On the following subject: "Presence in the environment and flows of organic contaminants of emerging interest in the north-western Mediterranean coastal zone and in the Rhône".
Thesis supervisor :M. RICHARD SEMPERE, RESEARCH DIRECTOR
Co-director: JAVIER CASTRO-JIMENEZ, RESEARCH LEADER
Abstract
Chemical pollution has become a global threat to the environment, including marine ecosystems, which receive large loads of contaminants from sewage and river inputs, among other sources. Phthalates (PAEs), organophosphate esters (OPEs), bisphenols (BPs) and perfluorinated compounds (PFCs) are synthetic organic chemicals used in a variety of products. PAEs and BPs are common plasticisers, as are non-halogenated OPEs. Halogenated OPEs are mainly used as flame retardants and are considered substitutes for polybrominated diphenyl ethers (PBDEs), which have been banned under the Stockholm Convention on Persistent Organic Pollutants. PFCs have water- and oil-repellent properties and are therefore used in the manufacture of resistant textiles and polytetrafluoroethylene, as well as in fire-fighting foams. These organic compounds, which are widespread in the environment due to their high rates of production and use and the inadequacy of the regulatory framework, are causing growing concern due to their proven or suspected endocrine disrupting and/or carcinogenic properties. Along with other environmental pollutants, such as microplastics, they are exerting increasing anthropogenic pressure on aquatic environments. Their temporal and spatial variability, their occurrence and local sources, their distribution in different compartments and their interactions with organisms, among other things, are not well characterised and many questions remain open. In this thesis, several of these aspects were studied at the scale of the Bay of Marseille (north-western Mediterranean) and the Rhône. In a first study, the daily transport rates of microplastics for the Northern Mediterranean Current (CNM) (0.18-86.46 t) and the Rhône (0.20-21.32 kg) were estimated from the collection of 3,193 microplastics in the zone of influence of the CNM, the Bay of Marseille and the Rhône and its plume. Secondly, organic plastic additives were analysed in the Rhône and it was estimated that 13.7 to 148 kg of dissolved organic plastic additives are exported each day by the Rhône, indicating that potential release by (surface) microplastics cannot fully explain the concentrations of additives present in the dissolved aqueous phase. In the third part, PFCs were analysed in the Bay of Marseille and in the Rhône, and it was found that concentrations of perfluorooctanesulphonic acid (PFOS) exceeded the EU annual average environmental quality standard in more than 80% of the samples. In addition, numerical modelling has shown that intrusions from the Rhône can transport significant quantities of PFOS into the Bay of Marseille. In the fourth section, the focus on the Bay of Marseille showed that the zooplankton samples in particular had high levels of organic plastic additives, while the water and sediment samples were only moderately or slightly contaminated. Diethylhexyl phthalate (DEHP) was the most abundant in zooplankton samples, with a wide range of concentrations (309 ng g-1 dw - 40 µg g-1 dw). Finally, water samples from the tropical North Atlantic were used to make comparisons between coastal regions (Marseille Bay), river regions (Rhône) and remote regions (tropical North Atlantic). Whereas in the Bay of Marseille, contaminant dynamics were dominated by coastal (WWTP discharge, port activities) and riverine inputs, medium- and long-range transport occurred in the tropical North Atlantic, where contaminants originated from the Amazon River and were then transported by the North Brazilian Current.
Key words: phthalates, organic contaminants, plasticisers, pollution, microplastics, Bay of Marseille.