Effect of Microplastic Types on the In Vivo Bioavailability of Polychlorinated Biphenyls

Microplastics' vector effect on Co-bioaccumulation of it and polychlorinated biphenyls in Crassostrea hongkongensis

Microplastics (MPs) and polychlorinated biphenyls (PCBs) are known with high persistence and toxicity, posing urgent threats to food safety and human health. However, little is known about the synergistic effect of MPs on PCBs bioaccumulation on Crassostrea hongkongensis. In the present study, diverse types of MPs were analyzed on sea water and C. hongkongensis sampled from three distinct estuary sites, and film-shaped MPs were discovered to be preferentially ingested by the oysters. Interestingly, the content of MPs and PCBs showed negative correlation (R2 = 0.452, p< 0.001) in the oysters sampled from site 2. Upon MPs and PCBs co-treatment, the in vivo accumulation of PCBs in C. hongkongensis was inhibited by 25.90 % when compared to the group treated with PCBs solely. PCBs stresses significantly induced the expression of genes of CYP2C31, GST, SOD and HSP70 in C. hongkongensis, while, the elevated state was compromised when co-treated with PCBs. The present research alleviates concerns about the potential effects of MPs on promoting PCBs bioaccumulation and provide a better understanding of the combined impact of MPs and PCBs on C. hongkongensis.

Polystyrene nanoplastics alter intestinal toxicity of 2,4-DTBP in a sex-dependent manner in zebrafish (Danio rerio)

Nanoplastics (NPs) and 2,4-di-tert-butylphenol (2,4-DTBP) are ubiquitous emerging environmental contaminants detected in aquatic environment. While the intestinal toxicity of 2,4-DTBP alone has been studied, its combined effects with NPs remain unclear. Herein, adult zebrafish were exposed to 80 nm polystyrene nanoplastics (PS-NPs) or/ and 2,4-DTBP for 28 days. With co-exposure of PS-NPs, impact of 2,4-DTBP on feeding capacity and intestinal histopathology was enhanced in males while attenuated in females. Addition of PS-NPs significantly decreased the uptake of 2,4-DTBP in females, while the intestinal concentrations of 2,4-DTBP were not different between the sexes in co-exposure groups. Furthermore, lower intestinal pH and higher contents of digestive enzymes were detected in male fish, while bile acid was significantly increased in co-exposed females. In addition, co-exposure of PS-NPs stimulated female fish to remodel microbial composition to potentially enhance xenobiotics degradation, while negative Aeromonas aggravated inflammation in males. These results indicated that in the presence of PS-NPs, the gut microenvironment in females can facilitate the detoxification of 2,4-DTBP, while exaggerating toxiciy in males. Overall, this study demonstrates that toxicological outcomes of NPs-chemical mixtures may be modified by sex-specific physiology and microbiota composition, furthering understanding for environmental risk assessment and management of aquatic environments.

Atmospheric microplastic deposition associated with GDP and population growth: Insights from megacities in northern China

Microplastic (MP) pollution is evolving into one of the most pressing environmental concerns worldwide. This study assessed the impact of economic activities on atmospheric MP pollution across 17 megacities in northern China, analyzing the correlation between the deposition flux of atmospheric MPs and variables such as city population, gross domestic product (GDP), and industrial structure. The results have shown that the MP pollution is obviously impacted by human activities related to increased GDP, population, as well as tertiary service sector, in which the MP pollution shows most close relationship with the GDP growth. Polypropylene, polyamide, polyurethane, and polyethylene were identified as the primary components of atmospheric MPs. The average particle size of MPs in atmospheric dustfall is 78.3 µm, and the frequency of MP particles increases as the particle size decreases. The findings highlight the complex relationship between socio-economic development and atmospheric MP accumulation, providing essential insights for the formulation of targeted emission reduction strategies.

Environmental condition-dependent effects of aquatic humic substances on the distribution of phenanthrene in microplastic-contaminated aquatic systems

Numerous studies have focused on the interaction between microplastics (MPs) and phenanthrene (PHE) in aquatic environments. However, the intricate roles of aquatic humic substances (HS), which vary with environmental conditions, in influencing PHE-MP interactions are not yet fully understood. This study investigates the variable and environmentally sensitive roles of HS in modifying the interactions between PHE and polyethylene (PE) MPs under laboratory-simulated aquatic conditions with varying solution chemistry, including pH, HS types, HS concentrations, and ionic strength. Our findings show that the presence of HS significantly reduces the adsorption of PHE onto both pristine and aged PE MPs, with a more pronounced reduction observed in aged PEs. This effect is highlighted by a notable decrease in the partitioning coefficient (Kd) of PHE, which falls from 2.60 × 104 to 1.30 × 104 L/kg on MPs in the presence of HS. The study also demonstrates that alterations in the net charge of HS solutions are crucial in modifying PHE distribution onto PEs. An initial decrease in Kd values at higher pH levels is reversed when HS is introduced. Furthermore, an increase in HS concentrations is associated with lower Kd values. In conditions of higher ionic strength, the retention of PHE by HS is intensified, likely due to an enhanced salting-out effect. This research highlights the significant role of aquatic HS in modulating the distribution of PHE in MP-polluted waters, which is highly influenced by various solution chemistry factors. The findings are vital for understanding the fate of PHE in MP-contaminated aquatic environments and can contribute to refining predictive models that consider diverse solution chemistry scenarios.

Co-exposure of microplastics and polychlorinated biphenyls strongly influenced the cycling processes of typical biogenic elements in anoxic soil

The co-exposure of microplastics (MPs) and polychlorinated biphenyls (PCBs) in soil is inevitable, but their combined effect on cycles of typical biogenic elements (e.g. C, N, Fe, S) is still unclear. And the co-exposure of MPs and PCBs caused more severe effects than single exposure to pollution. Therefore, in this study, a 255-day anaerobic incubation experiment was conducted by adding polyethylene microplastics (PE MPs, including 30 ± 10 μm and 500 μm) and PCB138. The presence of PE MPs inhibited the PCB138 degradation. Also, PE MPs addition (1%, w/w) enhanced the methanogenesis, Fe(Ⅲ) reduction, and sulfate reduction while inhibited nitrate reduction and the biodegradation of PCB138. And PCB138 addition (10 mg·kg-1) promoted the methanogenesis and Fe(Ⅲ) reduction, but inhibited sulfate reduction and nitrate reduction. Strikingly, the presence of PE MPs significantly reduced the impact of PCB138 on the soil redox processes. The abundance changes of special microbial communities, including Anaeromyxobate, Geobacter, Bacillus, Desulfitobacterium, Thermodesulfovibrio, Metanobacterium, etc., were consistent with the changes in soil redox processes, revealing that the effect of PE MPs and/or PCB138 on the cycle of typical biogenic elements was mainly achieved by altering the functional microorganisms. This study improves the knowledge of studies on the impact of MPs and combined organic pollutants to soil redox processes, which is greatly important to the stabilization and balance of biogeochemical cycling in ecology.