Petroleum Hydrocarbon Biodegradation under Seasonal Freeze−Thaw Soil Temperature Regimes in Contaminated Soils from a Sub-Arctic Site

Abstract

Several studies have shown that biostimulation in ex situ systems such as landfarms and biopiles can facilitate remediation of petroleum hydrocarbon contaminated soils at sub-Arctic sites during summers when temperatures are above freezing. In this study, we examine the biodegradation of semivolatile (F2: C10-C16) and nonvolatile (F3: C16-C34) petroleum hydrocarbons and microbial respiration and population dynamics at post-and presummer temperatures ranging from -5t o1 4°C. The studies were conducted in pilot-scale tanks with soils obtained from a historically contaminated sub-Arctic site in Resolution Island (RI), Canada. In aerobic, nutrient-amended, unsaturated soils, the F2 hydrocarbons decreased by 32% during the seasonal freeze-thaw phase where soils were cooled from 2 to -5°C at a freezing rate of -0.12°Cd -1 and then thawed from -5t o4°C at a thawing rate of +0.16°Cd -1.I nt h e unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the 14 C-hexadecane mineralization in soil samples obtained from the nutrientamended tank steadily increased. Hydrocarbon degrading bacterial populations identified as Corynebacterineae-and Alkanindigesrelated strains emerged during the freezing and thawing phases, respectively, indicating there were temperature-based microbial community shifts.

Predictable bacterial composition and hydrocarbon degradation in Arctic soils following diesel and nutrient disturbance

“…Diesel degradation and bacteria in Arctic soils TH Bell et al Hydrocarbons in Soil, as used previously for the determination of hydrocarbon concentrations in sub-Arctic soils (Chang et al, 2011). Detailed procedures for soil and hydrocarbon analyses are presented in the Supplementary Material.…”

Hydrocarbon degraders establish at the costs of microbial richness, abundance and keystone taxa after crude oil contamination in permafrost environments

“…In particular research on permafrost soil bioremediation is at present under-represented, with only a few studies available on the topic61521. In previous works1522 we used a 16 S rRNA gene pyrosequencing approach to describe the bacterial biodiversity of uncontaminated/contaminated deep active layers and upper permafrost (i.e.…”

Selective biostimulation of cold‐ and salt‐tolerant hydrocarbon‐degrading Dietzia maris in petroleum‐contaminated sub‐Arctic soils with high salinity

“…The intrinsic halotolerance of cold‐tolerant bacteria and its relevance to microbial survival mechanisms in cryohabitats have been suggested previously in fundamental research on bacteria in cold habitats, which include the eutectic interface associated with brine‐filled veins, pockets and networks in sea ice and water . Other cold‐region studies have reported significant hydrocarbon biodegradation activity in frozen sub‐Arctic soils at subzero temperatures . Cold‐adapted hydrocarbon‐degrading bacteria that can survive in moderate salinities (<2.5% NaCl), as well as the hydrocarbon degradation associated with their activity, have also been frequently reported .…”

“…The soils from the Northwest Territories and Resolution Island are denoted as NW and RI soils, respectively. Hydrocarbon‐degrading bacteria are abundant in both soils . The detailed properties of the NW and RI soils were characterized in previous studies by the current authors .…”

“…Interestingly, Chang et al . indicated the selective emergence of Corynebacterineae relatives as nutrient‐amended, petroleum‐contaminated sub‐Arctic soils were slowly freezing under a site‐representative seasonal freeze–thaw rate, implying the presence of bacterial populations adapted to multiple stresses such as cold temperatures, limited unfrozen water, and/or salinity …”