Comprehensive analytical approaches to determine the sources, fate and effects of marine oil spills

[spa] A pesar de las tendencias positivas en las últimas décadas, los vertidos ocasionados por la exploración, extracción y transporte de petróleo siguen siendo una importante amenaza para los ecosistemas marinos y especialmente costeros. Esta Tesis se ocupa de todos los aspectos importantes sobre los vertidos marinos de petróleo: el origen, el destino ambiental y sus posibles efectos. Para permitir su comprensión global, se utilizaron diferentes metodologías complementarias. En primer lugar, se ha creado una base de datos físico-químicos de diferentes petróleos (crudos y refinados) que se transportan frecuentemente usando el análisis elemental, la cromatografía en capa fina (TLC) acoplada a un detector de ionización de llama (FID) de los principales grupos de compuestos de petróleo, la toma de huellas químicas de los hidrocarburos aromáticos policíclicos (HAP) y los biomarcadores mediante cromatografía de gases acoplada a espectrometría de masas (GC-MS), y ensayos de petróleo disponibles. A continuación, se aplicó esta base de datos para evaluar su posible destino en el caso de un vertido, y para modelar tres escenarios de vertidos en diferentes mares regionales europeos usando el software ADIOS2 de la Administración Nacional Oceánica y Atmosférica (NOAA). Las huellas químicas de los petróleos seleccionados fueron evaluadas y comparadas estadísticamente para investigar las diferencias de composición más relevantes que podrían facilitar la identificación del origen de vertido. En segundo lugar, la metodología de GC-MS utilizada para crear la base de datos de las huellas químicas de los petróleos seleccionados se ha evaluado en una prueba interlaboratorio internacional. El objetivo fue investigar la capacidad que tiene esta metodología de toma de huellas químicas para identificar el tipo y el origen de las muestras envejecidas (biodegradadas) de petróleo. En tercer lugar, se ha estudiado el envejecimiento de las muestras de petróleo de los vertidos de Prestige (2002) y de la plataforma Deepwater Horizon (2010), en particular, debido a la fotooxidación. Se analizaron muestras envejecidas en el campo y en experimentos de laboratorio mediante TLC-FID, GCMS, cromatografía de gases bidimensional integrada (GCxGC) acoplada a un FID, y espectroscopia infrarroja por transformada de Fourier (FT-IR) para investigar los cambios de composición tanto a nivel global como a nivel molecular. Los HAP y esteranos triaromáticos fueron de especial interés, así como los efectos de la fotooxidación en la robustez de la metodología de toma de huellas químicas de petróleo. Finalmente, se estudiaron los efectos de las muestras no tratadas y envejecidas (evaporadas, fotooxidadas) de los petróleos crudos y refinados seleccionados, utilizando el análisis dirigido por los efectos tóxicos (EDA). Las muestras se fraccionaron secuencialmente usando la cromatografía líquida en columna abierta y la cromatografía líquida de alta eficacia (HPLC) semipreparativa en fase normal. Las fracciones obtenidas se sometieron a bioensayos para investigar su actividad agonista de los receptores AhR y la actividad antagonista de los receptores AR. En el siguiente paso, las fracciones más activas fueron analizadas mediante GCxGC acoplada a espectrometría de masas en tiempo de vuelo (TOFMS), y estos datos se relacionaron con los resultados de los bioensayos utilizando un modelo quimiométrico de regresión por mínimos cuadrados parciales en N direcciones (N-PLS), con el fin de identificar los compuestos responsables de los efectos observados.[eng] In the past two decades we witnessed a decrease in both the number of oil spill incidents, and of the quantity of oil released in these incidents, which led to a diminished interest for basic oil spill science. With the introduction of more stringent oil spill legislation, much of the spill response, assessment and restoration activities were passed to governmental agencies and other stakeholders. Their capabilities were perhaps sufficient to deal with the most frequently occurring small-scale spills, however, recent large, catastrophic incidents such as the sinking of Prestige in 2002, or the Deepwater Horizon blowout in 2010, renewed the need for fundamental science in order to be able to fully understand and estimate the scope of the impacts such spills can have on the environment, economy and society. This is particularly important in the context of new explorations and discoveries of hydrocarbon resources in pristine regions such as Arctic, where extreme weather and the lack of infrastructure emphasize even more the need for a comprehensive assessment of all of the possible effects the future oil production could cause. The objectives of this thesis were set to provide new approaches and methodologies, and to improve and reevaluate the previously existing ones, in a way which can contribute to this comprehensive and proactive strategy. Their scope is comprehensive because it covers all the important aspects of marine oil spills – the sources, environmental fate and possible toxic effects. In addition, particular relevance of this thesis is drawn from the fact that the studies presented here include the investigation of real major oil spills (Prestige, DWH), and of a broad range of oils and oil products that are currently produced and transported worldwide. In order to fulfill the abovementioned general objectives, the following specific objectives had to be accomplished: Firstly, a physicochemical database of frequently transported crude and refined oils was created using elemental analysis, thin-layer liquid chromatography (TLC) with flame ionization detector (FID) analysis of principal oil compound groups, gas chromatography-mass spectrometry (GC-MS) fingerprinting of polycyclic aromatic hydrocarbons (PAHs) and biomarkers, and available oil assays. This database was then applied to assess their possible fate in the case of a spill, and to model three spill scenarios in different European regional seas using ADIOS2 software from NOAA (National Oceanic and Atmospheric Administration). Fingerprints of selected oils were assessed and statistically compared to discover the most relevant compositional differences that could facilitate the identification of oil spill sources. Secondly, the GC-MS methodology used to create the fingerprint database of selected oils was evaluated in an international interlaboratory ring test. The objective was to test the capability of this fingerprinting methodology to identify the type and source of weathered (biodegraded) oil samples. Thirdly, the weathering of oil samples from Prestige and Deepwater Horizon spills, in particular the photooxidation, was studied. Samples weathered in field and in laboratory experiments were analyzed using TLC-FID, GC-MS, comprehensive two dimensional gas chromatography (GCxGC) with FID, and Fourier transform infrared spectrometry (FT-IR) to discover compositional changes on the bulk level as well as on the molecular level. PAHs and triaromatic steranes (TAS) were of particular interest, as well as the effects of the photooxidation on the robustness of the oil fingerprinting methodology. Finally, the effects of selected fresh and weathered (evaporated, photooxidized) crude and refined oils were studied, using the effect-directed analysis (EDA). The samples were sequentially fractionated using open-column liquid chromatography and normal-phase semipreparative HPLC, and the obtained fractions were subjected to bioassays to test their AhR agonist and AR antagonist activity. The most active fractions were then analyzed using GCxGC coupled to time-of-flight mass spectrometry (TOFMS), and this data was related to bioassay results using N-way partial least square (N-PLS) chemometric model, in order to identify the compounds responsible for the observed effect