Regional distribution of styrene analogues generated from polystyrene degradation along the coastlines of the North-East Pacific Ocean and Hawaii

Plastic additives in the ocean: Use of a comprehensive dataset for meta-analysis and method development

In excess of 13,000 chemicals are added to plastics ('additives') to improve performance, durability, and production of plastic products. They are categorized into numerous chemical classes including flame retardants, light stabilizers, antioxidants, and plasticizers. While research on plastic additives in the marine environment has increased over the past decade, there is a lack of methodological standardization. To direct future measurement of plastic additives, we compiled a first-of-its-kind dataset of literature assessing plastic additives in marine environments, delineated by sample type (plastic debris, seawater, sediment, biota). Using this dataset, we performed a meta-analysis to summarize the state of the science. Currently, our dataset includes 217 publications published between 1978 and May 2023. The majority of publications analyzed plastic additives in biota collected from Europe and Asia. Analyses concentrated on plasticizers, brominated flame retardants, and bisphenols. Common sample preparation techniques included Solvent - Agitation extraction for plastic, sediment, and biota samples, and Solid Phase Extraction for seawater samples with dichloromethane and solvent mixtures including dichloromethane as the organic extraction solvent. Finally, most analyses were performed utilizing gas chromatography/mass spectrometry. There are a variety of data gaps illuminated by this meta-analysis, most notably the small number of compounds that have been targeted for detection compared to the large number of additives used in plastic production. The provided dataset facilitates future investigation of trends in plastic additive concentration data in the marine environment (allowing for comparison to toxicity thresholds) and acts as a starting point for optimizing and harmonizing plastic additive analytical methods.

Internalization and toxicity of polystyrene nanoplastics on inmortalized human neural stem cells

Global plastic production has increased exponentially in recent decades, and a significant part of it persists in the environment, where it degrades into microplastics and nanoplastics (MPs and NPs). These can enter in humans by ingestion, inhalation, and dermal routes, and there is scientific evidence that they are able to reach the systemic circulation and penetrate and accumulate in various tissues and organs. Neurodevelopmental toxicity of NPs is one of the most worrying effects, as they can cross the blood-brain barrier. In the following study, we analyzed, by transmission electron microscopy, the in vitro uptake of 30-nm polystyrene nanoplastics (PS-NPs) into human neural stem cells (NSCs), their accumulation and subcellular localization within the cell. Furthermore, we studied the effects of different concentrations of PS-NPs on cell death, proliferation, and cell differentiation using immunocytochemistry and quantitative real time PCR for specific markers. This study demonstrated that PS-NPs were able to enter the cell, probably by endocytosis, accumulate, and aggregated in human NSCs, without being detected in the nucleus, causing cell death by apoptosis and decreased cell proliferation. This study provides new insights into the interaction and effects of PS-NPs in human NSC and supports the scientific evidence for the involvement of nanoplastic in neurodevelopmental disorders.

Recent progress and future directions of the research on nanoplastic-induced neurotoxicity

Many types of plastic products, including polystyrene, have long been used in commercial and industrial applications. Microplastics and nanoplastics, plastic particles derived from these plastic products, are emerging as environmental pollutants that can pose health risks to a wide variety of living organisms, including humans. However, it is not well understood how microplastics and nanoplastics affect cellular functions and induce stress responses. Humans can be exposed to polystyrene-microplastics and polystyrene-nanoplastics through ingestion, inhalation, or skin contact. Most ingested plastics are excreted from the body, but inhaled plastics may accumulate in the lungs and can even reach the brain via the nose-to-brain route. Small-sized polystyrene-nanoplastics can enter cells by endocytosis, accumulate in the cytoplasm, and cause various cellular stresses, such as inflammation with increased pro-inflammatory cytokine production, oxidative stress with generation of reactive oxygen species, and mitochondrial dysfunction. They induce autophagy activation and autophagosome formation, but autophagic flux may be impaired due to lysosomal dysfunction. Unless permanently exposed to polystyrene-nanoplastics, they can be removed from cells by exocytosis and subsequently restore cellular function. However, neurons are very susceptible to this type of stress, thus even acute exposure can lead to neurodegeneration without recovery. This review focuses specifically on recent advances in research on polystyrene-nanoplastic-induced cytotoxicity and neurotoxicity. Furthermore, in this review, based on mechanistic studies of polystyrene-nanoplastics at the cellular level other than neurons, future directions for overcoming the negative effects of polystyrene-nanoplastics on neurons were suggested.

Direct observation and identification of nanoplastics in ocean water

Millions of tons of plastics enter the oceans yearly, and they can be fragmented by ultraviolet and mechanical means into nanoplastics. Here, we report the direct observation of nanoplastics in global ocean water leveraging a unique shrinking surface bubble deposition (SSBD) technique. SSBD involves optically heating plasmonic nanoparticles to form a surface bubble and leveraging the Marangoni flow to concentrate suspended nanoplastics onto the surface, allowing direct visualization using electron microscopy. With the plasmonic nanoparticles co-deposited in SSBD, the surface-enhanced Raman spectroscopy effect is enabled for direct chemical identification of trace amounts of nanoplastics. In the water samples from two oceans, we observed nanoplastics made of nylon, polystyrene, and polyethylene terephthalate-all common in daily consumables. The plastic particles have diverse morphologies, such as nanofibers, nanoflakes, and ball-stick nanostructures. These nanoplastics may profoundly affect marine organisms, and our results can provide critical information for appropriately designing their toxicity studies.

Aquatic toxicity and fate of styrene oligomers in the environment

Styrene oligomers (SOs) are ubiquitous contaminants that appear in the environment, sometimes to significant extent (see section 3.1). Despite the ongoing international debate on the human health risks posed by SOs, to the best of my knowledge, there are no studies on the aquatic toxicity and environmental fates (biodegradation and atmospheric degradation) of SOs in the environment. This study is to predict the aquatic toxicity and environmental fate of SOs by using the US EPA EPI suite program as an in-silico method. For better understanding, the risks and fates of SOs are compared with those of the well-known bisphenol A (BPA) and styrene monomer (SM or styrene). As a result of this study, SOs are predicted to be relatively more toxic than BPA and SM to aquatic and terrestrial organisms in the freshwater, marine, and terrestrial environments. In particular, the biodegradability of SOs is predicted to be relatively very slow in the environment, and most SOs are more likely to be effectively decomposed by hydroxyl radicals than by ozone in the atmosphere. As a result, this study can contribute to motivating understanding of the aquatic toxicity and fate of ubiquitous SOs in the environment.

Alleviation of neurotoxicity induced by polystyrene nanoplastics by increased exocytosis from neurons

Nanoplastics (NPs) are potentially toxic and pose a health risk as they can induce an inflammatory response and oxidative stress at cellular and organismal levels. Humans can be exposed to NPs through various routes, including ingestion, inhalation, and skin contact. Notably, uptake into the body via inhalation could result in brain accumulation, which may occur directly across the blood-brain barrier or via other routes. NPs that accumulate in the brain may be endocytosed into neurons, inducing neurotoxicity. Recently, we demonstrated that exposure to polystyrene (PS)-NPs reduces the viability of neurons. We have also reported that inhibiting the retrograde transport of PS-NPs by histone deacetylase 6 (HDAC6) prevents their intracellular accumulation and promotes their export in mouse embryonic fibroblasts. However, whether HDAC6 inhibition can improve neuronal viability by increasing exocytosis of PS-NPs from neurons remains unknown. In this study, mice were intranasally administered fluorescent PS-NPs (PS-YG), which accumulated in the brain and showed potential neurotoxic effects. In cultured neurons, the HDAC6 inhibitor ACY-1215 reduced the fluorescence signal detected from PS-YG, suggesting that the removal of PS-YG from neurons was promoted. Therefore, these results suggest that blocking the retrograde transport of PS-NPs using an HDAC6 inhibitor can alleviate the neurotoxic effects of PS-NPs that enter the brain.

Microplastics: A Real Global Threat for Environment and Food Safety: A State of the Art Review

Microplastics are small plastic particles that come from the degradation of plastics, ubiquitous in nature and therefore affect both wildlife and humans. They have been detected in many marine species, but also in drinking water and in numerous foods, such as salt, honey and marine organisms. Exposure to microplastics can also occur through inhaled air. Data from animal studies have shown that once absorbed, plastic micro- and nanoparticles can distribute to the liver, spleen, heart, lungs, thymus, reproductive organs, kidneys and even the brain (crosses the blood-brain barrier). In addition, microplastics are transport operators of persistent organic pollutants or heavy metals from invertebrate organisms to other higher trophic levels. After ingestion, the additives and monomers in their composition can interfere with important biological processes in the human body and can cause disruption of the endocrine, immune system; can have a negative impact on mobility, reproduction and development; and can cause carcinogenesis. The pandemic caused by COVID-19 has affected not only human health and national economies but also the environment, due to the large volume of waste in the form of discarded personal protective equipment. The remarkable increase in global use of face masks, which mainly contain polypropylene, and poor waste management have led to worsening microplastic pollution, and the long-term consequences can be extremely devastating if urgent action is not taken.

Swelling-Induced Fragmentation and Polymer Leakage of Nanoplastics in Seawater

Nanoplastics (NPs) have been successively detected in different environmental matrixes and have aroused great concern worldwide. However, the fate of NPs in real environments such as seawater remains unclear, impeding their environmental risk assessment. Herein, multiple techniques were employed to monitor the particle number concentration, size, and morphology evolution of polystyrene NPs in seawater under simulated sunlight over a time course of 29 days. Aggregation was found to be a continuous process that occurred constantly and was markedly promoted by light irradiation. Moreover, the occurrence of NP swelling, fragmentation, and polymer leaching was evidenced by both transmission electron microscopy and scanning electron microscopy techniques. The statistical results of different transformation types suggested that swelling induces fragmentation and polymer leakage and that light irradiation plays a positive but not decisive role in this transformation. The observation of fragmentation and polymer leakage of poly(methyl methacrylate) and poly(vinyl chloride) NPs suggests that these transformation processes are general for NPs of different polymer types. Facilitated by the increase of surface functional groups, the ions in seawater could penetrate into NPs and then stretch the polymer structure, leading to the swelling phenomenon and other transformations.

Increased clearance of non-biodegradable polystyrene nanoplastics by exocytosis through inhibition of retrograde intracellular transport

Nanoplastics (NPs) are derived from microplastics and may cause health problems. We previously showed that 100 nm polystyrene (PS)-NPs enter cells, including mouse embryonic fibroblasts (MEFs), and their intracellular accumulation induces inflammatory and oxidative stress. Moreover, PS-NP uptake was found to occur via endocytosis, and they accumulated mostly at the juxtanuclear position, but never within the nucleus. We speculated that PS-NPs were cleared from cells when they were no longer exposed to PS-NPs. However, the effects of PS-NPs on the cellular machinery remain unknown. The accumulation of PS-NPs at the juxtanuclear position may be due to retrograde transport along microtubules. To confirm this, we treated PS-NP-exposed MEFs with inhibitors of histone deacetylase 6 (HDAC6), dynein, or microtubule polymerization and found greatly diminished intracellular and juxtanuclear accumulation. Moreover, rapid clearance of PS-NPs was observed when MEFs were treated with an HDAC6 inhibitor. PS-NPs were removed by exocytosis, as confirmed by treatment with an exocytosis inhibitor. Furthermore, inhibiting the retrograde transport of PS-NPs alleviated the activation of the antioxidant response pathway, inflammatory and oxidative stress, and reactive oxygen species generation. In summary, inhibition of the retrograde transport of non-biodegradable PS-NPs leads to their rapid export by exocytosis, which may reduce their cytotoxicity.

Spatial distribution and source identification of traditional and emerging persistent toxic substances in the offshore sediment of South Korea

While the coastal pollution of persistent toxic substances (PTSs) has been widely documented, information on offshore environments remains limited. Here, we investigated the spatial distribution and sources of PTSs in the offshore sediments (n = 34) of South Korea. Sediment samples collected from the Yellow Sea (n = 18), the South Sea (n = 10), and the East Sea (n = 6), in 2017-18 were analyzed for a total of 71 PTSs. Target compounds include 31 PCBs, 15 PAHs, 9 emerging PAHs (e-PAHs), 10 styrene oligomers (SOs), and 6 alkylphenols (APs). Sedimentary PCBs showed relatively low concentrations with no significant difference across the three seas (0.16-6.9 ng g^-1 normalized organic carbon, OC). Low-chlorinated PCBs (tri- and tetra Cl-CBs) were predominant (mean: 77%), primarily indicating atmospheric inputs. PAHs widely accumulated in the three seas with low to moderate level (22-250 ng g^-1 OC), and dominated by high molecular weight PAHs (4-6 rings). PMF analysis revealed coast-specific PAHs sources; i.e., originated from mainly coke production (77%) in the Yellow Sea, vehicle emissions (68%) in the South Sea, and fossil fuel combustion (49%) in the East Sea. SOs showed significant contamination than other PTSs, with elevated concentrations in the Yellow Sea (mean: 350 ng g^-1 OC). APs showed a similar regional distribution to SOs, but concentrations were much lower (mean: 17 ng g^-1 OC). SOs and APs seemed to be introduced from rivers and estuaries on the west coast of Korea, where industrial and municipal activities are concentrated, then might be transported to offshore through tide or currents. Overall, the novel data presented for various PTSs in offshore Korean sediments warrant the necessity of a long-term monitoring effort and urgent management practice to protect marine ecosystem.

Stress Response of Mouse Embryonic Fibroblasts Exposed to Polystyrene Nanoplastics

Polystyrene (PS) nanoplastic exposure has been shown to affect the viability of neuronal cells isolated from mouse embryonic brains. However, the viability of mouse embryonic fibroblasts (MEFs) was not affected although PS nanoplastics accumulated in the cytoplasm. It is currently unknown whether MEFs do not respond to PS nanoplastics or their cellular functions are altered without compromising viability. Here, we found that PS nanoplastics entered the cells via endocytosis and were then released into the cytoplasm, probably by endosomal escape, or otherwise remained in the endosome. Oxidative and inflammatory stress caused by intracellular PS nanoplastics induced the antioxidant response pathway and activated the autophagic pathway. However, colocalization of the autophagic marker LC3B and PS nanoplastics suggested that PS nanoplastics in the cytoplasm might interfere with normal autophagic function. Furthermore, autophagic flux could be impaired, probably due to accumulation of PS nanoplastic-containing lysosomes or autolysosomes. Intriguingly, the level of accumulated PS nanoplastics decreased during prolonged culture when MEFs were no longer exposed to PS nanoplastics. These results indicate that accumulated PS nanoplastics are removed or exported out of the cells. Therefore, PS nanoplastics in the cytoplasm affect cellular functions, but it is temporal and MEFs can overcome the stress caused by PS nanoplastic exposure.

Sandy beaches as hotspots of bisphenol A

Bisphenol A (BPA) poses a serious environmental threat and health concern. This study presents the global monitoring of BPA on oceanic sandy beaches. According to monitoring results, many beach sands contain a harmful concentrations of BPA. Likewise, styrene oligomers (SOs), anthropogenic chemicals derived from polystyrene plastics, show similar concentrations as BPA. This study shows a strong, positive correlation between BPA and SOs. The results indicate that probably BPA-containing materials including micro- and nano-plastics can be an important source of BPA to the sand beaches. Therefore, BPA presents potential health risks to people spending considerable time on the beach.

Global distribution of two polystyrene-derived contaminants in the marine environment: A review

Plastic pollution is one of the major issues impacting on the marine environment. Plastic polymers are known to leach industrial chemicals and associated contaminants. In this review, we focused on assessing the global distribution and concentration of two polystyrene-derived contaminants, hexabromocyclododecanes (HBCDs) and styrene oligomers (SOs), in marine sediments and seawater. Overall, most of the studies were carried out in Asia, North America, and Europe. Relatively high concentrations of these contaminants are generally attributed to the proximity of urban cities, plastic industries, polystyrene pollution, and aquaculture. Moreover, the concentrations in sediments are many times higher than in seawater. HBCDs were found to be a negligible risk to marine biota when compared to the ecotoxicological endpoints. However, realistic concentrations of SOs could compromise the wellbeing of certain species in highly polluted sites. The future perspectives and research were discussed.

Size-dependent cellular internalization and effects of polystyrene microplastics in microalgae P. helgolandica var. tsingtaoensis and S. quadricauda

Microplastics (MPs) are persistent contaminants in aquatic environments. Microalgae, as the main phytoplankton and primary producers, usually co-exist with MPs. Despite previous studies that have proved the interaction of MPs and microalgae, it is largely unknown whether MPs can be uptake into cells of microalgae. In this study, both marine P. helgolandica var. tsingtaoensis and freshwater microalgae S. quadricauda were respectively exposed to 10 mg/L polystyrene microbeads with five diameter sizes: 1.0, 2.0, 3.0, 4.0, and 5.0 μm. Confocal laser scanning and 3D image analysis showed that mean 24.0 % or 11.3 % cells of P. helgolandica var. tsingtaoensis contained 1.0 μm or 2.0 μm MPs after 72 h exposure. While mean 43.3 % or 15.3 % of S. quadricauda individuals engulfed 1.0 μm or 2.0 μm MPs within cells. But, none of 3.0-5.0 μm MPs were observed within algal cells. These results demonstrate the size-dependent cellular internalization of MPs in microalgae. Exposure to 1.0-2.0 μm PS MPs caused a significant reduction in the density of microalgae and influenced photosynthesis, which suggests cellular internalization of MPs can influence algal fertility and growth. This discovery first confirms cellular internalization of MPs in phytoplankton, of significance for the fate and eco-toxicity of MPs in the aquatic ecosystem.

Environmental Distribution of Styrene Oligomers (SOs) Coupled with Their Source Characteristics: Tracing the Origin of SOs in the Environment

Despite growing concerns regarding plastic additives, their environmental fate coupled with leaching from source materials are not well known. Styrene oligomers (SOs), which are unintended additives in expanded polystyrene (EPS), are estrogenic micropollutants. Here, we identified the effects of their potential sources (i.e., EPS buoy and its leachate) and environmental dilution on SO distribution within coastal sediments. SO content in fresh EPS particles was 0.1% (w/w), dominated by 2,4,6-triphenyl-hexene (ST-1), while 2,4-diphenyl-1-butene (SD-2) accounted for most of the SOs in EPS leachate, indicating its faster leachability. In lake and offshore environments, the SO composition profiles from their terrestrial inputs and inner sites were similar to those of EPS leachate; meanwhile, the exponentially decreasing SO concentration and increasing styrene trimers (STs) fraction with distance from the inner to outer sites were evident. These profiles indicated continuous SO leaching from their potential sources in the inland, followed by a change in SOs due to environmental dilution. SOs in beach sediment implied the presence of micro-sized EPS particles. We suggest the ST-1 to SD-2 ratio as an index to differentiate among freshly leached SOs (∼0.02), environmentally diluted SOs after leaching (∼0.1), SOs in fresh EPS (∼1.2), and SOs in aged EPS (> 2).

Current contamination status of traditional and emerging persistent toxic substances in the sediments of Ulsan Bay, South Korea

Contamination status of traditional and emerging persistent toxic substances (PTSs) in sediments and their major sources were investigated in Ulsan Bay, Korea. A total of 47 PTSs, including 15 traditional PAHs, ten styrene oligomers (SOs), six alkylphenols (APs), and 16 emerging PAHs (E-PAHs) were analyzed. Concentrations of traditional PAHs, SOs, and APs ranged from 35 to 1300 ng g^-1 dry weight (dw), 30 to 3800 ng g^-1 dw, and 30 to 430 ng g^-1 dw, respectively. For the last 20 years, PTSs contamination in the bay area has been improved. However, 12 E-PAHs were widely detected in sediments, with a maximum of 240 ng g^-1 dw (for benzo[e]pyrene) at the creek site. These E-PAHs seemed to originate from surrounding activities, such as biomass combustion, mobile sources, and diesel combustion. Due to environmental concerns for E-PAHs, further research on the potential toxicity, distribution, and behavior of these compounds should be implemented.

Neurotoxic potential of polystyrene nanoplastics in primary cells originating from mouse brain

Polystyrene (PS) and chemically modified compounds in the PS family have long been used in commercial and industrial fields. However, it is poorly understood whether nanoscale-PS microplastic or PS nanoplastic exposure leads to perturbations in fundamental cellular functions, such as proliferation, differentiation, and apoptosis. Herein, we cultured three types of primary cells, including mouse embryonic fibroblasts (MEFs), mixed neuronal cells isolated from embryonic cortex, and cortical astrocytes, and investigated the effects of their exposure to PS nanoplastics with a 100 nm diameter. Although PS nanoplastic exposure did not affect the viability of MEFs or astrocytes, it significantly reduced the viability of mixed neuronal cells. Consistent with the observed effect on cellular viability, levels of the apoptosis marker, cleaved caspase-3, were elevated exclusively in mixed neuronal cells. To investigate whether cells uptake PS nanoplastics into the cytoplasm, we exposed MEFs and neurons to fluorescent PS latex beads and monitored fluorescence over time. We found that PS nanoplastics were deposited and accumulated in the cytoplasm in a concentration-dependent manner. Although astrocytes were not apoptotic upon exposure to PS nanoplastics, they underwent reactive astrocytosis, with increased levels of lipocalin-2 and proinflammatory cytokines. Therefore, our findings suggested that the vulnerability of cells to the deposition and accumulation of PS nanoplastics in the cytoplasm was dependent on cell type. Furthermore, based on our data from primary cells originating from mouse brains, we suggest that reactive astrocytosis may contribute to the neuronal apoptosis seen in defective neurons with PS nanoplastics accumulated in the cell body.

Effects of polystyrene diet on Tenebrio molitor larval growth, development and survival: Dynamic Energy Budget (DEB) model analysis

The presence of polystyrene (PS) waste increases constantly. Styrofoam, the most popular form of PS, is one of the major plastic pollutants in the environment. An efficient and environmentally friendly method of PS recycling is still needed. The biodegradation of PS by insects has been presented by researchers as a promising alternative to chemical, mechanical and thermal methods. The main aim of this study was to assess the survival, growth, and development of yellow mealworms (the larvae of Tenebrio molitor) fed with PS to determine if the insects are able to use PS as a source of mass and energy. The Dynamic Energy Budget (DEB) model was used to analyze the effects of food type on the growth trajectory and metabolism of tested organisms. We investigated five possible modes of influence of PS diet on DEB model parameters including a decrease of food availability, an increase in somatic maintenance power, an increase in costs for structure, allocation of energy, and a decrease in somatic maintenance power. Our results show that changes in the development of larvae fed with PS are mainly caused by a decrease in reserves density and reaction of the organism to the insufficient food supply. The inability or difficulty in completing the life cycle of T. molitor larvae fed with PS raises doubts about the use of mealworms as an effective technology for utilizing polystyrene.

Long-term exposure to nanoplastics reduces life-time in Daphnia magna

Plastics are widely used in todays society leading to an accelerating amount of plastic waste entering natural ecosystems. Over time these waste products degrade to micro- and, eventually, nanoplastic particles. Therefore, the break-down of plastics may become a critical threat to aquatic ecosystems and several short term studies have demonstrated acute toxicity of nanoplastics on aquatic organisms. However, our knowledge about effects of chronic or life-time exposure on freshwater invertebrates remains elusive. Here, we demonstrate results from life-time exposure (103 days) of a common freshwater invertebrate, Daphnia magna, exposed to sub-lethal concentrations of polystyrene nanoparticles. 53 nm positively charged aminated polystyrene particles were lethal at concentration of 0.32 mg/L which is two magnitudes lower than previously used concentrations in short-term (24 h) tests. At this concentration the life-time of individuals was shortened almost three times. Negatively charged carboxylated 26 and 62 nm polystyrene particles, previously demonstrated to be non-toxic at 25 and 50 mg/L concentrations in short-term tests, were toxic to D. magna at all concentrations used in our long-term study. Although total reproductive output was not significantly affected at increasing concentrations of polystyrene nanoparticles, there was a decreasing trend in the number of offspring over their life-time. Hence, in order to understand how the potential future environmental problem of nanoplastic particles may affect biota, long-term or life-time studies resembling environmental concentrations should be performed in order to provide information for predictions of future scenarios in natural aquatic environments.

Large-scale monitoring and ecological risk assessment of persistent toxic substances in riverine, estuarine, and coastal sediments of the Yellow and Bohai seas

The Yellow and Bohai seas comprise one of the most rapidly developing regions in the world, but efforts to assess coastal pollution by persistent toxic substances (PTSs) on wide spatial scale are lacking. The present study aimed to (1) measure the concentrations of PTSs, such as polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and styrene oligomers (SOs) via large-scale sediment monitoring (total of 125 locations), (2) assess potential ecological risk of PTSs in sediments to coastal ecosystems, (3) estimate various sources and fresh inputs of PTSs, (4) determine distribution patterns of PTSs by human activities and land-use type, and (5) address decadal (2008-2018) changes in distributions of PTSs. The high concentrations of PAHs [> 7000 ng g^-1 dry weight (dw)] in sediments were detected in Nantong in the Yellow Sea of China (YSC) and Huludao and Qinhuangdao in the Bohai Sea (BS), whereas lesser concentrations (< 200 ng g^-1 dw) were detected in the Yellow Sea of Korea (YSK). We found relatively high concentrations of sedimentary APs and SOs in Nantong, Huludao, and Qinhuangdao from the YSC and BS regions, but corresponding concentrations were generally below < 100 ng g^-1 dw in other locations. Concentrations of PAHs at 38 locations (30% of YSC and BS) posed a potential risk to aquatic ecosystems, whereas relatively low risk concentrations occurred in all locations of YSK. The main source of PAHs (concentrated in YSC and BS) were by-products of diesel and gasoline combustion (42% of total concentration), whereas biomass combustion (24%) dominated in YSK. Fresh inputs of PTSs indicated that the generation and use of PTSs continue across all regions and locations. Among PTSs, concentrations of PAHs were significantly associated with location (p < 0.05) relative to land-use within a given region, whereas concentrations of APs and SOs showed no significant relationships (p > 0.05) among or within regions. Over time, concentrations of PAHs have generally declined, but sediment contamination has increased at some locations in China, with sources shifting from a mixture of PAHs types to those linked to diesel and gasoline combustion. Additional studies are needed on the fate and potential ecological risk posed by certain PTSs in hotspots. This is one of the first efforts providing backgrounds on PTS pollution in the large marine ecosystem of the Yellow and Bohai seas.

Effect of aging on adsorption behavior of polystyrene microplastics for pharmaceuticals: Adsorption mechanism and role of aging intermediates

In the environment, aging obviously changes physicochemical properties of microplastics (MPs), but the effects of aging process on adsorption behavior of MPs are not fully understood. In this study, the aging of polystyrene (PS) was accelerated by photo-Fenton reaction. The adsorption mechanism of different aged PS toward atorvastatin (ATV) and amlodipine (AML) and the role of PS-derived intermediates in adsorption process were investigated. Results showed that the adsorption of pristine PS toward pharmaceuticals relied on hydrophobic and π-π interaction, while for aged PS, electrostatic interaction and hydrogen bonding controlled the adsorption. The study revealed that the intermediates released from aging process in high concentration (TOC of 10 mg/L) significantly decreased the adsorption of ATV (10 mg/L) on PS (5.0 g/L) but increased the adsorption of AML (10 mg/L). However, those intermediates at environmental concentration (0.1 mg/L) exhibited low effects on adsorption of pharmaceuticals (1.0 mg/L) on MPs (0.5 g/L of PS). The impact mainly depended on electrostatic interaction between MPs and aging intermediates. Besides, the adsorption of low-degree aged PS was more susceptible to the aging intermediates than that of high-degree aged ones. These findings highlight significant implication of MP-derived intermediates in aquatic environments.

Marine Debris Polymers on Main Hawaiian Island Beaches, Sea Surface, and Seafloor

Polymeric differences of plastic debris were assessed across four compartments of the Main Hawaiian Islands (sea surface, windward beaches, leeward beaches, and seafloor) to better describe sources and fate. Plastic debris pieces (n = 4671) were collected from 11 beaches, three sea surface tows, and three seafloor dives. Fourier transform infrared spectroscopy identified the polymers of 3551 pieces. Significant differences (p < 0.05) in concentration, types, polymer composition, and weathering were found among four compartments. Windward beaches had 1-2 orders of magnitude more plastic pollution (g/m²) than leeward beaches, despite smaller human populations on windward sides. Sea surface and windward beaches were dominated by severely weathered, less dense floating polymers (polyethylene and polypropylene comprised 92.7 and 93.5% on average, respectively, of the total debris mass), while leeward beaches and the seafloor debris consisted of less weathered and more dense sinking polymers (e.g., 41.0 and 44.7% of total mass consisted of the sum of polystyrene, nylon, cellulose acetate, polyethylene terephthalate, and additive-masked debris). These results are some of the first to provide evidence of polymeric stratification in the marine environment and emphasize that the majority of marine debris in Hawaii is floating in from distant sources rather than from Hawaii's residents or tourists.

Physicochemical properties of styrene oligomers in the environment

Currently, styrene oligomers (SOs) are persistent contaminants that are present in the environment globally. SOs are artificial substances originating from styrene-based polymer materials, mainly including PS plastic, resin, and rubber. However, the behavior of SOs in the environment is not well-understood yet due to the scarcity of experimental data. The objective of this study was to use in-silico tool to estimate key physicochemical properties of these SOs. The US EPA EPI suite program was used to predict SOs' physicochemical properties including solubility, vapor pressure, LogKow, Henry's constant, LogKoc, and fugacity-based multimedia mass balance. Although styrene monomer (SM) and SOs have structural similarity, the physicochemical properties of SOs are significantly different from those of SM, a precursor of SOs. In particular, it is estimated that as much as the heavy molecular weight, most SOs persist for comparable periods of time in a sandy environment. Although there is uncertainty, this preliminary in-silico study provides a sufficient reason to assure an experimental study to better determine properties of SOs.

Plastic-derived contaminants in sediments from the coastal zone of the southern Baltic Sea

Plastics may leach out harmful chemicals, such as plastic additives and monomers, to the environment. This study focused on three intrinsic plastic-derived contaminants, viz. bis(2-ethylhexyl) phthalate (DEHP), bisphenol A (BPA), and styrene, based on surface (0-5 cm) sediment samples taken from transition areas located in the human-impacted coastal zone of the southern Baltic Sea. The concentrations of DEHP in the sediments from the Gulf of Gdańsk and the Szczecin Lagoon ranged from 38 to 228 ng/g d.w. and from 494 to 807 ng/g d.w., respectively. The levels of sedimentary BPA varied from <1 to 32 ng/g d.w., whereas styrene was not detected in any of the samples studied. Compared to worldwide data, the levels of plastic-derived contaminants in the sediments from the Gulf of Gdańsk and the Szczecin Lagoon were generally not high. However, according to sediment quality guidelines, some adverse environmental effects are probable.

Occurrence and bioaccumulation of persistent toxic substances in sediments and biota from intertidal zone of Abu Ali Island, Arabian Gulf

North Abu Ali Island is contaminated by crude oil from exogenous sources with a variety of persistent toxic substances (PTSs) being input into intertidal sediments. We detected an array of PTSs in sediments and benthic biota off north Abu Ali Island (Arabian Gulf), including 35 polycyclic aromatic hydrocarbons (PAHs), 6 alkylphenols (APEOs), 10 styrene oligomers (SOs), and tributyltin. The PTS concentrations were generally greater than those reported in other areas of Arabian Gulf. PAHs mainly originated from petrogenic sources, and APEOs and SOs seem to be of recent origin. Field-based biota-sediment accumulation factors (BSAF) varied by taxa and compounds, but clearly depended on the log K_ow values of individual compounds. Some PTSs exceeded the established guidelines for sediments and biota; we found particularly great BSAFs for alkyl-naphthalenes (C1- and C2-), nonylphenol monoethoxylates, and 2,4,6-triphenyl-1-hexene. Remediation will require on-site clean-up of toxic chemicals together with immediate efforts on preventing input of current pollution sources in the given area.

Evidence of transport of styrene oligomers originated from polystyrene plastic to oceans by runoff

This study demonstrates for the first time that styrene oligomers (SOs), which are indicators of polystyrene (PS) plastic contamination in the environment, are transported from land to the ocean. Samples of sand and seawater were taken from the coastline of the Tokyo Bay over the past four years, and all samples of both sand and seawater were found to contain SOs such as styrene monomer (SM), styrene dimers (SD), and styrene trimers (ST), with the concentration distributions of these being in the order of ST > SD > SM. The concentrations of these SOs are linearly proportional to monthly precipitation. These results indicate that various land-based SOs sources are connected with the estuary, a substantial amount of which are transported into Tokyo Bay through runoff as overland flow. As a result, runoff by precipitation is a potential transport pathway of land-based SOs sources. This finding is of interest in terms of both the extent of PS plastic pollution and the transport of SOs to the ocean. CAPSULE ABSTRACT: The assessment of the transport of styrene oligomers (SOs) in the coastal environment is performed.

Nanoplastics formed during the mechanical breakdown of daily-use polystyrene products

Large amounts of plastics are released into the environment every day. These released plastics have a clearly documented negative effect on wildlife. Much research attention has been given to large plastic pieces and microplastics. However, if the breakdown of plastics is a continous process, eventually nanoplastics will be produced. Nanoplastics will affect wildlife differently from larger plastic pieces. We have studied the products formed by the mechanical breakdown of two commonly used polystyrene products, takeaway coffee cup lids and expanded polystyrene foam. After breakdown using a food processor, we characterized the breakdown products using seven different methods and found nanosized polystyrene particles with different shapes and negative or nearly neutral surface charges. These results clearly demonstrate that daily-use polystyrene products can break down into nanoparticles. Model polystyrene particles with different sizes and surface modifications have previously been shown to have different negative effects on wildlife. This indicates that breakdown nanoparticles might have the potential to cause cocktail effects in nature.

Marine microplastics bound dioxin-like chemicals: Model explanation and risk assessment

Microplastics have become one of the most pervasive emerging pollutants in the marine environment because of their wide occurrence and high sorption ability for hydrophobic organic contaminants (HOCs). Among the associated HOCs, dioxin-like chemicals (DLCs) can pose severe health risks; however, information on effects of microplastics bound DLCs is lacking. To fill this knowledge gap, this study integrated chemical analysis and in vitro bioassays to elucidate the potential dioxin-like effects of microplastics bound DLCs. Chemical analysis results demonstrated that styrofoams possessed significantly greater DLCs than other coastal or open ocean plastic particles. This was probably due to the presence of additives and greater sorption ability of expanded polystyrene. However, styrofoams did not show as strong dioxin-like effects as predicted by the bioanalysis equivalent model in bioassays. This could be attributed to the decreased DLC bioavailability and increased competition with the presence of styrene oligomers. Besides, bioassay results also demonstrated that aging increased the associated DLC concentrations, since extra sorption from surrounding environment occurred during prolonged retention periods. Finally, it was estimated that the leaching of DLCs could induce dioxin-like effects in marine organisms under 100% (11/11) and 18% (2/11) scenarios for aged pellets and styrofoams through aqueous or dietary exposures.

Floating plastics in Adriatic waters (Mediterranean Sea): From the macro- to the micro-scale

Macro- and microplastics abundances were determined in the Adriatic Sea following the MSFD TG10 protocol. The studied areas included populated gulfs, river outlets and offshore waters in five Adriatic countries. The use of small ships enabled us to detect small sized plastics (2.5-5 cm) and record average macroplastics densities of 251 ± 601 items km^-2, one order of magnitude higher than previously considered. Results from manta net tows for microplastics revealed an average abundance of 315,009 ± 568,578 items km^-2 (217 ± 575 g km^-2). We found significantly higher microplastics abundances in nearshore (≤4 km) than in offshore waters (>4 km) and this trend seems to affect also the small sized macro plastic fragments (2.5-5 cm). The dominant polymers were polyethylene and polypropylene while the presence of some rare polymers and waxes used in food and dentistry indicated waste water treatment plants as potential sources of microplastics.

The Microbial Production of Polyhydroxyalkanoates from Waste Polystyrene Fragments Attained Using Oxidative Degradation

Excessive levels of plastic waste in our oceans and landfills indicate that there is an abundance of potential carbon sources with huge economic value being neglected. These waste plastics, through biological fermentation, could offer alternatives to traditional petrol-based plastics. Polyhydroxyalkanoates (PHAs) are a group of plastics produced by some strains of bacteria that could be part of a new generation of polyester materials that are biodegradable, biocompatible, and, most importantly, non-toxic if discarded. This study introduces the use of prodegraded high impact and general polystyrene (PS0). Polystyrene is commonly used in disposable cutlery, CD cases, trays, and packaging. Despite these applications, some forms of polystyrene PS remain financially and environmentally expensive to send to landfills. The prodegraded PS0 waste plastics used were broken down at varied high temperatures while exposed to ozone. These variables produced PS flakes (PS1⁻3) and a powder (PS4) with individual acid numbers. Consequently, after fermentation, different PHAs and amounts of biomass were produced. The bacterial strain, Cupriavidus necator H16, was selected for this study due to its well-documented genetic profile, stability, robustness, and ability to produce PHAs at relatively low temperatures. The accumulation of PHAs varied from 39% for prodegraded PS0 in nitrogen rich media to 48% (w/w) of dry biomass with the treated PS. The polymers extracted from biomass were analyzed using nuclear magnetic resonance (NMR) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) to assess their molecular structure and properties. In conclusion, the PS0⁻3 specimens were shown to be the most promising carbon sources for PHA biosynthesis; with 3-hydroxybutyrate and up to 12 mol % of 3-hydroxyvalerate and 3-hydroxyhexanoate co-monomeric units generated.

Styrene impairs normal embryo development in the Mediterranean mussel (Mytilus galloprovincialis)

This study analysed the effects of styrene, a main monomer in plastic manufacturing and acknowledged to be amongst the most common plastic leachates, on early embryo development of the Mediterranean mussel. Embryotoxicity tests showed that styrene impaired normal embryo development at concentrations (0.01 μg/L-1 mg/L) encompassing the environmental range. Occurrence of normal D-veligers was significantly reduced up to 40% of the total, and larval size was reduced of about 20%. D-veligers grown in the presence of styrene (0.1 and 10 μg/L) showed significant reduction of total Multixenobiotic resistance (MXR) efflux activity that was not apparently related to transcriptional expression of genes encoding P-glycoprotein (ABCB) and Mrp (ABCC), the two main ABC transporters of embryonal MXR system. Indeed, ABCB transcription was not affected by styrene, while ABCC was up-regulated. At these same concentrations, transcriptional profiles of 15 genes underlying key biological functions in embryo development and potential targets of adverse effects of styrene were analysed. Main transcriptional effects were observed for genes involved in shell biogenesis and lysosomal responses (down-regulation), and in neuroendocrine signaling and immune responses (up-regulation). On the whole, results indicate that styrene may affect mussel early development through dysregulation of gene transcription and suggest the possible conservation of styrene mode of action across bivalve life cycle and between bivalves and humans, as well as through unpredicted impacts on protective systems and on shell biogenesis.

Selective conversion of polystyrene into renewable chemical feedstock under mild conditions

The aim of this work is to prepare catalysts for energy efficient conversion of polystyrene (PS) and its waste into valuable products with high conversion at 250 °C. The FeCo/Alumina bimetallic catalyst was synthesized by aqueous impregnation and structurally determined using scanning-transmission electron microscopy, temperature programmed desorption, X-ray diffraction, and X-ray photoelectron spectroscopy. Successfully, we have achieved up to 91% liquid yield with selectivities for styrene monomer (SM) up to 45 wt% and ethylbenzene (EB) up to 55 wt%, depending on the exposure time at 250 °C by FeCo/Alumina which is comparable to those of reactions at high temperatures (≥350 °C). Further increase of catalyst loadings from 200 to 400 mg also led to the decrease in styrene yield and increase in ethylbenzene yield. The analysis of the resulting clear liquid by gas chromatography/mass spectrometry (GC/MS) indicates the generation of products in the gasoline range.

Integrated assessment of persistent toxic substances in sediments from Masan Bay, South Korea: Comparison between 1998 and 2014

Complexity of anthropogenic influences on coastal ecosystems necessitates use of an integrated assessment strategy for effective interpretation and subsequent management. In this study a multiple lines of evidence (LOE) approach for sediment assessment, that combined use of chemistry, toxicity, and benthic community structure in the sediment quality triad was used to assess spatiotemporal changes and potential risks of persistent toxic substances (PTSs) in sediments of Masan Bay highlighting "long-term changes" between 1998 and 2014. Specific target objectives encompassed sedimentary PTSs (PAHs, alkylphenols (APs), and styrene oligomers), potential aryl hydrocarbon receptor (AhR; H4IIE-luc assay)- and estrogen receptor (ER; MVLN assay)-mediated activities, and finally several ecological quality (EcoQ) indices of benthic community structure. Concentrations of target PTSs in Masan Bay sediments were generally less by half in 2014 compared to those measured in 1998. Second, AhR-mediated potencies in sediments also decreased during this time interval, whereas ER-mediated potencies increased (+3790%), indicating that there has been substantial ongoing, input of ER agonists over the past 16 years. Potency balance analysis revealed that only 3% and 22% of the AhR- and ER-mediated potencies could be explained by identified known chemicals, such as PAHs and APs, respectively. This result indicated that non-targeted AhR and ER agonists had a considerable presence in the sediments over time. Third, EcoQ indices tended to reflect PTSs contamination in the region. Finally, ratio-to-mean values obtained from the aforementioned three LOEs indicated that quality of sediments from the outer region of the bay had recovery more during the period of 16-years than did the inner region. Overall, the results showed that even with the progress supported by recent efforts from the Korean governmental pollution control, PTSs remain a threat to local ecosystem, especially in the inner region of Masan Bay.

Mapping coastal marine debris using aerial imagery and spatial analysis

This study is the first to systematically quantify, categorize, and map marine macro-debris across the main Hawaiian Islands (MHI), including remote areas (e.g., Niihau, Kahoolawe, and northern Molokai). Aerial surveys were conducted over each island to collect high resolution photos, which were processed into orthorectified imagery and visually analyzed in GIS. The technique provided precise measurements of the quantity, location, type, and size of macro-debris (>0.05m²), identifying 20,658 total debris items. Northeastern (windward) shorelines had the highest density of debris. Plastics, including nets, lines, buoys, floats, and foam, comprised 83% of the total count. In addition, the study located six vessels from the 2011 Tōhoku tsunami. These results created a baseline of the location, distribution, and composition of marine macro-debris across the MHI. Resource managers and communities may target high priority areas, particularly along remote coastlines where macro-debris counts were largely undocumented.

The Hidden Microplastics: New Insights and Figures from the Thorough Separation and Characterization of Microplastics and of Their Degradation Byproducts in Coastal Sediments

The environmental pollution by plastic debris directly dispersed in or eventually reaching marine habitats is raising increasing concern not only for the vulnerability of marine species to ingestion and entanglement by macroscopic debris, but also for the potential hazards from smaller fragments down to a few micrometer size, often referred to as "microplastics". A novel procedure for the selective quantitative and qualitative determination of organic solvent soluble microplastics and microplastics degradation products (<2 mm) in shoreline sediments was adopted to evaluate their concentration and distribution over the different sectors of a Tuscany (Italy) beach. Solvent extraction followed by gravimetric determination and chemical characterization by FT-IR, Pyrolysis-GC-MS, GPC and ¹H NMR analyses showed the presence of up to 30 mg microplastics in 1 kg sand, a figure corresponding to about 5.5 g of generally undetected and largely underestimated microplastics in the upper 10 cm layer of a square meter of sandy beach ! The extracted microplastic material was essentially polystyrene and polyolefin byproducts from oxidative degradation and erosion of larger fragments, with accumulation mainly above the storm berm. Chain scission and oxidation processes cause significant variations in the physical and chemical features of microplastics, promoting their adsorption onto sand particles and thus their persistence in the sediments.

Adsorption of perfluoroalkyl substances on microplastics under environmental conditions

Plastic debris has become an environmental problem during recent years. Among the plastic debris, microplastics (<5 mm; MPLs) imply an extra problem due to their capacity to enter into the fauna through ingestion. In this work, we study the capacity of three MPLs, that include high-density polyethylene (HDPE), polystyrene (PS) and polystyrene carboxylate (PS-COOH), to sorb 18 perfluoroalkyl substances (PFASs; including carboxylic acids, sulphonates and one sulphonamide) from the surrounding waters (freshwater and seawater). Conclusions drawn from the results are that perfluoro sulphonates and sulphonamides have more tendency to be sorbed onto MPLs. In addition, PS and PS-COOH have more affinity for PFASs than HDPE. Finally, the increment of conductivity and pH of the water decreases the exposure time that is necessary to reach equilibrium. However, the presence of salts decreases the tendency of PFASs to be sorbed onto plastic surfaces. These results highlight the problem associated with the presence of MPLs in inland and marine waters since toxic compounds can be sorbed onto surrounding plastics that could be ingested by aquatic fauna.

Qualitative assessment to determine internal and external factors influencing the origin of styrene oligomers pollution by polystyrene plastic in coastal marine environments

The objective of this study is to investigate the qualitative contribution of internal and external factors of the area contaminated by polystyrene (PS) in coastal marine environments. This study is based on the extensive results of monitoring the styrene oligomers (SOs) present in sand and seawater samples along various coastlines of the Pacific Ocean. Here, anthropogenic SOs is derived from PS during manufacture and use, and can provide clues about the origin of SOs by PS pollution. The monitoring results showed that, if the concentration of SOs in water is higher than those concentrations in beach sand, this area could be affected by PS plastic caused by an external factor. On the other hand, if the concentration of SOs is higher in the beach sand, the region can be mainly influenced by PS plastic derived from its own area. Unlike the case of an external factor, in this case (internal influence), it is possible to take policy measures of the area itself for the PS plastic problem. Thus, this study is motivated by the need of policy measures to establish a specific alternative to the problems of PS plastic pollution in ocean environments.

Monitoring of styrene oligomers as indicators of polystyrene plastic pollution in the North-West Pacific Ocean

Styrene oligomers (SOs) as global contaminants are an environmental concern. However, little is known on the distribution of SOs in the ocean. Here, we show the distribution of anthropogenic SOs generated from discarded polystyrene (PS) plastic monitored from the coastal ocean surface waters (horizontal distribution) and deep seawaters (vertical distribution) in the North-West Pacific Ocean. SOs concentrations in surface seawater and deep seawater ranged from 0.17 to 4.26 μg L^-1 (total mean: 1.48 ± 1.23 μg L^-1) and from 0.31 to 4.31 μg L^-1 (total mean: 1.32 ± 0.87 μg L^-1), respectively. Since there is no significant difference in the mean concentrations, SOs seems to be spread across marine environment selected in this study. Nevertheless, regional SOs appears to persist to varying degrees with their broad horizontal and vertical distribution in the ocean. Each horizontal and vertical distribution of SOs differs by approximately 1.95-2.57 times, probably depending on the events of weather and global ocean circulation. These results provide the distribution pattern of SOs for assessing environmental pollution arising from PS plastic.

Long-term changes in distributions of dioxin-like and estrogenic compounds in sediments of Lake Sihwa, Korea: Revisited mass balance

In the late 1990s, severe pollution by persistent organic contaminants (POCs) was observed in Lake Sihwa by use of a combination of instrumental analyses and in vitro bioassays. To determine long-term changes (>15-year gaps) in distributions of POCs and their potential toxic potencies in the given region, sediment assessments were reconducted. Target chemicals include polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and recently reported emerging chemicals, styrene oligomers (SOs). We employed in vitro bioassays (such as H4IIE-luc and MVLN) to determine potential sediment toxicities. The reduction rates of mean concentrations of APs and SOs in sediments between the two sampling years (1998 vs. 2015) were estimated to be 99% and 67%, respectively. Although APs and SOs significantly declined over the 15-year period, concentrations of PAHs were consistent. Results of the bioassays were consistent with the instrumental data, with relatively great concentrations of all target compounds being detected, particularly in inland creeks. Compositions of all target compounds exhibited changes in homologue patterns over the 15 years considered. This result indicated varying and/or continuing sources in this region. In particular, PAHs were dominated by higher-molecular-weight PAHs (e.g., benzo[g,h,i]perylene and benzo[b]fluoranthene) in recent years. This result might indicate consumption of oil-related fuels. Quantitative potency balance analysis revealed that concentrations of instrumentally-derived equivalents accounted for as little as 18.5% of bioassay-derived equivalents, which indicated significant amounts of unknown and/or unmeasured compounds were present. The present study documented the continuing severe pollution by selected POCs in the Lake Sihwa region over the last 15 years, indicating a lack of management in the area studied.

Distributions of persistent organic contaminants in sediments and their potential impact on macrobenthic faunal community of the Geum River Estuary and Saemangeum Coast, Korea

Over the last 30 years, the Geum River Estuary and Saemangeum Coast have been subject to major environmental changes, including dike construction, reclamation, and development of industrial complexes. This study aimed to: 1) investigate the occurrence of polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), and styrene oligomers (SOs), 2) identify the sources of sedimentary organic matter, and 3) determine key environmental factors controlling the macrozoobenthos community structure. A total of 58 surface sediments were collected from the estuary and coastal area in 2014. Specific persistent organic contaminants (POCs), including 24 PAHs, 6 APs, and 10 SOs were measured. PAHs, APs, and SOs were detected in the sediments at all sites, with concentrations varying among sites. Although POCs concentrations were generally below the Canadian sediment quality guidelines, relatively greater concentrations of POCs were found at some sites adjacent to industrial complexes and the estuarine area. Sediment organic carbon, total nitrogen, and the stable carbon isotope ratio (δ¹³C) were determined. Some sites near watergate had about 2-3‰ lighter δ¹³C values compared to other areas, indicating that these sites are affected by terrestrial organic matter. The number of species in the macrofaunal community was significantly correlated with δ¹³C values (p < 0.001), positively, suggesting that the origin of sedimentary organic matter is important for controlling the macrozoobenthos distribution. Overall, this research provides information about the level and sources of sediment pollution, the origins of organic matter, and the relationships with the macrofaunal community.

Are styrene oligomers in coastal sediments of an industrial area aryl hydrocarbon-receptor agonists?

Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5-8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740 ng g(-1) dry mass (dm), while lesser concentrations were found in inner (mean = 33 ng g(-1) dm) and outer regions (mean = 25 ng g(-1) dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (<1%), primarily due to their smaller RePs. Overall, the present study provides information on distributions and AhR binding affinities for SOs as baseline data for degradation products of polystyrene plastic in the coastal environment.

The flip-or-flop boutique: Marine debris on the shores of St Brandon's rock, an isolated tropical atoll in the Indian Ocean

Isolated coral atolls are not immune from marine debris accumulation. We identified Southeast Asia, the Indian sub-continent, and the countries on the Arabian Sea as most probable source areas of 50 000 items on the shores of St. Brandon's Rock (SBR), Indian Ocean. 79% of the debris was plastics. Flip-flops, energy drink bottles, and compact fluorescent lights (CFLs) were notable item types. The density of debris (0.74 m(-)(1) shore length) is comparable to similar islands but less than mainland sites. Intact CFLs suggests product-facilitated long-range transport of mercury. We suspect that aggregated marine debris, scavenged by the islands from currents and gyres, could re-concentrate pollutants. SBR islets accumulated debris types in different proportions suggesting that many factors act variably on different debris types. Regular cleaning of selected islets will take care of most of the accumulated debris and may improve the ecology and tourism potential. However, arrangements and logistics require more study.

Global styrene oligomers monitoring as new chemical contamination from polystyrene plastic marine pollution

Polystyrene (PS) plastic marine pollution is an environmental concern. However, a reliable and objective assessment of the scope of this problem, which can lead to persistent organic contaminants, has yet to be performed. Here, we show that anthropogenic styrene oligomers (SOs), a possible indicator of PS pollution in the ocean, are found globally at concentrations that are higher than those expected based on the stability of PS. SOs appear to persist to varying degrees in the seawater and sand samples collected from beaches around the world. The most persistent forms are styrene monomer, styrene dimer, and styrene trimer. Sand samples from beaches, which are commonly recreation sites, are particularly polluted with these high SOs concentrations. This finding is of interest from both scientific and public perspectives because SOs may pose potential long-term risks to the environment in combination with other endocrine disrupting chemicals. From SOs monitoring results, this study proposes a flow diagram for SOs leaching from PS cycle. Using this flow diagram, we conclude that SOs are global contaminants in sandy beaches around the world due to their broad spatial distribution.