Microplastic contamination in benthic organisms from the Arctic and sub-Arctic regions

The seafloor is recognized as one of the major sinks for microplastics (MPs). However, to date there have been no studies reported the MP contamination in benthic organisms from the Arctic and sub-Arctic regions. Therefore, this study provided the first data on the abundances and characteristics of MPs in a total of 413 dominant benthic organisms representing 11 different species inhabiting in the shelf of Bering and Chukchi Seas. The mean abundances of MP uptake by the benthos from all sites ranged from 0.02 to 0.46 items g−1 wet weight (ww) or 0.04–1.67 items individual−1, which were lower values than those found in other regions worldwide. The highest value appeared at the northernmost site, implying that the sea ice and the cold current represent possible transport mediums. Interestingly, the predator A. rubens ingested the maximum quantities of MPs, suggesting that the trophic transfer of MPs through benthic food webs may play a critical role. Fibers constituted the major type (87%) in each species, followed by film (13%). The colors of fibers were classified as red (46%) and transparent (41%), and the film was all gray. The predominant composition was polyamide (PA) (46%), followed by polyethylene (PE) (23%), polyester (PET) (18%) and cellophane (CP) (13%). The most common sizes of MPs concentrated in the interval from 0.10 to 1.50 mm, and the mean size was 1.45 ± 0.13 mm. Further studies about the temporal trends and detrimental effects of MPs remain to be carried out in benthic organisms from the Arctic and sub-Arctic regions.

Chao Fang, Ronghui Zheng, Yusheng Zhang and al., Chemosphere, Volume 209, October 2018, Pages 298–306

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Toxicities of polystyrene nano- and microplastics toward marine bacterium Halomonas alkaliphila

Nano- and microplastics have been shown to cause negative effects on marine organisms. However, the toxicities of nano- and microplastics toward marine bacteria are poorly understood. In this study, we investigated the toxic effects of polystyrene nano- and microplastics on the marine bacterium Halomonas alkaliphila by determining growth inhibition, chemical composition, inorganic nitrogen conversion efficiencies and reactive oxygen species (ROS) generation. The results showed that both nano- and microplastics inhibited the growth of H. alkaliphila in high concentrations, while nanoplastics rather than microplastics influenced the growth inhibition, chemical composition and ammonia conversion efficiencies of H. alkaliphila at concentration of 80 mg/L. The ROS generation indicated oxidative stress induced by nano- but not microplastics, and the oxidative stress induced by nanoplastics may provide a significant effect on bacteria. Furthermore, the positively charged nanoplastics (amine-modified 50 nm) induced higher oxidative stress toward bacteria than that induced by negatively charged nanoplastics (non-modified 55 nm). The increased extracellular polymeric substances as evidenced by transmission electron microscope (TEM) observation suggested the possible bacterial protective mechanisms. The present study illustrates for the first time the impact of plastics debris on the inorganic nitrogen conversion efficiencies of marine bacteria. Our findings highlight the effects of microplastics on the ecological function of marine organisms.

Xuemei Sun, Bijuan Chen, Qiufen Li, Nan Liu, Bin Xia, Lin Zhu, Keming Qu, Science of The Total Environment, Volume 642, 15 November 2018, Pages 1378–1385

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Abundance and characterization of microplastics in the coastal waters of Tuscany (Italy): The application of the MSFD monitoring protocol in the Mediterranean Sea

Monitoring efforts are required to understand the sources, distribution and abundance of microplastic pollution. To verify the abundance of microplastics along the Tuscan coastal waters (Italy), water-column and surface samples were collected in two seasons across four transects at different distances to the coast (0.5, 5, 10 and 20 km), within the implementation of the European Marine Strategy Framework Directive. The results show an average concentration of 0.26 items/m3 in the water-column samples and 41.1 g/km2 and 69,161.3 items/km2 of floating microplastics, with an increase with the distance to the coast The seasonality and the sampling area do not affect the abundance of microplastics. The most abundant size class is 1–2.5 mm as fragments and sheets suggesting that fragmentation of larger polyethylene and polypropylene items could be the main source of microplastics. These data represent the application of a harmonized protocol to make the data on microplastics comparable and reliable.

Matteo Baini, Maria Cristina Fossi, Matteo Galli, Ilaria Caliani, Tommaso Campani, Maria Grazia Finoia, Cristina Panti, Marine Pollution Bulletin, Volume 133, August 2018, Pages 543–552

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Investigating microplastic trophic transfer in marine top predators

Microplastics are highly bioavailable to marine organisms, either through direct ingestion, or indirectly by trophic transfer from contaminated prey. The latter has been observed for low-trophic level organisms in laboratory conditions, yet empirical evidence in high trophic-level taxa is lacking. In natura studies face difficulties when dealing with contamination and differentiating between directly and indirectly ingested microplastics. The ethical constraints of subjecting large organisms, such as marine mammals, to laboratory investigations hinder the resolution of these limitations. Here, these issues were resolved by analysing sub-samples of scat from captive grey seals (Halichoerus grypus) and whole digestive tracts of the wild-caught Atlantic mackerel (Scomber scombrus) they are fed upon. An enzymatic digestion protocol was employed to remove excess organic material and facilitate visual detection of synthetic particles without damaging them. Polymer type was confirmed using Fourier-Transform Infrared (FTIR) spectroscopy. Extensive contamination control measures were implemented throughout. Approximately half of scat subsamples (48%; n = 15) and a third of fish (32%; n = 10) contained 1–4 microplastics. Particles were mainly black, clear, red and blue in colour. Mean lengths were 1.5 mm and 2 mm in scats and fish respectively. Ethylene propylene was the most frequently detected polymer type in both. Our findings suggest trophic transfer represents an indirect, yet potentially major, pathway of microplastic ingestion for any species whose feeding ecology involves the consumption of whole prey, including humans.

S. E. Nelms, T. S. Galloway, B. J. Godley and al., Environmental Pollution, Volume 238, July 2018, Pages 999-1007

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Separation and Identification of Microplastics in Digestive System of Bivalves

A pretreatment method was established for separating microplastics from digestive system of bivalve sample. Qualitative and quantitative analysis of microplastics was carried out by micro-Fourier transformed infrared (μ-FT-IR) spectroscope and Stereo microscope. The method was applied to analyze the microplastics in the digestive system in Chlamys farreri and Mytilus galloprovincialis. The results showed that the digestion system of using 10% KOH had high digestion efficiency. With this digestion system, the recoveries of polypropylene (PP), polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) ranged from 96.7% to 98.6%, with relative standard deviation (RSD, n = 3) of ≤ 3.19%. We collected Chlamys farreri from local markets (n = 50) and Mytilus galloprovincialis from both local markets (n = 50) and wild environments (n = 15) in Qingdao, China. The results showed that microplastics were found in over 80% of the individuals purchased from the market and 40% of the wild collected individuals. The average abundance of microplastics in Chlamys farreri purchased from different markets varied between 5.2 and 19.4 items/individual or between 3.2 and 7.1 items g−1 (wet weight of digestive system), while in Mytilus galloprovincialis, the numbers varied between 1.9 and 9.6 items/individual or between 2.0 and 12.8 items g−1. Farmed mussels (Mytilus galloprovincialis) contained more microplastics (average 1.9 items per individual, 3.17 items g−1) than wild mussels (average 0.53 items individual, 2.0 items g−1). Three shapes of microplastics, including fibers, fragments and granules were separated from the samples above. Among which, fibrous microplastics, being the most dominant ones, took up 84.11% of total microplastics. The average size of fibrous microplastics ((0.66 ± 0.70) mm) was larger than that of the other two shapes of microplastics. The number of microplastics decreased with increasing microplastic sizes. Microplastics of less than 500 μm coming from different markets were in the range of 26% to 84%. And it was found that the most common polymer component in the samples was cellophane (CP), followed by polypropylene (PP). The method has some advantages such as simplicity, high efficiency, and low damage to the microplastics in the sample, and can be used to detect and analyze microplastics in seafood.

J. F. Ding, J. X. Li, C. J. Sun and al., Chinese Journal of Analytical Chemistry, Volume 46, Issue 5, May 2018, Pages 690-697

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Microplastic pollution in North Yellow Sea, China: Observations on occurrence, distribution and identification

Microplastics are emerging contaminants and have attracted widespread environmental concerns about their negative effects on the marine ecosystems. In this study, we investigated the abundances, distributions and characteristics of microplastics in surface seawater and sediments from the North Yellow Sea. The results showed that the abundance of microplastics was 545 ± 282 items/m3 in surface seawater and 37.1 ± 42.7 items/kg dry weight in sediments, representing a medium microplastic pollution level compared with other sea areas. Small microplastics (<1 mm) made up >70% of the total microplastic numbers. Films and fibers were the dominant shapes of microplastics in both the surface seawater and sediments. Transparent microplastics were generally more common than microplastics of other colors. Based on the identification by a Fourier transform infrared microscope, polyethylene (PE) was the dominant composition of microplastics in surface seawater, while polypropylene (PP) was the most common polymer type in sediments. These results will improve our understanding of the environmental risks posed by microplastics to marine ecosystems.

Lin Zhu, Huaiyu Bai, Bijuan Chen and al., Science of The Total Environment, Volume 636, 15 September 2018, Pages 20-29

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Arctic sea ice is an important temporal sink and means of transport for microplastic

Microplastics (MP) are recognized as a growing environmental hazard and have been identified as far as the remote Polar Regions, with particularly high concentrations of microplastics in sea ice. Little is known regarding the horizontal variability of MP within sea ice and how the underlying water body affects MP composition during sea ice growth. Here we show that sea ice MP has no uniform polymer composition and that, depending on the growth region and drift paths of the sea ice, unique MP patterns can be observed in different sea ice horizons. Thus even in remote regions such as the Arctic Ocean, certain MP indicate the presence of localized sources. Increasing exploitation of Arctic resources will likely lead to a higher MP load in the Arctic sea ice and will enhance the release of MP in the areas of strong seasonal sea ice melt and the outflow gateways.

Ilka Peeken, Sebastian Primpke, Birte Beyer, Julia Gütermann, Christian Katlein, Thomas Krumpen, Melanie Bergmann, Laura Hehemann,  Gunnar Gerdts, Nature Communications, volume 9, 24 April 2018

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