Laboratory Assessment for Determining Microplastics in Freshwater Systems—Characterization and Identification along the Somesul Mic River

Microplastics (MPs) pollution has become a persisting problem over the last decades and
is a critical issue for environmental protection and human health. In this context, scientific data
able to reveal MPs presence and improve the characterization and identification of this pollution via
different systems are valuable. The aim of this paper is to assess available techniques for determining
MPs in real freshwater samples and subsequently to highlight the occurrence and type of MPs in
the study case area (Somesul Mic River). The MPs sampling was performed from fresh water and
sediment using planktonic nets and sieves with different mesh sizes (from 20 to 500 μm). Using both
classical microscopic techniques as well as scanning electron microscopy (SEM), large (1–5 mm) and
small (1 μm to 1 mm) MPs were observed in the shape of fibers, fragments, foam, foils and spheres
in various colors (red, green, blue, purple, pink, white, black, transparent, and opaque). Raman
and FT-IR spectroscopic methods were used for MPs identification. The presence of polyethylene
(PE), polypropylene (PP), and polystyrene (PS) was registered for all sampling points. The MPs
laboratory investigations have raised some issues regarding the identification of MPs particles smaller
than 500 μm, these being characterized especially under microscope. Some small MPs particles
were identified using micro-Raman spectroscopy that highlighted the same type of polymers. No
differences were registered between the sampling points due to the widespread presence of MPs. The
sediment samples presented a greater abundance as compared to the water samples. Overall, it is
necessary to continue the optimization of MPs separation protocol and identification according to the
complexity of samples, mainly due to the limitation and lack of spectral databases.