Browsing by Author "Pippingsköld, Ella"

Microplastics (usually particles smaller than 5 mm) have the potential to cause environmental damage in the ocean as they disperse efficiently accumulating on beaches and sea sediments. The effects are partly still unknown, but physiological changes in organisms have been detected with a relation to the plastic material. This study focuses on the microplastic abundances in southern Thailand and its shallow sandy sediments in Phuket. Plastic materials were also identified. The existence of a depth gradient in relation to the plastic abundance was studied. The density separation method was validated experimentally. A meta-analysis on existing microplastic studies was conducted. Samples were collected from four locations on the western side of Phuket from two eastern locations from an island (south of Phuket, called Racha Yai). Underwater samples from the depths of 3-5 meters and 8-10 meters were collected from the island locations. All sites are open sandy beaches affected by strong tides. Samples were dried and microplastics were separated with a saturated sugar-salt solution from the sediment. Organic matter was oxidized with H2O2 (30%). Plastic were recovered using a microscope and analysed with FTIR spectrometry and pyrolysis gas chromatography mass spectrometry. Differences in microplastic concentration in relation to the sampling site were studied statistically. Microplastic fibres were excluded from this study due to a high external contamination risk. The meta-analysis was conducted from 10 separate microplastic studies focusing on sandy beaches on 5 different continents. An equation was applied to transform all microplastic abundances such that they were comparable with each other (particles kg-1 dry sediment). This was done due to different practices in reporting microplastic abundances. Five studies were chosen to evaluate the plastic materials and their relation to global production proportions of different plastic materials A total of 12 microplastic particles were recovered from Phuket. The size class 1-5 mm was the most abundant size and polyethylene the most common plastic type. The island locations lacked microplastics in the depth of 3-5 m. No significant differences were found in the gradient or between the continental and island sampling sites despite a small difference in the mean values. Validation of the density separation method resulted in a recovery percentage of 94,5. Based on the meta-analysis microplastic abundances vary greatly (on average 2,4 to 740 particles kg-1 in the chosen studies). Some differences were seen in the relations of microplastic in beach sediments and global production rates. These might be due to the differences in accumulation of plastic materials and the life cycles of different plastic products. The microplastic abundance on beaches in Phuket was relatively low. A possible explanation for this can be found in the beach characteristics, these areas not being the accumulation areas for microplastics. Constructing the meta-analysis, it was evident, that microplastic study methods must be made comparable using the same protocols and reporting practices (preferably particles kg-1 dry sediment). The monitoring of microplastic abundances in different environments should be continued to ensure better understanding on the patterns of accumulation and to eventually reduce the plastic pollution globally.