Exposure to polystyrene nanoplastics and PCB77 induced oxidative stress, histopathological damage and intestinal microbiota disruption in white hard clam Meretrix lyrata.

The toxic effects of organic pollutants and nanoplastics on fish have been extensively studied, but there is limited research available on their combined toxicity to bivalves. This research aimed to investigate the accumulation and ecotoxicological impacts such as antioxidant capacity, histopathology and intestinal microbiota in white hard clam Meretrix lyrata, resulting from 7 days of single and mixture exposure to 3,3',4,4'-tetrachlorobiphenyl (PCB77, 0.1 mg/L) and polystyrene nanoplastics (PS-NPs, 80 nm, 1 mg/L). Our findings revealed that PS-NPs accumulated in various tissues such as the intestine, gill, mantle, foot, and siphon. And when compared to the PCB-PSNPs (PP) co-exposure group, the intestinal fluorescence intensity mediated by plastic particles in the PS-NPs (PS group) was significantly higher. The gill, digestive gland, and intestine were all damaged to varying extent by single exposure to PS-NPs or PCB77, according to histopathological analysis, which was aggravated by PP group. Moreover, the co-exposure induced a higher level of oxidative stress, which reflected by increase of activities of superoxide dismutase, catalase, glutamate oxaloacetate transaminase and glutamic-pyruvic transaminase and malondialdehyde content. In addition, the intestine microbial composition was dramatically altered by the combined exposure, reducing the abundance of probiotics such as Firmicutes, thereby posing a great threat to the health and metabolism of M. lyrata. In conclusion, our findings showed that PS-NPs and PCB77 co-exposure induced a higher toxicity to M. lyrata, including histopathological changes, altered antioxidant capacity and intestinal microbiota disruption. This study provides novel insights into PCB77 and PS-NPs' combined toxicity to marine organisms and its underlying molecular mechanisms of ecotoxicological effects.

Single and combined toxicity of polystyrene nanoplastics and PCB-52 to the aquatic duckweed Spirodela polyrhiza.

As nanoplastics and persistent organic pollutants are broadly distributed in aquatic ecosystems and pose a potential threat to ecosystem, most pertinent studies have focused on aquatic animals, while studies on freshwater plants have been rarely reported. Therefore, we analyzed the single and combined toxicological impacts of various concentrations of 80 nm polystyrene nanoplastics (PS-NPs) including 0.5, 5, 10, and 20 mg/L and polychlorinated biphenyl-52 (PCB-52, 2,2',5,5'- tetrachlorobiphenyl) at 0.1 mg/L on the aquatic plant Spirodela polyrhiza (S. polyrhiza) after a 10-day hydroponic experiment. Laser confocal scanning microscopy (LCSM) showed the accumulation of PS-NPs mainly in the root surface and the lower epidermis of leaves, and the enrichment of PS-NPs was aggravated by the presence of PCB-52. PS-NPs at 10 mg/L and 20 mg/L alone or in combination with PCB-52 notably inhibited the growth of S. polyrhiza, reduced the synthesis of chlorophylls a and b, and increased the activities of superoxide dismutase (SOD) and peroxidase (POD) as well as malondialdehyde (MDA) levels, and induced osmotic imbalance (soluble protein and soluble sugar contents) (p < 0.05). However, a single treatment with low levels of PS-NPs had positive effects on the growth (0.5 mg/L) and photosynthetic systems (0.5, 5 mg/L) of S. polyrhiza, while co-exposure exacerbated the damaging impacts of PS-NPs on the antioxidant defense system of S. polyrhiza, which was more pronounced in the roots. Furthermore, correlation analysis revealed that plant growth parameters were positively correlated with chlorophyll a and b content and negatively correlated with soluble sugars, antioxidant enzymes, lipid peroxidation, and carotenoid content (p < 0.05). These results provide data to improve the understanding of the single and combined ecotoxicological effects of nanoplastics and polychlorinated biphenyls (PCBs) in aquatic plants and their application in phytoremediation measures.

Trophic transfer of nanoplastics and di(2-ethylhexyl) phthalate in a freshwater food chain (Chlorella Pyrenoidosa-Daphnia magna-Micropterus salmoides) induced disturbance of lipid metabolism in fish.

Nanoplastics and di(2-ethylhexyl) phthalate (DEHP) are ubiquitous emerging contaminants that are transferred among organisms through food chain in the ecosystem. This study evaluated the trophic transfer of polystyrene nanoplastics (PSNPs) and DEHP in a food chain including Chlorella pyrenoidosa, Daphnia magna and Micropterus salmoides (algae-crustacean-fish) and lipid metabolism at a higher trophic level in fish. Our results showed that the PSNPs and DEHP accumulated in C. pyrenoidosa or D. magna were transferred to the M. salmoides, of which the DEHP were not biomagnified, while the PSNPs were trophically amplified by the food chain. It is suggested that more PSNPs might be accumulated by higher level consumers in a longer food chain. Additionally, the trophic transfer of PSNPs and DEHP resulted in antioxidant response and histopathological damage in M. salmoides. Moreover, the lipid biochemical parameters and lipid metabolism related genes (fasn, hsl, cpt1a, atgl, apob, fabp1, lpl, cetp) of M. salmoides were significantly affected, which indicated disturbance of lipid metabolism. This study offers great insight into the transfer of contaminants by trophic transfer and their negative effects on organisms at higher trophic levels, which cause human exposure to MNPs and organic contaminants in the ecosystem.

Combined exposure to polystyrene nanoplastics and bisphenol A induces hepato- and intestinal-toxicity and disturbs gut microbiota in channel catfish (Ictalurus punctatus).

The widespread consumption of nanoplastics (NPs) and bisphenol A (BPA) affected the aquatic ecosystem and imposed risks to the safety of aquatic organisms. This study was aimed at assessing the ecotoxicological effects of single and combined exposure to BPA and polystyrene nanoplastics (PSNPs) on the channel catfish (Ictalurus punctatus). A total of 120 channel catfish were separated into four groups with triplicate (each contains 10 fish) and exposed to chlorinated tap water (control group), PSNP single exposure (0.3 mg/L), BPA single exposure (500 µg/L) and PSNPs (0.3 mg/L) + BPA (500 µg/L) co-exposure for 7 days. Our results showed a relatively higher intestinal accumulation of PSNPs in co-exposure group, compared to PSNP single exposure group. Histopathological analysis showed that single exposure to PSNPs and BPA caused breakage of intestinal villi and swelling of hepatocytes in channel catfish, while the co-exposure exacerbated the histopathological damage. In addition, co-exposure significantly increased SOD, CAT activities and MDA contents in the intestine and liver, inducing oxidative stress. In terms of immune function, the activities of ACP and AKP were significantly decreased. The expressions of immune-related genes such as IL-1ß, TLR3, TLR5, hepcidin and ß-defensin were significantly up-regulated, and the expression of IL-10 was down-regulated. Additionally, the co-exposure significantly altered the composition of the intestinal microbiota, leading to an increase in the Shannon index and a decrease in the Simpson index. In summary, this study revealed that mixture exposure to PSNPs and BPA exacerbated toxic effects on histopathology, oxidative stress, immune function and intestinal microbiota in channel catfish. It emphasized the threat of NPs and BPA to the health of aquatic organisms and human food safety, with a call for effective ways to regulate the consumption of these anthropogenic chemicals.

Interactive effects of polystyrene nanoplastics and 6:2 chlorinated polyfluorinated ether sulfonates on the histomorphology, oxidative stress and gut microbiota in Hainan Medaka (Oryzias curvinotus).

Nanoplastics adsorb surrounding organic contaminants in the environment, which alters the physicochemical properties of contaminants and affects associated ecotoxicological effects on aquatic life. The current work aims to explore the individual and combined toxicological implications of polystyrene nanoplastics (80 nm) and 6:2 chlorinated polyfluorinated ether sulfonate (Cl-PFAES, trade name: F-53B) in an emerging freshwater fish model Hainan Medaka (Oryzias curvinotus). Therefore, O. curvinotus were exposed to 200 µg/L of PS-NPs or 500 µg/L of F-53B in the single or mixture exposure for 7 days to investigate the effects on fluorescence accumulation, tissue damage, antioxidant capacity and intestinal flora. The PS-NPs fluorescence intensity was significantly higher in the single exposure treatment than it in combined exposure treatment (p < 0.01). Histopathological results showed that exposure to PS-NPs or F-53B inflicted varying degree of damages to the gill, liver, and intestine, and these damage were also present in the corresponding tissues of the combined treatment group, illustrating a stronger extent of destruction of these tissues by the combined treatment. Compared to the control group, combined exposure group elevated the malondialdehyde (MDA) content, superoxide dismutase (SOD) and catalase (CAT) activities except in the gill. In addition, the adverse contribution of PS-NPs and F-53B on the enteric flora in the single and combined exposure groups was mainly characterised in the form of reductions in the number of probiotic bacteria (Firmicutes) and this reduction was aggravated by the combined exposure group. Collectively, our results indicated that the toxicological effects of PS-NPs and F-53B on pathology, antioxidant capacity and microbiomics of medaka may be modulated by the interaction of two contaminants with mutually interactive effects. And our work offers fresh information on the combined toxicity of PS-NPs and F-53B to aquatic creatures along with a molecular foundation for the environmental toxicological mechanism.

Parental exposure to polystyrene nanoplastics and di(2-ethylhexyl) phthalate induces transgenerational growth and reproductive impairments through bioaccumulation in Daphnia magna.

The ubiquitous presence of polystyrene nanoplastics (PSNPs) and di(2-ethylhexyl) phthalate (DEHP) in the aquatic environment may cause unpredictable negative effects on aquatic organisms and even continue to the offspring. This study assessed the transgenerational impacts of parental exposure to PSNPs and DEHP over four generations (F0-F3) of Daphnia magna. A total of 480 D. magna larvae (F0, 24 h old) were divided into four groups with six replicates (each of them contains 20 D. magna) and exposed with dechlorinated tap water (control), 1 mg/L PSNPs, 1 µg/L DEHP, and 1 mg/L PSNPs + 1 µg/L DEHP (PSNPs-DEHP) until spawning begins. Subsequent to exposure, all the surviving F1 offspring were transferred to new water and continued to be cultured until the end of F3 generation births in all groups. The results showed that the PSNPs accumulated in F0 generation and were inherited into F1 and F2 generations, and disappeared in F3 generation in PSNPs and PSNPs-DEHP groups. However, the accumulation of DEHP lasted from F0 generation to F3 generation, despite a significant decline in F2 and F3 generations in DEHP and PSNPs-DEHP groups. The accumulation of PSNPs and DEHP caused overproduction of reactive oxygen species in F0-F2 generations and fat deposition in F0-F3 generations. Additionally, single and in combination parental exposure to PSNPs and DEHP induced regulation of growth-related genes (cyp18a1, cut, sod and cht3) and reproduction-related genes (hr3, ftz-f1, vtg and ecr) in F0-F3 generations. Survival rates were decreased in F0-F1 generations and recovered in F2 generation in all treatment groups. Furthermore, the spawning time was prolonged and the average number of offspring was increased in F1-F2 generaions as a defense mechanism against population mortality. This study fosters a greater comprehension of the transgenerational and reproductive effects and associated molecular mechanisms in D. magna.

Polystyrene nanoplastics' accumulation in roots induces adverse physiological and molecular effects in water spinach Ipomoea aquatica Forsk.

The ubiquity of plastic pollution has emerged as a perplexing issue for aquatic and terrestrial plants. To assess the toxic effects of polystyrene NPs (PS-NPs, 80 nm), we conducted a hydroponic experiment in which water spinach (Ipomoea aquatica Forsk) was subjected to low (0.5 mg/L), medium (5 mg/L), and high (10 mg/L) concentrations of fluorescent PS-NPs for 10 days to examine their accumulation and transportation in water spinach and associated impacts on growth, photosynthesis, antioxidant defense systems. Laser confocal scanning microscopy (LCSM) observations at 10 mg/L PS-NPs exposure indicated that PS-NPs only adhered to the root surface of water spinach and were not transported upward, indicating that short-term exposure to high concentrations of PS-NPs (10 mg/L) did not cause the internalization of PS-NPs in the water spinach. However, this high concentration of PS-NPs (10 mg/L) discernibly inhibited the growth parameters (fresh weight, root length and shoot length), albeit failed to induce any significant impact on chlorophyll a and chlorophyll b concentrations. Meanwhile, high concentration of PS-NPs (10 mg/L) significantly decreased the SOD and CAT activities in leaves (p < 0.05). At the molecular level, low and medium concentrations of PS-NPs (0.5, 5 mg/L) significantly promoted the expression of photosynthesis (PsbA and rbcL) and antioxidant-related (SIP) genes in leaves (p < 0.05), and high concentration of PS-NPs (10 mg/L) significantly increased the transcription levels of antioxidant-related (APx) genes (p < 0.01). Our results imply that PS-NPs accumulate in the roots of water spinach, compromising the upward transport of water and nutrients and undermining the antioxidant defense system of the leaves at the physiological and molecular levels. These results provide a fresh perspective to examine the implications of PS-NPs on edible aquatic plants, and future efforts should be focused intensively on the impacts of PS-NPs on agricultural sustainability and food security.

Transgenerational impacts of micro(nano)plastics in the aquatic and terrestrial environment.

Plastic particles of diameters ranging from 1 to 1000 nm and > 1 µm to 5 mm are respectively known as nanoplastics and microplastics, and are collectively termed micro(nano)plastics (MNPs). They are ubiquitously present in aquatic and terrestrial environments, posing adverse multifaceted ecological impacts. Recent transgenerational studies have demonstrated that MNPs negatively impact both the exposed parents and their unexposed generations. Therefore, this review summarizes the available research on the transgenerational impacts of MNPs in aquatic and terrestrial organisms, induced by exposure to MNPs alone or in combination with other organic and inorganic chemicals. The most commonly reported transgenerational effects of MNPs include tissue bioaccumulation and transfer, affecting organisms' survival, growth, reproduction, and energy metabolism; inducing oxidative stress; enzyme and genetic responses; and causing tissue damage. Similarly, co-exposure to MNPs and chemicals (organic and inorganic pollutants) significantly impacts survival, growth, and reproduction and induces oxidative stress, thyroid disruption, and genetic toxicity in organisms. The characteristics of MNPs (degree of aging, size, shape, polymer type, and concentration), exposure type and duration (parental exposure vs. multigenerational exposure and acute exposure vs. chronic exposure), and MNP-chemical interactions are the main factors affecting transgenerational impacts. Selecting MNP properties based on their realistic environmental behavior, employing more diverse animal models, and considering chronic exposure and MNP-chemical mixture exposure are salient research prospects for an in-depth understanding of the transgenerational impacts of MNPs.

Wastewater plastisphere enhances antibiotic resistant elements, bacterial pathogens, and toxicological impacts in the environment.

Microplastics (MPs) are plastic particles with a size <5 mm that have raised alarming concerns owing to their ecological and human health impacts. They are largely released into the environment through the dumping of plastic waste and wastewater from treatment plants, domestic sewage, agricultural runoff, and industrial sources. Conventional wastewater treatment plants (WWTPs) are unable to remove micro and nano-sized plastic particles, which end up in the natural aquatic and terrestrial environment, causing multifaceted toxic impacts. Moreover, plastics in wastewater generate biofilm that potentially enriches antibiotic resistant bacteria (ARBs), antibiotic resistant genes (ARGs), and bacterial pathogens, which can largely impact antibiotic resistance development among organisms in the environment and transfer to humans through the food chain. Therefore, the current review aims to highlight the potential role of wastewater plastisphere in the enrichment and dissemination of ARBs, ARGs, and potential bacterial pathogens through mobile genetic elements (MGEs) in the environment. Further, the interaction of wastewater MPs with organic and inorganic contaminants and the associated ecological and human health impacts have been presented. Last but not the least, control strategies and future research perspectives on wastewater plastisphere are also highlighted.

Di-(2-ethylhexyl) phthalate exacerbated the toxicity of polystyrene nanoplastics through histological damage and intestinal microbiota dysbiosis in freshwater Micropterus salmoides.

Organic pollutants such as di-(2-ethylhexyl) phthalate (DEHP) interact with nanoplastics (NPs) and change their bioavailability and toxicity to aquatic organisms. This study aims to assess the ecotoxicological impacts of NPs in the presence and absence of DEHP on juvenile largemouth bass (LMB) Micropterus salmoides. Therefore, LMB was fed with diets containing various concentrations (0, 2, 10, and 40 mg/g) of polystyrene nanoplastics (PSNPs) by the weight of diets. After a 21-day of PSNPs dietary exposure, LMB was treated with DEHP at 450 µg/L through waterborne exposure for three days. Our results showed that PSNPs were accumulated in the intestinal tissues, which significantly decreased the feeding and growth rates in LMB. The histopathological analysis showed the intestine and liver of LMB were subjected to various degrees of structural damage caused by PSNPs, and DEHP-PSNP co-exposure enhanced those histopathological damages in both tissues. Additionally, the co-exposure induced oxidative stress in terms of increased activities of glutathione S-transferase, catalase, and superoxide dismutase enzymes in the liver, intestine, spleen, and serum. Furthermore, the co-exposure significantly changed the intestinal microbial composition, i.e., the decrease in the abundance of probiotics (Bacteroidetes and Proteobacteria) and the increase in pathogenic bacteria (Firmicutes) posed a great threat to fish metabolism and health. Therefore, this study highlights that the presence of DEHP enhances the toxicity of NPs on LMB in freshwater and suggests the regulated use of plastic and its additives for improving the health status of aquaculture fish for food safety in humans.

Toxicological impacts of micro(nano)plastics in the benthic environment.

Micro(nano)plastics (MNPs) have sparked growing public and scientific concerns as emerging pollutants in recent decades, due to their small size and potential for significant ecological and human health impacts. Understanding the toxicological effects of MNPs on aquatic organisms is of great importance; however, most of the available research on aquatic organisms has focused on the pelagic organisms, and studies on benthic organisms are lacking yet. Being bottom-dwelling creatures, benthos perhaps confronts more extreme pressure from MNPs. Therefore, this review summarizes the current literature on the impacts of MNPs on benthic organisms to reveal their toxicity on the survival, growth, development and reproductive systems. MNPs can accumulate in various tissues of benthos and probably cause tissue-specific damage, resulting in genotoxicity and reproductive toxicity to benthic organisms. And, in severe cases, they may also pass on the adverse effects to the next generations. The complexity of co-exposure to MNPs with other aquatic contaminants is also highlighted. Furthermore, we have comprehensively discussed the internal and external factors affecting the toxicity of MNPs in benthic organisms. Additionally, we also presented the current research gaps and potential future challenges, providing overall background information for a thorough understanding of the toxic effects of MNPs in the benthic aquatic ecosystem.

Eco-corona formation and associated ecotoxicological impacts of nanoplastics in the environment.

Nanoplastics (NPs, diameter < 100 nm), are ubiquitously found in the environment including water, atmosphere, and soil because of their widespread applications and degradation resistant nature. Similarly, large quantities of natural organic matter (NOM) are present in the environment, in the form of extracellular polymeric substances (DNA, proteins, carbohydrates, etc.) and humic substances (humic acid, fulvic acid, humin, etc.), respectively released by organisms and degradation products of organic matter. These biomolecules interact with NPs and encapsulate to form a unique layered structure termed as eco-corona, which can alter the physicochemical characteristics, interaction, fate, and effects of plastic particles in the environment. The current study collated and reviewed recent findings emphasizing the progress of ecological (eco)-corona formation on NPs and affiliated toxicological effects in freshwater, marine water, and terrestrial ecosystems. The eco-corona layer formed around NPs may vary in sizes and biochemical composition, attributed mainly to the abundance, properties and physicochemical nature of both biomolecules and plastic particles, as well as medium properties and source of NOM in the ecosystem. Besides, most of the reviewed literature showed that eco-corona can reduces the toxicity of NPs with few exceptions, which demonstrates that eco-corona may enhance the NPs toxicity through the Trojan horse effect and longer retention time in biological system. Overall, this review also highlights future research perspectives for a better understanding of NPs toxicity modified by eco-corona, which is crucial to realizing the complex nature of interactions among plastic particles and NOM in a natural ecosystem.

Toxic effects of polystyrene nanoplastics and polybrominated diphenyl ethers to zebrafish (Danio rerio).

Nanoplastics (NPs) are good carriers of persistent organic pollutants (POPs) such as polybrominated diphenyl ethers (PBDEs), and can alter their bioavailability and toxic impacts to aquatic organisms. This study highlights the single and combined toxic effects of polystyrene nanoplastics (PS-NPs) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47, one of the dominant congeners of PBDEs) on zebrafish embryos after an exposure duration of up to 120 hpf. Results showed that PS-NPs and BDE-47 co-exposure exacerbated the morphological deformities in terms of pericardial edema, yolk sac edema and curved tail in zebrafish larvae. Compared to BDE-47 single exposure, the combined exposure caused lower survival rates, shorter body lengths, and accelerated spontaneous movements. Further, PS-NPs were quickly aggregated on the surface of the embryonic chorions covered almost the entire membrane at 12 and 48 hpf, and concentration dependent accumulation was also found in the brain, mouth, trunk, gills, heart, liver and gastrointestinal tract at the larval stages. During the recovery period (7 days), PS-NPs were released from all the organs, with the highest elimination from the gastrointestinal tract. Histopathological examination revealed that co-exposure caused greater damage to retinal structures, muscle fibers and cartilage tissues. Responses of hypothalamic-pituitary-thyroid axis (CRH, TSHß, NIS, TTR, Dio2, TG, TRα and TRß) and reproduction (Esr2 and Vtg1) related genes were also investigated, and results showed that the co-exposure induced more significant upregulated expressions of TSHß, TG, Doi 2, and TRß, compared to BDE-47 single exposure. In conclusion, co-exposure to NPs and BDE-47 exacerbated developmental and thyroid toxicity in zebrafish, generally elucidating the toxicological effects mediated by complex chemical interactions between NPs with POPs in the freshwater environment.

Application of hyperspectral imaging technology in the rapid identification of microplastics in farmland soil.

Microplastics (MPs) are emerging environmental pollutants and their accumulation in the soil can adversely affect the soil biota. This study aims to employ hyperspectral imaging technology for the rapid screening and classification of MPs in farmland soil. In this study, a total of 600 hyperspectral data are collected from 180 sets of farmland soil samples with a hyperspectral imager in the wavelength range of 369- 988 nm. To begin, the hyperspectral data are preprocessed by the Savitzky-Golay (S-G) smoothing filter and mean normalization. Second, principal component analysis (PCA) is used to minimize the dimensions of the hyperspectral data and hence the amount of data, making the subsequent model easier to construct. The cumulative contribution rate of the first three principal components is reached 98.37%, including the main information of the original spectral data. Finally, three models including decision tree (DT), support vector machine (SVM), and convolutional neural network (CNN) are established, all of which can achieve well classification effects on three MP polymers including polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC) in farmland soil. By comparing the recognition accuracy of the three models, the classification accuracy of DT and SVM is 87.9% and 85.6%, respectively. The CNN model based on the S-G smoothing filter obtains the best prediction effect, the classification accuracy reaches 92.6%, exhibiting obvious advantages in classification effect. Altogether, these results show that the proposed hyperspectral imaging technique identifies the soil MPs rapidly and nondestructively, and provides an effective automated method for the detection of polymers, requiring only rapid and simple sample preparation.

Distribution of Geochemical Fractions of Phosphorus in Surface Sediment in Daya Bay, China.

Surface sediment samples were collected from 19 sites throughout Daya Bay, China, to study the concentrations, and spatial distributions of different fractions of phosphorus through sequential extraction methods. Like many coastal and marine areas, De-P was the dominant form of P, contributing 47.5% of TP, followed by O-P, contributing 25.5% of TP. Ex-P and Fe-P contribute the lowest to TP. The concentration of sedimentary TP ranged from 290.3~525.1 µg/g, with the average of 395.3 µg/g, which was a similar range to other estuaries and coastal areas. Based on the spatial distribution, Pearson correlation and Principal component analysis, different fractions of phosphorus showed different spatial distributions due to different sources. The molar ratio of organic carbon to phosphorus (TOC/O-P) ranged from 199 to 609, with the average of 413, which was much higher than the Redfield ratio, suggesting terrestrial sources of organic matter in Daya Bay surface sediment. The average bioavailable phosphorus was 149.6 µg/g and contributed 37.8% (24.6~56.0%) of TP, indicating that the surface sediments of Day Bay act as an important internal source of P.