AUTHOR=Dimante-Deimantovica Inta , Bebrite Alise , Skudra Māris , Retike Inga , Viška Maija , Bikše Jānis , Barone Marta , Prokopovica Anda , Svipsta Sanda , Aigars Juris 

TITLE=The baseline for micro- and mesoplastic pollution in open Baltic Sea and Gulf of Riga beach

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1251068

DOI=10.3389/fmars.2023.1251068

ISSN=2296-7745

ABSTRACT=Microplastic pollution has become widespread, occurring even in areas with low anthropogenic impacts, small human populations, and low tourism intensity. Marine beach sand represents the interface between inland and marine environments and act like a fingerprint of all the processes happening within the onshore catchment and in the sea driven by marine hydrodynamic processes. An extensive dataset is required from different coastal ecosystems to understand microplastic pollution.  Here we set the baseline for micro- and mesoplastic pollution distribution in 24 beaches along the Latvian coastline (Northern Europe, Baltic States) filling existing knowledge gap and contributing to global understanding of microplastic particles presence, transport and processes governing its dynamics. We also highlight citizen science as a fundamental tool to support data collection and raise awareness about microplastic pollution as samples were collected by up to 250 volunteers during organized campaigns. To improve the understanding of driving forces responsible for plastic pollution distribution along beaches we analysed sand granulometry, sample location, hydrodynamic variables (waves and currents) and tourism/leisure intensity. Our results demonstrate that semi-closed Gulf of Riga beach environment contains less micro- and mesoplastic particles (0.10 particles/kg dry sand) compared to open Baltic Sea (0.16 particles/kg dry sand). For microplastic size fraction particularly, a separate cluster can be distinguished showing higher microplastic concentration and greater fibers presence associated with coarser beach sand in the open Baltic Sea and eastern part of Gulf of Riga. Recreational activity was not observed to have any statistically significant effect on microplastic distribution. We conclude that hydrodynamics is an important factor for microplastics distribution and accumulation, but the impacts are of local scale and results vary significantly among existing studies.