MICROPLASTICS CONTENT IN ICE, SNOW AND UNDER-ICE WATER OF THE CURONIAN LAGOON IN WINTER 2021

Abstract

Contamination of the water column, bottom sediments and beaches with small plastic particles (microplastics, MPs, < 5 mm) is currently being actively investigated, but data on ice and snow contamination are still very limited. The paper presents the results of the analysis of the number of MPs particles (0.3–5 mm) in ice cores, snow samples and underice water of the Curonian Lagoon (Baltic Sea), sampled at five stations on February 19, 2021. Higher ice contamination is confirmed: expressed in the number of MPs particles (0.3–5 mm) per 1 liter of (thawed or natural) water, it averaged at 66.4 items/l for snow, 90.5 items/l for ice and 9.1 items/l for under-ice water. Significantly increased amount of MPs particles (up to 281 items/l) were observed in the surface layer of ice (1.5–3 cm). This may in the given case be the consequence of the accumulation of contamination coming from the atmosphere: in the mild Baltic climate, the alternation of thaws and frosty periods favoures the formation of the upper layers of ice from the snow on it. The synthetic nature of the particles was confirmed by Raman spectrometry, which showed the presence along with polyethylene (15 %) also, a significant number of heavy types of plastics (polyurethane, polyvinyl acetate, polyacrylonitrile, etc., in total more than 24 %). Fibers made up about 95 % of the particles, films 1% and fragments – 4 %. The under-ice waters of the Curonian Lagoon, containing from 5.9 to 15.3 MPs particles per liter, turned out to be more than two orders of magnitude more contaminated than the waters of the Baltic Sea, having an average of 0.03 MPs particles per liter in the same particle’ size range. This confirms the general tendency of accumulation of MPs in bays and estuaries of rivers with limited water exchange with the sea.