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Abstract Microplastic is an umbrella term that covers particles with various physical and chemical properties. However, microplastics with a consistent shape, polymer type and size are generally used in exposure studies (e.g., spherical polyethylene or polystyrene beads 1–100 μm in size). In the present study, we exposed freshwater Asian clams (Corbicula fluminea) to microfibers with different physicochemical properties at concentrations of 100 and 1000 fibers/L. The first experiment in this study exposed clams to microfibers made from six different polymers, demonstrating that Asian clams uptake more polyester (PET) (4.1 items/g) relevant to other polymers. The next experiment exposed clams to PET fibers of different size classes, demonstrating that uptake in the size range 100–250 μm (1.7 items/g) was greater than other size classes. These results suggest that physicochemical properties such as polymer and size play important roles in the uptake of microfibers by organisms. Thus, we strongly suggest that the properties of microplastics used in future laboratory exposure experiments be considered, with the aim of being "environmentally relevant", i.e., similar to what is found in nature. Graphical abstract Image 1 Highlights • The uptake of microfibers by clams varies by polymer type and size. • The uptake of fibers was greater in 1000 items/L than that in 100 items/L groups. • Clams were more likely to uptake polyester fibers in the smaller size range. • Microplastics with "environmentally relevant properties" should be used in future. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFAS) are contaminants of global concern due to their persistence and associated negative health effects. Considerable attention has been given to monitoring PFAS in the aquatic environment, however, few investigations have done so using freshwater benthic macroinvertebrates (BMIs). As these bottom-dwelling animals are known to bioconcentrate exogenous pollutants to a high degree, studying their PFAS levels may provide a more integrated view of PFAS contamination in the aquatic environment. In this study, BMIs, sediment, and surface water were collected from two streams in the Hudson River Watershed (one historically-impacted by PFAS) and analyzed for 44 PFAS using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Orbitrap high-resolution mass spectrometry (HRMS) was used to confirm the identities of quantitated analytes. Across all matrices, 17 analytes were detected with PFOA dominating in surface water and PFOS in sediment/BMIs. PFOS bioaccumulation factors (BAFs) were approximately one order of magnitude higher than those of PFOA and ranged from 857 to 5151 L kg−1 across different BMI taxa. While PFAS concentrations in surface water and sediment were not excessively high, elevated levels were still measured in most BMI taxa. This observation suggests that the extent of PFAS contamination in a local system may be severely underestimated if only surface water and sediment are used for monitoring. Moreover, these findings have relevance for human exposure assessment considering BMIs are the primary food source of many fish. [Display omitted] • Elevated levels of PFAS were measured across 8 different freshwater BMI taxa. • Levels of PFAS in water were elevated years after industrial discharge ceased. • Levels of PFAS in BMIs were far higher than in surface water or sediment. • Predatory BMIs showed the highest PFAS bioaccumulation factors. • This study highlights the potential of BMIs for routine PFAS monitoring. [ABSTRACT FROM AUTHOR]

Per- and polyfluoroalkyl substances (PFAS) are contaminants of global concern due to their persistence and associated negative health effects. Considerable attention has been given to monitoring PFAS in the aquatic environment, however, few investigations have done so using freshwater benthic macroinvertebrates (BMIs). As these bottom-dwelling animals are known to bioconcentrate exogenous pollutants to a high degree, studying their PFAS levels may provide a more integrated view of PFAS contamination in the aquatic environment. In this study, BMIs, sediment, and surface water were collected from two streams in the Hudson River Watershed (one historically-impacted by PFAS) and analyzed for 44 PFAS using liquid chromatography–tandem mass spectrometry (LC–MS/MS). Orbitrap high-resolution mass spectrometry (HRMS) was used to confirm the identities of quantitated analytes. Across all matrices, 17 analytes were detected with PFOA dominating in surface water and PFOS in sediment/BMIs. PFOS bioaccumulation factors (BAFs) were approximately one order of magnitude higher than those of PFOA and ranged from 857 to 5151 L kg−1 across different BMI taxa. While PFAS concentrations in surface water and sediment were not excessively high, elevated levels were still measured in most BMI taxa. This observation suggests that the extent of PFAS contamination in a local system may be severely underestimated if only surface water and sediment are used for monitoring. Moreover, these findings have relevance for human exposure assessment considering BMIs are the primary food source of many fish. [Display omitted] • Elevated levels of PFAS were measured across 8 different freshwater BMI taxa. • Levels of PFAS in water were elevated years after industrial discharge ceased. • Levels of PFAS in BMIs were far higher than in surface water or sediment. • Predatory BMIs showed the highest PFAS bioaccumulation factors. • This study highlights the potential of BMIs for routine PFAS monitoring. [ABSTRACT FROM AUTHOR]

A core-shell covalent organic framework encapsulated Co 1.2 Fe 1. 8 O 4 magnetic particles (CFO@COF) was designed and prepared successfully to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) degradation. It displays amazing catalytic reactivity since the unique interior structure and synergistic effect between COF shell and CFO core, reaching 99.8% removal of SMX (10 mg/L) within 30 min and 90.8% TOC removal. The synergy between bimetals vests high reactivity to CFO core. And the outer COF shell can stabilize the CFO core under intricate reaction conditions to restrain the leaching of Co ions (decreased from 0.75 to 0.25 mg/L). Further investigation compared the activation mechanism in two different system, CFO/PMS system and CFO@COF/PMS system. The result showed that the radical mechanism controlled by SO 4 ⋅- guided the SMX degradation in CFO/PMS system whereas the 1O 2 played a pivotal role in CFO@COF/PMS system called non-radical leading. The influences of various factors on degradation experiments and SMX degradation pathway were also studied. Most importantly, risk assessment in CFO@COF/PMS/SMX system was estimated via "ecological structure activity relationships". In most case, the toxicities of intermediates were lower than the initial samples, which confirmed the effectiveness of CFO@COF/PMS/SMX system in the reduction of toxicity of SMX. [Display omitted] • Core-shell CFO@COF was successfully synthetized via hydrothermal method. • The outer COF shell significantly improve the leaching problem of Co ions. • Different mechanisms of CFO and CFO@COF activated PMS were summarized. • Risk assessment in CFO@COF/PMS/SMX system were estimated via ECOSAR. [ABSTRACT FROM AUTHOR]

Dehalogenation is one of the highly important degradation reactions for halogenated organic compounds (HOCs) in the environment, which is also being developed as a potential type of the remediation technologies. In combination with the experimental results, intensive efforts have recently been devoted to the development of efficient theoretical methodologies (e.g. multi-scale simulation) to investigate the mechanisms for dehalogenation of HOCs. This review summarizes the structural characteristics of neutral molecules, anionic species and excited states of HOCs as well as their adsorption behavior on the surface of graphene and the Fe cluster. It discusses the key physiochemical properties (e.g. frontier orbital energies and thermodynamic properties) calculated at various levels of theory (e.g. semiempirical, ab initio, density functional theory (DFT) and the periodic DFT) as well as their connections to the reactivity and reaction pathway for the dehalogenation. This paper also reviews the advances in the linear and nonlinear quantitative structure–property relationship models for the dehalogenation kinetics of HOCs and in the mathematical modeling of the dehalogenation processes. Furthermore, prospects of further expansion and exploration of the current research fields are described in this article. [ABSTRACT FROM AUTHOR]