Dynamics of microbial populations and diversity in NAPL contaminated peat soil under varying water table conditions

Abstract

Despite the risks that hydrocarbon contamination from pipeline leaks or train derailments impose on the health of peatlands in hydrocarbon production areas and transportation corridors, assessing the effect of such contaminations on the health and sustainability of peatlands has received little attention. This study investigates the impacts of hydrocarbons on peat microbial communities. Column experiments were conducted on non-aqueous phase liquid (NAPL) contaminated undisturbed peat core (0-35 cm) under static and fluctuating water table conditions. Water table fluctuations reduced residual NAPL saturation from 8.1-11.3% to 7.7-9.5%. Biodegradation of n-C₈ and n-C₁₂ along with oxidation of CH₄ together produced high CO₂ concentrations in the headspace. Clear patterns in dynamics in the microbial community structure were observed, with a more pronounced population growth. However, a significant loss of microbial richness was observed in contaminated columns. The result indicates that the phylum Proteobacteria benefited most from NAPL; however, their families differed between static and fluctuating water table conditions. This study established strong evidence that peat microbes and water table fluctuation can be an excellent tool for hydrocarbon removal and its control in peatlands.

Keywords: 16S rRNA sequencing; Biodegradation; Column experiment; Hydrocarbon spill; Methane dynamics; Microbial shifting; Peatlands.