Assessment of plastic pollution in the Bohai Sea: Abundance, distribution, morphological characteristics and chemical components.

Plastics are globally distributed in oceans and can pose a threat to the environment and organisms. In this study, plastic pollution in surface water and sediments of the Bohai Sea was assessed based on plastic abundance, distribution and characteristics (shape, polymer, size and color). Water and sediment samples were collected across the sea using a plankton net (330 μm) and a grab sampler, respectively. The following conclusions were reached. 1) In surface water, large plastics were less abundant (0.14 items/m3) and showed less diverse characteristics than microplastics (0.79 items/m3) but did not significantly differ in spatial distribution. 2) Microplastics in water were more abundant (1.95 items/m3) with more diverse characteristics in Liaodong Bay than in other regions of the sea (0.26-0.59 items/m3). Plastic waste from highly concentrated agricultural, industrial and fishery activities could make large contributions to microplastics in Liaodong Bay. Additionally, low hydrodynamics and long distance to Bohai Strait are unfavorable for diffusion of particles, facilitating the retention of microplastics and increasing the abundance in this bay. 3) Microplastics in sediments were smaller in terms of dominant sizes (<0.5 mm) with less diverse characteristics than particles in water (0.5-1.5 mm). Specifically, fragments, foams and lines dominated among the microplastics in water, whereas fibers and fragments were dominant particles in sediments; alkyd resin, polyethylene, polystyrene and polypropylene (PP) predominated among the particles in water, but rayon, cellulose and PP were dominant particles in sediments. 4) Neither abundance nor size of microplastics in the two media was proportionally correlated and showed low similarity indexes of polymer (0.16), shape (0.29) or color (0.38). This could be related to mismatch in spatiotemporal distributions and variations in the characteristics, fate and behavior of microplastics in the two media. The findings provide knowledge for tracing the sources of plastics in the Bohai Sea.

Xu L ，Cao L ，Huang W ，Liu J ，Dou S ... -  《-》

Spatio-temporal distribution of plastic and microplastic debris in the surface water of the Bohai Sea, China.

As an emerging marine environmental issue, marine plastic debris pollution has attracted worldwide attention. Studies have covered more and more areas of the world's oceans. To further understand the sources and variation of marine plastic debris in the surface water of the Bohai Sea, in this study, plastic debris was collected during the four seasons of 2016-2017. The results showed the mean density of plastic debris over these seasons was 0.49 ± 0.18 particles/m3. Macro-, meso-, and micro- plastics accounted for 5%, 26%, and 69% of the total number of plastic debris, respectively. The density of the microplastics was 0.35 ± 0.13 particles/m3. The highest density was found in spring, followed by summer and winter, and the lowest in autumn. High distribution densities were observed in the Liaodong Bay and the Bohai Strait, which were attributed to the dynamics of the rim current, terrain, and fishery activities. CAPSULE ABSTRACT: Riverine input, dynamics of the rim current, terrain, and fishery activities contribute to the variations in marine plastic debris in the surface water of the Bohai Sea.

Zhang W ，Zhang S ，Zhao Q ，Qu L ，Ma D ，Wang J ... -  《-》

Microplastic Pollution in Nearshore Sediment from the Bohai Sea Coastline.

Microplastics are recognized as an emerging global issue in marine environments. In this study, microplastic pollution in subtidal sediments from nine typical stations in the Bohai Sea was investigated. The mean concentration was 458.6 ± 150.0 items/kg of dry weight, varying from 280.0 to 773.4 items/kg. All of the microplastics were categorized according to shape, color and size. Among these microplastics, fiber (77.1%), white/blue/black (85.0%) and small microplastics (< 1500 μm) (82.9%) were the most abundant types. Seven polymer types were identified and were, in decreasing order of abundance, rayon > PE > PS > PP > PET > ABS > PA. The microplastics abundance was of the same order of magnitude as that of other similar areas. The microplastic characteristics suggest that tourism, maritime activities and sewage discharge are possible sources. Our results provide useful information for performing an environmental risk assessment of microplastic pollution in this area.

Zhu X ，Ran W ，Teng J ，Zhang C ，Zhang W ，Hou C ，Zhao J ，Qi X ，Wang Q ... -  《-》

Pollution characteristics and ecological risk of microplastic in sediments of Liaodong Bay from the northern Bohai Sea in China.

Microplastics (MPs) are widely distributed in marine environments. The pollution characteristics and risk assessment of MPs in estuarine sediments are still insufficient. In this study, the MPs pollution characteristics in surface sediments of the Liao Estuary and Daliao Estuary were investigated. The characteristics of MPs in sediments were determined by stereo microscopy and micro-Fourier transform infrared spectroscopy. The results showed that the average MPs abundance ranged from 32.33 to 49.91 items·kg-1 d.w. The MPs were mainly composed of 500-2000 μm black and blue fibers. Five polymer types were identified, including rayon (RA) (87.46 %), polyethylene terephthalate (PET) (6.81 %), polyamide (PA) (2.94 %), polypropylene (PP) (2.17 %) and polyethylene (PE) (0.62 %). The pollution load index (PLI) risk assessment showed that all sampling sites were at Hazard Level I. Our results can provide useful information for assessing the environmental risks of MPs in coastal areas of China.

Ye Y ，Zhang A ，Teng J ，Yang X ，Yuan X ，Wang Q ，Zhao J ，Zhang B ，Zhang T ，Chen X ，Guan T ，Ma X ... -  《-》

Microplastic pollution in the surface waters of the Bohai Sea, China.

The ubiquitous presence and persistency of microplastics in aquatic environments is of particular concern because these pollutants represent an increasing threat to marine organisms and ecosystems. An identification of the patterns of microplastic distribution will help to understand the scale of their potential effect on the environment and on organisms. In this study, the occurrence and distribution of microplastics in the Bohai Sea are reported for the first time. We sampled floating microplastics at 11 stations in the Bohai Sea using a 330 μm trawling net in August 2016. The abundance, composition, size, shape and color of collected debris samples were analyzed after pretreatment. The average microplastic concentration was 0.33 ± 0.34 particles/m3. Micro-Fourier transform infrared spectroscopy analysis showed that the main types of microplastics were polyethylene, polypropylene, and polystyrene. As the size of the plastics decreased, the percentage of polypropylene increased, whereas the percentages of polyethylene and polystyrene decreased. Plastic fragments, lines, and films accounted for most of the collected samples. Accumulation at some stations could be associated with transport and retention mechanisms that are linked to wind and the dynamics of the rim current, as well as different sources of the plastics.

Zhang W ，Zhang S ，Wang J ，Wang Y ，Mu J ，Wang P ，Lin X ，Ma D ... -  《-》