Characteristics and spatiotemporal distribution of microplastics in sediments from a typical mariculture pond area in Qingduizi Bay, North Yellow Sea, China.

Microplastics (MPs) in mariculture environments may have an impact on mariculture and ecosystems. This study sampled the sediments in mariculture ponds and offshore areas in Qingduizi Bay during winter and summer. The abundance, characteristics, spatiotemporal distribution and pollution risk of microplastics were analyzed. The results showed that the abundance of MPs in the mariculture pond and offshore area was 49.2 ± 35.9 items·kg-1 d.w. and 17.1 ± 9.9 items·kg-1 d.w.; the MPs were mainly composed of transparent fibers of thickness 2000-5000 μm, with the main polymers being polyethylene terephthalate (PET) and cellophane (CP). The spatial distribution showed a downward trend from the inside to the outside, but the difference was not significant when comparing different seasons. The pollution load index (PLI) risk assessment showed that all sampling sites were at Hazard Level I. This study can provide valuable information for the risk assessment of microplastic pollution in mariculture areas.

Chen L ，Yuan X ，Ye Y ，Teng J ，Zhao J ，Wang Q ，Zhang B ... -  《-》

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 environment and organisms of Xiangshan Bay, East China Sea: An area of intensive mariculture.

Microplastic (MP) pollution in oceans is an emerging environmental problem that poses ecological risks for marine ecosystems. Based on the abundance, distribution, and characteristics of microplastics (MPs) in surface water, sediment, and organisms, MP sources, pollution, trophic transfer, and ecological risk in Xiangshan Bay, an area of intensive mariculture in East China Sea, were assessed in this study. MPs were prevalent in the environment and organisms, with overall abundances at a low-medium level compared with the levels in the coastal areas. In water, MPs were more abundant in the inner bay (0.32 items m-3), which is a more significant source of MPs with intensive mariculture than the central (0.09 items m-3) and outer bays (0.07 items m-3). The narrow and land-enclosed inner bay, with weak hydrodynamics for water exchange, retained MPs, thus increasing their abundance. The ecological risk of MPs in water was at a low-moderate level. The MP abundance in sediment did not vary significantly among the three regions of the bay. The morphological characteristics and polymers of the MPs differed in sediment from those in water, which was related to their diverse environmental redistribution routes. MP abundance ingested by organisms were related to their biological features and foraging habits. Overall, fish ingested more MPs than crustaceans, bivalves, and cephalopods, while zooplankton ingested the minimal MPs. Filter feeders ingested less MPs, with a preference for smaller particles than predators. MPs did not show trophic transfer behavior in organisms. Additionally, MPs ingested by infauna showed similar morphological and chemical characteristics compared to sediment at the point of organism residence, whereas MPs ingested by pelagic species were dissimilar to those in surface water. Our findings provide information for understanding MP pollution, source tracing, trophic transfer, and ecological risk assessment in coastal ecosystems.

Yu X ，Huang W ，Wang Y ，Wang Y ，Cao L ，Yang Z ，Dou S ... -  《-》

Observation of microplastics in mariculture water of Longjiao Bay, southeast China: Influence by human activities.

The fishery and mariculture industry contributes to social food supply and offers high-quality protein to humans. However, mariculture is recently regarded as an important source of marine microplastic pollution, which might even pose a threat to human health. Here we investigated a shrimp-culturing farm for 9 months in Longjiao Bay, a typical mariculture area in southeast China, to study the occurrence and seasonal variations of microplastics in the mariculture water. Results showed that microplastics were widely present (250-5150 particles/m3, mean 1594 particles/m3) in the water of culture ponds. Granules (41.36%) and fibers (34.93%) were the main components of microplastics and white (45.42%) is the dominant color, followed by yellow (32.13%) and black (19.55%). Most of microplastics had a particle size between 0.30 mm and 5.00 mm (92.03%). The proportions of PE (34.40%) and PET (30.18%) accounted for more than 60% of detected microplastics. The abundance of microplastics in mariculture water had a potential positive correlation with local seafood yield and a negative correlation with land areas. This study suggested that further research is needed to figure out the impact of the high levels of microplastic abundance in mariculture environments on organisms, especially cultured ones.

Chen B ，Fan Y ，Huang W ，Rayhan ABMS ，Chen K ，Cai M ... -  《-》

Microplastic pollution in surface seawater of Sanggou Bay, China: Occurrence, source and inventory.

Microplastic pollution in marine environments has become a major global environmental issue. However, the source of microplastics in marine environments is poorly understood. Here, we investigated the distribution and the source of microplastics in surface seawater from Sanggou Bay, China. The results showed that the average abundance of microplastics was 20.06 ± 4.73 items/L, which represented a medium and high level relative to other sea areas. Microplastics of <0.5 mm dominated. Most particles were granular and transparent, and polyethylene was the dominant polymer. We estimated that 62.76% of the microplastics originated from mariculture facilities, an indication that mariculture contributes significantly to microplastics pollution, and calculated that 96.15 kg was present in surface seawater of Sanggou Bay. Our findings indicated that more attention should be paid to mariculture-derived microplastics pollution in the future.

Xia B ，Sui Q ，Sun X ，Zhu L ，Wang R ，Cai M ，Chen B ，Qu K ... -  《-》