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Browsing by Subject "ihmispaine"

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  • Tirroniemi, Jyri (2019)
    Microplastics are small 1–5000 μm plastic particles, which can be found all around the world. In this Master thesis I explored how microplastics are spatially distributed in bottom sediments in the northern Baltic Sea. As part of this work effects of methods on microplastics extraction from sediment were evaluated. The Marine Strategy Framework Directive requires European member states to monitor the state of the marine waters, which includes also micro sized litter in subtidal sediments. As for now there is no ready-made methods. In this Master thesis work I tested if Gemax- multi corer and Petite Ponar-grab had significant effect on number of microplastics in the sample and if filter’s mesh size affects results significantly. As part of this work I developed a protocol for extracting microplastics from sediment without harming them and a way to count and measure particles from samples by using semi-automated software. Microplastics were extracted from the sediment with density separation using sediment-microplastic separation unit. Extracted microplastic samples were purified from organic matter by using hydrogen peroxide, enzymes and second density separation. After extraction and purification, sample filters were fluorescent stained with Nile red dye and photographed with camera attached to stereomicroscope under fluorescent light. Pictures were processed and fluorescent particles analyzed with ImageJ- software. Results were corrected with control samples and with results from Fourier transfer infrared spectroscopy, which was used to verify synthetic part of the fluorescent particles. First part of samples was sediment from seven subtidal locations along the Finnish coast from Kotka to Vaasa, which were collected during summer 2017. Second part of sediment samples were collected in 2018 from semi enclosed Pojo bay from Southwest Uusimaa. Laboratory work was conducted in Finnish Environment Institute’s (SYKE) Marine Research Laboratory in Viikki. There was no significant difference in microplastic concentration between sediment core or grab samplers, but filter’s mesh size had significant effect on the results. There were significant differences in microplastic concentrations between sampling stations on the coastline and in Pojo bay. Greatest concentrations, 22 microplastics per gram of dry sediment, was found from Porvoo, which differed significantly from Kotka and Vaasa. In this thesis I explore possible reasons for the differences between areas. Smallest and second smallest size fractions differed significantly from three largest size classes. Two smallest size classes (25-100 μm) made up 80 % of all the particles found. This finding is in line with other studies that studied microplastic concentrations in different size classes. In the thesis, I discuss how disproportionally into size classes divided microplastics affects results and monitoring. Suggestions are presented for improving microplastic extraction protocol and monitoring. This study is one of the very first microplastic studies from subtidal sediments of the northern Baltic Sea where quantities and spatial distribution of microplastics are evaluated. These results can be used in future for establishing national microplastic extraction protocol and monitoring program.