Microplastics In Surface Seawater Research Articles

Occurrence and Risk Assessment of Microplastics in the Coastal Seawater of Guangdong Province

Microplastics （MPs） are ubiquitous in the marine environment and have become an emerging pollutant that is attracting great attention. To reveal the pollution characteristics of MPs in surface seawater of coastal waters in Guangdong Province, nine bays （estuaries） were selected from Jiangmen to Shantou. The distribution and compositional characteristics of MPs were investigated through field sampling, oxidation digestion, and visual and compositional identification, and their potential sources were analyzed. The ecological risks were assessed by combining the pollution load index and the polymer risk index. The results showed that MPs were detected in all 30 surface seawater samples from the coastal waters of Guangdong Province, with an abundance range of 70-920 n·m-3 and an average abundance of （295.3 ±175.3） n·m-3. The highest MPs abundance was found in the Pearl River estuary, and the lowest abundance was found in Shenquan bay. The distribution patterns were mainly influenced by human activities and ocean currents. The dominant polymer types included polypropylene （31.2%）, phenol resin （16.0%）, polyethylene terephthalate （15.3%）, and polyethylene （10.9%）. The main shape, color, and size categories of MPs were fiber （57.5%）, transparent （72.0%）, and 0.5-1 mm （32.8%）, respectively. The possible sources of MPs mainly included aquaculture, fishing, navigation, tourism, municipal sewage discharge, and ocean current transportation. The model assessment results showed that the pollution load risk of MPs was relatively low, but the polymer risk was at a medium-high level. This study provides a data basis for the action plan of plastic pollution control in Guangdong Province and supports the prevention and control of marine MPs pollution.

Assessment of mariculture-derived microplastic pollution in Dapeng Cove, China

Marine microplastic pollution just as ocean acidification and greenhouse effect has attracted much environmental concern and become a hot research subject for marine researchers globally. The abundances, distribution, and characteristics of microplastics in surface seawater and sediments from Dapeng Cove were investigated in this study. The results indicated that the abundance of microplastics was 1333 ± 773 items/m3 in surface seawater and 1381 ± 1021 items/kg in sediments, showing a medium microplastic pollution level compared with other sea areas. Fibers were the prevailing shapes of microplastics in both surface seawater and sediments, representing 65.4% and 52.1% of the total microplastic numbers, respectively. Moreover, small microplastics (<1mm) in surface seawater and sediments accounted for 69.6% and 62.2%, respectively. According to the identification by Fourier Transform Infrared microscope (micro-FTIR), the main composition of microplastics in surface seawater and sediments was polyethylene (PE) or polypropylene (PP). It is necessary to enhance the regulation of current plastic products used in aquaculture, reduce the production and release of microplastics during the mariculture process, and develop alternatives to plastic fishing gear. The results of this study suggested that long-term mariculture development had caused the accumulation of a large amount of microplastics in water and sediments in Dapeng Cove. We constructed the first basic data of microplastics pollution about Dapeng Cove. This study will serve as a reference for further studies of the distribution and migration of microplastics in mariculture zones.

Distribution Characteristics of Microplastics in Surface Seawater off the Yangtze River Estuary Section and Analysis of Ecological Risk Assessment.

Microplastics are widespread in the oceans as a new type of pollutant. Due to the special geographical environment characteristics, the Yangtze River estuary region become hotspot for microplastics research. In 2017 and 2019, surface seawater microplastics samples were collected from five stations off the Yangtze River estuary during four seasons (spring, summer, autumn, and winter). The abundance and characteristics of microplastics in seawater were researched. The results showed that microplastics widely existed in surface seawater; the average abundance of microplastics in seawater was (0.17 ± 0.14) items/m3 (0.00561 ± 0.00462) mg/m3; and accounting for 80% of the total plastic debris, the abundance of microplastics was at moderately low levels compared to national and international studies. The particle size of most microplastics was between 1 mm to 2 mm, accounting for 36.1% of the total microplastics. The main shapes of microplastics were fiber, flake, and line, accounting for 39.5%, 28.4%, and 20.8%, respectively. Polypropylene, polyethylene terephthalate, and polyethylene were the main components of microplastics, accounting for 41.0%, 25.1%, and 24.9%, respectively. Yellow, green, black, and transparent were the most common colors, accounting for 21.9%, 19.6%, 16.5%, and 15.7%, respectively. This study shows that the spatial distribution of microplastics in the surface waters off the Yangtze River estuary shows a decreasing trend from nearshore to farshore due to the influence of land-based inputs, hydrodynamics, and human activities; the distribution of microplastics has obvious seasonal changes, and the level of microplastic pollution is higher in summer. The potential ecological risk of microplastics in the surface waters off the Yangtze River estuary is relatively small.

Microplastic pollution and ecological risk assessment of Yueqing Bay affected by intensive human activities

Microplastics (MPs) are a widespread environmental problem posing ecological risks in the ocean. We investigated the abundance, spatial distribution, characteristics and ecological risks of MPs in surface seawater, sediments and organisms in Yueqing Bay, China. MPs were detected in both environmental media and organisms. The overall abundance (0.24 items/m3 seawater, 6.13 items/kg dry sediment, 0.77 items/individual in organisms) was low to medium compared with other coastal areas. The MPs were mainly derived from the high-intensity mariculture and shipping in the bay, as well as industrial and human activities along the surrounding coast. The abundance of MPs in water of the left (western) bay (0.39 items/m3) was considerably higher than that of the right (north-eastern) bay (0.07 items/m3) due to the different levels of population and economic development on the left and right coasts. The ecological risk assessment showed generally low to medium risk from MPs pollution in Yueqing Bay, with higher ecological risk index (H) and potential ecological hazards (RI) of MPs polymers in water samples. These data emphasize the need for timely and effective action to reduce the contribution of intensive human activities to MPs pollution and provide information for further ecotoxicological studies, pollution control, and policy development of MPs.

Impacts of extreme weather events on microplastic distribution in coastal environments

Microplastic pollution is a pressing environmental threat to the ecosystem, which can be influenced by varying weather factors. With arising weather extremes in recent years, it is crucial to assess the weather effects on coastal microplastic pollution. In this study, we conducted a year-long baseline survey on beach sediment and surface seawater in Hong Kong, and additional surveys after rainstorm and typhoon events. Our data reveals that microplastic abundance was 5 times higher in wet season over dry season. Yet, the seasonal variation was insignificant when considering only the baseline condition, suggesting the role of extreme weather as the main driver of the seasonal variation in microplastic distribution. Typhoons and rainstorms induced 5.1 to 36.4 times and 1.9 to 11.7 times more microplastics in beach sediment, respectively, and 3.5 to 6.0 times and 2.5 to 4.3 times more microplastics in surface seawater, respectively. The larger microplastic mass in beach sediment and the increased proportion of hard fragments under extreme weather conditions indicate the larger mobility of heavier plastic debris from a wider source. We identified positive correlations between plastic levels and multiple weather factors (including rainfall, wind and tide), suggesting the potential terrestrial inputs of microplastics via surface runoff and wind transport, and the potential redistribution of microplastics from deep to surface sediment via wave agitation. We also identified a strongly positive correlation between macro- and microplastic abundance in beach sediment, suggesting the potential plastic fragmentation under strong wave abrasion, which may intensify the coastal microplastic pollution. This study sheds light on the need for reinforced security of waste management systems to avoid terrestrial plastic inputs under extreme weather forces, as well as the timing of coastal cleanup work in terms of limiting plastic fragmentation and achieving better cleanup efficiency.

A microfluidic approach for label-free identification of small-sized microplastics in seawater

Marine microplastics are emerging as a growing environmental concern due to their potential harm to marine biota. The substantial variations in their physical and chemical properties pose a significant challenge when it comes to sampling and characterizing small-sized microplastics. In this study, we introduce a novel microfluidic approach that simplifies the trapping and identification process of microplastics in surface seawater, eliminating the need for labeling. We examine various models, including support vector machine, random forest, convolutional neural network (CNN), and residual neural network (ResNet34), to assess their performance in identifying 11 common plastics. Our findings reveal that the CNN method outperforms the other models, achieving an impressive accuracy of 93% and a mean area under the curve of 98 ± 0.02%. Furthermore, we demonstrate that miniaturized devices can effectively trap and identify microplastics smaller than 50 µm. Overall, this proposed approach facilitates efficient sampling and identification of small-sized microplastics, potentially contributing to crucial long-term monitoring and treatment efforts.

Prediction of microplastic abundance in surface water of the ocean and influencing factors based on ensemble learning

Microplastics are regarded as emergent contaminants posing a serious threat to the marine ecosystem. It is time-consuming and labor-intensive to determine the number of microplastics in different seas using traditional sampling and detection methods. Machine learning can provide a promising tool for prediction, but there is a lack of research on this. To screen high-performance models for the prediction of microplastic abundance in the marine surface water and explore the influencing factors, three ensemble learning models, random forest (RF), gradient boosted decision tree (GBDT), and extreme gradient boosting (XGBoost), were developed and compared. A total of 1169 samples were collected, and multi-classification prediction models were constructed with 16 features of the data as inputs and six classes of microplastic abundance intervals as outputs. Our results show that the XGBoost model has the best performance of prediction, with a total accuracy rate of 0.719 and an ROC AUC (Receiver Operating Characteristic curve, Area Under Curve) value of 0.914. Seawater phosphate (PHOS) and seawater temperature (TEMP) have negative effects on the abundance of microplastics in surface seawater, while the distance between the sampling point and the coast (DIS), wind stress (WS), human development index (HDI), and sampling latitude (LAT) have positive effects. This work not only predicts the abundance of microplastics in different seas but also offers a framework for the use of machine learning in the study of marine microplastics.

Spatial Patterns of Microplastics in Surface Seawater, Sediment, and Sand Along Qingdao Coastal Environment

Coastal environments, ecologically fragile zones, are subjected to great human pressures, particularly, xenobiotic pollutants such as microplastics (MPs) and trace metals. Yet, the impact of anthropogenic intervention on the spatial patterns of MPs in different coastal environmental compartments of Qingdao, a city located in the west Yellow Sea, is still unclear. Therefore, the spatial distribution, characteristics, and diversity of MPs (≥ 50 µm) in seawater, sediment, and sand samples collected from 10 zones intervened by different anthropogenic activities in Qingdao coastal environment were investigated. The abundance of MPs was 93.1 ± 63.5 items/m3 in seawater, which was 4577 ± 2902 items/kg in sediments and 3602 ± 1708 items/kg in the beach sands. A spatial analysis indicated that the distribution characteristics of MPs, including abundance, color, and type, greatly varied among the zones with different extent of human activities. The highest abundance of MPs in the seawater was detected in the abandoned aquafarm, followed by harbors, beaches, estuary, sewage discharge areas, operational aquafarm, and rural areas, whereas the highest MP abundance in the sediments followed the order of harbor, sewage discharge, estuary, abandoned aquafarm, beaches, rural area, and operational aquafarm. The highest MP abundance in the scenic and recreational beach sands was, respectively, in the intertidal and supratidal zone. The transparent chlorinated polyethylene fragments with the relatively small size of 50–100 μm were the dominant MPs in the coastal environment. The higher physicochemical characteristic diversity in terms of size, color, shape, and type of MPs in the aquafarms, harbors, and recreational beach than those of the other zones, illustrated the higher complexity and diversity of MP pollution sources in these zones. These results jointly indicated that aquaculture, navigation, and tourism mainly determined MP spatial distribution patterns in the coastal environment of Qingdao. These results also extend the understanding of the inventory and fate of MPs in coastal environment, thus providing important data to establish effective strategies for abating MP pollution in marine ecosystems.

Spatial Distribution and Composition of Surface Microplastics in the Southwestern South China Sea

Plastic pollution is one of the growing environmental problems in the world currently. The situation of microplastics (MPs) in the South China Sea (SCS) is not yet fully understood. This study investigated the spatial distribution, morphological characterization, and chemical composition of MPs in surface seawater in the southwestern SCS, based on cruise data in 2018. Our analysis shows that the average abundance of surface MPs in seawater was 0.072 ± 0.053 particles/m3 and 88.4% of MPs were <2 mm. 97.3% of MPs were fibers and fragments. Polyethylene terephthalate (PET), polyvinyl chloride (PVC), and cellophane were predominant polymer components of surface MPs. Higher MPs abundance (0.083 ± 0.063 particles/m3) and bigger MPs sizes were found at surface water in Nansha Islands than in Xisha Islands (0.032 ± 0.01 particles/m3). In addition, more polymer types of MPs were found in Nansha Islands, while more MPs films were found in Xisha Islands. PET and cellophane dominated in Nansha Islands, while PVC dominated in Xisha Islands with no cellophane detected. The surface MPs were low in abundance and diverse in polymers in the southwestern SCS with apparent differences between islands and between onshore and offshore, owing to plastics wastes from vessel traffics and some inhabited islands.

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.

Composition and distribution of microplastics in the surface seawater of Xisha Islands

<p indent="0mm">Marine microplastics are emerging pollutants in the ocean and have become a major global environmental issue in recent decades. However, microplastic pollution has not been frequently studied in the oligotrophic oceanic regions around the Xisha Islands, the largest marine coral reef area of China. In this study, microplastics in surface seawater were sampled from 30 stations in the region around the Xisha Islands. Marine microplastics were classified via a microscopic method using an Olympus stereo microscope. Microplastic photographs were taken by an inner imaging system, and the size of the microplastics was estimated using Image J software. Additionally, a portion of the microplastic samples was randomly selected for component analysis based on the shape, color, and size of the particles. Our results indicate that microplastics are widely distributed in the surface seawater of the Xisha region. The abundance of microplastics was in the range of 10–130 pieces/m³, with an average value of 54.7 pieces/m³. The size range of microplastics was <sc>0.02−5 mm</sc> with the length of <sc>0.02−1 mm</sc> accounting for 32.1% and the length of <sc>1−3 mm</sc> accounting for 64.8% of the total abundance. The microplastics from the Xisha region can be classified into five color types, namely transparent, blue, black, green, and red, with the average percentages being 56.8%, 40.2%, 1.2%, 1.2%, and 0.6%, respectively. Moreover, the local microplastics can be divided into fiber and film according to their morphology with fiber accounting for more than 99% of the total abundance. Polyethylene terephthalate (PET) and polypropylene (PP) were the two major chemical components of the microplastics, accounting for 56.2% and 20.3% of the chemical components, respectively. The average concentration of microplastics in Xisha region is relatively lower than that in many other regions of the South China Sea, as well as that in other regions of the global oceans. Our results suggest that the spatial distribution of microplastics is influenced by water movement, anthropogenic activities, and topographic features in the Xisha region. Although there is a large spatial variation in the surface seawater in the Xisha region, the concentration of microplastics in the near-shore stations is typically high, which may indicate that the microplastics in these areas originate from terrestrial sources. On the other hand, a reduced wave energy due to the topographic structure of shallow coral reefs allows more microplastics to settle and accumulate in the nearshore waters around the islands. Meanwhile, there were nearshore stations (S12, S19, S22) with low microplastic abundance, particularly in areas with high internal tides caused by local topography, strong mixing or upwelling induced by internal tides, and waves. These phenomena can bring subsurface waters to the surface and thus lead to the dilution of surface seawater pollutants at the nearshore stations. Analysis of microplastic morphology revealed the presence of large-diameter microplastic fibers in the surface seawater of the Xisha region, which may indicate that these microplastics are young in age. Most likely, they originated from recent fishery activities in the region, as both PET and PP are common types of plastics used in local fishery operations. Furthermore, microplastics have already been found in local soil samples and in the bodies of seabirds living on the Xisha Islands, due to an increase in island development and construction. Therefore, plastic waste discharge caused by increasing human activities may be another important source of microplastics to the surface seawater of the Xisha region.

Microplastic ingestion by zooplankton in Terengganu coastal waters, southern South China Sea.

This study investigates the presence of microplastics in surface seawater and zooplankton at five different locations off the Terengganu coast in Malaysia, southern South China Sea. A total of 983 microplastic particles, with an average abundance of 3.3 particles L-1 were found in surface seawater. An average of one plastic particle was detected in 130 individuals from 6 groups of zooplankton. These groups include fish larvae, cyclopoid, shrimps, polychaete, calanoid and chaetognath where they ingested 0.14, 0.13, 0.01, 0.007, 0.005 and 0.003 particle per individual, respectively. Microplastics in the form of fragments are the most common type of ingested microplastics that ranged between 0.02 mm (cyclopoid) - 1.68 mm (shrimp and zoea). Contrastingly, fibers, which are identified as polyamide are the main type of microplastics that dominate in seawater.

Microplastic pollution in North Yellow Sea, China: Observations on occurrence, distribution and identification

Microplastics are emerging contaminants and have attracted widespread environmental concerns about their negative effects on the marine ecosystems. In this study, we investigated the abundances, distributions and characteristics of microplastics in surface seawater and sediments from the North Yellow Sea. The results showed that the abundance of microplastics was 545 ± 282 items/m3 in surface seawater and 37.1 ± 42.7 items/kg dry weight in sediments, representing a medium microplastic pollution level compared with other sea areas. Small microplastics (<1 mm) made up >70% of the total microplastic numbers. Films and fibers were the dominant shapes of microplastics in both the surface seawater and sediments. Transparent microplastics were generally more common than microplastics of other colors. Based on the identification by a Fourier transform infrared microscope, polyethylene (PE) was the dominant composition of microplastics in surface seawater, while polypropylene (PP) was the most common polymer type in sediments. These results will improve our understanding of the environmental risks posed by microplastics to marine ecosystems.

Abundance and Distribution Characteristics of Microplastics in Surface Seawaters of the Incheon/Kyeonggi Coastal Region.

Microplastics in marine environments are of emerging concern due to their widespread distribution, their ingestion by various marine organisms, and their roles as a source and transfer vector of toxic chemicals. However, our understanding of their abundance and distribution characteristics in surface seawater (SSW) remains limited. We investigated microplastics in the surface microlayer (SML) and the SSW at 12 stations near-shore and offshore of the Korean west coast, Incheon/Kyeonggi region. Variation between stations, sampling media, and sampling methods were compared based on abundances, size distribution, and composition profiles of microsized synthetic polymer particles. The abundance of microplastics was greater in the SML (152,688 ± 92,384 particles/m(3)) than in SSW and showed a significant difference based on the sampling method for SSWs collected using a hand net (1602 ± 1274 particles/m(3)) and a zooplankton trawl net (0.19 ± 0.14 particles/m(3)). Ship paint particles (mostly alkyd resin polymer) accounted for the majority of microplastics detected in both SML and SSWs, and increased levels were observed around the voyage routes of large vessels. This indicates that polymers with marine-based origins become an important contributor to microplastics in coastal SSWs of this coastal region.