Description: Microplastic pollution within the marine environment is of pressing concern globally. Accordingly, spatial monitoring of microplastic concentrations, composition and size distribution may help to identify sources and entry pathways, and hence allow initiating focused mitigation. Spatial distribution patterns of microplastics were investigated in two compartments of the southern North Sea by collecting sublittoral sediment and surface water samples from 24 stations. Large microplastics (500−5000 μm) were detected visually and identified using attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The remaining sample was digested enzymatically, concentrated onto filters and analyzed for small microplastics (11−500 μm) using Focal Plane Array (FPA) FTIR imaging. Microplastics were detected in all samples with concentrations ranging between 2.8 and 1188.8 particles kg−1 for sediments and 0.1–245.4 particles m−3 for surface waters. On average 98% of microplastics were 〈100 μm in sediments and 86% in surface waters. The most prevalent polymer types in both compartments were polypropylene, acrylates/polyurethane/varnish, and polyamide. However, polymer composition differed significantly between sediment and surface water samples as well as between the Frisian Islands and the English Channel sites. These results show that microplastics are not evenly distributed, in neither location nor size, which is illuminating regarding the development of monitoring protocols.

Description: Journal of the American Chemical Society DOI: 10.1021/jacs.6b12437

Description: Anthropogenic litter, especially highly persistent plastic litter, has become a global problem. It is present in almost all marine habitats and freshwater ecosystems. Plastic production volume has continuously risen throughout the last 100 years, making its future monitoring and removal one of the greatest challenges for environmental protection. In this context, microplastics, which are defined as synthetic polymer particles smaller than 5 mm in diameter or length, are way more difficult to handle than larger plastic debris. Moreover, microplastic particles pose a threat to a huge spectrum of organisms. Animals ingest particles, which then accumulate along the food chain via biomagnification. Microplastics’ potential adverse effects stem from the obstruction of different Lumina and their chemical properties, i.e. due to sorption and transfer of Persistent Organic Pollutants or leaching of toxic additives or residual monomers. According to their formation, microplastics are divided into two categories: primary and secondary microplastics. Primary microplastics are produced in micrometer dimensions for domestic applications, brasives (e.g. shot blasting) or industrial processing (e.g. virgin pellets for injection molding), whereas secondary microplastics result from the fragmentation of larger items. Regrettably, degradation rates of plastics in general are very slow and depend on the presence of UV radiation, weathering, physical stress and biological factors such as biofilm formation. Once microplastics reach the seafloor, degradation can come to a nearly complete halt or at least be reduced by several orders of magnitude which means that marine sediments can become an ultimate repository for microplastics. In the present study, microplastics in 14 sediment samples from locations close to the Frisian Island, from the English Channel and offshore locations were isolated, quantified, measured and assigned to polymer clusters by state-of-the-art methods. In contrast to studies that solely use visual identification, this study employed µ-FTIR imaging to detect microplastics. Density separation with the MicroPlastic Sediment Separator in combination with ZnCl2 solution (ρ = 1.7 g mL-1) was used to separate the microplastics from sediment. Subsequently, the samples were subdivided into a fraction ≥ 500 µm and one 〈 500 µm. The first fraction was visually sorted and manually analyzed using ATR-FTIR spectroscopy whereas the latter was enzymatically and chemically purified using recently developed microplastic-reactors. Afterwards, the samples were enriched on inorganic membrane filters and automatically analyzed using µ-FTIR imaging. The concentrations of microplastics for the different stations ranged between 34 and 1457 particles per kg dry weight. All particles had a size ≤ 300 µm. Most particles (69%) were between 11 µm and 25 µm in size which indicates a high risk for ingestion, e.g. by filter feeding marine organisms. The study provides a substantial contribution to the assessment of the microplastic contamination status of the North Sea which the Marine Strategy Framework Directive targets. To date, data on microplastic burden of North Sea sediments are very scarce as only three studies exist with inter-study comparability being hampered by the lack of a standard operation procedure.

Description: It is well known that microplastics (〈5 mm in size) are omnipresent in the marine environment and will hardly degrade but merely fragment over time. Furthermore, standardized and reliable methods to securely detect microplastics are yet to be set. Determining the abundance and identity of microplastics is a crucial objective in microplastic research, especially with regard to requested monitoring. Nevertheless, information on the abundance and composition of microplastics in the North Sea is still scarce particularly concerning the lower-micrometer range (〈500 µm). Hence, we analysed samples from two complex environmental matrices at 24 stations in the southern North Sea. Surface water samples were collected with a 100 µm net attached to a neuston catamaran and sublittoral sediments were taken with a Van Veen grab. To isolate microplastics (11–5000 µm) sediments were first subjected to a density separation performed with the MicroPlastic Sediment Separator (MPSS) and a zinc chloride solution (ρ = 1.7 g cm-³). Subsequently, a highly promising enzymatic-oxidative purification was applied to all samples using newly developed microplastic reactors. This was followed by a state-of-the-art analysis via Fourier transform infrared spectroscopy (FTIR) imaging. This provides information on polymer quantities, types and sizes as well as spatial distribution of microplastics in North Sea surface waters and sediments. Results show that microplastics are present in all of the analysed North Sea samples exhibiting a variety of polymer types, dominated by rubbers, polyethylene, polypropylene and acrylates/polyurethane. Concentrations ranged from 0.1 to 2.1×10² particles m-3 in surface waters and from 2 to 1.5×10³ particles kg-1 of dry sediment. Concerning size, the vast majority of the detected microplastic particles (95%) was less than 75 µm in length. Finally, this study aims at contributing to a basis for future monitoring measures and stresses the need to include microplastics in the lower-micrometer range into these approaches.

Description: Microplastic pollution within the marine environment is of pressing concern globally. Accordingly, spatial monitoring of microplastic concentrations, composition and size distribution may help to identify sources and entry pathways, and hence allow initiating focused mitigation. Spatial distribution patterns of microplastics were investigated in two compartments of the southern North Sea by collecting sublittoral sediment and surface water samples from 24 stations. Large microplastics (500−5000 μm) were detected visually and identified using attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy. The remaining sample was digested enzymatically, concentrated onto filters and analyzed for small microplastics (11−500 μm) using Focal Plane Array (FPA) FTIR imaging. Microplastics were detected in all samples with concentrations ranging between 2.8 and 1188.8 particles kg−1 for sediments and 0.1–245.4 particles m−3 for surface waters. On average 98% of microplastics were 〈100 μm in sediments and 86% in surface waters. The most prevalent polymer types in both compartments were polypropylene, acrylates/polyurethane/varnish, and polyamide. However, polymer composition differed significantly between sediment and surface water samples as well as between the Frisian Islands and the English Channel sites. These results show that microplastics are not evenly distributed, in neither location nor size, which is illuminating regarding the development of monitoring protocols.