Microplastic Concentrations in Bottom Sediments of the Lakes of Specially Protected Natural Territories: Case Study of the Kizhskie Skerries, Lake Onega and Vodlozero Lake

Abstract

The concentrations of microplastic were determined in bottom sediments of water bodies in specially protected natural territories—Vodlozerskii National Park (Lake Vodlozero) and Kizhi Museum–Reserve (Kizhskie skerries, Lake Onega). The samples were taken at four stations in the Kizhskie skerries, Lake Onega, and at five stations in Lake Vodlozero. Microplastic (≥200 µm) was extracted from the samples by density separation. A random sample of particles was subject to chemical analysis with the use of micro-Fourier-spectrometry. Microplastic was found in all samples. In the Kizhskie skerries, the average concentration of the particles was 3413 ± 1965 pcs/kg dry weight of sediment, which is slightly higher than that determined before for Petrozavoskaya Bay and the open part of Lake Onega. According to chemical analysis, synthetic polymers account for 55% of particles, 21% are modified cellulose, and 24% are of natural origin. Microplastic concentration was maximal near the main passenger berth of Kizhi Museum–Reserve. The mean concentration of particles in the bottom sediments of Vodlozero Lake was lower than that in the Kizhskie Skerries and amounted to 1506 ± 845 pcs/kg, of which 81% are synthetic polymers, 9% are modified cellulose, 10% are polymers of natural origin. The lower concentration of particles of anthropogenic origin in Lake Vodlozero compared with the Kizhskie Skerries is in agreement with the number of tourists-visitors to these natural territories.