CONICET | Buscador de Institutos y Recursos Humanos

Petroleum can pollutepristine shorelines as a consequence of accidental spills or chronic leaks. Inthis study, the fate of petroleum hydrocarbons in soft pristine sediment ofCaleta Valdés (Argentina) subject to exsitu simulated oil pollution was assessed. Sedimentary columns were exposedto medium and high concentrations of Escalante Crude Oil (ECO) and incubated inthe laboratory during 30 days. Levels of aliphatic hydrocarbons at differentdepths of the sedimentary column were determined by gas chromatography. Oilpenetration was limited to the first three centimetres in both treatments, andunder this depth, hydrocarbons were clearly biogenic (terrestrial plants) as inthe whole sedimentary column of the control assay. Bioturbation by macrobenthicinfauna was strongly impacted by oil pollution which resulted in reducedsediment oxygenation and low burial of petroleum hydrocarbons. This may partlyexplain the limited hydrocarbon biodegradation observed, as indicated by the relativelyhigh values of the ratios nC17/pristane, nC18/phytane, and total resolvedaliphatic hydrocarbons/unresolved complex mixture. Correspondingly, at the endof the experiment the most probable number of hydrocarbon-degrading bacteriareached ~103 MPN g-1 dry weight. These values were lowerthan those found in chronically polluted coastal sediments, reflecting a lowactivity level of the oil-degrading community. The results highlight the lowattenuation capacities of Caleta Valdés pristine sediments to recover itsoriginal characteristics in a short time period if an oilspill occurs. In this work, we present a novel and integrative tool toevaluate the fate of petroleum hydrocarbons and their potential damage onpristine sediments.

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