Microplastics in the water of transboundary Lake Khanka and rivers of its basin
A.YU. POPOVA
Pacific Geographical Institute, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
Keywords: microplastic pollution, surface layer of water, qualitative composition, concentration, freshwater ecosystems, Khanka State Nature Biosphere Reserve
Abstract
For the first time, an assessment is made of the content of microplastics in the surface waters of Lake Khanka and its tributaries. The sampling, preparation and analysis were carried out during the period 2021-2022. Five geographical points were selected (the source of the Sungacha River; the mouth of the Spasovka River; the Vostochnyi cordon; the Ilistaya River, and the Komissarovka River) as the areas most susceptible to pollution. Scanning spectrophotometry was carried out using the AIM-9000 SHIMADZU IR microscope, which showed that microplastic particles were present in all water samples examined. Microplastics of mixed and synthetic nature predominated, the concentration varied depending on the season (from 6 to 27 units/m3) in the spring-summer and (from 5 to 24 units/m3) in the autumn-winter sampling period. Microplastics were identified, mostly of secondary origin, and the vast majority was identified as fibers. A spectral analysis of the particles showed that polyester and natural fibers were the most common types of microplastics. An increased concentration of microplastics was observed at the mouths of the Spasovka and Komissarovka Rivers, in the area of the Vostochnyi cordon which is located in the eastern coastal part of the lake on the territory of the Khanka State Nature Reserve as well as at the source of the Sungachi River which drains Lake Khanka. It is concluded that the likely sources of microplastic pollution in Lake Khanka and the rivers of its basin are the river flow from the wastewater treatment plants, the runoff from agricultural land, and precipitation and/or untreated wastewater. A comparative analysis of the surface waters of Lake Khanka, the Haihe River (PRC), the Songhua River (PRC), and the rivers of Japan and South Korea was carried out. In all the water bodies presented, the predominant type of microplastic was represented by fibers of synthetic origin. The average concentration of microplastics in Lake Khanka was found to be noticeably lower than in the others, only exceeding in the Haihe River.
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