Levels of 14C-phenanthrene detected by the click here liquid scintillation counter were corrected for background radioactivity. All samples were analysed in triplicate and errors bars presented in graphs are standard error

mean for n = 3. sigma stat version 2.03 software package was used for the analysis of the data. Significance of 14C-phenanthrene degradation between soils and temperatures were assessed by implementing anova and Tukey’s tests. Selected soils in different sections of Livingstone Island were found to have similar physicochemical properties. The soils are mostly sandy and slightly alkaline, with low TOC and N contents. The sum of 23 PAH (ΣPAHs) concentrations was low, with values ranging between 0.14 and 1.47 ng g−1 dw soil with higher contribution of low molecular weight PAHs (see Table 1). The catabolism of 14C-phenanthrene in Antarctica soils at 4, 12 and 22 °C (nonslurried and slurried)

as determined by the mineralization of 14C-phenanthrene to 14CO2 by indigenous microbial communities is shown in Fig. 2. Lag Erismodegib order phases decreased as temperatures increased (see Table 2). The longest lag phase (26.92 ± 0.06 days) was observed in soil 5 at 12 °C and the shortest (1.13 ± 0.16 days) was in soil 2 at 22 °C. At 4 °C, < 5% 14C-phenanthrene was mineralized in all the five soils after a period of 35 days. Only at 22 °C did 14C-phenanthrene mineralize in all five soils exceed 5%. Lowest rates of 14C-phenanthrene mineralization were observed for all soils at 4 °C, the fastest rate observed for all five soils at this temperature being 0.002 ± 0.001% h−1. The rates others of 14C-phenanthrene mineralization were fastest at 22 °C under slurry conditions (0.56 ± 0.01% h−1 for soil 5). Though rates increased with increasing temperature, a significant increase in rates of 14C-phenanthrene mineralization (P < 0.05) was only observed when the rates of

14C-phenanthrene mineralization at 4, 12 and 22 °C were compared with those of the slurry system at 22 °C. Increasing the temperature from 4 to12 °C, 12 to 22 °C and 4 to 22 °C did not significantly increase fastest rates of mineralization (P > 0.05). Generally, 14C-phenanthrene was mineralized at higher rates and to greater extents as temperatures increased. At 4 °C, maximum 14C-phenanthrene mineralized was 1.14% in soil 2. Increasing the temperature to 12 °C resulted in a maximum of 17.85% (soil 5) and a significant increase (P < 0.05) in the amount of 14C-phenanthrene mineralized only in soils 2 and 5. A further increase to 22 °C resulted in a significant increase in the amount of 14C-phenanthrene mineralized in all five soils (P < 0.05). The maximum amount of 14C-phenanthrene mineralized at 22 °C was 39.09% and was significantly greater (P < 0.05) than that mineralized at both 4 and 12 °C for all the soils.