Microscopic techniques as means for the determination of microplastics and nanoplastics in the aquatic environment: A concise review

The global concern about the fate of plastic particles, including microplastics (MPs) and nanoplastics (NPs), in aquatic ecosystems has undoubtedly grown as million tons of polymeric fragments are released in oceans in an annual basis. The ability of these plastic items being transferred into the several aquatic ecosystems in combination with their ability to absorb organic or inorganic pollutants onto their surface, raises the need for a sufficient monitoring of MPs/NPs in complex aquatic environmental matrices. In the frame of these, microscopic techniques are considered as ideal tools to critically assist other analytical techniques due to their fast-screening character or even complete a detailed analysis of plastic particles in some cases. In the light of the above, the present review discusses a group of microscopic techniques used in the analysis of plastic particles isolated from aquatic samples most likely to be important in future monitoring actions, emphasizing on their operating fundamentals, merits and limitations. Moreover, the microscopic techniques are highlighted as green tools in the analysis of plastic particles/fragments due to their minimum need of reagents, solvents, and energy required for the implementation of such a kind of analysis. Finally, the effective combination of microscopic techniques with spectroscopic ones are also presented.