PhD Thesis Defence by Núria Trilla i Prieto

The predoctoral researcher Núria Trilla i Prieto, from the Global Change and Genomic Biogeochemistry group, will defend her thesis on 25th April at 10:00h at the aula Magna of the Faculty of Biology (University of Barcelona)

Directors: Jordi Dachs and Begoña Jiménez

Thesis Committee: Assumpció Borrell, Antonio Tovar and Andre G. Bravo

Abstract:
Large-scale oceanic assessments provide key knowledge on the persistence and potential for long-range transport of organic pollutants. This thesis investigates the latitudinal and depth distribution and biogeochemical cycling of dissolved black carbon (DBC), organophosphate esters (OPEs), and perfluoroalkyl acids (PFAAs) in the ocean. The assessment of DBC occurrence and cycling in the ocean was based on a meta-analysis, while OPEs and PFAAs were analyzed for samples collected during two oceanographic expeditions covering a latitudinal transect from 42ºN to 71ºS in the Atlantic and Southern oceans. It is shown that semivolatile aromatic hydrocarbons account for ~16% of oceanic DBC, implying that DBC is less persistent than previously thought, and that there are important atmospheric inputs of semivolatile DBC to the ocean. OPE concentrations decreased from the Northern Atlantic toward Antarctic waters, but showed unexpected enrichment in the sea surface microlayer (SML)—particularly in the Southern Ocean—likely linked to its surfactant and hydrophobic properties. Depth distribution of OPEs were clearly influenced by the biological pump and other biogeochemical processes. In contrast, PFAAs showed similar concentrations in the remote Southern Ocean than in the open north Atlantic, while concentrations were lower in the tropical south Atlantic. PFAAs concentrations in the Southern Ocean are currently larger than two decades ago, suggesting that Antarctic waters are a long term sink and reservoir for PFAAs. This accumulation is consistent with PFAAs sea-spray driven aerosolization followed by wet deposition. These results shows that persistence is a key property explaining the long-range transport and accumulation of emerging contaminants in remote oceanic regions.