A new green protocol for the identification of microplastics and microfibers in marine sediments, a case study from the Vesuvian Coast, Southern Italy

Microplastics (MP; 1 μm–5 mm) and microfibers (MF; thin, elongated particles with a high length-to-width ratio) have become a major global environmental issue due to their ubiquity in the oceans and their complex physicochemical properties, which affect their mobility, bioavailability, and toxicity toward organisms, as well as their interactions with surrounding pollutants. Nevertheless, a reliable methodology capable of facilitating and automating the monitoring of MPs is still lacking. To address the need for practical and standardized methods and overcome the limitations related to the lack of practicality and standardization of currently applied approaches, a new analysis protocol based on optical microscopy for the counting and morphological analysis of particles has been developed. This method does not involve sieving, washing, heating, density separation, or digestion processes. Our method is green and requires a minimum quantity of sediment, i.e. 1.5 g, while also reducing analysis timeframes. Future research efforts may focus on developing and implementing new analytical tools and combinations of technologies to complement current detection limitations and achieve reliable characterization of both MFs and MPs. The protocol was tested on samples from both marine and land sediments in the Vesuvian area of the Gulf of Naples (Italy).