Microplastics in Water and Problems of Its Identifi cation (the Water Bodies in the South of the European Part of Russia are Example)

Abstract

The purpose is to assess the microplastic content in the Lower Don, Seversky Donets, Tsimlyansk Reservoir, and the Lower Volga, and to test various sampling techniques and to identify the composition of particles. Materials and methods. Two sampling methods were used: full-volume sampling in 2021 and 2022 and concentrated sampling in 2023. In the fi rst case, sampling was performed by a bathometer, the size range was 0.1-5 mm; the second sampling method consisted of trawling a neuston net, the lower limit corresponded to a cell rating of 0.3 mm. Sample preparation was carried out according to the modifi ed NOAA method, visual separation of particles was performed using a microscope, composition was determined by Raman spectroscopy and IR Fourier spectroscopy, MP surface was studied using SEM, and PHI polymer hazard level was calculated. Results and discussion. The average concentrations according to the data of 2021 were: in the Lower Don 36 units/l, in Seversky Donets 38 units/l, Tsimlyansk Reservoir 33 pcs/l. In 2022, 21 pcs/l were found in Lower Don, in the Tsimlyansk Reservoir ‒ 10 pcs./l, in the Lower Volga ‒ 16 pcs./l. In 2023, when sampled by trawling, microplastic concentrations in the waters of the Lower Don River were 94.32 pcs./m3 , in the Tsimlyansk Reservoir ‒ 12.3 pcs./m3 , in the Lower Volga ‒ 81.06 pcs./m3 . Conclusion. The characteristics of the particles diff er depending on the sampling method: the bathometer mainly covered transparent fi bers, 0.3 mm in size, and the use of nets resulted in a higher diversity and coarseness. Maximum concentrations of MP in water were recorded near urbanized areas, pools of hydroelectric power plants, mouths of tributaries, and also under the infl uence of sheet washout.