| dc.description.abstract | Microplastics (plastics <5 mm) have been discovered buried in soil and sediment globally, in sandy beaches, farmer’s fields, and beneath the seabed. While microplastic pollution is generally increasing across the earth’s surface, this PhD thesis highlights the mobility of microplastics and patchy distribution in terms of different shapes, sizes, densities, and chemical compositions as seen across different sedimentary environments in Norway. Critical evaluations of research methods were combined with practical studies of different fjord sections in Longyearbyen-Adventfjord, Svalbard and Trondheimsfjord, mainland Norway to complete this work. Microplastics, which include fibres (for example, threads from synthetic clothing), tend to accumulate in stable, protected environments. On land, the unsorted glacial till of Norway can act as a trap, capturing microplastics in the spaces between rocks and gravel. This was seen in heightened microplastic concentrations of a Svalbard moraine compared to the surrounding river valley (Longyeardalen). Despite often predating the production of plastics, pro-glacial landforms and landscapes, like ice-marginal moraines, may support microplastic accumulation at rates equivalent to some modern coastal settings. The highest concentrations of microplastics of the entire study were found in an enclosed cave (tourist attraction) inside a glacier (Longyearbreen). Microplastic concentrations inside the glacier were equivalent to those reported for some indoor living spaces. This highlights the relationship between people’s activities, low airflow environments, and microplastic buildup. Microplastics also accumulate in zones downstream of human activities. For the fjords, microplastics were found to be concentrated on the seafloor when compared to the hinterland catchment above Adventfjord, and to seawater, in Trondheimsfjord. Radiometric dating of a sediment core indicated microplastic pollution reached the seafloor of Trondheimsfjord as early as the 1960s. However, the same patchy, uneven distributions of microplastics observed on land were observed across the seafloor and down through the sediment column. This depositional inconsistency challenges attempts to evaluate larger microplastic pollution trends in the ‘fossil’ record preserved on the earth’s surface. Careful consideration of natural processes of disturbance, as well as actual plastic pollution events, is therefore required. These findings also highlight the importance of pooled samples in evaluating microplastic pollution levels across entire landscapes and regions. | en_US |
