followed from the beginning of October to the middle of February. Soil samples from the actual depths at B and R were characterised by soil chemical parameters, nutrients, hydrocarbon concentration and enumeration of relevant microbial populations. The objective of the study was to assess whether in situ biodegradation of hydrocarbons was taking place in the contaminated frozen soil and to follow a possible reduction in the degradation activity in the following winter months. he results we concluded that zero degrees are not an ultimate limit for in situ biodegradation of hydrocarbons by cold-adapted microorganisms and that biodegradation may proceed with the same activity at subzero temperatures. From the comparison between calculated and measured reaeration of the hydrocarbon contaminated soil profile it appeared that biodegradation of hydrocarbons may also proceed at subzero temperatures during the winter at this arctic site. The observations in this study increase the possible scenarios concerning temperature design and effects in future in situ bioremediation strategies in arctic soil.