Polystyrene foam is widely used due to its lightweight, impact resistance, and excellent thermal insulation properties. Meanwhile, weak adhesion between beads in polystyrene foam leads to fragmentation, generating a substantial amount of microplastics (<5 mm). Such polystyrene foam debris littered on beaches diminishes the aesthetic value of coastal areas, negatively impacting tourism. Due to its density lower than other plastics, polystyrene foam macroplastics float on the sea surface and, thus, they are significantly influenced by wind drag during oceanic transport. In contrast, polystyrene foam microplastics drifting beneath the sea surface are carried mostly by ocean currents. These properties of polystyrene foam macroplastics and microplastics hinder the elucidation of their transport, distribution, and fate in nature, despite their potential to adversely impact marine ecosystems. To elucidate the generation, transport, and fragmentation processes of polystyrene foam ocean plastics, we conducted concurrent visual observations and surface net towing from seven training vessels around Japan during 2014-2020. Overall, the abundances of polystyrene foam ocean plastics were higher in the Sea of Japan than in the North Pacific south of Japan. The average abundances of polystyrene foam microplastics and macroplastics were 0.33 pieces/m3 and 0.45 pieces/km, respectively, over the entire sea area around Japan. In the Sea of Japan, the peak abundances of polystyrene foam macroplastics occurred in upstream of the Tsushima Current, while the peak for microplastics occurred downstream, suggesting that continuous fragmentation occurred during transport between the two peaks. Backward-in-time particle tracking model experiments suggested that the sources of polystyrene foam macroplastics observed in the Sea of Japan included aquaculture buoys and styrene debris beached around the Tsushima Strait. The present study demonstrated that reducing the release of polystyrene foam aquaculture floats will likely diminish the abundance of ocean plastics in the Sea of Japan.

Microplastic (plastic smaller than 5mm in size) is ubiquitous around the world both in the ocean and the freshwater system. Due to their potential serious negative impact on marine organisms and human beings, marine microplastics have attracted worldwide attention in the past decade. Information and knowledge of the spatial and temporal distribution of marine microplastics are crucial for accurately assessing our current and future environmental health conditions. This is also important for developing mitigation plans and measures to protect our environment. Since the measured microplastic pollution level is closely related to the sampling methods and identification techniques, it is important to employ standardized sampling and analysis operation procedures for cross-comparison. In this chapter, we present the basic sampling, sample pretreatment and microplastic identification techniques involved in microplastic pollution assessment and discuss the adaptability of different sampling and pretreatment methods. The pros and cons of different techniques are also discussed.

The combination of a representative microplastic sampling method and a fast-quantitative analysis using Pyrolysis-GC-MS (Py-GC-MS) for investigation of the microplastic load and mass balances is presented in this work. A representative microplastic filtration requires a method allowing quick extraction of the sample. The developed steel based cascadic microplastic filtration uses steel basket filters with mesh sizes of 100 μm, 50 μm and 10 μm and a mean recovery of 86 % without cross contamination was achieved. Thermoanalytical methods have the advantage of minimal sample preparation with short analysis times. The presented platinum filament-based Py-GC-MS method requires little sample preparation and quantification limits for polystyrene (PS) and polyethylene (PE) were 0.03 μg and 1 μg absolute, respectively. The relative standard deviation of the analytical method is 11 %. The combined method allows representative sampling and analysis of MP from water bodies and waste water treatment plants within 48 h. •Presentation of a validated steel based cascadic microplastic filtration plant.•Fast and reproduceable Py-GC-MS analysis method for microplastic.•Py-GC-MS allows microplastic analysis with little sample preparation.

Processed fibers are highly present in our daily life and can be either natural, artificial (regenerated cellulose) and synthetic (made with petrochemicals). Their widespread use lead inevitably to a high contamination of environment. Previous studies focus on plastic particles regardless of their type or shape as long as they are comprised between 330μm and 5mm. On the contrary, this study focuses exclusively on fibers using a smaller mesh size net (80μm) to sample freshwater. Moreover, all processed organic fibers are considered, irrespective to their nature. First, the short term temporal variability of the fibers in the environment was assessed. While exposing the sampling net during 1min a coefficient of variation of approx. 45% (with n=6) was determined. It was of only 26% (n=6) when the exposure was of 3min. The assessment of the distribution through the section showed a possible difference in concentrations between the middle of the water surface and the river banks which could be attributed to the intense river traffic within the Paris Megacity. The vertical variability seems negligible as turbulence and current conditions homogenize the distribution of the fibers. A monthly monitoring showed concentrations of 100.6±99.9fibers·m-3 in the Marne River and of: 48.5±98.5, 27.9±26.3, 27.9±40.3 and 22.1±25.3fibers·m-3 from the upstream to downstream points in the Seine River. Once these concentrations are converted into fluxes, it seems that the impact generated by the Paris Megacity cannot be distinguished. Investigations on the role of sedimentation and deposition on the banks are required. This study helped fill some major knowledge gaps regarding the fibers in rivers, their sampling, occurrence, spatial-temporal distribution and fluxes. It is encouraged that future studies include both synthetic and none synthetic fibers.