Exposure to leachates from post-consumer plastic and recycled rubber causes stress responses and mortality in a copepod Limnocalanus macrurus.

Effects of household post-consumer plastics and tyre rubber on a Baltic Sea copepod Limnocalanus macrurus were assessed. Fragments of commercial recycled low-density polyethylene vegetable bags and rubber originating from recycled car tyres were incubated in seawater, and the copepods were exposed to the filtrate of the water. L. macrurus experienced erratic swimming behaviour and increased mortality in the filtrate of unwashed vegetable bags, containing elevated concentrations of alcohols, organic acids and copper. Responses of the antioxidant defence system (ADS) were recorded in copepods exposed to rubber treatments containing high concentrations of zinc. Significant responses in the ADS enzymes indicate that reactive oxygen species (ROS) formation was exceeding the detoxification capacity of the ADS which may further lead to prolonged state of oxidative stress. Observed effects of exposure on the biochemical level coincide with impaired swimming activity of the copepods, indicating possible irreversible cellular responses leading to behavioural changes and mortality.

Sediment trapping - An attempt to monitor temporal variation of microplastic flux rates in aquatic systems.

Sediment trapping as a tool to monitor microplastic influx was tested in an urban boreal lake basin. The one-year-long trap monitoring consisted of 5-month and 7-month periods representing growing season and winter season (including the spring flood event), respectively. Sediment accumulation rate (SAR), and organic content were determined, highest SAR - 14.5 g/m2/d - was measured during the winter period. Microplastics were extracted from the sediment applying heavy-liquid density separation method and collected under a microscope for further identification with FTIR spectroscopy. PE was identified as the most abundant synthetic polymer type, while PP and PET are also present. The annual microplastic flux rate is 32 400 pieces/m2/year, and highest accumulation does not coincide with the highest SAR, but occurs during the growing season. Changes in the microplastic accumulation rates are related to seasonal conditions. Highest microplastic concentration with respect to dry sediment weight (10 200 pieces/kg) was observed in a growing season sample, while highest concentration with respect to sediment volume (1800 pieces/l) was observed during winter. This finding underlines the problems related to reporting microplastic concentrations in various units. The results highlight that sediment trap monitoring is an efficient tool for monitoring microplastic accumulation rate in aquatic environments and provides an opportunity to better understand and define processes controlling microplastic accumulation.

Plastic debris composition and concentration in the Arctic Ocean, the North Sea and the Baltic Sea.

Neuston samples were collected with a Manta trawl in the rim of the Arctic Ocean, in the Northern Atlantic Ocean and the Baltic Sea at eleven coastal and open-sea locations. All samples contained plastics identified by FTIR microscopy. Altogether, 110 microplastics pieces were classified according to size, shape, and polymer type. The concentrations at the locations were generally low (x̅ = 0.06, SD ± 0.04 particles m-3) as compared to previous observations. The highest concentrations were found towards the Arctic Ocean, while those in the Baltic Sea were generally low. The most abundant polymer type was polyethylene. Detected particle types were mainly fragments. The number of films and fibers was very low. The mean particle size was 2.66 mm (SD ± 1.55 mm). Clustering analyses revealed that debris compositions in the sea regions had characteristic differences possibly reflecting the dependences between compositions, drifting distances, sinking rates, and local oceanographic conditions.

Microplastic concentrations, size distribution, and polymer types in the surface waters of a northern European lake.

We examined microplastic concentrations, size distributions, and polymer types in surface waters of a northern European dimictic lake. Two sampling methods, a pump sieving water onto filters with different pore sizes (20, 100, and 300 µm) and a common manta trawl (333 µm), were utilized to sample surface water from 12 sites at the vicinity of potential sources for microplastic emissions. The number and polymer types of microplastics in the samples were determined with optical microscopy and µFTIR spectroscopy. The average concentrations were 0.27 ± 0.18 (mean ± SD) microplastics/m3 in manta trawled samples and 1.8 ± 2.3 (>300 µm), 12 ± 17 (100-300 µm) and 155 ± 73 (20-100 µm) microplastics/m3 in pump filtered samples. The majority (64%) of the identified microplastics (n = 168) were fibers, and the rest were fragments. Materials were identified as polymers commonly used in consumer products, such as polyethylene, polypropylene, and polyethylene terephthalate. Microplastic concentrations were high near the discharge pipe of a wastewater treatment plant, harbors, and snow dumping site. PRACTITIONER POINTS: Samples were taken with a manta trawl (333 µm) and a pump filtration system (300/100/20 µm) With pump filtration, small 20-300 µm particles were more common than >300 µm particles The average concentration of manta trawled samples was 0.27 ± 0.18 (mean ± SD) microplastics/m3 FTIR analysis revealed PE, PP, PET, and PAN to be the most common polymers.