Weathering of hydrocarbons in mangrove sediments: testing the effects of using dispersants to treat oil spills

Burns, Kathy, Codi, Susan, Pratt, Catherine, and Duke, Norman (1999) Weathering of hydrocarbons in mangrove sediments: testing the effects of using dispersants to treat oil spills. Organic Geochemistry, 30. pp. 1273-1286.

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Abstract

This field study was a combined chemical and biological investigation of the relative effects of using dispersants to treat oil spills impacting mangrove habitats. The aim of the chemistry was to determine whether dispersant affected the short- or long-term composition of a medium range crude oil (Gippsland) stranded in a tropical mangrove environment in Queensland, Australia. Sediment cores from three replicate plots of each treatment (oil only and oil plus dispersant) were analyzed for total hydrocarbons and for individual molecular markers (alkanes, aromatics, triterpanes, and steranes). Sediments were collected at 2 days, then 1, 7, 13 and 22 months post-spill. Over this time, oil in the six treated plots decreased exponentially from 36.6±16.5 to 1.2±0.8 mg/g dry wt. There was no statistical difference in initial oil concentrations, penetration of oil to depth, or in the rates of oil dissipation between oiled or dispersed oil plots. At 13 months, alkanes were >50% degraded, aromatics were ~30% degraded based upon ratios of labile to resistant markers. However, there was no change in the triterpane or sterane biomarker signatures of the retained oil. This is of general forensic interest for pollution events. The predominant removal processes were evaporation (≤27%) and dissolution (≥56%), with a lag-phase of 1 month before the start of significant microbial degradation (≤17%). The most resistant fraction of the oil that remained after 7 months (the higher molecular weight hydrocarbons) correlated with the initial total organic carbon content of the soil. Removal rate in the Queensland mangroves was significantly faster than that observed in the Caribbean and was related to tidal flushing.

Item ID: 48914
Item Type: Article (Refereed Research - C1)
Keywords: oil spill; mangroves; weathering; dispersants; biomarker patterns; degradation
ISSN: 1873-5290
Funders: Australian Petroleum Production and Exploration Association (APPEA), Energy Research and Development Corporation, Australian Institute of Marine Science
Date Deposited: 02 Aug 2017 04:57
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 40%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050206 Environmental Monitoring @ 30%
06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 30%
96 ENVIRONMENT > 9612 Rehabilitation of Degraded Environments > 961201 Rehabilitation of Degraded Coastal and Estuarine Environments @ 30%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960503 Ecosystem Assessment and Management of Coastal and Estuarine Environments @ 40%
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