Search

This study investigated the presence of microplastics (MPs) in mussels from an urbanized bay in Korea, focusing on intra-annual variation. The average MP concentration was 0.36 ± 0.14 n/g w.w. (1.24 ± 0.56 n/individual). MPs were detected throughout the year with minor monthly variation and no significant monthly changes. Although there was no correlation between MP concentration in mussel and seawater, a positive relationship was observed when normalizing MPs to mussel's condition index (except for July). Polypropylene, polyethylene and acrylate polymer were dominant MPs, with high-density polymers comprising 59 % of the total. Most MPs were fragments and particles <200 μm. This study indicates that strict time restrictions for mussel sampling may not be necessary to assess MP levels in this bay. Additionally, considering MPs in seawater, biological conditions of mussel may be essential for understanding variations in MP levels in mussels. Including small MPs (<200 μm) and high-density polymers in MP assessment is recommended. • One-year monthly monitoring of microplastics (MPs) using mussel was performed. • MPs were detected year-round in mussel with minor monthly variation. • High-density polymers and MP <200 μm were abundant. • MP characteristics between mussel and seawater were similar. • MPs in seawater and biological conditions may co-influence in MP levels in mussel. [ABSTRACT FROM AUTHOR]

Microplastic pollution is emerging as a global environmental issue, and its potential for transferring hazardous chemicals to aquatic organisms is gaining attention. Studies have investigated the transfer of chemicals, mainly sorbed chemicals, through ingestion of microplastics by organisms, but limited information is available regarding chemical additives and uptake via the aqueous route through plastic leaching. In this study, we compared two bioaccumulation pathways of the additive hexabromocyclododecane (HBCD) by exposing mussels (Mytilus galloprovincialis) to two different sizes of expanded polystyrene (EPS): inedible size (4.2–5.5 mm) for leachate uptake and edible size (20–770 μm) for particle ingestion and leachate uptake. Over 10 days, the HBCD concentration increased significantly in mussels in the EPS exposure groups, indicating that EPS microplastic acts as a source of HBCD to mussels. The concentration and isomeric profiles of HBCD in mussels show that uptake through the aqueous phase is a more significant pathway for bioaccumulation of HBCD from EPS to mussels than particle ingestion. HBCD levels measured in EPS, leachate and exposed mussels from this study are environmentally relevant concentration. The fate and effects of chemical additives leached from plastic debris in ecosystem requires further investigation, as it may affect numerous environments and organisms through the aqueous phase. Image 1 • Additive HBCD uptake via EPS particle ingestion and EPS leachate were compared. • Mussels were exposed to edible and inedible sizes of EPS microplastics. • Aqueous leachate uptake is an important exposure route of EPS additives for mussels. • EPS microplastic acts as a source of plastic additives HBCD to mussel. Aqueous leachate uptake can be an important exposure route of microplastic additives for aquatic invertebrates. [ABSTRACT FROM AUTHOR]

This study assessed the ecological risk posed by microplastics in surface and subsurface seawaters in coastal, continental shelf, and deep-sea areas of South Korea. The target microplastics for risk assessment were specified as only non-spherical type microplastics in the size range 20–300 μm, because this type was predominantly observed in our study areas, and adverse biological effects have previously been reported. Exposure data for non-spherical microplastics were obtained from a previous study or were measured for microplastics of sizes down to 20 μm. A predicted no-effect concentration (PNEC) of 12 particles/L was derived by employing a species sensitivity distribution approach. Then the results were compared to the in situ observed concentrations at each site. The detected microplastic concentrations did not exceed the derived PNEC, i.e., the current pollution levels of fragment and fiber microplastics in the size range 20–300 μm would not pose a significant threat to the marine ecosystem in South Korea. However, predictions are that microplastic pollution will increase to 50-fold by 2100 at the current rates, and in this scenario, the microplastic concentration is expected to far exceed the derived PNEC values for marine ecosystems. It is therefore urgent to take precautionary actions to prevent a further increase in microplastic concentrations in these environments. Image 1 • Predicted no effect concentration (PNEC) for non-spherical microplastic was derived. • The microplastic concentrations in Korean marine water was lower than PNEC. • No ecological risk in Korean saltwater environments is suspected. • The microplastic concentration is predicted to well exceed PNEC value by 2100. • Actions to prevent a further increase in microplastic concentrations should be taken. Ecological risk assessment was conducted by matching size range and morphology of microplastics in both toxicity data and field monitoring data. [ABSTRACT FROM AUTHOR]

Bivalves are useful bioindicators of microplastic contamination in the marine environment for several reasons, such as extensive filter feeding activity, broad geographical distribution, and limited movement capability. This study conducted a nationwide monitoring of microplastic pollution along the Korean coasts using filter-feeding bivalves (including oyster, mussel, and Manila clam) as bioindicators to identify the national contamination level and characteristics of microplastics. Seawater sample was collected from the same sampling stations of oyster and mussel for comparison. Microplastics were widely distributed in both coastal bivalves and waters with mean concentrations of 0.33 ± 0.23 n/g (1.21 ± 0.68 n/individual) in oyster/mussel, 0.43 ± 0.32 n/g (2.19 ± 1.20 n/individual) in Manila clam, and 1400 ± 560 n/m3 in seawater. Despite the lack of significant relationship in the abundance of microplastics, their dominant features such as size, shape, color and polymer type were similar between bivalves and seawater. Fragments (69% for oyster/mussel, 72% for Manila clam, and 77% for seawater), particles smaller than 300 μm (96% for oyster/mussel, 83% for Manila clam, and 84% for seawater) and colorless (79% for oyster/mussel, 85% for Manila clam, 75% for seawater) were the dominant shape, size and color, respectively. The major polymer types were polypropylene, polyethylene, and polyester. The microplastic level in bivalves was relatively high in urbanized areas with a wide diversity of polymer types compared with those in non-urbanized areas, and the proportion of polystyrene in the Korean samples was abundant compared with other regions due to wide use of polystyrene products in Korea. Our result suggests that microplastic contamination is widespread in the Korean coastal environment, and bivalves can reflect the microplastic pollution characteristics of the surrounding waters where they live. Image 1 • Microplastic (MP) was widespread in bivalves and seawater from the Korea coasts. • Size, shape, and polymer type were similar between bivalves and nearby seawater. • Bivalves from urbanized areas exhibited high abundance and diversity of MP. A nationwide biomonitoring study was conducted to identify the national contamination level and characteristics of microplastics in Korea. [ABSTRACT FROM AUTHOR]

Human activity is thought to affect the abundance and contamination characteristics of microplastics (MPs) in the environment, which may in turn affect aquatic species. However, few studies have examined the impact of coastal area use pattern on characteristics of MPs in coastal regions. In this study, we investigated MP contamination of abiotic matrices (seawater and sediment) and biotic matrices (bivalves and polychaetes) in three coastal regions characterized by different types of human activity, covering urban, aquafarm, and rural areas. MP abundance was higher in sediment from the urban site than in that from the rural site, but similar to that from the aquafarm site. In the abiotic matrices, different MP polymer compositions were observed among the three sites. Diverse polymers were found in marine matrices from the urban site, implying diverse MP sources in highly populated and industrialized areas. Polystyrene was more abundant in the aquafarm site, reflecting the wide use of expanded polystyrene aquaculture buoys. Polypropylene was more abundant at the rural site, probably due to the use of polypropylene ropes and nets in fishing activity. MP accumulation profiles in marine invertebrates showed trends similar to those exhibited by abiotic matrices, reflecting coastal area use patterns. These results indicate that marine MPs are generated from both land- and marine-based sources, and that the abiotic and biotic marine matrices reflect the MP characteristics. Image 1 • Microplastic (MP) contamination was compared in urban, aquafarm, and rural areas. • MP shape, size, and polymer type were examined in various marine matrices. • Coastal area use pattern and MP contamination were found to be closely related. • Diverse polymers were found in marine matrices, creek, and road dust from urban. • Marine-based activities are important contributors to MP contamination. [ABSTRACT FROM AUTHOR]

This is the first report to evaluate the potential effects of microplastics (MPs) on wild wharf roaches (Ligia exotica) in a shoreline habitant. L. exotica is an important plastic detritus consumer in coastal area. A survey was conducted from May to June in the years 2019 and 2020 in two South Korean nearshore sites: Nae-do (as MPs-uncontaminated) and Maemul-do (as MPs-contaminated). MPs (>20 μm in size) were detected highly in gastrointestinal tracts of the L. exotica from Maemul-do, at an average level of 50.56 particles/individual. They were detected in much lower levels in the L. exotica from Nae-do. at an average rate of 1.00 particles/individual. The polymer type and shape were dominated by expanded polystyrene (EPS, 93%) and fragment (99.9%) in L. exotica from Maemul-do. Especially, Hexabromocyclododecanes, brominated flame retardants added to EPS, have been detected highly in L. exotica from Maemul-do (630.86 ± 587.21 ng/g l. w.) than those of Nae-do (detection limit: 10.5 ng/g l. w). Genome-wide transcriptome profiling revealed altered expression of genes associated with fatty acid metabolic processes, the innate-immune response-activating system and vesicle cytoskeletal trafficking in L. exotica from Maemul-do. The activation of the p53 signaling pathway (which is related to proteasome, ER regulation and cell morphogenesis) is likely to be involved in the EPS-uptake of wild L. exotica. Four neurosteroids were also detected in head tissue, and cortisol and progesterone concentrations differed significantly in L. exotica from Maemul-do. Our findings also suggest that resident plastic detritus consumer might be a useful indicator organism for evaluating pollution and potential effects of environmental microplastics. [Display omitted] • This is the first study to clarify the toxic effects derived from MP contamination in L. exotica. • MP contamination was higher in L. exotica from Maemul-do (50.56 particles/individual). • Composition of MP was dominated by the expanded polystyrene in L. exotica from Maemul-do (93%). • Abundant MP concentration altered the metabolic and immune system. • Significant variated neurosteroids also might be caused by MP contamination. [ABSTRACT FROM AUTHOR]