Composition, spatial distribution and sources of macro-marine litter on the Gulf of Alicante seafloor (Spanish Mediterranean)

The composition, spatial distribution and source of marine litter in the Spanish Southeast Mediterranean were assessed. The data proceed from a marine litter retention programme implemented by commercial trawlers and were analysed by GIS. By weight, 75.9% was plastic, metal and glass. Glass and plastics were mainly found close to the coast. A high concentration of metal was observed in some isolated zones of both open and coastal waters. Fishing activity was the source of 29.16% of the macro-marine litter, almost 68.1% of the plastics, and 25.1% of the metal. The source of the other 60.84% could not be directly identified, revealing the high degree of uncertainty regarding its specific origin. Indirectly however, a qualitative analysis of marine traffic shows that the likely sources were merchant ships mainly in open waters and recreational and fishing vessels in coastal waters.

Santiago García-Rivera, Jose Luis Sánchez Lizaso, Jose María Bellido Millán, Marine Pollution Bulletin, Available online 12 June 2017, In Press

The article

Microplastics in the sediments of a UK urban lake

While studies on microplastics in the marine environment show their wide-distribution, persistence and contamination of biota, the freshwater environment remains comparatively neglected. Where studies on freshwaters have been undertaken these have been on riverine systems or very large lakes. We present data on the distribution of microplastic particles in the sediments of Edgbaston Pool, a shallow eutrophic lake in central Birmingham, UK. These data provide, to our knowledge, the first assessment of microplastic concentrations in the sediments of either a small or an urban lake and the first for any lake in the UK. Maximum concentrations reached 25–30 particles per 100 g dried sediment (equivalent to low hundreds kg−1) and hence are comparable with reported river sediment studies. Fibres and films were the most common types of microplastic observed. Spatial distributions appear to be due to similar factors to other lake studies (i.e. location of inflow; prevailing wind directions; propensity for biofouling; distribution of macroplastic debris) and add to the growing burden of evidence for microplastic ubiquity in all environments.

Rebecca Vaughan, Simon D. Turner, Neil L. Rose, Environmental Pollution, Volume 229, October 2017, Pages 10–18

The article

Ubiquity of microplastics in coastal seafloor sediments

Microplastic pollutants occur in marine environments globally, however estimates of seafloor concentrations are rare. Here we apply a novel method to quantify size-graded (0.038–4.0 mm diam.) concentrations of plastics in marine sediments from 42 coastal and estuarine sites spanning pollution gradients across south-eastern Australia. Acid digestion/density separation revealed 9552 individual microplastics from 2.84 l of sediment across all samples; equating to a regional average of 3.4 microplastics·ml− 1 sediment. Microplastics occurred as filaments (84% of total) and particle forms (16% of total). Positive correlations between microplastic filaments and wave exposure, and microplastic particles with finer sediments, indicate hydrological/sediment-matrix properties are important for deposition/retention. Contrary to expectations, positive relationships were not evident between microplastics and other pollutants (heavy metals/sewage), nor were negative relationships with neighbouring reef biota detected. Rather, microplastics were ubiquitous across sampling sites. Positive associations with some faunal-elements (i.e. invertebrate species richness) nevertheless suggest high potential for microplastic ingestion.

S.D. Ling , M. Sinclair, C.J. Levi, S.E. Reeves, G.J. Edgar, Marine Pollution Bulletin, Available online 29 May 2017, In Press

The article

Microplastics in Sediment Cores from Asia and Africa as Indicators of Temporal Trends in Plastic Pollution

Microplastics (<5 mm) were extracted from sediment cores collected in Japan, Thailand, Malaysia, and South Africa by density separation after hydrogen peroxide treatment to remove biofilms were and identified using FTIR. Carbonyl and vinyl indices were used to avoid counting biopolymers as plastics. Microplastics composed of variety of polymers, including polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethyleneterphthalates (PET), polyethylene-polypropylene copolymer (PEP), and polyacrylates (PAK), were identified in the sediment. We measured microplastics between 315 µm and 5 mm, most of which were in the range 315 µm–1 mm. The abundance of microplastics in surface sediment varied from 100 pieces/kg-dry sediment in a core collected in the Gulf of Thailand to 1900 pieces/kg-dry sediment in a core collected in a canal in Tokyo Bay. A far higher stock of PE and PP composed microplastics in sediment compared with surface water samples collected in a canal in Tokyo Bay suggests that sediment is an important sink for microplastics. In dated sediment cores from Japan, microplastic pollution started in 1950s, and their abundance increased markedly toward the surface layer (i.e., 2000s). In all sediment cores from Japan, Thailand, Malaysia, and South Africa, the abundance of microplastics increased toward the surface, suggesting the global occurrence of and an increase in microplastic pollution over time.

Yukari Matsuguma, Hideshige Takada, Hidetoshi Kumata and al., Archives of Environmental Contamination and Toxicology, pp 1–10, Special Issue: Indicators of Ocean Pollution, First Online 22 May 2017

The article

Bioturbation transports secondary microplastics to deeper layers in soft marine sediments of the northern Baltic Sea

Microplastics (MPs) are observed to be present on the seafloor ranging from coastal areas to deep seas. Because bioturbation alters the distribution of natural particles on inhabited soft bottoms, a mesocosm experiment with common benthic invertebrates was conducted to study their effect on the distribution of secondary MPs (different-sized pieces of fishing line < 1 mm). During the study period of three weeks, the benthic community increased MP concentration in the depth of 1.7–5.1 cm in the sediment. The experiment revealed a clear vertical gradient in MP distribution with their abundance being highest in the uppermost parts of the sediment and decreasing with depth. The Baltic clam Macoma balthica was the only study animal that ingested MPs. This study highlights the need to further examine the vertical distribution of MPs in natural sediments to reliably assess their abundance on the seafloor as well as their potential impacts on benthic communities.

Pinja Näkki, Outi Setälä, Maiju Lehtiniemi, Marine Pollution Bulletin, Volume 119, Issue 1, 15 June 2017, Pages 255–261

The article

A review of analytical techniques for quantifying microplastics in sediments

In this review the analytical techniques for measuring microplastics in sediment have been evaluated. Four primary areas of the analytical process have been identified that include (1) sampling, (2) extraction, (3) quantitation and (4) quality assurance/quality control (QAQC). Each of those sections have their own subject specific challenges and require further method development and harmonisation. The most common approach to extracting microplastics from sediments is density separation. Following extraction, visual counting with an optical microscope is the most common technique for quantifying microplastics; a technique that is labour intensive and prone to human error. Spectroscopy (FTIR; Raman) are the most commonly applied techniques for identifying polymers collected through visual sorting. Improvements and harmonisation on size fractions, sampling approaches, extraction protocols and units for reporting plastic abundance would aid comparison of data generated by different research teams. Further, we advocate the development of strong QAQC procedures to be adopted like other fields of analytical chemistry. Finally, inter-laboratory proficiency testing is recommended to give an indication of the variation and reliability in measurements reported in the scientific literature that may be under- or overestimations of environmental burdens.

Joanne S. Hanvey, Phoebe J. Lewis, Jennifer L. Lavers, Nicholas D. Crosbie, Karla Pozo and Bradley O. Clarke, Analytical Methods, 2017, 9, 1369-1383

The article

Microplastics in sediments of the Changjiang Estuary, China

Microplastics are plastics that measure less than 5 mm in diameter. They enter the marine environment as primary sources directly from industrial uses, as well as secondary sources resulting from the degradation of large plastic debris. To improve the knowledge of microplastic pollution in China, we investigated samples from 53 estuarine sediment locations collected with a box corer within the Changjiang Estuary. Microplastics (<5 mm) were extracted from sediments by density separation, after which they were observed under a microscope and categorized according to shape, color and size. Identification was carried out using Micro-Fourier-Transform Infrared Spectroscopy (μ-FT-IR).

The abundance of microplastics in the Changjiang Estuary was mapped. The mean concentration was 121 ± 9 items per kg of dry weight, varying from 20 to 340 items per kg of dry weight. It was found that the concentration of microplastics was the highest on the southeast coast of Shanghai. The distribution pattern of microplastics may be affected by the Changjiang diluted water in summer. All of the microplastics collected were categorized according to shape, color and size. Among which fiber (93%), transparent (42%) and small microplastics (<1 mm) (58%) were the most abundant types. No clear correlation between microplastics and the finer sediment fraction was found. Rayon, polyester, and acrylic were the most abundant types of microplastics identified, indicating that the main source of microplastics in the Changjiang Estuary was from washing clothes (the primary source). It is possible to compare microplastic abundance in this study with the results of other related studies using the same quantification method. The identification of microplastics raises the awareness of microplastic pollution from drainage systems. The prevalence of microplastic pollution calls for monitoring microplastics at a national scale on a regular basis.

Guyu Peng, Bangshang Zhu, Dongqi Yang, Lei Su, Huahong Shi, Daoji Li, Environmental Pollution, Volume 225, June 2017, Pages 283–290

The article