Microplastic identification in marine environments: A low-cost and effective approach based on transmitted light measurements

Microplastics have become a significant concern for the well-being of marine ecosystems. Small fragments of plastic debris are released into the environment from both the direct disposal of plastic products and the deterioration of larger items. Ingestion of microplastics by marine life can result in detrimental effects, including physical harm and the accumulation of toxic chemicals in their tissues. The aim of this research is to design a compact and cost-effective measurement system for effectively detecting and quantifying microplastics in marine environments. The proposed system uses a 2.4-inch liquid-crystal display (LCD) panel and a digital USB microscope, both of which are connected to a single-board computer, with a dedicated python-based graphical user interface (GUI). Specifically, the light transmitted through plastic and organic samples was measured in order to identify and classify them. Various types of materials, such as polypropylene, polyvinyl chloride, polycarbonate, polyethylene, and organic algae samples, were tested and the metrological performance of the system has been estimated. The transmittance of the samples analyzed was primarily influenced by their opacity and thickness. In general, thicker materials exhibited significantly lower transmittance values. This trend was particularly evident in organic components and opaque plastic samples, where transmittance was significantly low. In addition, the experimental results suggest that the colour of the material also affects transmittance, although as a secondary factor. The employed technique could be used to identify and distinguish samples based on material properties, thereby allowing the proposed system to be a valuable tool for further research on microplastics in marine environments.