Are we underestimating microplastic contamination in aquatic environments?

Plastic debris, specifically microplastic in the aquatic environment, is an escalating environmental crisis. Efforts at national scales to reduce or ban microplastics in personal care products are starting to pay off, but this will not affect those materials already in the environment or those that result from unregulated products and materials. To better inform future microplastic research and mitigation efforts this study (1) evaluates methods currently used to quantify microplastics in the environment and (2) characterizes the concentration and size distribution of microplastics in a variety of products. In this study, 50 published aquatic surveys were reviewed and they demonstrated that most (~80%) only account for plastics ≥ 300 μm in diameter. In addition, we surveyed 770 personal care products to determine the occurrence, concentration and size distribution of polyethylene microbeads. Particle concentrations ranged from 1.9 to 71.9 mg g−1 of product or 1649 to 31,266 particles g−1 of product. The large majority ( > 95%) of particles in products surveyed were less than the 300 μm minimum diameter, indicating that previous environmental surveys could be underestimating microplastic contamination. To account for smaller particles as well as microfibers from synthetic textiles, we strongly recommend that future surveys consider methods that materials < 300 μm in diameter.

Jeremy L. Conkle, Christian D. Báez Del Valle, Jeffrey W. Turner, Environmental Management, pp 1–8,

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Spatial variability in the concentrations of metals in beached microplastics

Heavy metals and microplastics have been considered as threats to the marine environment and the interactions between these two pollutants are poorly understood. This study investigates the interactions between metals adsorbed in pellets collected randomly from 19 beaches along the coast of São Paulo State in southeastern Brazil, comparing these levels with those in virgin pellets. The samples were analyzed for Al, Cr, Cu, Fe, Mn, Sn, Ti and Zn by inductively coupled plasma optical emission spectroscopy (ICP-OES). The polymers were solubilized via acid digestion. The highest levels occurred with Fe (227.78 mg kg− 1 – Itaguaré) and Al (45.27 mg kg− 1 – Guaraú) in the same areas, which are closer to the Port of Santos. The metal adsorption on pellets collected is greater than that on virgin pellets. In this context, pellets can be considered to be a carrier for the transport of metals in the environment, even in small quantities.

M.C. Vedolin, C.Y.S. Teophilo, A. Turra, R.C.L. Figueira, Marine Pollution Bulletin, Available online 13 October 2017, In Press

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Chronic ingestion of polystyrene microparticles in low doses has no effect on food consumption and growth to the intertidal amphipod Echinogammarus marinus?

The ingestion of microplastics (plastic particles <5 mm) has been observed in a range of marine organisms, and adverse effects have been reported in several species after high concentration exposure. However, the long-term effects of low-dose ingestion remains unclear. The aim of this study was thus to assess the chronic effects of low concentrations of polystyrene microparticles to the intertidal amphipod Echinogammarus marinus, using food consumption, growth, and moulting as endpoints. Amphipods were fed a gelatinous algal feed spiked with microbeads (8 μm) in concentrations of ∼0.9, 9 and 99 microplastics/g for 35 days. E. marinus was also analysed for retention of microplastics, and egestion rate was calculated in a separate high-dose feeding experiment. No significant effects were found in the food consumption or growth assays. There was no accumulation of microplastics in the gut, with only one microbead recorded internally in three (8%) of the exposed amphipods. The low number is likely linked to gastrointestinal functions, allowing for easy egestion of indigestible items. This assumption was supported by the observation that after high-dose exposure, 60% of E. marinus egested all microbeads within 24 h. This study suggests that ingesting low concentrations of 8 μm microplastics do not impair the feeding or growth of amphipods along the exposure period. We hope that negative results such as these may further assist in assessing the impact posed by microplastics to marine organisms.

Sarah Bruck, Alex T. Ford, Environmental Pollution, Available online 14 October 2017, In Press

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Variation in plastic abundance at different lake beach zones – A case study

Image 2Plastic particles in marine and freshwater environments span from macroscopic to microscopic size classes. Each may have a different impact on individuals, populations and ecosystems, but still the wide variety of methods used in beach sediment sampling inhibit comparisons among studies and therefore hampers a risk assessment. A large portion of the uncertainties is due to differing sampling strategies.

By quantifying the alongshore distribution of macro- and microplastic particles within five beaches of Lake Garda, we aim to shed light on the accumulation behavior of microplastic particles at an exemplary lake which might give indications for potential sampling zones. The identification of plastic at the single particle level with a spatial resolution down to 1 μm was performed by Raman microspectroscopy. Given the time consuming approach we reduced the number of samples in the field but increased the spatial area where a single sample was taken, by utilizing a transect approach in combination with sediment cores (5 cm depth).

The study revealed that, in comparison to the water line and the high-water line, the drift line of all five beaches always contained plastic particles. Since the drift line accumulate particulate matter on a relatively distinct zone, it will enable a comparable sampling of microplastic particles. The applied sampling approach provided a representative method for quantifying microplastic down to 1 μm on a shore consisting of pebbles and sand. Hence, as first step towards a harmonization of beach sediment sampling we suggest to perform sampling at the drift line, although further methodological improvements are still necessary.

Hannes K. Imhof, Alexandra C.Wiesheu, Philipp M. Anger and al., Science of The Total Environment, Volumes 613–614, 1 February 2018, Pages 530-537

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Beach litter dynamics on Mediterranean coasts: Distinguishing sources and pathways

We assessed amounts, composition and net accumulation rates every ~ 15 days of beach macro litter (≥ 2.5 cm) on 4 Mediterranean beaches, on Corfu island, N. Ionian Sea, taking into account natural and anthropogenic drivers. Average net accumulation rate on all beaches was found 142 ± 115 N/100 m/15 d. By applying a Generalized Linear Model (GzLM) it was shown that sea transport is the dominant pathway affecting the amount and variability in beach litter loadings. Principal Component Analysis (PCA) on compositional data and indicator items discerned two more pathways of beach litter, i.e. in situ litter from beach goers and wind and/or runoff transport of litter from land. By comparing the PCA results to those from a simple item to source attribution, it is shown that regardless their source litter items arrive at beaches from various pathways. Our data provide baseline knowledge for designing monitoring strategies and for setting management targets.

Michael Prevenios, Christina Zeri, Catherine Tsangaris and al., Marine Pollution Bulletin, Available online 10 October 2017, In Press

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A large-scale investigation of microplastic contamination: Abundance and characteristics of microplastics in European beach sediment

Here we present the large-scale distribution of microplastic contamination in beach sediment across Europe. Sediment samples were collected from 23 locations across 13 countries by citizen scientists, and analysed using a standard operating procedure. We found significant variability in the concentrations of microplastics, ranging from 72 ± 24 to 1512 ± 187 microplastics per kg of dry sediment, with high variability within sampling locations. Three hotspots of microplastic accumulation (> 700 microplastics per kg of dry sediment) were found. There was limited variability in the physico-chemical characteristics of the plastics across sampling locations. The majority of the microplastics were fibrous, < 1 mm in size, and blue/black in colour. In addition, using Raman spectrometry we identified particles as polyester, polyethylene, and polypropylene. Our research is the first large spatial-scale analysis of microplastics on European beaches giving insights into the nature and extent of the microplastic challenge.

Froukje A.E. Lots, Paul Behrens, Martina G. Vijver, Alice A. Horton, Thijs Bosker, Marine Pollution Bulletin, Available online 12 October 2017, In Press

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Marine litter at the seafloor – Abundance and composition in the North Sea and the Baltic Sea

Litter is present in all marine waters around the globe. It consists of several compound classes of which plastic is of special interest because of its high abundance and possible threat to marine organisms. The regional distribution, composition and abundance of large litter items (LI) at the sea floor of the North Sea and the Baltic Sea were investigated based on 175 bottom trawls between 2013 and 2015. Different types of marine litter > 2.5 cm were classified according to the protocol of the ICES International Bottom Trawl Survey. The results showed considerable geographical variation: In the North Sea, a mean litter abundance of 16.8 LI/km2 was found, whereas the litter abundance in the Baltic Sea was significantly lower (5.07 LI/km2). In general, plastic represented 80% of the litter items. During the study, some methodical aspects with possible impact on the results were identified that need to be addressed in future sampling campaigns.

Ulrike Kammann, Marc-Oliver Aust, Horst Bahl, Thomas Lang, Marine Pollution Bulletin, Available online 12 October 2017, In Press

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