Correlations between PAH bioavailability, degrading bacteria, and soil characteristics during PAH biodegradation in five diffusely contaminated dissimilar soils

Abstract

The natural biodegradation of seven polycyclic aromatic hydrocarbons (PAHs) by native microorganisms was studied in five soils from Normandy (France) from diffusely polluted areas, which can also pose a problem in terms of surfaces and amounts of contaminated soils. Bioavailability tests using cyclodextrin-based extractions were performed. The natural degradation of low molecular weight (LMW) PAHs was not strongly correlated to their bioavailability due to their sorption to geosorbents. Conversely, the very low degradation of high molecular weight (HMW) PAHs was partly correlated to their poor availability, due to their sorption on complexes of organic matter and kaolinites or smectites. A principal component analysis allowed us to distinguish between the respective degradation behaviors of LMW and HMW PAHs. LMW PAHs were degraded in less than 2-3 months and were strongly influenced by the relative percentage of phenanthrene-degrading bacteria over total bacteria in soils. HMW PAHs were not significantly degraded, not only because they were less bioavailable but also because of a lack of degrading microorganisms. Benzo[a]pyrene stood apart since it was partly degraded in acidic soils, probably because of a catabolic cooperation between bacteria and fungi.

Changes in Polycyclic Aromatic Hydrocarbons (PAHs) and Soil Biological Parameters in a Revegetated Coal Mine Spoil

“…Most of the microbial parameters were also associated with PC-1; thus, it appears that the microbial community in the revegetated coal mine spoil is more effective in degradation of LMW PAHs (Table III). In a similar study, Crampon et al (2014) employed PCA and found the same differential degradation pattern of LMW and HMW PAHs.…”

Linking initial soil bacterial diversity and polycyclic aromatic hydrocarbons (PAHs) degradation potential

“…The detection and quantification thresholds, calculated respectively as 3 and 10 times the standard deviation of the blank sample noise, were 1.5/5 µg L −1 for PHE, 2.5/8.5 µg L −1 for FLT, PYR, BbF and BkF, 3.5/11.5 µg L −1 for BaP and 5/16.5 µg L −1 for BghiP. Again, the complete procedure can be found in Crampon et al (2014) [43]. In this study, we decided to compare only the biodegradation of LMW PAH to the biodegradation of HMW PAH in the five soils.…”

“…Pv and SER soils are Gleysols located close to the Seine river (periodically flooded). The soil named TB is a forest soil (Gleysol), also located close to the Seine River, and also periodically flooded [43].…”

“…Each soil (triplicates for each date) was spiked with a total of 300 mg kg −1 of seven selected PAHs. The complete procedure, which gives a good contamination homogeneity in the spiked soils without adverse effects on the organic matter and microorganism communities, is described in Crampon et al [43]. PAH analyses were carried out just after microcosm preparation and after 8, 30, 60 and 90 days of incubation.…”

“…Degradation kinetics of the seven spiked PAHs were monitored during 90 days on the five studied soils and presented in a previous study [43]. The degradation curves for the 7 studied PAHs in the five soils and the summary of degradation results are however provided in the supplementary material (SM2).…”