Sticky tape and simulations help assess microplastic risk

Tiny pieces of plastic, now ubiquitous in the marine environment, have long been a cause of concern for their ability to absorb toxic substances and potentially penetrate the food chain. Now scientists are beginning to understand the level of threat posed to life, by gauging the extent of marine accumulation and tracking the movement of these contaminants. (…)

N. Grover, Horizon EU magazine, 23/04/2018

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Two forage fishes as potential conduits for the vertical transfer of microfibres in Northeastern Pacific Ocean food webs

We assessed the potential role played by two vital Northeastern Pacific Ocean forage fishes, the Pacific sand lance (Ammodytes personatus) and Pacific herring (Clupea pallasii), as conduits for the vertical transfer of microfibres in food webs. We quantified the number of microfibres found in the stomachs of 734 sand lance and 205 herring that had been captured by an abundant seabird, the rhinoceros auklet (Cerorhinca monocerata). Sampling took place on six widely-dispersed breeding colonies in British Columbia, Canada, and Washington State, USA, over one to eight years. The North Pacific Ocean is a global hotspot for pollution, yet few sand lance (1.5%) or herring (2.0%) had ingested microfibres. In addition, there was no systematic relationship between the prevalence of microplastics in the fish stomachs vs. in waters around three of our study colonies (measured in an earlier study). Sampling at a single site (Protection Island, WA) in a single year (2016) yielded most (sand lance) or all (herring) of the microfibres recovered over the 30 colony-years of sampling involved in this study, yet no microfibres had been recovered there, in either species, in the previous year. We thus found no evidence that sand lance and herring currently act as major food-web conduits for microfibres along British Columbia’s outer coast, nor that the local at-sea density of plastic necessarily determines how much plastic enters marine food webs via zooplanktivores. Extensive urban development around the Salish Sea probably explains the elevated microfibre loads in fishes collected on Protection Island, but we cannot account for the between-year variation. Nonetheless, the existence of such marked interannual variation indicates the importance of measuring year-to-year variation in microfibre pollution both at sea and in marine biota.

J. M. Hipfner, M. Galbraith, S. Tucker and al., Environmental Pollution, Volume 239, August 2018, Pages 215-222

The article

Abundance, composition, and distribution of microplastics larger than 20 μm in sand beaches of South Korea

To support microplastic management, the abundance, composition, and spatial distribution of microplastics on a national scale must be known. Hence, we studied the baseline level of microplastic pollution at 20 sandy beaches along the South Korean coast. All microplastic particles extracted from the sand samples were identified down to 20 μm in size using Fourier transform infrared spectroscopy. The abundances of large microplastics (L-MPs; 1–5 mm) and small microplastics (S-MPs; 0.02–1 mm) were in the range of 0–2088 n/m2 and 1400–62800 n/m2, respectively. Maximum microplastic abundance was in the size range of 100–150 μm, and particles smaller than 300 μm accounted for 81% of the total abundance. Expanded polystyrene (EPS) accounted for 95% of L-MPs, whereas S-MPs were predominantly composed of polyethylene (49%) and polypropylene (38%). The spatial distribution of L-MPs, excluding EPS, was significantly related to population, precipitation, proximity to a river mouth and abundance of macroplastic debris on beach. However, there were no relationships between S-MPs and other environmental and source-related factors, except for macroplastic debris and L-MPs excluding EPS. These results imply that S-MPs are mainly produced on beaches by weathering, whereas L-MPs other than EPS are mainly introduced from land-based sources and are also partly produced on beaches.

Soeun Eo, Sang Hee Hong, Young Kyoung Song and al., Environmental Pollution, Volume 238, July 2018, Pages 894-902

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Low levels of microplastics (MP) in wild mussels indicate that MP ingestion by humans is minimal compared to exposure via household fibres fallout during a meal

Microplastics (MPs) are the most numerous debris reported in marine environments and assessment of the amounts of MPs that accumulate in wild organisms is necessary for risk assessment. Our objective was to assess MP contamination in mussels collected around the coast of Scotland (UK) to identify characteristics of MPs and to evaluate risk of human exposure to MPs via ingestion of mussels. We deployed caged mussels (Mytilus edulis) in an urbanised estuary (Edinburgh, UK) to assess seasonal changes in plastic pollution, and collected mussels (Mytilus spp and subtidal Modiolus modiolus) from eight sampling stations around Scotland to enumerate MP types at different locations. We determined the potential exposure of humans to household dust fibres during a meal to compare with amounts of MPs present in edible mussels. The mean number of MPs in M. modiolus was 0.086 ± 0.031 (SE, n = 6)/g ww (3.5 ± 1.29 (SE) per mussel). In Mytilus spp, the mean number of MPs/g ww was 3.0 ± 0.9 (SE, n = 36) (3.2 ± 0.52 (SE) per mussel), but weight dependent. The visual accuracy of plastic fibres identification was estimated to be between 48 and 50%, using Nile Red staining and FT-IR methodologies, respectively, halving the observed amounts of MPs in wild mussels. We observed an allometric relationship between the number of MPs and the mussels wet weight. Our predictions of MPs ingestion by humans via consumption of mussels is 123 MP particles/y/capita in the UK and can go up to 4620 particles/y/capita in countries with a higher shellfish consumption. By comparison, the risk of plastic ingestion via mussel consumption is minimal when compared to fibre exposure during a meal via dust fallout in a household (13,731–68,415 particles/Y/capita).

A. I. Catarino, V. Macchia, W. G. Sanderson and al., Environmental Pollution, Volume 237, June 2018, Pages 675–684

The article

Application of an enzyme digestion method reveals microlitter in Mytilus trossulus at a wastewater discharge area

The ingestion of microlitter by blue mussels (450) was studied at a wastewater recipient area in the Baltic Sea. The mussel soft tissues were digested using enzymatic detergents and the detected litter particles characterized with FT-IR imaging spectroscopy. Microlitter concentration in seawater and WWTP effluent were also measured. Microlitter was found in 66% of the mussels. Mussels from the WWTP recipient had higher microlitter content compared to those collected at the reference site. Plastics made up 8% of all the analysed microlitter particles. The dominating litter types were fibres (~90% of all microlitter), 42% of which were cotton, 17% linen, 17% viscose and 4% polyester. The risk of airborne contamination during laboratory work was lowered when mussels were digested with their shells on instead of dissecting them first. The approach was found applicable and gentle to both non-synthetic and synthetic materials including fragile fibres.

Saana Railo, Julia Talvitie, Outi Setälä and al., Marine Pollution Bulletin, Volume 130, May 2018,  Pages 206–214

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Conférence « Microplastiques : impacts, enjeux et comportements » jeudi 22 mars, Océanopolis (Brest)

Accès libre (20h30, Auditorium Marion Dufresne, Océanopolis, Brest)

Les microplastiques, une menace pour les organismes marins ?

Résumé : Les plastiques sont des matériaux persistants qui s’accumulent dans l’environnement marin et peuvent affecter les organismes marins. Les microplastiques sont généralement définis comme l’ensemble des particules de plastique inférieures à 1 mm. Ils sont composés de matériaux persistants, d’origine anthropique, qui s’accumule dans l’environnement marin. Ils proviennent notamment (origine primaire) d’abrasifs industriels, de la pré-production de pastilles plastiques, du rejet de fibres synthétiques issus de nos lessives ou sont les produits de dégradation (origine secondaire) des macro-déchets plastiques.

Ils contiennent des additifs potentiellement toxiques, mais sont aussi concentrateurs de contaminants organiques persistants ainsi que véhicules de microorganismes. Ils peuvent être ingérés par les organismes marins et ainsi entrer dans la chaine alimentaire.

Notre travail consiste à caractériser les niveaux de contamination dans le milieu marin, et notamment en rade de Brest, pour ensuite permettre des expositions en conditions de laboratoire à des doses et sous conditions environnementales afin d’estimer les impacts de particules de plastiques sur les organismes marins, information importante pour permettre de l’aide à la décision.

Macroplastic and microplastic contamination assessment of a tropical river (Saigon River, Vietnam) transversed by a developing megacity

Both macroplastic and microplastic contamination levels were assessed for the first time in a tropical river estuary system, i.e. the Saigon River, that traverses a developing South East Asian megacity, i.e. Ho Chi Minh City, Vietnam. The analysis of floating debris collected daily on the Nhieu Loc – Thi Nghe canal by the municipal waste management service shows that the plastic mass percentage represents 11–43%, and the land-based plastic debris entering the river was estimated from 0.96 to 19.91 g inhabitant−1 d−1, namely 350 to 7270 g inhabitant−1 yr−1. Microplastics were assessed in the Saigon River and in four urban canals by sampling bulk water for anthropogenic fiber analysis and 300 μm mesh size plankton net exposition for fragment analysis. Fibers and fragments are highly concentrated in this system, respectively 172,000 to 519,000 items m−3 and 10 to 223 items m−3. They were found in various colors and shapes with smallest size and surface classes being predominant. The macroplastics and fragments were mainly made of polyethylene and polypropylene while the anthropogenic fibers were mainly made of polyester. The relation between macroplastic and microplastic concentrations, waste management, population density and water treatment are further discussed.

Lisa Lahens, Emilie Strady, Thuy-Chung Kieu-Le and al., Environmental Pollution, Volume 236, May 2018, Pages 661–671

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