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

The article

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Three-dimensional distribution of anthropogenic microparticles in the body of sandy beaches

External oceanographic conditions rather than anthropogenic influence are shown to cause the 3-dimensional distribution of anthropogenic microparticles (MP, 0.5–5 mm) within the body of sandy beaches of a non-tidal sea with strong wind/wave climate and seasonal sea level variations (the Baltic Sea). A patchy structure is confirmed in all three dimensions, with background concentrations of several tens of MP items per kg of dry sample weight versus peaking spots with several hundreds of items per kg dry weight. The background MP concentrations are of the same order of magnitude for the beach surface, beach body, and sands of underwater coastal slopes, highlighting that the contaminated by MPs sand cover of the entire sea coastal zone is one single entity, repeatedly re-distributed between its underwater and beach parts by every next storm. Peaking concentrations are related to stormy events and places with stronger water dynamics, and are associated with locations of coarser sands within the beach body and wracklines at the beach surface. This suggests that marine waters are the source of anthropogenic microparticles for the beach, and not vice versa. The prevalence of wave-driven over wind-driven beaching mechanism for MPs extracted from the beach samples is confirmed by the flotation tests. Size distribution of the extracted MPs is found to be similar to that obtained for plastics floating at the ocean surface. Such a coherency for different oceanic environments speaks in favor of independence of general fragmentation processes on the particular external conditions, shifting the attention to the fragmentation process and material properties of synthetic particles in marine environment.

I.P. Chubarenko, E.E. Esiukova, A.V. Bagaev and al., Science of The Total Environment, Volumes 628–629, 1 July 2018, Pages 1340–1351

The article

Marine litter on the seafloor of the southern Baltic

Marine litter occurrence and composition were investigated during routine bottom trawl fish surveys type BITS performed in the Polish Maritime Areas (the southern Baltic Sea). Sampling covered a distance of 325 km and an area of 16 km2 at a depth range of 19–110 m. Litter densities varying between 0 items/ha (34% of tows) and 2.23 items/ha with a mean of 0.20 items/ha (SD = 0.30) are at the bottom range of densities reported from other shelf habitats worldwide at similar water depths. The majority of the items (40%) were found at a depth range of 51–60 m. Overall, plastic was the most common litter type (67% of all items) found in all tows with litter. The results of this study indicate that despite the Baltic being a semi-enclosed basin, with a densely populated coastline and extensive shipping, marine litter pollution of the southern Baltic seafloor is low compared to other coastal areas.

Barbara Urban-Malinga, Tycjan Wodzinowski, Bartosz Witalis, Mariusz Zalewski, Krzysztof Radtke, Włodzimierz Grygiel, Marine Pollution Bulletin, Volume 127, February 2018, Pages 612–617

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Anthropogenic microlitter in the Baltic Sea water column

Microlitter (0.5–5 mm) concentrations in water column (depth range from 0 to 217.5 m) of the main Baltic Proper basins are reported. In total, 95 water samples collected in 6 research cruises in 2015–2016 in the Bornholm, Gdansk, and Gotland basins were analysed. Water from 10- and 30-litre Niskin bathometers was filtered through the 174 μm filters, and the filtrate was examined under optical microscope (40 ×). The bulk mean concentration was 0.40 ± 0.58 items per litre, with fibres making 77% of them. Other types of particles are the paint flakes (19%) and fragments (4%); no microbeads or pellets. The highest concentrations are found in the near-bottom samples from the coastal zone (2.2–2.7 items per litre max) and from near-surface waters (0.5 m) in the Bornholm basin (5 samples, 1.6–2.5 items per litre). Distribution of particles over depths, types, and geographical regions is presented.

A. Bagaev, L. Khatmullina, I. Chubarenko, Marine Pollution Bulletin, Available online 26 October 2017, In Press

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No increase in marine microplastic concentration over the last three decades – A case study from the Baltic Sea

Microplastic is considered a potential threat to marine life as it is ingested by a wide variety of species. Most studies on microplastic ingestion are short-term investigations and little is currently known about how this potential threat has developed over the last decades where global plastic production has increased exponentially. Here we present the first long-term study on microplastic in the marine environment, covering three decades from 1987 to 2015, based on a unique sample set originally collected and conserved for food web studies. We investigated the microplastic concentration in plankton samples and in digestive tracts of two economically and ecologically important planktivorous forage fish species, Atlantic herring (Clupea harengus) and European sprat (Sprattus sprattus), in the Baltic Sea, an ecosystem which is under high anthropogenic pressure and has undergone considerable changes over the past decades. Surprisingly, neither the concentration of microplastic in the plankton samples nor in the digestive tracts changed significantly over the investigated time period. Average microplastic concentration in the plankton samples was 0.21 ± 0.15 particles m− 3. Of 814 fish examined, 20% contained plastic particles, of which 95% were characterized as microplastic (< 5 mm) and of these 93% were fibres. There were no significant differences in the plastic content between species, locations, or time of day the fish were caught. However, fish size and microplastic in the digestive tracts were positively correlated, and the fish contained more plastic during summer than during spring, which may be explained by increased food uptake with size and seasonal differences in feeding activity. This study highlights that even though microplastic has been present in the Baltic environment and the digestive tracts of fishes for decades, the levels have not changed in this period. This underscores the need for greater understanding of how plastic is cycled through marine ecosystems. The stability of plastic concentration and contamination over time observed here indicates that the type and level of microplastic pollution may be more closely correlated to specific human activities in a region than to global plastic production and utilization as such.

Sabrina Beer, Anders Garm, Bastian Huwer, Jan Dierking, Torkel Gissel Nielsen, Science of The Total Environment, Volume 621, 15 April 2018, Pages 1272-1279

The article

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, Volume 127, February 2018, Pages 774-780

The article

Persistent organic pollutants in selected fishes of the Gulf of Finland

Fish samples of Baltic herring, sprat, flounder, perch, salmon, and river lamprey were collected from the Gulf of Finland in 2013 and 2014 with the aim to get an overview of the occurrence of pollutants in fish caught in Estonian waters. The content of non-dioxin-like polychlorinated biphenyls (ndl PCBs), polybrominated diphenyl ethers (PBDEs), organic tin (OT) and perfluorocompounds (PFAS) are examined and discussed in the study. The results revealed that potentially higher content of organo-tin compounds, perfluorocompounds and polybrominated diphenyl ethers in Baltic herring, salmon and river lamprey may cause concern regarding human exposure.

It is important to link pollutant content to lipid content of fish taking into account their seasonal variation in different age classes.

Leili Järv, Hannu Kiviranta, Jani Koponen and al., Journal of Marine Systems, Volume 171, July 2017, Pages 129–133

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