Characteristics of expanded polystyrene microplastics on island beaches in the Pearl River Estuary: abundance, size, surface texture and their metals-carrying capacity.

While expanded polystyrene (EPS) microplastics have been widely recognized as one of the most important components of plastic litter in the intertidal zones of the global ocean, our understanding of their environmental fate on island beaches is insufficient. In this study, we intended to reveal that the latest EPS microplastic pollution status on 5 island beaches in the Pearl River Estuary, China, by comprehensively assessing the abundance, distribution, size, surface texture and carrying capacity of heavy metals (Cd, As, Cr, Ni, Cu, Pb, Mn, Fe, Al). High level of EPS microplastic abundance ranged from 328 to 82,276 particles m-2 was found, with the highest abundance at Guishan Island and the lowest at Dong'ao Island. Spatial distribution of EPS microplastic abundance was significantly different among different islands. EPS microplastics in the size range of 1-2 mm were the most abundant. The content of heavy metals in EPS microplastics collected on the beaches was greater than that in the new EPS products. The average concentrations of heavy metals in EPS microplastics from 5 islands are Cd (0.27 ± 0.19 µg g-1), As (5.50 ± 3.84 µg g-1), Cr (14.9 ± 8.25 µg g-1), Cu (15.0 ± 7.66 µg g-1), Ni (17.2 ± 17.6 µg g-1), Pb (24.8 ± 7.39 µg g-1), Mn (730 ± 797 µg g-1), Fe (8340 ± 4760 µg g-1), and Al (9624 ± 6187 µg g-1), respectively. The correlation between heavy metals in EPS microplastics and sediments was better than that between heavy metals in EPS microplastics and seawater. The study results indicated that EPS microplastics could act as a carrier for the transport of heavy metals, which might pose a threat to biological and human health.

Effects of Toxic Leachate from Commercial Plastics on Larval Survival and Settlement of the Barnacle Amphibalanus amphitrite.

Plastic pollution represents a major and growing global problem. It is well-known that plastics are a source of chemical contaminants to the aquatic environment and provide novel habitats for marine organisms. The present study quantified the impacts of plastic leachates from the seven categories of recyclable plastics on larval survival and settlement of barnacle Amphibalanus (=Balanus) amphitrite. Leachates from plastics significantly increased barnacle nauplii mortality at the highest tested concentrations (0.10 and 0.50 m(2)/L). Hydrophobicity (measured as surface energy) was positively correlated with mortality indicating that plastic surface chemistry may be an important factor in the effects of plastics on sessile organisms. Plastic leachates significantly inhibited barnacle cyprids settlement on glass at all tested concentrations. Settlement on plastic surfaces was significantly inhibited after 24 and 48 h, but settlement was not significantly inhibited compared to the controls for some plastics after 72-96 h. In 24 h exposure to seawater, we found larval toxicity and inhibition of settlement with all seven categories of recyclable commercial plastics. Chemical analysis revealed a complex mixture of substances released in plastic leachates. Leaching of toxic compounds from all plastics should be considered when assessing the risks of plastic pollution.

Adsorption of heavy metals on biodegradable and conventional microplastics in the Pearl River Estuary, China.

In recent years, microplastics (MPs) as emerging carriers for environmental pollutants have attracted increasing worldwide attention. However, the adsorption of heavy metals on MPs, especially for biodegradable MPs, has been still poorly understood in estuarine environments. In this study, we investigated the aging of biodegradable and conventional MPs in the Pearl River Estuary after long-term exposure and their impacts on the adsorption of heavy metals from seawater. The results showed that the changes in surface characteristics were more prominent on biodegradable MPs than on conventional MPs after aging. Both biodegradable and conventional MPs could adsorb heavy metals, and their adsorption capacities fluctuated greatly on different MPs and different exposure times. The adsorption capacities of Cu, Pb, and As on biodegradable MPs were higher than those on conventional MPs, whereas Mn, Cr, and Co had lower adsorption on biodegradable MPs after 9-12 months by inductively coupled plasma-mass spectrometry (ICP-MS). The aging characteristics (CI, O/C, and Xc) of MPs accounted for a contribution of 51.0% on heavy metal adsorption, while the environmental factors (temperature, salinity, pH, and heavy metal concentration) only contributed to 13.2%. Therefore, the present study can provide important evidence on the environmental behaviors and ecological risks of biodegradable and conventional MPs in estuarine systems.

Expanded polystyrene buoys as an important source of hexabromocyclododecanes for aquatic ecosystem: Evidence from field exposure with different substrates.

The production and use of hexabromocyclododecanes (HBCDs) have been strictly limited due to their persistence, toxicity and bioaccumulation. However, the release of HBCDs from related products and wastes would continue for a long time, which may cause many environmental problems. In this study, we investigated the occurrence and distribution of HBCDs and microplastics (MPs) in aquatic organisms inhabiting different substrates. HBCDs were measurable in the seawater, sediment, expanded polystyrene (EPS) substrates and organism samples. Mostly, the concentrations of HBCDs in organisms inhabiting EPS buoys were significantly higher than those of the same species inhabiting other substrates. Meanwhile, the diastereomeric ratio (α/γ) of HBCDs in organisms inhabiting EPS buoys was closer to that in EPS buoys. The fugacity values of HBCDs in EPS buoys were much higher than those in other media, implying that HBCDs can be transferred from EPS buoys to other media. Additionally, MPs derived from EPS buoys would be mistaken as food and ingested by aquatic organisms. The transfer of HBCDs from EPS buoys to aquatic organisms can be achieved by aqueous and dietary exposures. In combination, the contribution of MP ingestion to HBCDs for aquatic organisms should be very limited. These results supported EPS buoys as an important source of HBCDs for the aquatic ecosystem. To effectively control HBCDs pollution, it is necessary to discontinue or reduce the use of EPS buoys.

Microplastics contamination in bivalves from the Daya Bay: Species variability and spatio-temporal distribution and human health risks.

Microplastic contamination is an emerging global threat for various marine organisms. Marine invertebrates such as bivalve mollusks are more susceptible to the widespread presence of microplastics due to their limited abilities to escape from pollution exposure and they can readily ingest environmental pollutants like microplastics through their filter-feeding behaviors. In this study, microplastic contamination in bivalves related to species, spatial, and temporal variability were conducted. Results showed that the frequency of microplastic occurrence varied from 86.7 % to 93.3 % in six species of bivalves, and the average abundance of microplastics ranged from 3.5 to 8.6 items per individual or from 0.2 to 3.1 items per gram tissues wet weight. No significant difference was observed in microplastic abundances of bivalves collected from different research regions and sampling seasons. However, the sediment-dwelling bivalves had higher microplastics abundances than the water-dwelling bivalves. Microplastic features with various shapes, colors, sizes, and polymer types detected in bivalves were similar with those in seawater and sediment environments that they are living in. The potential risk assessment of microplastics in bivalves basing on polymer hazard index (PHI) was in the risk levels of II-III, implying that microplastic contamination in bivalves may pose health risk to human via seafood consumption.

Microplastic contamination in marine-cultured fish from the Pearl River Estuary, South China.

Microplastics are ubiquitous in the aquatic environment. However, the occurrence of microplastics in farmed fish is under-researched. Herein, microplastic abundance in the stomach and intestine of marine-cultured hybrid groupers (Epinephelus fuscoguttatus × Epinephelus lanceolatus) in the Pearl River Estuary (PRE) was examined. Microplastics were detected in all fish samples, with an average abundance of 35.36 n/individual or 0.62 n/g. The fish intestine contained more microplastics (23.91 n/individual, i.e., 1.10 n/g) than the stomach (12.80 n/individual, i.e., 0.37 n/g). In addition, the ingested microplastics were predominantly fibre-shaped (70.1%), and nearly 70% were smaller than 1 mm in diameter. Potential factors affecting the ingestion of microplastics by farmed hybrid groupers include fish diet and the availability of microplastics in their feeding habitat.

Microplastic pollution in the surface seawater in Zhongsha Atoll, South China Sea.

The prevalence of microplastics in the marine environment has attracted extensive attention. So far, no information is known regarding the temporal and spatial variations of microplastics in Zhongsha Atoll. This study, for the first time, comprehensively investigated the occurrence and distribution of microplastics in the surface seawater in Zhongsha Atoll based on two ocean cruises. The abundances of microplastics measured in the surface seawater of Zhongsha Atoll were in the ranges of not detected (ND) to 67 items/m3, and ND to 160 items/m3 in 2019 and 2020, respectively. All microplastics detected in Zhongsha Atoll were fibers, most of which were transparent and less than 2 mm. Polyethylene terephthalate was the dominating composition of microplastics. These results suggested that sewage, surface runoff, atmospheric deposition by neighboring land, and fishing activities may be the primary pollution sources. This study provides critical information on microplastic pollution in Zhongsha Atoll for the first time, calling for more research in the management of marine plastic debris in the future.

Spatial variation of floatable plastic debris and microplastics in the Pearl River Estuary, South China.

The estuaries of populated catchments have been documented as hotspots of plastic pollution. In this study, microplastics (0.355-5.0 mm) and large plastic debris (>5.0 mm) of surface water collected from the Inner Lingding Bay of the Pearl River Estuary (PRE) were quantified and categorized according to their size, shape, colour and composition. Both microplastics and large plastic debris were detected at all sampling sites with mean abundances of 2.376 ± 0.700 n/m3 and 0.110 ± 0.039 n/m3, respectively. Microplastics constitute 95.4% of the total abundance by number. The average microplastic concentration in the inner PRE was almost 3.5 times higher than that in the central PRE, indicating a positive correlation between plastic concentration and proximity to the river mouth. This result reveals the important role of rivers in transporting plastic debris from land to the oceans.

Assessment of micro and macroplastics along the west coast of India: Abundance, distribution, polymer type and toxicity.

Considering the magnitude of pollution caused by marine plastics, the present study assessed their abundance, distribution, surface morphology and polymer type in ten sandy beaches spread across three states (Maharashtra, Karnataka and Goa) along the west coast of India (WCI). The total abundance of plastics (∼1-100 mm) in the studied beaches ranged from 4.1 to 23.4% (19±1-346 ± 2 items/m2). Location-wise, the abundances of both micro (43.6 ± 1.1-346 ± 2 items/m2) and macroplastics (21.6±3-195 ± 6 items/m2) were relatively higher in beaches along the Maharashtra coast. Surface morphology-wise, fragments were predominantly abundant in both micro (76±2-346 ± 2 items/m2) and macroplastics (50.6 ± 1.5-195 ± 6 items/m2) followed by pellets (43.3 ± 2.5-245.6 ± 2 items/m2). Fourier-transform infrared spectroscopy (FT-IR) analysis of plastics revealed a dominance of polyethylene (PE) followed by polypropylene (PP). IR spectra of the collected plastics at absorption band at 1750-1700 cm-1 reflect minimal surface oxidation. White-colored plastics were observed most frequently, followed by pale-yellow, dark-brown, green, blue, transparent and red. A short-term (72 h) experimental study to assess the toxicity of PE microbeads (∼1 mm) in a commercially important shrimp species, Litopenaeus vannamei revealed toxicological changes. An elevated level of lipid peroxidation (LPX)-the tagged biochemical marker, was recorded only at the maximum dose (0.15 mg/L) of PE microbeads. A moderate increase in the levels of enzymatic antioxidants (catalase and glutathione S-transferase) was also recorded at the same dose. Comprehensive information on marine plastics, including ecotoxicity provided in this study, would help in evolving strategies in minimizing plastic pollution along the WCI.

Low level of microplastic contamination in wild fish from an urban estuary.

Microplastic accumulation in estuarine environments is considered the dominant input of land-based plastics into the oceans. In this study, the level of microplastic contamination was evaluated in 26 species of wild fish from the Pearl River Estuary, South China. Results showed that microplastics abundance ranged from 0.17 items individual-1 (Boleophthalmus pectinirostris & Acanthogobius flavimanus) to 1.33 items individual-1 (Plectorhynchus cinctus) among different species. The distribution of microplastic abundance in the gills and gastrointestinal tracts was not significantly different. Microplastics in gills are strongly related to the filtration area of gills in 15 fish species. Fibers were the dominant shapes accounting for 93.45% of the total shapes. The majority of microplastics were <3 mm in size. The most common polymer composition was polyethylene terephthalate (38.2%) and the most common color was black (30.36%). The findings of this study provide baseline data for microplastic contamination in wild fish from an urban estuary.

Occurrence and mass loads of biocides in plastic debris from the Pearl River system, South China.

Chemical pollution in the plastic debris is an increasing global concern as most pollutants might transfer from the environment to living organisms via plastic debris. In this study, biocides in the plastic debris floating on the surface water of the Pearl River system were investigated. The abundances of large plastic debris and microplastics in the surface water were 0.07 ± 0.13 and 0.94 ± 1.87 items/m3, respectively. Totally, 15 and 16 out of 19 biocides were detected in the large plastic debris and microplastics, with the concentration of each biocide in the ranges of 22.6-2460 ng/g and 16.9-2890 ng/g, respectively. Meanwhile, the concentration ranges of the detected biocides were 0.01-215 ng/L in surface water. Triclosan, triclocarban, methylparaben, and N,N-diethyl-3-methylbenzamide (DEET) were the frequently detected compounds in the plastic samples and surface water. The partition coefficients (Kd) of biocides between the plastic debris and surface water showed a weak positive correlation with Kow values. Biocides were also detected on the natural floats (tree leaves and branches) at concentrations of 13.7-786 ng/g. The annual mass load of biocides in plastic debris at each site was up to 265 g/y, thereby suggesting that plastic debris might be an important carrier for the emerging contaminants, such as biocides.

Occurrence of microplastics in gastrointestinal tracts and gills of fish from Beibu Gulf, South China Sea.

Microplastics are widespread across the global oceans, yet the potential risks of the ubiquitous environmental contaminant to marine organisms has been less known. Accumulation of microplastics and associated contaminants in marine fish, may pose adverse impacts to human health via seafood consumption. This study evaluated microplastic contamination in 24 fish species collected from Beibu Gulf, one of the world's largest fishing grounds in South China Sea. Microplastics were detected in 12 fish species at an abundance of 0.027-1.000 items individual-1 and found in fish stomach, intestines and gills with the count percentage of 57.7%, 34.6% and 7.7%, respectively. Transparent fibers were observed as the predominant microplastics, which might be ingested accidently by fish or transferred through other animals at lower trophic levels. Majority of microplastics were identified as polyester (44%) and nylon (38%), whereas polypropylene (6%), polyethylene (6%), and acrylics (6%) were also found. Relatively, higher microplastic abundances were found in demersal fish compared to the pelagic species. Overall, the abundance of microplastics was documented as relatively low in the commercial fish collected from the open water of Beibu Gulf, South China Sea.

Microplastic accumulation in fish from Zhanjiang mangrove wetland, South China.

Microplastics (MPs) are widespread in marine and estuarine environments, but the contamination of MPs in mangrove wetlands is relatively unknown. Here, we quantify the presence of MPs in fish collected from Zhanjiang mangrove wetland, the largest mangrove in South China, which provide baseline data on MPs accumulation in fish in mangrove environment as the first evidence in China. MPs were found in 30 out of 32 fish species at an average abundance of 2.83 ±â€¯1.84 items individual-1, ranged from 0.6 to 8.0 items individual-1 in each species. MPs were detected in gills, stomach and intestine, and not found in muscles and livers. Positive relationship was found between MPs abundance and body length or weight of mangrove fish. The dominant polymers identified by micro-FTIR were polyethylene, polyethylene terephthalate, polypropylene and cellophane. MPs consisted primarily of fibers and with the prominent size range of 0.02-1 mm. The body sizes, living habitats and feeding habits of fish are important factors affecting MPs accumulation in different fish species. This study revealed the wide presences of MPs in fish species within a mangrove wetland.

Sorption and desorption of phenanthrene on biodegradable poly(butylene adipate co-terephtalate) microplastics.

Biodegradable plastics, as alternatives to conventional plastics, are increasingly used, but their interactions with organic pollutants are still unknown. In this study, the sorption and desorption behaviors on a type of biodegradable plastic-poly(butylene adipate co-terephtalate) (PBAT) were investigated, and at the same time two types of conventional plastics-polyethylene (PEc and PEv) and polystyrene (PS) were used for comparison. Phenanthrene (PHEN) was chosen as one of representative organic pollutants. Results indicated that the sorption and desorption capacities of PBAT were not only higher than those of the other types of microplastics, but also higher than those of carbonaceous geosorbents. The surface area normalized results illustrated that sorption and desorption of the microplastics were positively correlated with their abundance of rubbery subfraction. The sorption kinetic results showed that the sorption rates of PBAT and PEc were higher than PEv and PS. The effects of water chemistry factors including salinity, dissolved organic matter and Cu2+ ion on the sorption process displayed the same trend, but the degrees of influence on the four microplastics differed. The degrees of influence were mainly dependent on the abundance of rubbery subfraction for microplastics. These findings indicate that the biodegradable poly(butylene adipate co-terephtalate) microplastics are actually stronger vectors than the conventional microplastics, and crystallization characteristics of the microplastics have great influences on the vector effect.

Impacts of leachates from single-use polyethylene plastic bags on the early development of clam Meretrix meretrix (Bivalvia: Veneridae).

Plastic debris in the oceans is a major and growing problem in global environmental pollution. There are increasing concerns that plastic debris is a source of contaminant, either added during manufacturing or adsorbed from the environment. However, there is little information about the acute toxicity of leachates from plastic debris on marine organisms. In this study, we conducted experiments to evaluate the toxicity of leachates from two single-use polyethylene plastic bags (PB1 and PB2) with the embryo and larvae of the commercial clam Meretrix meretrix. Results showed that fertilization of the embryos was not affected by plastic leachates, but the developments of D-veliger larvae, including survival, deformity, and shell height, were significantly affected by plastic leachates from both PB1 and PB2 compared to the controls of filtered seawater. We speculate that compounds leaching from plastic bags are responsible for the observed toxicity. Therefore, leaching toxicity from plastic debris should be considered when assessing the risks of plastic pollution in the oceans.

Preparation of the recycled and regenerated mesocarbon microbeads-based solid acid and its catalytic behaviors for hydrolysis of cellulose.

Mesocarbon microbeads (MCMB) from coal tar pitch have excellent mechanical strength, high density, and good thermal stability. Moreover, a great deal of aromatic constituents occur on its surface, favoring the substitution reaction of sulfonic group. Results showed that the total acid and -SO3H amount was 4.36 mmol/g and 2.18 mmol/g, respectively. Moreover, the yield of total reducing sugar (TRS) and conversion ratio (Cr) for pretreated cellulose (DP = 101.5) can reach 66.7% and 68.8% at 140 °C for 240 min in distilled water, respectively. After four recycles, the TRS and Cr decreased by 12.6% and 10.2%, respectively. Through the secondary and third regeneration for the catalyst, acid density still reached 88.1% and 87.2% of the initial R1-MCMB-SO3H, demonstrating excellent regeneration ability and recyclability of the solid acid. Therefore, MCMB-based solid acid exhibits an attractive potential in the conversion of cellulose into platform chemical compounds.

Microplastics in oysters Saccostrea cucullata along the Pearl River Estuary, China.

As a transitional zone between riverine and marine environments, an estuary plays an important role for the sources, accumulation and transport of microplastics. Although estuarine environments are hotspots of microplastic pollution, the correlation between microplastic pollution and aquatic organisms is less known. Here we investigated microplastic pollution in wild oysters Saccostrea cucullata from 11 sampling sites along the Pearl River Estuary in South China. The microplastic abundances in oysters ranged from 1.4 to 7.0 items per individual or from 1.5 to 7.2 items per gram tissue wet weight, which were positively related to those in surrounding waters. The oysters near urban areas contained significantly more microplastics than those near rural areas. Fibers accounted for 69.4% of the total microplastics in oysters. Microplastic sizes varied from 20 to 5000 µm and 83.9% of which were less than 100 µm. Light color microplastics were significantly more common than dark color ones. Based on the results, oysters are recommended as a biomonitor for the microplastic pollution in estuaries.

Recyclable plastics as substrata for settlement and growth of bryozoans Bugula neritina and barnacles Amphibalanus amphitrite.

Plastics are common and pervasive anthropogenic debris in marine environments. Floating plastics provide opportunities to alter the abundance, distribution and invasion potential of sessile organisms that colonize them. We selected plastics from seven recycle categories and quantified settlement of (i) bryozoans Bugula neritina (Linnaeus, 1758) in the lab and in the field, and of (ii) barnacles Amphibalanus (= Balanus) amphitrite (Darwin, 1854) in the field. In the laboratory we cultured barnacles on the plastics for 8 weeks and quantified growth, mortality, and breaking strength of the side plates. In the field all recyclable plastics were settlement substrata for bryozoans and barnacles. Settlement depended on the type of plastic. Fewer barnacles settled on plastic surfaces compared to glass. In the lab and in the field, bryozoan settlement was higher on plastics than on glass. In static laboratory rearing, barnacles growing on plastics were initially significantly smaller than on glass. This suggested juvenile barnacles were adversely impacted by materials leaching from the plastics. Barnacle mortality was not significantly different between plastic and glass surfaces, but breaking strength of side plates of barnacles on polyvinyl chloride (PVC) and polycarbonate (PC) were significantly lower than breakage strength on glass. Plastics impact marine ecosystems directly by providing new surfaces for colonization with fouling organisms and by contaminants shown previously to leach out of plastics and impact biological processes.

[Epidemiological investigation on endemic fluorosis along the Yellow River alluvial plain of Shandong province].

OBJECTIVE: To investigate the current prevalent status of endemic fluorosis in the floodplain area of the lower Yellow River in Shandong province. METHODS: According to "The National Technical Scheme for Endemic Disease Control in 2008", 16 counties were chosen to carry out the epidemiological survey of endemic fluorosis. Three villages were chosen in each county, to determine the fluoride content of drinking water and to check the dental fluorosis of children aged 8 to 12 year old, the skeletal fluorosis of adults over 16 years of age. Both children and adults were tested for urine fluoride. The content of fluoride in drinking water and urine was determined by F-ion selective electrode while dental fluorosis of children aged 8 to 12 years old was diagnosed by Dean's method and adults skeletal fluorosis by the National Standard for "Diagnosis of endemic skeletal fluorosis" (WS 192-2008). RESULTS: The investigation was taken place in 26 'improved-water-quality' villages in 16 counties, among which 19 villages had water fluoride content ≤ 1.00 mg/L and accounted for 73.08% (19/26), 7 villages had water fluoride content > 1.00 mg/L and accounted for 26.92% (7/26), with the highest water fluoride content as 3.73 mg/L. In 22 'yet to improve-water quality' villages in 16 counties, 5 villages had water fluoride content ≤ 1.00 mg/L (accounted for 22.73%), 17 villages had water fluoride content > 1.00 mg/L (accounted for 77.27%), with the highest water fluoride content as 3.38 mg/L. The overall rate of dental fluorosis among children aged 8 to 12 years old was 52.18% (1042/1997), with the index of dental fluorosis as 1.17 and the rate of dental damage as 8.01% (160/1997). The urinary fluoride values above 1.40 mg/L were found in 65.00% (845/1300) of children aged 8 to 12 years old, with the highest urinary fluoride concentrations as 18.53 mg/L. The rate of skeletal fluorosis by clinic and X-rays in adults older than 16 years old were 4.35% (1121/25 781) and 11.36% (5/44), respectively. The urinary fluoride values above 1.60 mg/L were found as 63.92% (606/948) in adults older than 16 years old, with the highest urinary fluoride concentrations as 21.35 mg/L. CONCLUSION: The status of endemic fluorosis had not been effectively controlled and the situation for endemic fluorosis control was still critical in the floodplain area of the lower Yellow River in Shandong province, suggesting that the preventive approaches on endemic fluorosis control should be strengthened.