Indigenous 14C-phenanthrene biodegradation in "pristine" woodland and grassland soils from Norway and the United Kingdom.

In this study, the indigenous microbial mineralisation of 14C-phenanthrene in seven background soils (four from Norwegian woodland and three from the UK (two grasslands and one woodland)) was investigated. ∑PAHs ranged from 16.39 to 285.54 ng g-1 dw soil. Lag phases (time before 14C-phenanthrene mineralisation reached 5%) were longer in all of the Norwegian soils and correlated positively with TOC, but negatively with ∑PAHs and phenanthrene degraders for all soils. 14C-phenanthrene mineralisation in the soils varied due to physicochemical properties. The results show that indigenous microorganisms can adapt to 14C-phenanthrene mineralisation following diffuse PAH contamination. Considering the potential of soil as a secondary PAH source, these findings highlight the important role of indigenous microflora in the processing of PAHs in the environment.

Effects of plant species identity, diversity and soil fertility on biodegradation of phenanthrene in soil.

The work presented in this paper investigated the effects of plant species composition, species diversity and soil fertility on biodegradation of (14)C-phenanthrene in soil. The two soils used were of contrasting fertility, taken from long term unfertilised and fertilised grassland, showing differences in total nitrogen content (%N). Plant communities consisted of six different plant species: two grasses, two forbs, and two legume species, and ranged in species richness from 1 to 6. The degradation of (14)C-phenanthrene was evaluated by measuring indigenous catabolic activity following the addition of the contaminant to soil using respirometry. Soil fertility was a driving factor in all aspects of (14)C-phenanthrene degradation; lag phase, maximum rates and total extents of (14)C-phenanthrene mineralisation were higher in improved soils compared to unimproved soils. Plant identity had a significant effect on the lag phase and extents of mineralisation. Soil fertility was the major influence also on abundance of microbial communities.

Biodegradation of phenanthrene by indigenous microorganisms in soils from Livingstone Island, Antarctica.

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soils has been linked to history of exposure to PAHs and prevailing environmental conditions. This work assessed the capacity of indigenous microorganisms in soils collected in Livingstone Island (South Shetlands Islands, Antarctica) with no history of pollution (∑PAHs: 0.14-1.47 ng g(-1) dw) to degrade (14) C-phenanhthrene at 4, 12 and 22 °C. The study provides evidence of the presence of phenanthrene-degrading microorganisms in all studied soils. Generally, the percentage of (14) C-phenanhthrene mineralized increased with increasing temperature. The highest extent of (14) C-phenanhthrene mineralization (47.93%) was observed in the slurried system at 22 °C. This work supports findings of the presence of PAH-degrading microorganisms in uncontaminated soils and suggests the case is the same for uncontaminated Antarctic remote soils.