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Coastal oceans, serving as transitional zones between land and sea, possess unique geographical features and complex hydrological conditions, functioning as regional reservoirs and crucial transport pathways for anthropogenic pollutants such as per- and polyfluoroalkyl substances (PFASs) to the open ocean. This study comprehensively investigates traditional perfluoroalkyl carboxylic and sulphonic acids (PFCAs and PFSAs) and emerging perfluoroalkyl ether carboxylic and sulfonic acids (PFECAs and PFESAs), fluorotelomer sulfonates (FTSAs) in seawater columns and surface sediments from the inner shelf of the East China Sea, by integrating hydrological and biogeochemical data. Comparable levels of traditional and emerging PFASs were observed in seawater samples, in contrast to higher concentrations of traditional PFASs in surface sediments. Waterborne PFASs exhibited a nearshore-to-offshore decreasing trend and a surface enrichment pattern in offshore waters, typically influenced by terrestrial inputs and oceanic processes. Significant terrestrial inputs for waterborne PFASs were identified, including large rivers like the Changjiang River (Yangtze) and semi-enclosed coastal bays such as Xiangshan Port and Sanmen Bay, where prolonged hydraulic retention times contribute to PFAS accumulation. The source apportionment model demonstrated that emerging fluorochemical manufacturing, textile production, and high-performance fluoropolymer materials are primary sources, consistent with PFAS releases from commercial products and industrial processes along the Changjiang River and in Xiangshan County. Hydrologically, the offshore transport barrier effect created by river plume fronts, and the vertical stratification of different water masses were significant for PFASs. Sediment inputs and resuspension also played a crucial role, with surface sediment-bottom water partitioning behavior primarily regulated by the hydrophobicity of PFASs and salting-out effects. While the overall ecological risks of PFASs were low, elevated risks associated with legacy perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and emerging hexafluoropropylene oxide dimer acid (HFPO-DA) warrant closer attention due to their accumulation in the environment. The methodologies and findings of this research provide valuable insights into PFAS cycling in coastal oceans worldwide., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Deposition in the deep ocean plays a crucial role in the global sink of persistent organic pollutants (POPs), yet observation-based assessments of their biogeochemical cycling are scarce. In this study, surface sediments were collected from deep sea of the Eastern Indian Ocean (2161-4545 m) and analyzed for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Long-range atmospheric transport was identified as the dominant pathway for OCPs (36.7-762.0 pg/g) and PCBs (25.5-110.0 pg/g) to reach the basin area from surrounding agricultural, manufacturing, and combustion emissions. Besides the TOC-dependent deposition, unique hydrodynamic conditions in the mid-ocean ridge might influence the transport and accumulation of POPs by altering their resuspension and repartitioning processes. Results of the machine learning analysis suggested that logK OW , TOC content, and pollutant residence time in the ocean are important parameters in determining PCB concentrations in the Indian Ocean. Additionally, concentrations of POPs generally exhibited logarithmic relationships with microplastic abundances, indicating that microplastics act as potential carriers for transporting these pollutants to deep-sea sediments. This study revealed the biogeochemical controls on the deposition of OCPs and PCBs in the Indian Ocean by combining field observation and model simulation. Given the rapid rate of surface warming and various biogeochemical responses in the Indian Ocean, it is recommended to conduct long-term, high-resolution field observations to understand the dynamic fate of POPs in these changing ocean environments., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

This study investigated the distribution, abundance, and mass budget of microplastics (MPs) in the Beibu Gulf, Northern South China Sea, focusing on their ecological significance and anthropogenic influence. Microplastics were found in all water and sediment samples, with concentrations in surface water ranging from 0.10 to 0.89 items/m³, and in bottom water from 0 to 0.85 items/m³. Sediment samples exhibited higher levels, ranging from 13.12 to 155.59 items/kg. The spatial distribution revealed higher concentrations along the northern Gulf and Guangxi Province, suggesting significant human influence from coastal activities, such as mariculture and industrial discharges. The study utilized both field data and a mass balance box model to estimate the MPs mass budget, revealing that oceanic flow and riverine discharge are major contributors, accounting for 49% and 52% of MPs, while Atmospheric deposition and sedimentation represents 8% and 1%, respectively. The inventory estimation calculated that 0.24 tons of MPs exist in the water column, and 137 tons in the sediment, emphasizing the substantial environmental burden posed by these pollutants. The significance of this research lies in its comprehensive assessment of MPs in a semi-enclosed gulf, providing critical insight into the role of coastal and hydrodynamic processes in MP distribution. This study highlights the urgent need for better waste management practices in coastal regions to mitigate microplastic pollution and its detrimental effects on marine ecosystems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Pharmaceuticals and personal care products (PPCPs) have received global attention owing to their potential risks to human health and the ecological environment. However, limited research has explored the occurrence and ecological risks of PPCPs in the Qiantang River (QTR). QTR, the largest water system in Zhejiang Province, China, is significantly influenced by human activities. This study investigated the occurrence, distribution, and ecological risks of 10 types of PPCPs in both surface water and sediment within QTR. The findings revealed that the concentrations of PPCPs detected in surface water ranged from 81.26 to 149.45 ng L -1 during the wet season (April) and from 98.66 to 198.55 ng L -1 during the dry season (September). Moreover, in the sediments, PPCP concentration ranged from 63.24 to 80.66 and 72.54 to 75.06 ng per g dw during both wet and dry seasons, respectively. Among the selected PPCPs, triclosan (TCS) exhibited the highest concentration across, different phases and seasons, followed by benzotriazole in surface water. The analysis of sediment-water equilibrium distribution indicated that the diffusion tendency of PPCPs was closely correlated with their molecular weights. Particularly, TCS exhibited dynamic equilibrium between water and sediment. Principal component analysis and positive matrix factorization model results indicated similar pollution sources for the detected PPCPs. The dominant sources of the detected PPCPs were identified as wastewater of electroplating enterprises, discharge from wastewater treatment plants, and domestic sewage. The ecological risk assessment based on the risk quotient method revealed that TCS with the highest detected concentration posed a high risk in surface water and a low risk in sediment across all sampling sites. However, other detected PPCPs showed either no or low risks. Additionally, PPCPs showed a higher ecological risk during the dry season than during the wet season.

Microplastics (MPs) and organophosphate flame retardants (OPFRs) have recently become ubiquitous and cumulative pollutants in the oceans. Since OPFRs are added to or adsorbed onto MPs as additives, it is necessary to study the composite contamination of OPFRs and MPs, with less focus on bio-based PLA. Therefore, this study focused on the ecotoxicity of the biodegradable MP polylactic acid (PLA) (5 μm, irregular fragments, 10 2 and 10 6 particles/L), and a representative OPFRs tris(1-chloro-2-propyl) phosphate (TCPP, 0.5 and 50 μg/L) at environmental and high concentrations. The mussel Mytilus coruscus was used as a standardised bioindicator for exposure experiments. The focus was on examining oxidative stress (catalase, CAT, superoxide dismutase, SOD, malondialdehyde, MDA), immune responses acid (phosphatase, ACP, alkaline phosphatase, AKP, lysozyme, LZM), neurotoxicity (acetylcholinesterase, AChE), energy metabolism (lactate dehydrogenase, LDH, succinate dehydrogenase, SDH, hexokinase, HK), and physiological indices (absorption efficiency, AE, excretion rate, ER, respiration rate, RR, condition index, CI) after 14 days exposure. The results of significantly increased oxidative stress and immune responses, and significantly disturbed energy metabolism and physiological activities, together with an integrated biomarker response (IBR) analysis, indicate that bio-based PLA MPs and TCPP could cause adverse effects on mussels. Meanwhile, TCPP interacted significantly with PLA, especially at environmental concentrations, resulting in more severe negative impacts on oxidative and immune stress, and neurotoxicity. The more severe adverse effects at environmental concentrations indicate higher ecological risks of PLA, TCPP and their combination in the real marine environment. Our study presents reliable data on the complex effects of bio-based MP PLA, TCPP and their combination on marine organisms and the environment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Phosphorus (P) is an essential biogenic element in ecosystems; but excessive or insufficient P in coastal waters caused by human activities has led to serious ecological issues. However, the understanding of the dynamic processes of different P forms in high turbidity estuaries/bays, as well as their impact on eutrophication and coastal algal blooms, is still relatively limited. To address this issue, we analyzed P dynamics and their impact on eutrophication in Hangzhou Bay (HZB), which is typical of eutrophic and turbid bay worldwide. The concentration of particulate P (PTP) was 3-5 times higher than that of dissolved inorganic phosphorus (DIP). Seasonal sediment resuspension led to the accumulation of suspended particulate matter (SPM) and PTP with regional variation, both maintaining DIP concentrations above 1 μmol/L within the bay. Furthermore, 3000 tons of bioavailable P were retained in the fine-grained SPM, with the potential for outward transport, fueling subsequent harmful algal blooms. A comparative analysis of global coastal waters highlighted that different turbidity levels significantly affect P cycling. Therefore, understanding the relationship between SPM and P in highly turbid waters is crucial for effective management of eutrophication., Competing Interests: Declaration of competing interest All authors declare no conflict of interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Due to continuous increase in marine plastic waste, microplastics are ubiquitous in the marine environment. However, there are few studies on the harmful effects caused by microplastics with different particle sizes, and the interaction between particle size and concentration requires further investigation. This study explored the differences in physiological and biochemical responses, photosynthesis and oxidative stress damage of the microalga Isochrysis galbana exposed to three different particle size microplastics. It was found that different particle sizes and concentrations of microplastics resulted in significant differences (p < 0.05) in the growth rate, photosynthesis, and oxidative stress level of I. galbana. With the decrease of the particle size and lowering concentration of microplastics, the growth rate, photosynthesis and oxidative stress levels of I. galbana were reduced. Significant differences in photosynthesis and oxidative stress levels were observed when I. galbana was exposed to smallest particle size and lowest concentration of microplastics. This study provides new insights about whether polystyrene microplastics of different particle sizes and concentrations exhibit complex effects on microalgae, and explores the underlying reasons for such effects. In short, this study predicts the exacerbating adverse effects of microplastic pollution on the primary productivity, with significant implications for marine food webs and ecosystem health., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Coastal estuaries are often heavily subject to riverine influences by the inputs of sediment from terrestrial sources. Hangzhou Bay (HZB) is threatened by the riverine derived trace metals from two large rivers of Qiantang River (QTR) and Yangtze River (YZR). However, previous studies mainly focused on the incidental transport from the largest river in China (YZR) and failed to simultaneously evaluate the contributions of these two rivers, especially the directly flowing river of QTR, by their trace elemental geochemical composition and distribution. Herein, a comprehensive study identified the river-derived sources of multiple trace metals in surface sediments which transported from both of the rivers. The sampling stations were separated into three regions of YZR, HZB, and QTR based on their spatial distributions of sediment grain size and components. The significant variations for most of the trace metals concentrations, except for Cd, Th, and U, were found among three regions (χ 2  ≥ 8.22, p ≤ 0.016). The highest concentrations in HZB were mainly resulted from the grain size effect (68.82% of the total variance), while the highest concentrations of Sr, Cd, and Ba in YZR and Zr and Hf in QTR were attributed to the anthropogenic source (11.90%) and mineral composition (6.21%) of river basins. After normalized the diversity of multiple trace metals concentrations and the influence of grain size by ratios of I geo and EF Li , three regions were effectively distinguished. It was indicated that As, Cd, and Sb were enriched in the sediments of rivers by anthropogenic source (EF Li  > 1.5 and/or I geo > 1). The results evidenced that, after removing the influence of grain size, elemental geochemical composition of the surface sediments confidently identified the river-derived anthropogenic sources of the enriched trace metals from two major rivers, and largely from YZR., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Rayon microfibers, micro-sized semi-synthetic polymers derived from cellulose, have been frequently detected and reported as "micropollutants" in marine environments. However, there has been limited research on their ecotoxicity and combined effects with persistent organic pollutants (POPs). To address these knowledge gaps, thick-shell mussels (Mytilus coruscus) were exposed to rayon microfibers at 1000 pieces/L, along with polychlorinated biphenyls (PCBs) at 100 and 1000 ng/L for 14 days, followed by a 7-day recovery period. We found that rayon microfibers at the environmentally relevant concentration exacerbated the irreversible effects of PCBs on the immune and digestive systems of mussels, indicating chronic and sublethal impacts. Furthermore, the results of 16 s rRNA sequencing demonstrated significant effects on the community structure, species richness, and diversity of the mussels' intestinal microbiota. The branching map analysis identified the responsive bacteria to rayon microfibers and PCBs belonging to the Proteobacteria, Actinobacteriota, and Bacteroidota phyla. Despite not being considered a conventional plastic, the extensive and increasing use of rayon fibers, their direct toxicological effects, and their interaction with POPs highlight the need for urgent attention, investigation, and regulation to address their contribution to "micropollution"., Competing Interests: Declaration of Competing Interest The authors state that they have no known competing financial interests or personal relationships that could affect the work reported in this article., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Marine nano-titanium dioxide (nano-TiO 2 ) and pentachlorophenol (PCP) pollution are escalating concerns in coastal areas. This study investigated the combined effects of continuous exposure to nano-TiO 2 (25 nm, 100 nm) and PCP (0, 1, 10 μg/L) for 28 days on the antioxidant, digestive, and immune abilities of the swimming crab Portunus trituberculatus. Compared with the control group, the interaction between nano-TiO 2 and PCP was significantly higher than exposure to a single stressor, with a pronounced decrease in amylase activity observed due to the reducing nano-TiO 2 particle sizes. Resulting in increased MDA and SOD activity. The expression levels of Toll4, CSP3, and SER genes in crab hemolymph showed perturbations following exposure to nano-TiO 2 and PCP. In summary, according to the results of CAT, GPX, PES and AMS enzyme activities, it was concluded that compared to the larger particle size (100 nm), the single stress of nano-TiO 2 at a smaller particle size (25 nm) and co-stress with PCP have more significant impacts on P. trituberculatus. However, the potential physiological regulation mechanism of the interaction between these pollutants remains elusive and requires further study., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Youji Wang reports financial support was provided by National Natural Science Foundation. Youji Wang reports financial support was provided by Shanghai Dawning Project. Youji Wang reports a relationship with National Natural Science Foundation of China that includes: funding grants. Youji Wang reports a relationship with Shanghai Dawning Project that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Micro-/nano-plastic particles (MNPs) are present in the ocean with potential detrimental impacts on marine ecosystems. Bivalves are often used as marine bioindicators and are ideal to evaluate the threat posed by various-sized MNPs. We exposed the mussel Mytilus coruscus to MNPs with different particle sizes (70 and 500 nm, 5, 10 and 100 μm) for 3, 72 h and 30 days. The antioxidant responses in digestive gland and the hemolymph were then evaluated. The time of exposure played a strong modulating role in the biological response. A 3-hour exposure had no significant impact on the digestive gland. After 72 h, an increase in oxidative stress was observed in the digestive gland, including increased hydrogen peroxide (H 2 O 2 ) level, catalase (CAT), glutathione peroxidase (GPx) activities and malondialdehyde (MDA) production. After a 30-day exposure, the oxidative stress decreased while lipid peroxidation increased. A 30-day exposure increased hemocyte mortality (HM) and reactive oxygen species (ROS) levels in the hemolymph, while phagocytosis (PA), lysosome content (LC), mitochondrial number (MN) and mitochondrial membrane potential (MMP) significantly decreased. Longer-term exposure to MNPs caused oxidative stress in the digestive gland as well as impaired viability and immunity of hemocytes. Particle size also influenced the response with smaller particles having more severe effects. A depuration for 7 days was enough to reverse the negative effects observed on the digestive gland and hemolymph. This study provides new insights on the effects of small-sized MNPs, especially nanoplastic particles (NPs), on aquatic organisms, and provides a solid theoretical knowledge background for future studies on toxic effects of MNPs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Pollution with complex mixtures of contaminants including micro- and nano-plastics (MNPs) and organic pollutants like polycyclic aromatic hydrocarbons (PAH) poses a major threat to coastal marine ecosystems. Toxic mechanisms of contaminant mixtures are not well understood in marine organisms. We studied the effects of single and combined exposures to polycyclic aromatic hydrocarbon phenanthrene (Phe) and MNPs mixture with sizes of 70 nm, 5 μm and 100 μm on the immune health and oxidative stress parameters in the thick-shell mussel Mytilus coruscus. Immune cells (hemocytes) were more sensitive to the pollutant-induced oxidative stress than the gills. In hemocytes of co-exposed mussels, elevated mortality, lower lysosomal content, high production of reactive oxygen species (ROS) and decrease mitochondrial were found. Disparate responses of antioxidant enzymes in the hemolymph (e.g. increased superoxide dismutase (SOD) activity without a corresponding increase in catalase (CAT) in Phe exposures and an increase in CAT without a change in SOD in MNPs exposures) suggests misbalance of the antioxidant defense in the pollutant-exposed mussels. Gill lacked pronounced oxidative stress response showing a decline in ROS and antioxidant levels. Tissue-specific single and combined effects of Phe and MNPs suggest variation in bioavailability and/or different sensitivity to these pollutants in the studied tissues. Notably, the combined effects of MNPs and Phe were additive or antagonistic, showing that MNPs do not enhance and occasionally mitigate the toxic effects of Phe on the hemocytes and the gills of the mussels. Overall, our study sheds light on the impact of long-term exposure to MNPs and Phe mixtures on mussels, showing high sensitivity of the immune system and modulation of the Phe toxicity by MNPs co-exposure. These findings that may have implications for understanding the impacts of combined PAH and MNPs pollution on the health of mussel populations from polluted coastal habitats., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

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/m 3 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/m 3 ) was considerably higher than that of the right (north-eastern) bay (0.07 items/m 3 ) 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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Microplastics (MPs) pollution is regarded as a global challenge for ocean. As an important food source of human, macroalgae could suffer MP pollution and transmit MPs into human via food web. However, few studies have revealed the relationship of MP pollution between macroalgae and its habitat. In order to evaluate the trapping and accumulation of MPs in macroalgae and surface water, the present study investigated MP pollution in a typical aquaculture macroalgae species, laver (Porphyra haitanensis) in the Yueqing Bay. The results indicated MP abundance in laver (1.45 ± 0.26 items/g) was at a medium level while MP abundance in surface water (0.21 ± 0.15 item/m 3 ) was at a relatively low level worldwide. Distribution trend and characteristics of MPs in laver and surface water showed highly similarity. Besides, heavy metal elements (Fe and Zr) were detected on the surface of MPs trapped by laver. Pollution load index (PLI) in surface water of the whole bay was low, indicating MP pollution was not serious in the Yueqing Bay. Due to the discharging of domestic sewage in recent years, fiber-shaped, textile MPs accounted for most in laver and surface water of the Yueqing Bay. These results indicated that MPs in surface water could be trapped by P. haitanensis, thus macroalgae cultivation might be a potential way to alleviate seawater MP pollution in the nearshore areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The production and use of organophosphate esters (OPEs) as substitutes for traditional halogenated flame retardants is increasing, resulting in greater global concern related to their ecological risks to marine environments. In this study, polychlorinated biphenyls (PCBs) and OPEs, representing traditional halogenated and emerging flame retardants, respectively, were studied in multiple environmental matrices in the Beibu Gulf, a typical semi-closed bay in the South China Sea. We investigated the differences in PCB and OPE distributions, sources, risks, and bioremediation potentials. Overall, the concentrations of emerging OPEs were much higher than those of PCBs in both seawater and sediment samples. Sediment samples from the inner bay and bay mouth areas (L sites) accumulated more PCBs, with penta- and hexa-CBs as major homologs. Chlorinated OPEs were prevalent in both seawater and sediment samples from the L sites, whereas tri-phenyl phosphate (TPHP) and tri-n-butyl phosphate (TNBP) were predominant at the outer bay (B sites) sediment samples. Source identification via principal component analysis, land use regression statistics, and δ 13 C analysis indicate that PCBs were mainly sourced from the atmospheric deposition of sugarcane and waste incineration, whereas sewage inputs, aquaculture, and shipping activity were identified as sources of OPE pollution in the Beibu Gulf. A half-year sediment anaerobic culturing experiment was performed for PCBs and OPEs, and the results only exhibited satisfactory dechlorination for PCBs. However, compared with the low ecological risks of PCBs to marine organisms, OPEs (particularly trichloroethyl phosphate (TCEP) and TPHP) exhibited low to medium threats to algae and crustaceans at most sites. Given their increasing usage, high ecological risks, and low bioremediation potential in enrichment cultures, pollution by emerging OPEs warrants close attention., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

As a class of persistent organic pollutants, polycyclic aromatic hydrocarbons (PAHs) are widely present and accumulate in multimedia environments. The pollution characteristics, spatiotemporal distribution, potential sources, influencing factors, and ecological risks of 16 PAHs were investigated in the water-sediment system of the Hangzhou Bay and outer bay area (HZB and OBA, respectively). The total concentrations of 16 PAHs (∑ PAHs ) were 220 ± 97.0 and 130 ± 36.0 ng/L in the seawater and 343 ± 179 and 505 ± 415 μg/kg (dry weight) in the sediments of the HZB and OBA, respectively. The pollution level of PAHs in the HZB seawater was higher than that in the OBA seawater, but the opposite result was found in the sediments. Moreover, ∑ PAHs exhibited high temporal variability in the HZB seawater (rainy season > dry season), whereas ∑ PAHs in the sediments showed no significant difference between seasons. The molecular diagnostic ratio method was used to identify pollution sources and showed that the PAHs in seawater came from different pollution sources (fuel combustion and petroleum), whereas the PAHs in the sediments originated from coincident sources (mixed combustion). Correlation analysis revealed that temperature was positively related to ∑ PAHs , whereas salinity was negatively related to seawater ∑ PAHs values. Ecological risk assessment demonstrated that the potential for adverse ecological effects was low to moderate in seawater but moderate to high in the sediments., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Effects of microplastics on microalgae have not been compared from different habitat. To answer this question, three marine microalgae species (Chlorella marined, Nannochloropsis oculate, and Phaeodactylum tricornutum) and two freshwater species (Chlorella vulgaris and Tetradesmus obliquus) were selected and exposed to the environment relevant concentrations of polystyrene microplastics. The results indicated that microplastics have a significant concentration effect on the growth of microalgae. The attachment of microalgae to microplastics surface and the aggregation of microalgae with each other were observed. Under exposure of microplastics, the photosynthesis of microalgae was inhibited while the antioxidant system was activated, indicating that microplastics had a negative impact on microalgae. At the end of exposure, the oxidative stress status caused by microplastics in marine microalgae were alleviated, but the antioxidant system of freshwater microalgae was still at high levels, indicating a stress response. In addition, integrated biomarker response (IBR) indicated that the effects of microplastics on freshwater microalgae were severer than marine microalgae, which might relate to their differences in removing reactive oxygen species (ROS) effectively and membrane structure. Our study provides a reliable data for understanding the complex effects of microplastics on microalgae, and especially for comparing the differential effects of microplastics among different microalgae., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The Beibu Gulf is a vital link between China and the ASEAN nations, and microplastic contamination is rising due to fast growth, coastal life, fisheries, and mariculture. The abundance, distribution, and source analyses were conducted at 25 sample points for this study. According to this study, the average MPs was 0.25 ± 0.05 items/m 3 , ranging from 0.01 items/m 3 to 0.89 items/m 3 . Fibers, white, cellulose, and 0.33-1 mm were abundant in shape, color, composition, and size, respectively. Multi-statistics-based source analysis indicated land-based inputs (packing materials, textile materials, fisheries, and mariculture) were dominant in the Beibu Gulf. In this study, we also acknowledged a comprehensive comparison and convenience between plankton pumps and other conventional designs to collect microplastic samples from water. We suggested that using a uniform design could elevate the data quality of microplastics., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

It remains unclear how the suspended non-fed bivalve mariculture will alter the coastal transfer and cleaning process of trace elements, the non-degradable contaminants, which have been reported to accumulate in sediment from bivalve mariculture areas. Herein, we set up a field in situ comparative test in the suspended oyster (Crassostrea plicatula) farming area (OF) and reference area (RA) of Xiangshan Bay to verify our hypothesis that the biodepositon of suspended oysters would consolidate trace elements from the water column and transport them to the sediment. Distribution of trace elements in multiple media of biodeposits (BDs), settling particles (SPs), sediments (SEs), and seawater demonstrate that the accelerated deposition of BDs which enriched trace elements from the water column by oysters filtering suspended particles led to trace elements accumulation in SEs from OF. Additionally, As, Cd, Co, Cr, Cu, Ni, V, and Zn were strongly regulated by this process with significant (p < 0.05) higher concentrations in SEs from OF (10.96, 0.20, 13.98, 82.40, 38.47, 38.22, 108.57, and 111.20 μg/g, repectively) than those from RA (9.43, 0.13, 11.76, 63.30, 30.34, 29.55, 86.59, and 100.24 μg/g, repectively), but the extent was different for Mn, Mo, Pb, and W with concentrations in SEs from OF (737.37, 0.81, 30.98, and 3.96 μg/g, repectively) and RA (765.25, 0.69, 31.27, and 3.34 μg/g, repectively), especially for Rb and Sr with concentrations in SEs from OF (131.13 and 96.24 μg/g, repectively) and RA (142.21 and 161.10 μg/g, repectively), due to their geochemical and geophysical properties. Moreover, the harvest of hyper-accumulated oysters as a sink for removing trace elements from water column cannot hide the impact of this process., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

To explore the ecological risks of trace metals in sediments and their relationship with benthic organisms, 12 trace metals were analyzed and the macrobenthos were identified in the sediments collected from the south coast of Zhejiang province which belongs to the East China Sea. Spatially, the concentrations of most trace metals were high in the estuary, except for Ba and Sr. There was no obvious enrichment for trace metals, except that the concentration of Cd slightly exceeded the coastal background. The ecological risks calculated by the concentrations of Cr, Cd, Cu, Zn, Pb, and Ni in sediments showed that the methods based on sediment quality guidelines could judge the ecological risk more intuitively than the methods based on background value (PN, PLI, RI). The significant correlations between ecological risks and benthos density and biomass revealed the negative impact of trace metals at high concentrations on macrobenthic survival in sediments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Zooplankton play an important role in energy transfer in the marine food web and form the dietary basis for the size of important fish stocks and the maintenance of their resources. Although zooplankton include numerous taxa with significantly different ecological characteristics and the interspecific differences in optimum body size and taxonomic specificity in fish feeding on zooplankton are remarkable, they are always considered as a whole (like a "black box") in current studies about the transport of persistent organic pollutants through the food chain. This approach might result in misjudgment of their bioaccumulation. In this study, the distribution properties of each taxa of zooplankton community were discerned using data from two cruise surveys conducted in the northern South China Sea. Twelve groups of zooplankton were identified, all of which had distinct ecological and functional characteristics. The carbon-based community structure of zooplankton could explain their variability with respect to polycyclic aromatic hydrocarbons (PAHs). Smaller-sized zooplankton (smaller calanoids and cyclopoids) were more likely to accumulate low molecular weight PAHs (LMW-PAHs), while larger-sized zooplankton (larger calanoids) were more likely to accumulate high molecular weight PAHs (HMW-PAHs). The bioaccumulation capacity of the zooplankton community for LMW-PAHs was negatively correlated with the proportion of omnivores and carnivores, while the opposite was true for HMW-PAHs. These results suggested that the effects of complex community structure within plankton communities should be taken into account when assessing the transfer and bioaccumulation effects of PAHs in the marine food chain., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Although microplastics (MPs) are known to be found in global oceans, their influencing factors and abundance in the deep sea remain largely unknown. Twenty-six surface sediment samples were collected in the deep basin of the Eastern Indian Ocean (EIO). This study showed that MPs abundance ranged from 30.30 particles/kg to 701.7 particles/kg, with an average of 170.5 ± 140.2 particles/kg. The MPs found in the sediment of the EIO mainly contain fragments and fibers, which account for 47.5% and 45.6%. The MPs were measured in a size range of 44-5000 μm, and the most frequently detected MPs in size of 200-500 μm. MPs were in various compositions, but most of them were found in rayon (62.2%) and polyester (25.7%). The spatial distribution of MPs in the sediments shows a decreasing trend from nearshore to the open sea. In the Bay of Bengal (BOB) and the coast of Sri Lanka (COSL), the abundance of MPs was relatively high, indicating that the spatial distribution of MPs is affected by land source input, river input, and anthropogenic activities. Principal component analysis indicated daily commodities and packaging applications/fishing accounted for 36.9% and 12.9% of the MPs occurrence in the EIO, respectively. Average MPs diversity indices for the BOB (0.87 ± 0.38), the COSL (0.64 ± 0.56), and the Eastern Indian Ocean Basin (EIOB) (0.60 ± 0.24) revealed the BOB had the most complicated MPs sources. In addition, we found that the abundance of MPs has no significant effect on organic carbon and sediment grain size. This study is the first report of MPs detection in the deep-sea sediment in the EIO and can provide a baseline of MPs pollution in this area., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The pollution characteristics, potential sources, and potential ecological risk of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the Hangzhou Bay (HZB) and East China Sea (ECS). Total OCPs concentration ranged from 2.62 to 102.07 ng/L and 4.41 to 75.79 μg/kg in the seawater and sediment samples, with PCBs concentration in the range of 0.40-51.75 ng/L and 0.80-45.54 μg/kg, respectively. The OCPs were positively correlated with nutrients, whereas PCBs presented a negative correlation. The newly imported dichlorodiphenyltrichloroethane (DDT) in HZB is mainly the mixing of technical DDT and dicofol sources. The PCB source composition is more likely related to the mixture of Kanechlor 300, 400, Aroclor 1016, 1242, and Aroclor 1248. Risk assessment results indicate that OCPs posed low risk in seawater. The potential risk of DDTs in the sediments is a cause of concern., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Legacy halogenated organic pollutants, including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), remain ubiquitous in the environment and continue to pose potential (eco-)toxicological threats because of their ongoing releases from land-based sources. This study investigated the spatial trends of freely dissolved PCBs and OCPs by polyethylene passive samplers, and provided evidence of their land-use-based sources and ecological risk in an urbanized estuary area of Narragansett Bay. Dissolved Σ 29 PCB concentrations ranged from 0.01 to 1.37 ng L -1 , and exhibited higher concentrations in the upper, more urban/built-up watershed, and in north coastal areas. Major inputs of PCBs were urban stormwater or treated wastewater that might carry past releases of Aroclors, pigment manufacturing byproducts, and volatilization-associated PCBs from ageing buildings from the Narragansett watershed to the bay. The dioxin toxicity equivalent values of Σ 5 PCBs were 8.6E-03 pg L -1 in water. Dissolved OCP concentrations had similar spatial trends to PCBs and were dominated by DDTs (average 230 pg L -1 ), followed by chlordanes (average 230 pg L -1 ), and HCB (average 22 pg L -1 ). Secondary sources of past usage and historic contamination were expected to re-enter the surface water via atmospheric transport and deposition. The risk quotients of DDE, DDD, DDT and α-Endosulfane showed medium to high ecological risks in the northern area, while chlordane, HCB, oxychlordane, and heptachlor epoxide showed low to negligible risks in all zones. This study presented new insights into the presence, sources and transport of legacy halogenated organic contaminants in an urban estuary's watershed by combining passive samplers and geographic information system (GIS) technology. The approach is promising and could be extended to get better understand of terrestrial pollutant mobilization into estuaries affected by anthropogenic activities., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

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., (Copyright © 2022. Published by Elsevier Ltd.)

Hangzhou Bay is facing severe anthropogenic perturbation because of its geographic position. We studied species-specific bioaccumulation of metals in commercially important fishes and shellfishes, and calculated the potential human health hazards through their consumption, which has not been reported earlier from this area. The hierarchy of metal concentration in organisms was in the decreasing order of Zn (10.32 ± 7.13) > Cu (2.40 ± 2.66) > As (0.42 ± 0.26) > Cr (0.11 ± 0.08) > Cd (0.07 ± 0.07) > Pb (0.05 ± 0.02) > Hg (0.012 ± 0.009). Except for Cd and As concentrations in fishes, metal concentrations have not exceeded the national and international guideline values. P. laevis and P. trituberculatus were the most bioaccumulative of the species studied. According to the non-carcinogenic risk assessment, children were more susceptible to metal contamination than adults. The carcinogenic risk (CR) values indicated that children were likely to experience carcinogenic threats for taking cancer-causing agents As and Cd through fish consumption. In terms of organisms, intake of two crab species, P. trituberculatus and E. sinensis, as well as the oyster species P. laevis, could be detrimental to consumers., (© 2022. The Author(s).)

Microplastic pollution is a major threat to the marine environment attracting attention from scientific and public communities. Although we have sufficient evidence that microplastic is ubiquitous in all ecosystems, the question of the harmfulness of microplastic exposure is still under debate. Filter feeders like bivalves are commonly exposed to microplastics in water and sediments and thus can serve as excellent biological indicators for microplastic pollution. A relatively rich toxicological literature has been focusing on microplastic effects on bivalves but we have yet to reach an agreement on the toxic effects and mechanisms of microplastics. Here, we conducted a meta-analysis and bibliometrics analysis of the microplastic studies in bivalves. The bibliometric analysis (used to evaluate the general research trends) showed that the investigation of microplastic distribution in the marine environment and the molecular mechanisms of microplastic toxicity are the two major hot spots of research. Based on analyses of ecologically and environmentally relevant microplastics concentrations, particle sizes and polymer types, we discuss the physiological effects of microplastics on bivalves, and the severity and direction of the effects at the cellular, tissue, organ and organismal levels. The meta-analysis results show that microplastics can induce time-dependent oxidative stress in bivalves. Generally, the activities of antioxidant enzymes, such as glutathione peroxidase (GPx), glutathione-S-transferase (GST) and superoxide dismutase (SOD) increased during short-term exposure but declined after long-term exposure to microplastics. Non-linear response of GPx, GST and SOD enzymes to MP exposure over time indicate that these enzymes are not good biomarkers of MPs effects in marine bivalves. The tissue glutathione levels and catalase (CAT activity) showed an increase during both short- and long term MP exposures and thus can be used as oxidative stress biomarkers of sublethal MPs effects in marine bivalves., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Knowing the polycyclic aromatic hydrocarbons (PAHs) pollution properties in ocean is highly needed to protect the open sea. In July to August of 2020, twenty surface water samples were obtained from the East China Sea to the Philippine Sea. The ranges of Σ 15 PAHs concentrations were 3.188-5.29 ng L -1 in dissolved phase, 0.455-1.305 ng L -1 in particulate phase in the Philippine Sea. 3, 4-Ring PAHs were the most abundant PAHs. Their spatial differences in dissolved phase were mainly caused by human activities, the summer monsoon from the Philippine Islands and the Northern Equatorial Current, and the Kuroshio Current and Subtropical Countercurrent. The source analysis showed that PAHs in surface water in the Philippine Sea may come from coal combustion. It is the first time to analyze the occurrence and distribution of PAHs in the Philippine Sea., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Airborne microplastics (MPs) are receiving increasing attention due to their ubiquitous nature and the potential human health consequences resulting from inhalation. The limited data for airborne MP concentrations vary widely among studies (∼4 orders of magnitude), but comparisons are tenuous due to the inconsistent collection and detection/enumeration methodologies among studies. Herein, we used uniform methodologies to obtain comparable airborne MP concentration data to assess MP exposure intensity in five Chinese megacities. Airborne MP concentrations in northern cities (358 ± 132 items/m 3 ) were higher than those in southeast cities (230 ± 94 items/m 3 ) but of a similar order of magnitude, unlike previous studies. The majority (94.7%) of MPs found in air samples were smaller than 100 μm, and the main shape of airborne MPs was fragments (88.2%). Polyethylene, polyester, and polystyrene were the dominant polymers comprising airborne MPs. No consistent relationships were detected between airborne MP concentration and typical socioeconomic indices, and the spatial and diurnal patterns for airborne MPs were different from various components of air quality indices (PM 2.5 , PM 10 , etc.). These findings reflect the contrasting source/generation dynamics between airborne MPs and other airborne pollutants. Maximum annual exposure of humans to airborne MPs was estimated in the range of 1-2 million/year in these megacities, highlighting the need for additional research examining the human health risks from the inhalation of airborne MPs.

Marine microplastic has become an important environmental issue of global concern due to its wide distribution and harmful impacts. However, there is still insufficient information on the toxicity mechanism of microplastics to marine organisms. In this study, we developed and applied a high-coverage quantitative metabolomics technique to investigate the toxicity mechanisms of the polystyrene microspheres (micro-PS) on marine mussels (Mytilus coruscus). A total of 3599 metabolites were quantified, including 163 positively identified metabolites, 318 high-confident putatively identified metabolites, and 2602 mass-matched metabolites from the hemolymph of mussels. Metabolomics analysis indicated that micro-PS disrupted the amino acid metabolism, particularly phenylalanine metabolism, which may lead to oxidative stress and neurotoxicity. Micro-PS at environmentally relevant concentrations induced oxidative stress and immunotoxicity in mussels. After 7 days of recovery, along with the significant clearance of micro-PS by mussels, both metabolite levels and biochemical indicators generally returned to the same level as the control group. Overall, the results showed that microplastics at environmentally-relevant concentrations can cause toxic effects on mussels but these influences are reversible. We envisage the usages of high-coverage metabolomics for investigating the toxicity of various types of microplastics under many different conditions, including those relevant to the marine environment., (Copyright © 2021 Elsevier B.V. All rights reserved.)

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/m 3 ) and showed less diverse characteristics than microplastics (0.79 items/m 3 ) but did not significantly differ in spatial distribution. 2) Microplastics in water were more abundant (1.95 items/m 3 ) with more diverse characteristics in Liaodong Bay than in other regions of the sea (0.26-0.59 items/m 3 ). 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., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study investigates the occurrence and distribution of microplastics in water, sediment, and crayfish samples within pond and rice-crayfish co-culture breeding modes in Jianli prefecture, China. Microplastics in environmental and biological samples were systematically extracted by CaCl 2 solution, digested by H 2 O 2 and KOH, and identified by μ-FTIR. A cleansing treatment for crayfish was performed in pure water before dissection and microplastic accumulation in different tissues (gill, stomach, gut, and flesh) of non-cleansed and cleansed crayfish were compared. The average microplastic abundances were 1.3 ± 0.1-2.5 ± 0.1 particles/L, 0.03 ± 0.01-0.04 ± 0.02 particles/g, and 0.17 ± 0.07-0.92 ± 0.19 particles/individual in water, sediment, and crayfish samples, respectively. Microplastics were detected in all studied crayfish tissues, except the flesh. There were no significant differences in microplastic abundances in water (P = 0.82), sediment (P = 0.90), and crayfish (P = 0.47 for non-cleansed samples; P = 0.30 for cleansed samples) between two breeding modes despite the detection of relatively higher microplastic abundances in the samples from the pond breeding mode. Microplastic accumulation in non-cleansed crayfish stomachs and guts (0.71 ± 0.18 particles/individual) was higher (P < 0.01) than that recorded in their gills (0.13 ± 0.06 particles/individual). Moreover, microplastics present in the stomachs and guts of cleansed crayfish were significantly less abundant (P < 0.01) than in non-cleansed crayfish, although this was not observed in the gills (P = 0.99). The majority of microplastic particles in this study had fiber-like shapes, blue and transparent colors, a size smaller than 1 mm, and polymer types of PP:PE and PE. The results demonstrate that microplastics in the environment can accumulate in the internal tissues of crayfish, which may pose a potential risk to humans through food consumption without the removal of the gills, stomach, and guts. This study provides valuable information for understanding microplastic accumulation in the different tissues of crayfish and the potential risk of human exposure to microplastics from crayfish as a food supplement., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Microplastic pollution in estuarine and coastal environments has recently been characterised in several countries but few researchers have addressed the influence of different forms of coastal zone use on the distribution of microplastic. Here, microplastic particles were sampled in Hangzhou Bay, which is heavily influenced by a range of human activities, and their abundance, size, and polymer type characterised. The abundance of microplastics was 0.14 ± 0.12 items/m 3 in water, 84.3 ± 56.6 items/kg dry weight of sediment, and between 0.25 ± 0.14 and 1.4 ± 0.37 items/individual in biota. These results show that Hangzhou Bay has a low level of microplastic contamination compared to other coastal systems in China, although abundance was spatially variable within the bay; relatively higher microplastic abundances were found in the southern area of the bay, which has adjacent industrial and urban land-use zones, while lower abundances were observed in the central and northern bay areas where mariculture, fisheries, and mineral and energy industries are most common. The relatively low microplastic abundance observed in the biota samples is consistent with the generally low values for the seawater and sediment samples. Pellets were the most common of four particle-shape classes (fibres, fragments, films, and pellets) in surface seawater, while fibres were most abundant in sediment and biota. Smaller-sized microplastics (<1.0 mm) were dominant in all samples. Microplastics in the surface seawater were dominated by low-density polypropylene and polyethylene particles, while rayon was dominant in the sediment and biota samples. Our results demonstrate that regional variability in anthropogenic activity and land-use are important controls on the spatial pattern of microplastic pollution in Hangzhou Bay., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Anthropogenic pollution has become a major issue governing ecosystem and human health risks. The Hangzhou Bay and Qiantang Estuary region are facing unusual perturbation due to rapid development along the embayment in recent decades. This study evaluated the organic and inorganic pollutants in water, sediment, and from the muscles of higher trophic organisms (fish, crustacean, shellfish) during four different seasons (in 2018-2019) along the Qiantang Estuary and Hangzhou Bay region to assess the ecosystem health and potential hazard status. Dissolved inorganic phosphate and nitrogen were the major pollutants in this area, which led to severe eutrophication throughout the study period. Eutrophication signals coincided well with the phytoplankton abundance, which revels the control of nutrient enrichment on the spatio-temporal distribution of phytoplankton. Food availability, along with salinity and temperature, drives the zooplankton population distribution. Heavy metals were not the issue of water quality as their concentrations meet the national and international baseline standards. However, in the sediments, Copper (Cu) and Arsenic (As) concentrations were higher than the baseline value. Towards the northwestern part of the Qiantang Estuary, the overall potential risk index of sediment with higher Cadmium (Cd) and Mercury (Hg) depicted delicate condition with moderate risk for the sediment contamination. The As concentration in fishes was close to the baseline standards limit irrespective of low As values within water and sediments. The higher concentrations of Zinc (Zn) and As in shellfish muscles, whereas other metals were within the limit of baseline standard in all the organisms. However, the hazard analysis (Targeted hazard quotient, THQ) values for the seafood consumption to human health indicates the potentially threatening consequences of shellfish and crustacean consumption on human health., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Rapid accumulation of aerosol nitrate (NO 3 - formation mechanisms remain scarce. To explore aerosol nitrate formation pathways, total suspended particulate (TSP) samples were collected in Beijing during the spring of 2013, and the concentration of NO 3 - formation mechanisms remain scarce. To explore aerosol nitrate formation pathways, total suspended particulate (TSP) samples were collected in Beijing during the spring of 2013, and the concentration of NO 3 - and δ 18 O- NO 3 - value were analyzed. The NO 3 - concentrations on polluted days (PD) were higher than those on non-polluted days (NPD). Furthermore, higher δ 18 O- NO 3 - values, the possible fractional contributions of HNO 18 O-HNO 3 values during PD. Based on the calculated δ 18 O-HNO 3 constrained calculations suggest that the pathways of N 18 O- NO 3 - values, the possible fractional contributions of HNO 3 formed via various pathways to TSP NO 3 - were estimated using the Bayesian isotope mixing model. The δ 18 O- NO 3  + OH pathway produced 37%-69% of the NO - constrained calculations suggest that the pathways of N 2 O 5  + H 2 O/Cl - , NO 3  + VOCs, and ClNO 3  + H 2 O possibly contributed 53%-89% to nitrate production during PD. During NPD, the NO 2  + OH pathway produced 37%-69% of the NO 3 - . Using the δ 18 O- NO 3 - value combined with the isotope mixing model is a promising approach for exploring NO 3 - formation pathways., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Concentrations of the heavy metals As, Cd, Cu, Hg, Pb, and Zn in various tissues of five marine fish species and one crab species collected from the middle coast of Zhejiang Province of China were investigated in this study. The results indicated considerable variation in heavy metal concentrations in different tissues and species. Elevated concentrations of most heavy metals were identified in fish gills and crab gills and hepatopancreas, with some differences by heavy metal type. In addition, carnivorous and benthivorous fish species generally contained relatively high concentrations of heavy metals due to feeding habits and habitats. Geographical variations of heavy metal concentrations in muscle may be attributable to species-dependent differences and terrigenous contamination. The potential health risk assessment suggested that exposure doses of most heavy metals were safe for human consumption, with the exception of As.