Summary:
Overview
Dr. Elizabeth Kujawinski at Woods Hole Oceanographic Institution and Prof. Helen White at Haverford College were awarded an RFP-II grant at $1,053,159 to conduct the RFP-II project entitled “Weathering of Petroleum and Dispersant Components in the Aftermath of the Deepwater Horizon Oil Spill”. The project consisted of 2 institutions and 11 research team members. Through this work, Dr. Kujawinski, Prof. White and their teams aimed to: 1) determine the composition of polar (and/or water- soluble) components of oil and dispersants in the subsurface plumes; 2) quantify the relative contribution of total oil, polar oil, dispersants, and weathering products in impacted sediments; and 3) assess the nature and extent of biological activity altering the composition of oil in sediments.
Research Highlights
Dr. Kujawinski and Prof. White’s research, which included 16 outreach products and activities, resulted in 7 peer-reviewed publications to date and 10 datasets being submitting to the GoMRI Information and Data Cooperative (GRIIDC), which are/will be available to the public. Prof. White and Dr. Kujawinski engaged 17 students, primarily at Haverford College, over the award period. Significant outcomes of their research according to GoMRI Research Theme are highlighted below.
Theme 1 & 3: Distribution of Petroleum and Its Constituents
- Dr. Kujawinski and her team investigated the chemical composition of oil that dissolves in water, specifically the polar molecules that contain oxygen, nitrogen and sulfur. They observed significant chemical differences between two fractions of oil commonly used in toxicological studies, the water-accommodated fraction which contains oil droplets and the water-soluble fraction which contains only molecules truly dissolved in water. These differences may affect interpretation of biological studies if imprecise chemical characterization is used.
- Prof. White led a study to assess dispersant presence and concentrations in deep sea coral and sediment samples and in oil soaked sand patties collected from Gulf of Mexico. White and her students developed a method to extract DOSS (dioctyl sodium sulfosuccinate), a component of Corexit from solid environmental matrices prior to analysis via LC/MS at WHOI. DOSS was detected in deep-sea coral communities 6 months after the spill and in oil soaked sand patties 26−45 months after the spill. These results indicate that the applied dispersant can remain associated with oil in the environment and persist.
Theme 2: Chemical/Biological Processes
- The team conducted an incubation experiment to examine the role of microbes such as bacteria on the weathering of oil, in particular its polar components.
- Prof. White and her team are processing assembled metagenomes for functional and taxonomic annotation using an analysis pipeline that involves functional gene prediction by prodigal (http://prodigal.ornl.gov/), and then annotation of thepredicted genes against NCBI’s Refseq database. Results will tabulate the functional (and taxonomic) abundance by category/species and evaluate any differences for statistical significance, using the program MEGAN.
- Dr. Kujawinski and her team putatively identified a suite of metabolites produced during the degradation of crude oil-derived aromatic compounds and confirmed their identity with commercial standards. These molecules are derived only from petroleum weathering in incubations and thus may be a new marker for hydrocarbon weathering in the environment. Indeed, these molecules are present in the Deepwater Horizon field samples collected in 2010.
