The occurrence of microplastic contamination in littoral sediments of the Persian Gulf, Iran

Microplastics (MPs; <5 mm) in aquatic environments are an emerging contaminant of concern due to their possible ecological and biological consequences. This study addresses that MP quantification and morphology to assess the abundance, distribution, and polymer types in littoral surface sediments of the Persian Gulf were performed. A two-step method, with precautions taken to avoid possible airborne contamination, was applied to extract MPs from sediments collected at five sites during low tide. MPs were found in 80% of the samples. Across all sites, fiber particles were the most dominate shape (88%), followed by films (11.2%) and fragments (0.8%). There were significant differences in MP particle concentration between sampling sites (p value <0.05). The sediments with the highest numbers of MPs were from sites in the vicinity of highly populated centers and municipal effluent discharges. FTIR analysis showed that polyethylene (PE), nylon, and polyethylene terephthalate (PET) were the most abundant polymer types. More than half of the observed MPs (56%) were in the size category of 1–4.7 mm length, with the remaining particles (44%) being in the size range of 10 μm to <1 mm. Compared to literature data from other regions, intertidal sediments in the Persian Gulf cannot be characterized as a hot spot for MP pollution. The present study could, however, provide useful background information for further investigations and management policies to understand the sources, transport, and potential effects on marine life in the Persian Gulf.

Abolfazl Naji, Zinat Esmaili, Sherri A. Mason, A. Dick Vethaak, Environmental Science and Pollution Research, pp 1–10, 14 July 2017

The article

Releasing of hexabromocyclododecanes from expanded polystyrenes in seawater -field and laboratory experiments

Expanded polystyrene (EPS) is a major component of marine debris globally. Recently, hazardous hexabromocyclododecanes (HBCDDs) were detected in EPS buoys used for aquaculture farming. Subsequently, enrichment of HBCDDs was found in nearby marine sediments and mussels growing on EPS buoys. It was suspected that EPS buoys and their debris might be sources of HBCDDs. To confirm this, the release of HBCDDs from EPS spherules detached from a buoy to seawater was investigated under field (open sea surface and closed outdoor chambers with sun exposure and in the dark) and laboratory (particle-size) conditions. In all exposure groups, initial rapid leaching of HBCDDs was followed by slow desorption over time. Abundant release of HBCDDs was observed from EPS spherules exposed to the open sea surface (natural) and on exposure to sunlight irradiation or in the dark in controlled saline water. Water leaching and UV-light/temperature along with possibly biodegradation were responsible for about 37% and 12% of HBCDDs flux, respectively. Crumbled EPS particles (≤ 1 mm) in samples deployed on the sea surface for 6 months showed a high degree of weathering. This implies that surface erosion and further fragmentation of EPS via environmental weathering could enhance the leaching of HBCDDs from the surface of EPS. Overall, in the marine environment, HBCDDs could be released to a great extent from EPS products and their debris due to the cumulative effects of the movement of large volumes of water (dilution), biodegradation, UV-light/temperature, wave action (shaking), salinity and further fragmentation of EPS spherules.

Manviri Rani, Won Joon Shim, Mi Jang and al., Chemosphere, Available online 11 July 2017, In Press, Accepted Manuscript

The article

Fouling assemblage of benthic plastic debris collected from Mersin Bay, NE Levantine coast of Turkey

The Mediterranean is an ecosystem that faces more and more microplastic pollution every day. This causes the whole of the Mediterranean to face the negative effects of plastic pollution. This study examines the state of plastic debris and fouling organisms found on it in one of the areas most affected by plastic pollution, Mersin Bay. As a result, a total of 3.88 kg plastic (mean = 0,97 kg; n = 120; 2670 item/km2; 86,3 kg/km2) was collected and based on the ATR-FTIR analysis, it was determined that this total contained 9 types of plastics. 17 different fouling species belonging to 6 phylum (Annelida, Arthropoda, Bryozoa, Chordata, Cnidaria, Mollusca) 7 class and 11 order were discovered on plastics. Spirobranchus triqueter, Hydroides sp. and Neopycnodonte cochlear were the most abundant species. In the end, the example of Mersin Bay shows that plastic debris as a substrate can contain a very high diversity of life just like natural substrates.

Sedat Gündoğdu, Cem Çevik, Serkan Karaca, Marine Pollution Bulletin, Available online 14 July 2017, In Press

The article

Microplastic contamination of intertidal sediments of Scapa Flow, Orkney: A first assessment

The concentration of microplastic particles and fibres was determined in the intertidal sediments at selected sites in Scapa Flow, Orkney, using a super-saturated NaCl flotation technique to extract the plastic and FT-IR spectroscopy to determine the polymer types. Mean concentrations were 730 and 2300 kg− 1 sediment (DW), respectively. Detailed spatial and quantitative analysis revealed that their distribution was a function of proximity to populated areas and associated wastewater effluent, industrial installations, degree of shore exposure and complex tidal flow patterns. Sediment samples from Orkney showed similar levels of microplastic contamination as in two highly populate industrialized mainland UK areas, The Clyde and the Firth of Forth. It was concluded that relative remoteness and a comparative small island population are not predictors of lower microplastic pollution. Furthermore, a larger concerted effort across Scotland and the UK is required to establish a baseline microplastic database for the evaluation of future policy measures.

J. Blumenröder, P. Sechet, J.E. Kakkonen, M.G.J. Hartl, Marine Pollution Bulletin, Available online 11 July 2017, In Press

The article

Screening for microplastics in sediment, water, marine invertebrates and fish: Method development and microplastic accumulation

Measurements of microplastics in biota and abiotic matrices are key elements of exposure and risk assessments for this emerging environmental pollutant. We investigated the abundance of microplastics in field-collected biota, sediment and water. An improved sediment extraction method, based on density separation was developed. For analysis of microplastics in biota we found that an adapted enzymatic digestion protocol using proteinase K performed best, with a 97% recovery of spiked plastic particles and no observed degradation effects on the plastics in subsequent Raman analysis. Field analysis revealed that 8 of 9 tested invertebrate species from the North Sea and 68% of analyzed individuals of brown trout (Salmo trutta) from the Swedish West Coast had microplastics in them. Based on the number of plastic particles per kg d.w. the microplastic concentrations found in mussels were approximately a thousand-fold higher compared to those in sediment and surface water samples from the same location.

Therese M. Karlsson, A. Dick Vethaak, Bethanie Carney Almroth, Freek Ariese, Martin van Velzen, Martin Hassellöv, Heather A. Leslie, Marine Pollution Bulletin, Available online 6 July 2017, In Press

The article

Benthic litter distribution on circalittoral and deep sea bottoms of the southern Bay of Biscay: Analysis of potential drivers

We analyze marine litter densities in soft bottoms of the southern Bay of Biscay using five years of demersal trawling data (2006- 2010). Marine litter densities amounted to 43 ± 33 kg·km−2 and 74 ± 28 items·km−2, with plastics and fisheries derived litter being the most widespread categories. Litter densities generally decreased along the water depth axis. To identify possible drivers for the observed litter distribution we performed a generalised additive model, which explained 14.8% of the variance and pointed to densely populated areas, number of fishing ports, geographical sector and fishing activity as the main explanatory factors. The most important driver for the benthic litter distribution was human population, as litter density linearly increased along this variable. Similarly, the number of ports in neighbouring areas had a positive effect on litter densities. Fishing effort had a negative and non-linear effect on benthic litter density which could be explained by litter delocalization during fishing operations. We hypothesise that litter might accumulate preferentially on the periphery of rocky bottoms, out of reach for our sampling methodology. Litter distribution differed among geographical sectors, pointing to other variables such as shipping traffic and oceanographic currents, which were not explicitly considered in the analysis. Our study sets a reference level for benthic macro-litter in the southern Bay of Biscay and identifies factors driving its distribution, which can be extrapolated to other continental shelf seas. Our findings lay the foundations to develop measures aiming to reduce macro-litter densities on the seafloor.

L. Lopez-Lopez, J.M. Gonzalez Irusta, A. Punzón, A. Serrano, Continental Shelf Research, Volume 144, 15 July 2017, Pages 112-119

The article

Biodegradable plastic bags on the seafloor: A future threat for seagrass meadows?

Marine plastic litter is a global concern. Carrier bags manufactured from non-biodegradable polymers constitute a large component of this litter. Because of their adverse impact on marine life, non-biodegradable bags have recently been replaced by biodegradable ones. However, growing evidence shows that these latter are not readily degradable in marine sediments and can alter benthic assemblages. The potential impact of biodegradable bags on seagrasses inhabiting sandy bottoms, which are the most widespread and productive ecosystems of the coastal zones, has been ignored. Mesocosm experiments were conducted to assess the effect of a commercialized biodegradable bag on a common seagrass species of the Mediterranean, Cymodocea nodosa, both at the level of individual plant (clonal growth) and of plant community (plant-plant relationships), under three culture regimes (plant alone, in combination with a neighbour of the same species or of the co-existing seagrass Zostera noltei) simulating different natural conditions (bare substrate, monospecific meadows or mixed meadows). The bag behaviour in marine sediment and sediment physical/chemical variables were also examined. After six months of sediment exposure, the bag retained considerable mass (85% initial weight) and reduced sediment pore-water oxygen concentration and pH. In the presence of bag, C. nodosa root spread and vegetative recruitment increased compared to controls, both intra- and interspecific interactions shifted from neutral to competitive, and the growth form changed from guerrilla (loosely arranged group of widely spaced ramets) to phalanx form (compact structure of closed spaced ramets) but only with Z. noltei. These findings suggest that biodegradable bags altering sediment geochemistry could promote the spatial segregation of seagrass clones and influence species coexistence.

Elena Balestri, Virginia Menicagli, Flavia Vallerini, Claudio Lardicci, Science of The Total Environment, Volumes 605–606, 15 December 2017, Pages 755–763