Search

Organic free radical intermediates are pivotal to our understanding of toxic chemicals formation from chlorophenols that widely exist in thermal processes. However, in most cases, multiple free radical intermediates exist and produce complex spectra that are hard to deconvolute. Identification of free radical intermediates is the current difficulty for detailed formation mechanisms of toxic products from chlorophenols. In this study, a universal bottom-up method was developed to identify the organic free radical intermediates. Candidate organic free radicals were firstly speculated according to the critical parameters obtained from experimental electron paramagnetic resonance (EPR) spectra and the calculated bond dissociation energies of precursors. Their theoretical spectra were then used retrospectively to justify the accordance with the experimental EPR spectra. Identification of the organic free radicals provides straightforward evidence for the formation pathways of pollutants from chlorophenol. Internal factors influencing formation of radical intermediates and the toxic products were also studied, including the ortho effect of the precursor, spin densities of the organic free radical intermediates, and steric hindrance effects of the molecular intermediates. In combination of the experimental results and theoretical calculations, detailed formation mechanisms of toxic pollutants intermediating by organic free radicals from thermal oxidation of chlorophenol were strongly evidenced.

Triphenyl phosphate (TPHP) is a widely used aryl organophosphate flame retardant (OPFR) that has attracted attention due to its frequent detection in the environment and living organisms. To date, the reproductive toxicity of TPHP has been investigated in organisms, but its molecular mechanisms are not fully understood. Caenorhabditis elegans (C. elegans) is the ideal animal for the study of reproductive toxicity following environmental pollutants, with short generation times, intact reproductive structures, and hermaphroditic fertilization. This study aimed to explore the reproductive dysfunction and molecular mechanisms induced by TPHP exposure in C. elegans. Specifically, exposure to TPHP resulted in a reduction in the number of eggs laid and developing embryos in utero, an increase in the number of apoptotic gonadal cells, and germ cell cycle arrest. The JNK signaling pathway is a potential pathway inducing reproductive toxicity following TPHP exposure based on transcriptome sequencing (RNA-seq). Moreover, TPHP exposure induced down-regulation of vhp-1 and kgb-2 gene transcription levels, and the knockout of vhp-1 and kgb-2 in the mutant strains exhibited more severe toxicity in apoptotic gonad cells, embryos, and eggs developing in utero, suggesting that vhp-1 and kgb-2 genes play a crucial role in TPHP-induced reproductive toxicity. Our data provide convergent evidence showing that TPHP exposure results in reproductive dysfunction through the JNK signaling pathway and improve our understanding of the ecotoxicity and toxicological mechanisms of aryl-OPFRs.

In urban waters, microplastics (MPs) usually form hetero-aggregates through adsorption of organics and microbes. However, the effects of hetero-aggregates on water quality are rarely reported. In this study we found that the hetero-aggregates, which accumulated contaminants, were like a "time bomb". Chlorination was able to trigger the "time bomb" through destruction of hetero-aggregates, lysis of microbial cells and elevation of the concentration of low-molecular-mass organics. Thereupon previously adhered organics desorbed from MPs, intracellular metabolites were released from lysed cells, and re-formation of hetero-aggregates was limited. This process rapidly increased the concentration of organics but prevented the re-adsorption of organics, which leads to secondary pollution. Thus, to alleviate the risks of secondary pollution caused by hetero-aggregates, the choice of oxidant species and dose should be optimized based on the characteristics of existent hetero-aggregates when purifying urban waters containing MPs.

Hexavalent chromium (Cr(VI)) contaminated wastewater should be addressed efficiently in the environmental field. In previous applications, nano iron sulfides amendment has not been well controlled for iron-sulfur transformation. In this study, the novel flake and nanoscale porous pyrrhotite (Fe

Chlorophenols are difficult to degrade and biohazardous in the natural environment. This study demonstrated that humic acid (HA) could promote Fe

In this work, activated carbon treated in N

Simultaneous determination of 58 congeners of polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), brominated polycyclic aromatic hydrocarbons (Br-PAHs), and polybrominated diphenyl ethers (PBDEs) from multiple stages of industrial-scale secondary copper smelting plants was conducted with the aim of understanding their variations and control. In addition to the historical manufacture of PBDEs as brominated flame retardants, this study confirmed that PBDEs can be unintentionally produced and released from the secondary copper industry. The average mass emission factors of PBDD/Fs, PBDEs, and Br-PAHs from different sources were 10.0, 5.21 × 10

Despite the extensive uses of ZnO nanoparticles as promising antimicrobial agents to tackle the severe microbial infections, the systematic antibacterial studies on ZnO nanoparticles with manipulable nanoscale morphologies at the genetic expression level remain ill-defined. In this study, via a controllable thermal decomposition, ZnO nanoparticles of different morphologies were facilely prepared. Additionally, the surface PEGylation of ZnO was conducted to obtain the nanoparticles of low biotoxicity. While all the prepared ZnO nanoparticles exhibited the significantly chemical activities, the pronounced antibacterial effect of obtained ZnO nanoparticles was also identified, in which the ultra-small ones (~5 nm) showed the best performance. Moreover, the antibacterial activities of ZnO nanoparticles were studied by bacterial nucleic acid leakage, alkaline phosphatase, biofilm and reactive oxygen species (ROS) assays. Furthermore, the transcriptome analysis of ZnO nanoparticles with different morphologies against Escherichia coli (E. coli) revealed the underlying antibacterial mechanism involved the signal transduction, material transport, energy metabolism and other biological processes. Therefore, the cost-effective preparation of ZnO nanoparticles with distinct morphological features provides insights for the development of application specific antibacterial agents.

Tris(1,3-dichloro-2-propyl) phosphate (TDCPP) has received concerns due to its frequent detection in environmental media and biological samples. Our previous study has indicated TDCPP reduced the lifespan of Caenorhabditis elegans (C. elegans) by triggering an unconventional insulin/insulin-like growth factor signaling (IIS) pathway. This study continued to investigate the possible deleterious effects of TDCPP relating to longevity regulation signal pathways and biological processes. Specifically, this study uniquely performed small RNA transcriptome sequencing (RNA-seq), focusing on the underlying mechanisms of TDCPP-reduced the longevity of C. elegans in-depth in microRNAs (miRNAs). Based on Small RNA-seq results and transcript levels of mRNA involved in the unconventional IIS pathway, a small interaction network of miRNAs-mRNAs following TDCPP exposure in C. elegans was preliminarily established. Among them, up-regulated miR-48 and miR-84 (let-7 family members) silence the mRNA of daf-16 (the crucial member of the FoxO family and pivotal regulator in longevity) via post-transcription and translation dampening abilities, further inhibit its downstream target metallothionein-1 (mtl-1), and ultimately contributed to the reduction of nematode longevity and locomotion behaviors. Meanwhile, the high binding affinities of TDCPP with miRNAs cel-miR-48-5p and cel-miR-84-5p strongly support their participation in the regulation of nematode mobility and longevity. These findings provide a comprehensive analysis of TDCPP-reduced longevity from the perspective of miRNAs.

Covalent organic frameworks (COFs) with well-defined supramolecular structures and high surface-area-to-volume ratio have received extensive attention on their adsorption of contaminants from micro- to nano-size. Here, we studied the adsorption mechanisms of three typical nanoplastics (NP), including polyethylene (PE), nylon-6 (PA 6), and polyethylene terephthalate (PET) on chemically stable COFs (TpPa-X, X = H, CH3, OH, NO2 and F) by molecular dynamics simulations. Depending on molecular structure and surface composition, two distinct interactions–electrostatic interaction and van der Waals (vdW) interaction–are identified to be responsible for the adsorption of different NP pollutants on TpPa-X. The vdW interaction is dominant during the adsorption process, while polar groups in polymers and COFs can enhance the adsorption because of the electrostatic interaction. Compared with other functional COFs, we found that TpPa-OH shows the strongest adsorption with the NP pollutants employed in this study. This work reveals the COF-polymer adsorption behavior and properties at atomic scale, which is crucial to the development of promising COF materials to deal with NP pollution.

Nonferrous metallurgical processes are important sources of carcinogenic polybrominated dibenzo-p-dioxin and dibenzofuran (PBDD/Fs) that transport globally. Studies on the profiles, spatial distributions and inventory of PBDD/F emissions into the atmosphere from nonferrous metallurgical plants are needed for better source control. In this study, field investigations on PBDD/F emissions from typical nonferrous metallurgical plants were conducted to characterize the PBDD/F profiles and derive their emission factors. Based on the PBDD/F profiles, diagnostic ratios of PBDD/Fs for secondary copper, zinc and lead smelting were proposed for identifying the potential sources of PBDD/Fs in environment. The PBDD/F emission factors for the secondary copper, lead, and zinc smelting plants were 0.71, 1.65, and 1.54 μg toxic equivalents/t, respectively. The estimated annual input of PBDD/Fs into atmosphere by secondary nonferrous metallurgical plants in China was 212.4 g by mass and 3511.3 mg by toxic equivalents, which is of significance for further evolving a global inventory. The spatial distribution of PBDD/F emissions from nonferrous metallurgical plants in China was mapped. Larger amounts of PBDD/Fs were emitted in the southeastern coastal region and northern China than elsewhere in China.