Comparing the efficiency of two water sampling methods for studying the content of microplastics in water bodies

Due to the lack of a unified sampling methodology for studying microplastics, there are difficulties in comparing the results obtained when sampling using different methods. A comparison was made of a pump filtration system and a Manta trawl to assess their effectiveness and applicability in collecting water samples for studying microplastics content using the example of Lake Ladoga, the Svir River and small lakes in the Leningrad region (Sukhodolskoye, Michurinskoye, Krasnoye). The results supported that despite higher average microplastics concentrations when sampling with the pump system (8.5±11.5 particles/m3) compared to the Manta trawl (0.7±0.6 particles/m3), the data were comparable. The methods have opposite advantages and disadvantages and are complementary. The Manta trawl is more suitable for collecting large volumes of water from the surface layer relatively quickly and in conditions with high contents of suspended matter present. Meanwhile, the pump filtration system is suitable for collecting samples at different water layers and in the surface layer of water when there is a small content of suspended matter and provides more accurate estimating of the sample volume. It is necessary to ensure the sampling of a large volume of water, which in the case of a pump filtration system is only possible during the period when the plankton content and water turbidity are minimal.