title: Experimental study of clay-hydrocarbon interactions relevant to the biodegradation of the Deepwater Horizon oil from the Gulf of Mexico.
abstract: Adding clay to marine oil pollution represents a promising approach to enhance bacterial hydrocarbon degradation in nutrient poor waters. In this study, three types of regionally available clays (Ca-bentonite, Fuller's Earth and kaolin) were tested to stimulate the biodegradation of source and weathered oil collected from the Deepwater Horizon spill. The weathered oil showed little biodegradation prior to experimentation and was extensively degraded by bacteria in the laboratory in a similar way as the alkane-rich source oil. For both oils, the addition of natural clay-flakes showed minor enhancement of oil biodegradation compared to the non-clay bearing control, but the clay-oil films did limit evaporation. Only alkanes of a molecular weight (MW) > 420 showed significant reduction by enhanced biodegradation following natural clay treatment. In contrast, all fertilized clay flakes showed major bacterial degradation of the oil, with a 6-10 times reduction in alkane content, and an up to 8 fold increase in the rate of O2 consumption. Compared to the control, such treatment showed particular reduction of longer chained alkanes (MW > 226). The application of natural and fertilized clay flakes also showed selective reduction of PAHs, mainly in the MW range of 200-300, but without significant change in the toxicity indices measured. These results imply that a large variety of clays may be used to boost oil biodegradation by aiding attachment of fertilizing nutrients to the oil.
authors: Institute of Geography and Geology, Ernst-Moritz-Arndt University, F.L. Jahn Strasse 17A, D-17487 Greifswald, Germany. Electronic address: warr@uni-greifswald.de.
authors: Laurence N
authors: LN
authors: Warr
authors: GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam, Germany.
authors: André
authors: A
authors: Friese
authors: Department of Geography, Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne NE1 8ST, United Kingdom.
authors: Florian
authors: F
authors: Schwarz
authors: Institute of Microbiology, Ernst-Moritz-Arndt University, F.L. Jahn Strasse 15, D-17487 Greifswald, Germany.
authors: Frieder
authors: F
authors: Schauer
authors: College of the Coast & Environment Louisiana State University, 1165 EC&E Bldg, Baton Rouge, LA 70803, USA.
authors: Ralph J
authors: RJ
authors: Portier
authors: College of the Coast & Environment Louisiana State University, 1165 EC&E Bldg, Baton Rouge, LA 70803, USA.
authors: Laura M
authors: LM
authors: Basirico
authors: College of the Coast & Environment Louisiana State University, 1165 EC&E Bldg, Baton Rouge, LA 70803, USA.
authors: Gregory M
authors: GM
authors: Olson
mesh_terms: D000538:Aluminum Silicates / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects* / Q000378:metabolism*; D001673:Biodegradation, Environmental / Q000187:drug effects; D000077215:Clay; D060851:Gulf of America; D006838:Hydrocarbons / Q000302:isolation & purification / Q000378:metabolism*; D010578:Petroleum / Q000032:analysis; D059392:Petroleum Pollution / Q000032:analysis; D014887:Weather
chemical_list: D000538:Aluminum Silicates; D006838:Hydrocarbons; D010578:Petroleum; D000077215:Clay
keywords: Biodegradation; Clay; Deepwater Horizon; Hydrocarbons; Pollution; Toxicity