Biodegradation Prerequisites for Microplastic Pollution in Freshwater Lakes in Armenia

For the first time, microplastics have been studied in the lakes of the Republic of Armenia. Samples of water and bottom sediments were taken from two mid-mountain lakes of the Lori plateau: the Clear Liman (area 10.7 ha) and the Horse Liman (area 2.4 ha). These lakes are designated as a Freshwater Key Biodiversity Area (FKBA). Sampling was carried out in the center of each lake. Bottom sediments were sampled using a cone sampler, surface water was sampled using a 75 µm polyamide mesh. The concentration of microplastics found in water samples is 100–153 MP/m3. Among the detected particles, fibers predominated (87%), and the rest were identified as fragments (13%). Bottom sediments contained 60–80 MP/kg (wet weight) of microplastics shaped like fibers. The detected fibers ranged in length from 100 µm to 10 mm, with their thickness varied from 13–45 µm. Qualitative analysis of microplastics was performed using an ATR-FTIR spectrometer (Nicolet iS50, Thermo Scientific). Not all particles were analyzed for polymer type, due to the limitations of the ATR lower detection limit of 20 µm. The analyzed particles were identified as polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET). The degradation of polymers in the environment is influenced by various factors: 259ultraviolet radiation, weathering, currents, waves, as well as the impact of biota. Alterations in microplastic properties are a matter of special interest in the way surficial biofilms over the microplastic particles can change their buoyancy, affect transport in the water column, and contribute to its degradation. Water and sediment samples were examined to establish algae populations in lake water. In the microalgae composition of the sediments, the diatom group was characterized by the greatest species diversity, where more than 26 species were recorded, with the dominance of Fragilaria capucina, Diatoma hiemale, and Cocconeis placentula. In the bottom communities of both lakes were dominated by diatom species (Clear Liman – 58%, Horse Liman – 49%). Subdominant groups were cyanobacteria and green algae, accounting for 41% and 31% in the Clear Liman and the Horse Liman, respectively. The data obtained will be the subject of future research on the microplastics and phytoplankton interaction.