Evidence of small microplastics in waters and sediments of the Venice Lagoon: quantitative analysis and polymer identification using Micro-FTIR

Microplastics are emerging pollutants in all environmental compartments (e.g. water, soil, sediments, etc.). Their contamination is well documented since 1970’s, although specific references to this topic were made in the US and in Europe in 2008. Microplastic particles are generally classified according their sizes, but the classification has been subject of lengthy debates. Finally, the European Chemical Agency (ECHA, 2019) has proposed the definition of microplastic as “a material composed of solid polymer-containing particles, to which additives or other substances may have been added, with particle dimensions ranging from 1 nm to 5 mm and with fiber lengths ranging from 3 nm to 15 mm and length to diameter ratio of >3. Furthermore, ECHA has firmly stated the need of polymer identification when analyzing microplastics. In literature several methods have been employed, especially microscopic methods which do not allow the identification of polymers. In these studies only a subset of samples was analyzed via FTIR. In several studies only large microplastics were studied and small microplastics were neglected, especially in water studies, since the mesh sizes of manta trawls can be either 330 µm or 100 µm. In this study small microplastics (1-100 µm) were studied in sediments and waters of the Venice Lagoon using micro-FTIR. These small particles can be mistaken as food particles and then ingested by the biota. Small microplastics can cause damages and obstructions of gastrointestinal tract, and they can be accumulated within the organisms along the trophic net. A method of purification, quantification and polymer identification was developed. Six sites in the Venice Lagoon were studied; preliminary findings showed differences among the sites studied.