Microbial community response to petroleum hydrocarbon contamination in the unsaturated zone at the experimental field site V�rl�se, Denmark

Abstract

This study investigates the influence of petroleum hydrocarbons on a microbial community in the vadose zone under field conditions. An artificial hydrocarbon mixture consisting of volatile and semi-volatile compounds similar to jet-fuel was emplaced in a previously uncontaminated vadose zone in nutrient-poor glacial melt water sand. The experiment included monitoring of microbial parameters and CO 2 concentrations in soil gas over 3 months in and outside the hydrocarbon vapor plume that formed around the buried petroleum. Microbial and chemical analyses of soil and vadose zone samples were performed on samples from cores drilled to 3.3 m depth on three dates and three lateral distances from the buried petroleum mass. Significantly elevated CO 2 concentrations were observed after contamination. Total cell numbers as determined by fluorescence microscopy were strongly correlated with soil organic carbon and nitrogen content but varied little with contamination. Redundancy analysis (RDA) allowed direct analysis of effects of selected environmental variables or the artificial contamination on microbiological parameters. Variation in biomass and CO 2 production was explained by soil parameters, to 46%, and by the duration of contamination, to 39.8%. The microbial community structure was assessed by community level physiological profiles (CLPP) analysis using Biolog TM Eco-Plates. In the CLPP data only 35.9% of the variation could be linked to soil parameters and contamination, however, the samples with greatest exposure to hydrocarbons grouped together on RDA plots. It is concluded that, at this nutrient-poor site, the microbial community was dominated by natural heterogeneity and that the influence of petroleum hydrocarbon vapors was weak.

Long-term oil contamination causes similar changes in microbial communities of two distinct soils

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Organic matter characterisation and turnover in the sediment and seawater of a tourist harbour

“…Biotic consumption and degradation, that should be the main processes of OM mobilisation, are not often efficient enough to maintain the ecosystem balance, due to the excess of detrital OM, increasing anoxic conditions and, often, the presence of significant levels of contamination by heavy metals and other toxic components (Cornelissen et al, 2008;Kaufman et al, 2004). In addition, the occurrence of biochemical interactions between labile OM and recalcitrant OM molecules (humic acids for instance, Hubberten et al, 1994) originating from allochthonous continental inputs (rivers and sewage) may modify the turnover times and pathways of organic matter recycling.…”

Applying multivariate methods to soil–solution interactions in carbonate media

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