The toxicity of residual hydrocarbons and polar metabolites on Antarctic soil microbial diversity
Hydrocarbon contamination in terrestrial Antarctica pose serious threats to the environment and the native species thriving. A legacy of fuel spills means that partially remediated soils are likely to contain fingerprints of unresolved complex mixture (UCM) which are comprised of residual hydrocarbo...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | unknown |
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UNSW Sydney
2019
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| Online Access: | https://dx.doi.org/10.26190/unsworks/21778 http://hdl.handle.net/1959.4/65813 |
| Summary: | Hydrocarbon contamination in terrestrial Antarctica pose serious threats to the environment and the native species thriving. A legacy of fuel spills means that partially remediated soils are likely to contain fingerprints of unresolved complex mixture (UCM) which are comprised of residual hydrocarbons and polar metabolites. However, their presence in hydrocarbon contaminated soil and ecotoxicity information is largely unknown. This lack of knowledge raises concerns on their potential toxicity. Since terrestrial Antarctica is dominated by microorganisms, the main aim of this study was to explore toxicity of residual hydrocarbons and polar metabolites on endemic Antarctic soil microorganisms of Casey station. Here, we used a synthetic residual fuel mixture (RFM) comprising five compounds that are present in Special Antarctic Blend diesel fuel, a commonly used fuel at Casey station and found that the bacterial community was more sensitive to RFM than the eukaryotic community. Dose-response modelling showed that the total DNA community produce more sensitive and reliable effective concentration (EC) values indicating DNA a better option for future ecotoxicity evaluations within these soils. Of five indices evaluated, Simpson and Shannon were the most reliable indicators for the bacterial and eukaryotic communities, respectively. For characterization of polar metabolites, out of 12 aldehydes and two ketones tested in both clean and contaminated elutriates (that mimics leachate runoff), only nine aldehydes were detected, with the majority being biogenic. Acetaldehyde was present at the highest concentration (821 µg/l) in the partially remediated soil, inferring it to be a potential chemical indicator for hydrocarbon degradation. Three major aldehydes (acetaldehyde, octanal, and undecanal) detected in the contaminated soil elutriates were selected for toxicity assessments using the single species toxicity assay Microtox (Aliivibrio fischeri) but were found below toxic level. The cumulative effect of water-soluble toxicants present in the contaminated soil elutriates were found toxic to Aliivibrio fischeri and site-specific bacterial communities. A higher proportion of bacterial genera (95-135) responded significantly (stimulated or inhibited) to contaminated soil elutriates. Our study found that both RFM and polar metabolites to have toxic effect on microbial communities, thus present a serious risk to the sensitive Antarctic environment and its microbial communities. |
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