Study of contaminants transported by microplastics in the Lebanese marine environment

Anthropogenic activities are increasingly putting pressure on the environment of the Lebanese Mediterranean coast. One of the main emerging sources of pollution is plastics ending up in the marine environment and persisting as small (so-called microplastics, 1 µm - 5 mm) particles which become a vector for the transport of a variety of contaminants. The assessment of microplastics-related environmental risks requires the development of multi-scope analytical approaches targeting different classes of organic and inorganic pollutants.A comprehensive study of microplastic pollution of the Lebanese Mediterranean coast was performed. The samples were collected from the shoreline in 2020-2021, sieved and sorted into different sizes. The nature of the microplastics was investigated by Fourier Transform Infrared Spectroscopy (FTIR) revealing the predominant presence of polyethylene and polypropylene. For the study of adsorbed organic pollutants, solid-liquid extraction (leaching) procedures targeting polar and non-polar compounds were optimized. Metals were analyzed after the complete microwave assisted digestion of samples. Prior to quantitative analysis, the organic pollutants were screened according to their accurate mass, chromatographic behavior and fragmentation. In this way, the lists of compounds for the subsequent targeted analysis were established. This study produced the first ever LC-MS/MS and GC-MS data on microplastics-adsorbed organic pollutants present on Lebanese Mediterranean coast and demonstrated the persistency of several legacy pesticides, such as DDT prohibited for use more than 20 years ago and chlorpyrifos that was banned for use in Lebanon several years ago. Also, the presence of personal care products and pharmaceuticals, such as phenacetin and minoxidil, polycyclic aromatic hydrocarbons (PAH), different polychlorinated biphenyl (PCB) congeners prohibited long time ago due to their toxic effect on human health, and different additives incorporated in plastics was demonstrated. The quantification of metals was carried out by ICP-MS. The obtained data were discussed in the context of their possible environmental and anthropogenic sources and also their presence in pigments and additives added to plastics during the manufacturing process.The performed study clearly shows that microplastics are not only a source of pollution by themselves, but also transport organic and inorganic contaminants in the marine environment and therefore represent a threat to the marine organisms and as well as human health. It is therefore important to study different types of pollutants to have a global view on the harmful and oblivious effect of microplastics in the marine environment.Moreover, as microplastics are becoming important targets of environmental studies, the perspectives for future green methodologies reducing the use of organic solvents in sample preparation were highlighted. For example, liquid-extraction surface analysis (LESA) was investigated for the screening of pollutants sorbed on the surface of microplastics.