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The microbial community colonized on microplastics (MPs), known as the 'plastisphere', has attracted extensive concern owing to its environmental implications. Coastal salt marshes, which are crucial ecological assets, are considered sinks for MPs. Despite their strong spatial heterogeneity, there is limited information on plastisphere across diverse environments in coastal salt marshes. Herein, a 1-year field experiment was conducted at three sites in the Yancheng salt marsh in China. This included two sites in the intertidal zone, bare flat (BF) and Spartina alterniflora vegetation area (SA), and one site in the supratidal zone, Phragmites australis vegetation area (PA). Petroleum-based MPs (polyethylene and expanded polystyrene) and bio-based MPs (polylactic acid and polybutylene succinate) were employed. The results revealed significant differences in bacterial community composition between the plastisphere and sediment at all three sites examined, and the species enriched in the plastisphere exhibited location-specific characteristics. Overall, the largest difference was observed at the SA site, whereas the smallest difference was observed at the BF site. Furthermore, the MP polymer types influenced the composition of the bacterial communities in the plastisphere, also exhibiting location-specific characteristics, with the most pronounced impact observed at the PA site and the least at the BF site. The polybutylene succinate plastisphere bacterial communities at the SA and PA sites were quite different from the plastispheres from the other three MP polymer types. Co-occurrence network analyses suggested that the bacterial community network in the BF plastisphere exhibited the highest complexity, whereas the network in the SA plastisphere showed relatively sparse interactions. Null model analyses underscored the predominant role of deterministic processes in shaping the assembly of plastisphere bacterial communities across all three sites, with a more pronounced influence observed in the intertidal zone than in the supratidal zone. This study enriches our understanding of the plastisphere in coastal salt marshes. [Display omitted] • Plastisphere bacterial community in salt marshes differs from that in sediment. • Differences in bacterial communities vary by geographic location. • MP polymer types affect the composition of plastisphere bacterial communities. • Plastisphere network characteristics exhibit variability with environmental change. • Deterministic processes primarily shape plastisphere bacterial communities. [ABSTRACT FROM AUTHOR]

Pollution status and ecological risks associated with sediment heavy metals (Cu, Pb, Zn, Cd, and Cr) were investigated around Xincun Bay, assessing their spatial variations and relationship with sediment physiochemical factors. Higher concentrations and associated risks were observed in the central region, where mariculture activities were concentrated, compared to non-maricultured areas. Despite with overall low concentrations, Cd had a higher ecological risk. Correlation and principal component analyses revealed similar sources for all metals in Xincun Bay. Heavy metal concentrations varied with expansion of mariculture operations in terms of quantity and scale, confirming the influence of mariculture activities. Sediments around mariculture had higher contents of clay, silt, and total organic carbon (TOC), and finer particle sizes. Quantitative analyses through correlation and linear regression indicated that TOC significantly regulated heavy metal concentration and distribution (p < 0.05). Considering its significant association with TOC, the influence of mean grain size should not be overlooked. [Display omitted] • Increased heavy metal pollution is observed near the mariculture area. • At lowest heavy metal contents, cadmium has the highest contamination risk. • TOC may control abundance and distribution of sediment heavy metal pollution. • Heavy metals of lagoon sediments have similar sources. • Mariculture is the primary source of heavy metal pollution in Xincun Bay. [ABSTRACT FROM AUTHOR]

Abstract To assess the impact of offshore wind farms (OWFs) on the structure and energy flow of coastal ecosystems, Ecopath models of the Jiangsu coastal ecosystem (JCE) based on biological field data collected before and after the establishment of the Rudong OWFs in 2007 and 2015, respectively, were constructed and compared. The results indicated that after OWF construction, detritus, phytoplankton, zooplankton, anchovies, and some benthic fish were positively impacted. The increased primary production and detritus resulted in the increased food supply for zooplankton, which made it possible for planktivorous species (particularly anchovies) to be fed. Consequently, the biomass and production of some benthic fish increased, which indicates a potential reef effect. Other groups with decreased biomasses and productions may have been negatively impacted by the OWFs. Herbivory flows dominated the pre- and post-construction JCE despite their low transfer efficiencies; however, the proportion of detritivory flow increased after OWF construction, and this was especially prominent at high trophic levels. The post-construction JCE was immature with lower system connectivity, trophic flow utilisation, and transfer efficiency. However, the ecosystem tended to develop towards higher maturity with higher energy throughput, ecosystem activity, and recycling capability. Highlights • Positively impacted functional groups: detritus, phytoplankton, zooplankton, anchovies, and other benthic fish. • Proportion of detritivory flow increased and this was especially prominent at high trophic levels. • Immature: lower system connectivity, trophic flow utilisation, and transfer efficiency. • Developing towards maturity: higher energy throughput, ecosystem activity, and recycling capability. [ABSTRACT FROM AUTHOR]

Abstract At present, the study of microplastic sources is in a relatively preliminary stage due to the complexity of microplastic features in the environment. Based on a literature review, we developed a source-specific classification system for the quantitative analysis of microplastic sources. The classification system includes ten types of microplastics based on morphology and composition and can identify their main sources and the associated probabilities. To reflect the complexity of types and sources in the regional combination of microplastics, we first propose a microplastic diversity index (D 1-D '(MP)). We use the South China Sea as an example to carry out quantitative source analysis and calculate the diversity index. Eight types of microplastics were found, mainly consisting of maritime coatings (type "Gran_coat") (33.0%) and synthetic fibers (type "Fib_thin") (29.6%). We also found that the diversity increased with offshore distance. In addition, we partitioned surface microplastics globally according to a two-dimensional microplastic abundance-diversity index. We believe that these indicators can effectively reflect pollution status and ultimately lead to different types of control measures. In the future, additional indicators for the characterization of microplastics must be included in the classification system to establish a one-to-one source analysis system for microplastic characteristics and source apportionment. In general, our study may provide new insights into the establishment of more accurate and quantitative source apportionment techniques and effective pollution control. Graphical abstract Image 1 Highlights • We proposed a classification system for the source apportionment of microplastics. • The classification includes ten types of microplastics based on morphology and polymer type. • To reflect the complexity of types and sources, we first propose a microplastic diversity index. • We selected floating microplastics in the South China Sea as an example. [ABSTRACT FROM AUTHOR]

Abstract Little data are available on the bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in coral reef fish from the South China Sea (SCS). In this study, we collected 21 coral reef fish species from the Xisha and Nansha Islands in the SCS to investigate the occurrence of 16 US-EPA PAHs. The total PAH concentrations (ΣPAH) in the collected fish ranged from 12.79 to 409.28 ng/g dry weight (dw, Xisha Islands) and from 32.71 to 139.09 ng/g dw (Nansha Islands), respectively. The ΣPAH concentration of Scarus niger collected from the Xisha Islands (237.13 ng/g dw) was about twofold higher than that of Scarus niger collected from the Nansha Islands (139.09 ng/g dw). The dominant compounds were found to be 2-ring and 3-ring PAHs. Based on qualitative and quantitative analyses, the main PAH sources were found to be coal and biomass combustion (50.43%), petroleum sources (25.86%), and vehicular emissions (16.10%). Highlights • The first report on PAH contamination in coral reef fish from the South China Sea • PAH levels from the Xisha Islands were higher than those from the Nansha Islands • Low molecular weight PAHs were dominant in coral reef fish • PAHs mainly originated from biomass combustion, petroleum sources, and vehicular emissions [ABSTRACT FROM AUTHOR]

The ecological impact of thermal discharge has become an important issue in the field of marine and environmental protection. We focused on the effects of thermal discharge on seawater temperature and biological communities based on data from before (2006) and after (2013–2014) the construction of a power plant. The thermal discharge induced stratification, which resulted in changes in the vertical hydrodynamic conditions. Stratification combined with elevated temperatures significantly affected the phytoplankton abundance and community structure. Elevated seawater temperatures decreased the chlorophyll- a concentrations by 34% and 63%, at the surface and bottom, respectively. The elevated seawater temperature at the bottom might not be high enough to significantly affect the macrobenthos, but significantly affected the phytoplankton and zooplankton communities. Because these communities serve as food for the macrobenthic community, their changes resulted in growth of the macrobenthos. Furthermore, this effect induced macrobenthic community succession, resulting in decreased species diversity and increased dominance. [ABSTRACT FROM AUTHOR]

Despite the rapid construction of offshore wind farms, the available information regarding the risks of this type of development in terms of emerging pollutants, particularly microplastics, is scarce. In this study, we quantified the level of microplastic pollution at an offshore wind farm in the Yellow Sea, China, in 2016. The abundance of microplastics was 0.330 ± 0.278 items/m 3 in the surface water and 2.58 ± 1.14 items/g (dry) in the sediment. To the best of our knowledge, the level of microplastic pollution in our study area was slightly higher than that in coastal areas around the world. The microplastics detected in the surface waters and sediments were mainly fibrous (75.3% and 68.7%, respectively) and consisted of some granules and films. The microplastics in the samples might originate from garments or ropes via wastewater discharge. The abundance of plastic in the water and sediment samples collected from the wind farm area was lower than that in the samples collected from outside the wind farm area. The anthropogenic hydrodynamic effect was the main factor affecting the local distribution of microplastics. The presence of a wind farm could increase the bed shear stress during ebb tide, disturbing the bed sediment, facilitating its initiation and transport, and ultimately increasing the ease of washing away the microplastics adhered to the sediment. This study will serve as a reference for further studies of the distribution and migration of microplastics in coastal zones subjected to similar marine utilization. [ABSTRACT FROM AUTHOR]

Intensive anthropogenic activities have a serious negative effect on the Jiangsu coastal area of China, especially on the distinctive intertidal zone. Humans are trying to eliminate this effect by taking protection and eco-compensation measures. However, when trying to determine the ecological status and quantify the anthropogenic impact for this area, the complex relationship between ecosystems and environmental stress leads to difficulties in reflecting general environmental quality. This study assessed the benthic ecological status of 10 transects (three stations/transect) across six different typologies over six years (2007, 2009–2013) in the Jiangsu intertidal zone. A unitary assessment of each transect was conducted using the multivariate AZTI Marine Biotic Index (M-AMBI), along with a radar chart (and its parameters). In the Jiangsu intertidal zone, the ecological status was noted as good or moderate at most sampling stations. Among the six assessed years, 2010 had the highest ecological status, while 2007 had the lowest. As for transects, transect 1 had the highest ratings, and transect 3 had the lowest ratings. Various stresses and advantageous human intervention and contributed to the ecological status for the different areas. The M-AMBI could be used in the future as a suitable index to assess the benthic ecological status of the Jiangsu intertidal zone. In addition, the new unitary method validated in this study could be used to assess ecosystems with several small biotopes, while accurately reflecting environmental quality. [ABSTRACT FROM AUTHOR]

To assess the environmental risks of polycyclic aromatic hydrocarbons (PAHs), 48 and 45 sediments were collected from the Yangtze River Estuary (YRE) and Pearl River Estuary (PRE), respectively. The toxicity equivalency concentration (TEQ) in the YRE and PRE were ranged from 1.68 to 76.13 and 9.28 to 129.24 ng TEQ g − 1 , respectively. Results of risk quotient suggest that ecological risks of two estuaries are at a moderate level, but are higher in the PRE than YRE. The increment lifetime cancer risks (ILCR) from the YRE via ingestion and dermal contact were 1 × 10 − 6 to 5.6 × 10 − 5 and 4 × 10 − 6 to 1.6 × 10 − 4 , and ranged from 7 × 10 − 6 to 9.4 × 10 − 5 and 2 × 10 − 5 to 2.8 × 10 − 4 in the PRE. ILCR results suggest that some low and moderate cancer risk exists in the YRE and PRE. Therefore, monitoring and control measures should be carried out immediately to reduce or eliminate the risks to human health from environmental exposure. [ABSTRACT FROM AUTHOR]

Marine microplastic pollution has become a major global concern in recent years and the fate of microplastics in the ocean is a hot issue of research. We investigated microplastic pollution in surface sediments in the northern South China Sea to explore its distribution characteristics and influencing factors across the continental shelf, continental slope, and deep-sea environments. It was found that the microplastic abundance of surface sediments was 130.56 ± 40.48 items/kg. The average abundance of microplastics in all three topographic areas gradually decreased with increasing distance offshore. However, the differences in microplastic diversity indices between the three areas were not significant and were higher than those in other seas of the world, indicating that the waters of the northern South China Sea are rich in microplastics from complex sources, with more pollution input channels. In the continental shelf, fibrous and low density microplastics accounted for the largest amount, with a low degree of microplastic aging, and were mostly transported by suspended-load. These microplastics were mainly influenced by human activities. In the deep sea, microplastics with higher density were the most abundant and the number of fibrous microplastics was fewer, while the average size was larger, mainly influenced by the bottom currents. These microplastics underwent long-term bedload transport. In the continental slope, the main factors affecting the distribution of microplastics were more complex. In addition to pollution by human activities, the slope also receives microplastic materials carried by bottom currents; therefore, the composition of microplastics in the slope combines those characteristics of microplastics in both the continental shelf and deep-sea areas. The findings of this study indicate that the South China Sea is affected by complex pollution sources under the dual effects of human activities and natural conditions; in particular, the pollution situation in the deep-sea area needs extensive attention. [Display omitted] • Distribution of microplastic and characteristics from the northern SCS are reported. • MPs distribution is mainly affected by human activities and bottom currents. • Continental shelf has higher abundance than continental slope and deep-sea areas. • Deep-sea areas potentially pool large amounts of microplastics. • Prominent MDI in northern SCS reflects the diversity of pollution input channels. [ABSTRACT FROM AUTHOR]

We investigated microplastics (MPs) pollution in 349 Larimichthys polyactis specimens from the coastal area of Jiangsu Province, China. The MP abundance in L. polyactis was 1.03 ± 1.04 items/individual and 0.95 ± 0.92 items/10 g (wet weight). The MP abundance in specimens from the Haizhou Bay fishing ground was slightly higher than that in specimens from the Lvsi fishing ground. Spearman's correlation showed that MP abundance was positively correlated with body length when expressed as items/individual, but not items/10 g. The abundance in the gastrointestinal tract was slightly higher than that in the gills, but the differences were not significant for either measurement index. The MPs predominantly ingested by L. polyactis were <1 mm, fibrous, blue and had a cellophane composition. The MP pollution in L. polyactis in the coast of Jiangsu Province is at a medium to low level, as compared with other regions of China. [Display omitted] • We studied microplastics (MPs) in 349 Larimichthys polyactis specimens in Jiangsu. • MP abundance was 1.03 ± 1.04 items/individual and 0.95 ± 0.92 items/10 g. • MPs were positively correlated with body length when expressed as items/individual. • MP pollution in Jiangsu was medium to low compared with other coastal areas in China. • The impact of MP pollution on more trophic levels deserves further attention. [ABSTRACT FROM AUTHOR]

Marine fishes are consumed in large quantities by humans as nutritious food. However, the intake of fish polluted by chemicals may pose a severe threat to human health. This study measured the concentrations of 16 priority polycyclic aromatic hydrocarbons (PAHs) in the muscles of 22 species of marine fish from two coastal regions, i.e. , Tanmen and Zhuhai, identified the source of PAHs, and assessed the human health risk by dietary exposure. Total PAH (Σ 16 PAHs) levels in Tanmen and Zhuhai fish were in the range of 24.29–684.83 ng g−1 dry weight (dw) and 13.74–42.59 ng g−1 dw, averaging 161.46 ng g−1 dw and 31.21 ng g−1 dw, respectively. Compared with other regions in the world, PAH concentrations in Tanmen fish were at median levels, and Zhuhai fish were at low levels. Low molecular weight PAHs (with 2- and 3-rings) were the predominant compounds detected. Molecular diagnostic ratios suggested that PAHs in Tanmen mainly originated from petrogenic sources such as vessel operations or tanker accidents, while Zhuhai fish were mainly polluted by pyrolytic sources such as combustion of coal and wood. The human health risk assessment results indicated that the risk of PAH intake via fish consumption from Zhuhai was negligible, while five species from Tanmen may pose potential health risks to local residents. • PAHs were detected in fish from two coastal regions. • Five species from Tanmen may pose potential health risks to local residents. • The risk of PAH intake via fish consumption from Zhuhai was negligible. [ABSTRACT FROM AUTHOR]

We investigated the pollution characteristics, the spatial distributions of microplastics, and the source compositions in the Jiangsu Coastal Area, China. The average abundance of microplastics in the surface water and sediment were 0.0998 ± 0.0720 items/m3 (using a trawl with 333-μm mesh)and 0.1858 ± 0.0927items/g, respectively. The concentration of microplastics showed a distribution trend of high near shore and low far shore in the east-west direction, and were the highest in the southernmost part. According to microplastics found in the surface water, the results of a quantitative source apportionment indicate that the most common source in the northernmost and southernmost regions were clothing fibers, accounting for 38.40% and 40.44% of the total source, respectively. While the major source type in the middle region was the decomposition of hard, large plastic waste. Finally, we suggested some control measures for the main types of microplastics observed in the different regions. [Display omitted] • The microplastic concentrations were the highest in the southernmost part of the study area. • The most common source in the northernmost and southernmost regions were clothing fibers. • The major source type in the middle region was the decomposition of hard, large plastic waste. • The major sources varying with region were clothing fiber and hard, large plastic waste. • We suggested some policies for the main types of microplastics observed. [ABSTRACT FROM AUTHOR]

The operation of coastal nuclear power plants and thermal power plants (CNATPPs) can cause regional sea surface temperature (SST) increases. To assess their effects on coastal ecosystems, the scope and extent of their impacts must be understood. We aimed to quantitatively assess the SST increases caused by thermal discharge under climate warming by comparing SSTs between control and test groups and among different offshore buffer zones based on daily MODIS SST data from 2002 to 2017. The results showed that (1) a good correlation occurred between the CNATPP installed capacity and SST increase in the 0–2 km offshore waters; (2) the SST increase caused by thermal discharge was the largest in summer and the smallest in winter; and (3) the effect of thermal discharge occurred within 2 km offshore when the installed capacity exceeded 2000 MW and extended to 5 km when it reaches more than 4000 MW. • Installed capacity of coastal plant is correlated with SST increment in 2 km offshore. • For an installed capacity below 2000 MW, the affected area is less than 2 km offshore. • For an installed capacity over 4000 MW, the affected area extends to 5 km offshore. • The SST increase caused was the largest in summer and the smallest in winter. • Thermal discharge can amplify the global warming effect in local sea area affected. [ABSTRACT FROM AUTHOR]

Surface seawater and lower atmosphere gas samples were collected simultaneously between 18°N and 40°S in the open Pacific Ocean in 2006–2007. Samples were analyzed for organochlorine pesticides (OCPs) to assess their distribution patterns, the role of ocean in the long-range transport (LRT), and the air-water exchange directions in the open Pacific Ocean. Such open ocean studies can yield useful information such as establishing temporal and spatial trends and assessing primary vs secondary emissions of legacy OCPs. Target compounds included hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and its derivatives, and chlordane compounds. Concentrations for α-HCH, γ-HCH, trans-chlordane (TC), and cis-chlordane (CC) were higher in the Northern Hemisphere (NH) than the Southern Hemisphere (SH) in both gaseous and dissolved phases, while the distribution patterns of DDTs and heptachlor exo -epoxide (HEPX) showed a reversed pattern. In the N Pacific, concentrations of α-HCH and γ-HCH in the present work were lower by 63 and 16 times than those observed in 1989–1990. The distribution patterns of DDT suggested there was usage in the SH around 2006. Calculated fugacity ratios suggested that γ-HCH was volatilizing from surface water to the atmosphere, and the air-water exchange fluxes were 0.3–11.1 ng m−2 day−1. This is the first field study that reported the open Pacific Ocean has become the secondary source for γ-HCH and implied that ocean could affect LRT of OCPs by supplying these compounds via air-sea exchange. • Study organochlorine pesticides cycling through N and S Pacific gyres. • α-HCH in the N Pacific decreased 63 times compared to 1989-1990. • Most pesticides had higher levels in the N than S Pacific. • Higher DDT levels in the S Pacific suggests recent usage in Southern Hemisphere. • First field study to report γ-HCH was volatilizing from open ocean to atmosphere. Most organochlorine pesticides levels were higher in N Pacific and S Pacific and declined compared to three decades ago, γ-HCH was found to volatilize from surface water to the atmosphere. [ABSTRACT FROM AUTHOR]

Sediment and marine organism samples collected from Haizhou Bay and Lusi fishing ground in South Yellow Sea, China were analysed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 PAHs in marine organisms ranged from 127.43 to 350.53 ng/g dry weight (dw, Haizhou Bay fishing ground) and from 86.37 to 213.02 ng/g dw (Lusi fishing ground). The dominant compounds were 2- and 3-ring PAHs in marine organism tissues. The main PAH sources were found to be coal combustion. Specific habitat, feeding habit, trophic level and environmental differences may affect the PAH levels in marine organisms in our study area. The biota–sediment accumulation factor (BSAF) decreased with increasing PAH log K ow and BSAF values might differ in response to various environmental conditions and species. The excess cancer risk from PAH-contaminated seafood consumption was slightly higher than the guideline value (10−6), but much lower than the priority risk level (10−4). • PAHs were determined in marine organisms from Haizhou Bay and Lusi fishing ground. • The main PAH sources were found to be coal combustion. • PAH-contaminated seafood consumption pose little threat to human health. • BSAFs were significantly negatively correlated with log K ow values. • BSAFs of organisms differed widely among species and regions. [ABSTRACT FROM AUTHOR]

This study investigated the distribution and characteristics of microplastics in surface sediments of the Gulf of Thailand (GoT), and discussed the correlation between sediment grain size and microplastic content. The results indicate the abundance of microplastics is 150.4 ± 86.2 pieces/kg dry weight, representing a medium microplastic pollution level compared to other sea areas. Small microplastics (0.5–1 mm) take up >70% of total microplastic numbers. Fibrous microplastics are the dominant component of microplastics. According to micro-Fourier transform infrared spectroscopy, rayon (37%) and polyester (PES: 16%) are the most typical polymer types found in sediments. The results imply that secondary microplastics are the dominant pollutant, while fibrous microplastics are mainly from municipal sewage discharge. We also find that inconspicuous correlation between grain size and microplastics, which is caused by the multi-sources and different flow field. This study deepens our understanding of the environmental risks posed by microplastics to marine ecosystems in the GoT. • Gulf of Thailand has medium plastic pollution level compared to surrounding areas. • Small microplastics (0.5–1 mm) dominate the microplastic share. • Fibrous microplastics are the dominant component in sediments. • Rayon and polyester are most common polymers found in sediments. [ABSTRACT FROM AUTHOR]