Typical Organic Pollutants Research Articles

Research Progress on Up-Conversion Fluorescence Probe for Detection of Perfluorooctanoic Acid in Water Treatment.

Perfluorooctanoic acid (PFOA) is a new type of organic pollutant in wastewater that is persistent, toxic, and accumulates in living organisms. The development of rapid and sensitive analytical methods to detect PFOA in environmental media is of great importance. Fluorescence detection has the advantages of high efficiency and low cost, in which fluorescent probes have excellent fluorescence properties, excellent bio-solubility, and remarkable photostability. It is necessary to review the fluorescence detection routes for PFOA. In addition, the up-conversion of fluorescent materials (UCNPs), as fluorescent materials to prepare fluorescent probes with, has significant advantages and also attracts the attention of researchers, however, reviews related to their application in detecting PFOA and comparing them with other routes are rare. Furthermore, there are many strategies to improve the performance of up-conversion fluorescent probes including SiO2 modification and amino modification. These strategies can enhance the detection effect of PFOA. Thus, this work reviews the types of fluorescence detection, the design, and synthesis of UCNPs, their recognition mechanism, properties, and their application progress. Moreover, the development trend and prospects of these detection probes are given.

The growth toxicity and neurotoxicity mechanism of waterborne TBOEP to nematodes: Insights from transcriptomic and metabolomic profiles

Tris(2-butoxy) ethyl phosphate (TBOEP) is a typical organophosphorus flame retardant (OPFR), which has been detected in natural water bodies and drinking water and has reached a certain concentration. As a new type of organic pollutant, the environmental health risk of TBOEP needs to be assessed urgently. Here, Caenorhabditis elegans were exposed to 0, 50, 500, and 5000 ng/L TBOEP in water for 72 h. The results showed that TBOEP exposure caused concentration-dependent inhibition to the growth of nematodes, while exposure to 5000 ng/L TBOEP significantly inhibited the locomotor behavior of nematodes. Transcriptomic and metabolomic analysis showed that the disturbances in neurotransmitter transmission and amino acid, carbohydrate, and lipid metabolism were the reason for the neurotoxicity and growth toxicity of TBOEP to nematodes. These results provide basic data and a theoretical basis for evaluating the environmental health risks of organophosphorus flame retardants.

Abatement of Aromatic Contaminants from Wastewater by a Heat/Persulfate Process Based on a Polymerization Mechanism.

A novel approach to the abatement of pollutants consisting of their conversion to separable solid polymers is explored by a heat/persulfate (PDS) process for the treatment of high-temperature wastewaters. During this process, a simultaneous decontamination and carbon recovery can be achieved with minimal use of PDS, which is significantly different from conventional degradation processes. The feasibility of this process is demonstrated by eight kinds of typical organic pollutants and by a real coking wastewater. For the treatment of the selected pollutants, 30.2-91.9% DOC abatement was achieved with 24.8-91.2% carbon recovery; meanwhile, only 5.2-47.0% of PDS was consumed compared to a conventional degradation process. For the treatment of a real coking wastewater, 71.0% DOC abatement was achieved with 66.0% carbon recovery. With phenol as a representative compound, our polymerization-based heat/PDS process is applicable in a wide pH range (3.5-9.0) with a carbon recovery of >87%. Both SO4•- and HO• can be initiators for polymerization, with different contribution ratios under various conditions. Phenol monomers are semioxidized to form phenolic radicals, which are polymerized via chain transfer or chain growth processes to form separable solid phenol polymers, benzenediol polymers, and cross-linked polymers.

Removal Efficiency and Performance Optimization of Organic Pollutants in Wastewater Using New Biochar Composites

The purpose is to optimize the catalytic performance of biochar (BC), improve the removal effect of BC composites on organic pollutants in wastewater, and promote the recycling and sustainable utilization of water resources. Firstly, the various characteristics and preparation principles of new BC are discussed. Secondly, the types of organic pollutants in wastewater and their removal principles are discussed. Finally, based on the principle of removing organic pollutants, BC/zero valent iron (BC/ZVI) composite is designed, among which BC is mainly used for catalysis. The effect of BC/ZVI in removing tetracycline (TC) is comprehensively evaluated. The research results reveal that the TC removal effect of pure BC is not ideal, and that of ZVI is general. The BC/ZVI composite prepared by combining the two has a better removal effect on TC, with a removal amount of about 275 mg/g. Different TC concentrations, ethylene diamine tetraacetic acid (EDTA), pH environment, tert-butanol, and calcium ions will affect the TC removal effect of BC composites. The overall effect is the improvement of the TC removal amount of BC composites. It reveals that BC has a very suitable catalytic effect on ZVI, and the performance of BC composite material integrating BC catalyst and ZVI has been effectively improved, which can play a very suitable role in wastewater treatment. This exploration provides a technical reference for the effective removal of organic pollutants in wastewater and contributes to the development of water resource recycling.

Pollution Characteristics and Risk Assessment of Typical Antibiotics and Persistent Organic Pollutants in Reservoir Water Sources

The major task of Chinese water governance has gradually shifted away from water environment protection to water ecology remediation, and the governance of trace organic pollutants, including persistent organic pollutants and antibiotics, has attracted growing concern. The present study examined the seasonal distribution and sources of typical persistent organic pollutants and antibiotics in six representative water sources in the lower reaches of the Yangtze River, as well as their ecological risk to the environment. Six representative surface water and surface sediment samples were collected at different time intervals, i.e., December 2018, March 2019, and June 2019, and the concentrations of nineteen organochlorine pesticides (OCPs), seventeen polychlorinated biphenyls (PCBs), and eight polybrominated diphenyl ethers (PBDEs) were analyzed by GC-MS. The major findings are listed below: ① Endosulfan sulfate, Beta-endosulfan, and methoxychlor were the major persistent organic pollutants (POPs) detected in the sediments from Gaoyou Lake, Gonghu Lake, and Gehu Lake, with concentrations ranging from 9.0 to 10.6 ng/g. ② The target antibiotics in water sources were at relatively low levels. Occurrences of sulfonamide antibiotics in water and surface sediments were NF~37.4 ng·L−1 and NF~47.3 ng·g−1. Concentrations of quinolone antibiotics in the two media were NF~5.3 ng·L−1, 0.4~32.5 ng·g−1. ③ The combined toxicity of antibiotics (risk quotient, RQ) in Lake Gehu was 0.18, which was at a moderate risk level. There was no obvious ecological risk in most water sources affected by POPs. However, there were certain ecological risks in the water sources of Gaoyou Lake, Gonghu Lake, and Sanjiangying, induced by OCPs and PCBs. This study provides a scientific basis for the treatment of antibiotics and organic pollutants in reservoir water sources.

La doping of manganese oxide leads to a dramatically promoted catalytic performance for UV–visible-infrared photothermocatalytic ethyl acetate abatement

La-doped manganese oxide catalysts with nanorod morphology, cryptomelane octahedral molecular sieve structure (OMS-2) and La/Mn atomic ratios of 0.0045, 0.0097, and 0.0459 (denoted as La-OMS-2-A, La-OMS-2-B, and La-OMS-2-C) were synthesized with the reaction among KMnO4, La(NO3)3, and Mn(NO3)2 at 90 °C. They were used for photothermocatalytic oxidation of ethyl acetate (typical organic pollutant) merely with UV–visible-infrared (UV–vis-IR) illumination. An appropriate amount of La doping was found to dramatically enhance photothermocatalytic activity and diminish the selectivity of more toxic by-product acetaldehyde. The optimal La-OMS-2-B demonstrated exceptionally large photothermocatalytic activity, low acetaldehyde selectivity, and good catalytic stability. Within initial five minutes, its CO2 formation rate (rCO2) was exceptionally high (1362.0 μmol g−1 min−1), a 67-fold increase as compared to pure OMS-2, while its acetaldehyde selectivity was very low (1.9%), a 37-fold decrease as compared to pure OMS-2. Even with λ > 830 nm IR illumination, it still possessed good photothermocatalytic performance. The photothermocatalytic oxidation abided by a light-driven thermocatalysis mechanism. The dramatic catalytic enhancement by the La-doping arose from a considerable promoted thermocatalytic activity due to the oxygen activity of OMS-2 being substantially improved with La-doping. A photoactivation on La-OMS-2-B, quite unlike photocatalysis on semiconductor photocatalysts, was discovered that further substantially improved catalytic activity and decreased acetaldehyde selectivity due to the oxygen activity of OMS-2 being considerably promoted with UV–vis-IR illumination.

Excellent photocatalysis of Bi2WO6 structured with oxygen vacancies in degradation of tetracycline

Photocatalysis is a green, efficient and clean pollutant degradation technology. In this work, a novel Bi2WO6 photocatalytic material with oxygen vacancies was synthesized by a simple solvothermal method using ethylene glycol and ethanol as solvents. Tetracycline, as typical antibiotic organic pollutant, was selected to evaluate the photocatalytic activity of the prepared photocatalyst. The prepared oxygen-deficient Bi2WO6 material has good photocatalytic activity under visible light irradiation. The results showed that the oxygen-deficient Bi2WO6 was regular microsphere in shape with narrower and more uniform pore size distribution than Bi2WO6. Moreover, when visible light irradiation was lasted for 180 min, the degradation rate of tetracycline reached 79.68%, showing a higher degradation rate compared with that of Bi2WO6. Furthermore, after four cycles, the degradation rate of tetracycline could still reach 68.64%. This was due to the oxygen vacancies significantly enhanced the photocatalytic activity of Bi2WO6. In addition, as shown by the UV–Vis DRS analysis, the presence of oxygen vacancies enhances the utilization of visible light by Bi2WO6, and reduces the band gap of Bi2WO6. This study will provide an innovative idea for the construction of oxygen-deficient photocatalysts for water treatment.

Remove humic acid from water quickly using only oxygen and sulfite at nickel cobalt spinel catalyst

The typical refractory organic pollutant, humic acid (HA), causes many water and wastewater treatment obstacles. In this study, a novel method was proposed to degrade HA based on the low-temperature (<100 °C) catalytic air oxidation technology (LTCAO) using the NiCo-spinel (NCO) as a catalyst and the sulfite as a promoter. Sulfite enhanced the quantity of mineralized HA to 2.4 times that without sulfite assistance, and the removal rate of total organic carbon reached 93.1% within 60 min at 90 °C. HA gradually degrades into small organic molecules and is mineralized through interfacial reactions and radical paths. Sulfite plays a triple role in these reactions. Sulfite sulfonated HA destroyed its pseudomicellar structure, making HA easily oxidized. Sulfite also coordinated with NCO and promoted the internal electronic hopping conduction of NCO because of the fast electron transfer between SO32− and the h+sites, thus accelerating the electron transfer between HA and O2 mediated by NCO. In addition, the coordinated SO32− was activated to form the radical ∙SO3−, which strengthened the oxidation of HA. This study supports a simple and green method for efficiently cleaning water and wastewater rich in HA.

Citrobacter sp. Y3 harbouring novel gene HBCD-hd-1 mineralizes hexabromocyclododecane via new metabolic pathways according to multi-omics characterization.

Hexabromocyclododecane (HBCD) is a typical persistent organic pollutant that is widely detected in the environment. Despite the significant efforts put into its mineralisation, there is still a lack of microorganism resources that can completely mineralise HBCD. Stable isotope analysis revealed that the Citrobacter sp. Y3 can use [13C]HBCD as its sole carbon source and degrade or even mineralise it into 13CO2, with a maximum conversion rate of 100% in approximately 14 days. Strain Y3 could completely mineralise HBCD, which it used as its only carbon source, and six debromination enzymes related to HBCD degradation were found in Y3, including haloalkane dehalogenase (DhaA), haloacid dehalogenase (HAD), etc. A functional gene named HBCD-hd-1, encoding a HAD, was found to be upregulated during HBCD degradation and heterologously expressed in Escherichia coli. Recombinant E. coli with the HBCD-hd-1 gene transformed the typical intermediate 4-bromobutyric acid to 4-hydroxybutanoic acid and showed excellent degradation performance on HBCD, accompanied by nearly 100% bromine (Br) ion generation. The expression of HBCD-hd-1 in Y3 rapidly accelerated the biodegradation of HBCD. With HBCD as its sole carbon source, strain Y3 could potentially degrade HBCD, especially in a low-nutrient environment.

Research progress of bio-slurry remediation technology for organic contaminated soil.

Bio-slurry remediation technology, as a controllable bioremediation method, has the significant advantage of high remediation efficiency and can effectively solve the problems of high energy consumption and secondary pollution of traditional organic pollution site remediation technology. To further promote the application of this technology in the remediation of organically polluted soil, this paper summarizes the importance and advantages of bio-slurry remediation technology compared with traditional soil remediation technologies (physical, chemical, and biological). It introduces the technical infrastructure and its technological processes. Then, various factors that may affect its remediation performance are discussed. By analyzing the applications of this technology to the remediation of typical organic pollutant-(polycyclic aromatic hydrocarbons(PAHs), polychlorinated biphenyls(PCBs), total petroleum hydrocarbons(TPH), and pesticide) contaminated sites, the following key features of this remediation technology are summarised: (1) the technology has a wide range of applications and can be used in a versatile way in the remediation projects of various types of organic-contaminated soil sites such as in clay, sand, and high organic matter content soil; (2) the technology is highly controllable. Adjusting environmental parameters and operational conditions, such as nutrients, organic carbon sources (bio-stimulation), inoculants (bio-augmentation), water-to-soil ratio, etc., can control the remediation process, thus improving the restoration performance. To sum up, this bio-slurry remediation technology is an efficient, controllable and green soil remediation technology that has broad application prospects.

Adsorption/desorption behavior of ciprofloxacin on aged biodegradable plastic PLA under different exposure conditions

Polylactic acid, one of the degradable plastics, and ciprofloxacin (CIP) are two typical organic pollutants in the water environment. Adsorption of CIP on aged-microplastics may result in their long-range transport and cause compound combination effects. In this study, the sorption of CIP to microplastics in a simulated aging state was examined. The microplastics aged alternately day and night have larger adsorption capacity than those aged continuously. Adsorption isotherms demonstrated that compared to monolayer adsorption of virgin plastic, the adsorption of aged-PLA is more consistent with the Freundlich model, indicating that adsorption is mainly based on multi-molecular layer adsorption on non-homogeneous surfaces. Moreover, the maximum adsorption capacity of continuous aging for CIP was 26.439 mg/g，the maximum adsorption capacity of alternate aging for CIP was 46.913 mg/g. The results of desorption experiments show that the sorption-desorption process of CIP on PLA is irreversible, and the aged have higher desorption capacity, which indicates that aged microplastics are helpful in enriching and fix CIP for a long time. Our results showed that commonly observed PLA can be a carrier of antibiotics in the aquatic environment.

ZnO photocatalysts applications in abating the organic pollutant contamination: A mini review

• Organic pollutants in water bodies exert serious environmental and human health risks. • ZnO has a high capability of degrading various ranges of organic pollutants. • Modification in ZnO design and composition can enhance its degradation ability in solar irradiation. This works encompasses a short review of the adversity of various types of organic pollutants and the viability of ZnO in abating their occurrence in water bodies. The classes of organic pollutants that have been selected for the analysis were: dyes, pesticides, antibiotics and analgesics, and finally stimulants. As a result of the established data analysis, it can be construed that the toxicity of the organic pollutant can pose serious threats to the environment, public health, and well-being. To combat this matter, earlier studies proposed the reliability of ZnO catalyst in elevating the efficiency of the organic pollutant degradation process due to its outstanding photophysical properties. However, as the optical response range of ZnO is often limited to UV light, various modification strategies in ZnO architecture have been executed to extend its functionality in solar irradiation. Overall, it can be concluded that ZnO exerts remarkable potential to remediate the contaminated wastewater. Nevertheless, there are still a lot of aspects that need to be enhanced before its actual utilization as a part of the future wastewater treatment technology.

Advances in the Agro-Environment Migration of Organic Chemical Pollutants and Their Biotransformation in Crops

Global production, consumption and emission of various chemicals continue to rise, despite growing evidence of their harmful effects on environmental quality, food safety and human health. Agronomy, a nature-dependent industry, is considered to be extremely sensitive to chemical pollution. Hence, it is of great importance for food safety and human health to study the migration and biotransformation of chemical pollutants among agricultural elements, such as soil, water and crops. Thus, this review focused on typical organic pollutants (TOPs) in the agro-environment, such as pesticides, antibiotics and persistent organic pollutants (POPs), firstly describing their sources and the current state. Then, we further elucidated the mechanism and influence factors of the TOP-based uptake, translocation and biotransformation of TOPs in crops, including the apoplastic and symplastic pathway, enzyme-assisted nontarget resistance and the physicochemical properties of different TOPs. In addition, future insight into the identification of detoxified genes and lower-toxic metabolism of TOPs was presented in this review, which provides valuable information for breeding agro-products with lower chemical contaminants. In a nutshell, our review discussed comprehensive research progress on TOPs’ fates and offered theoretical guidance for pollution control and ecological risk assessment in agroecosystems.

Visualizing the Distribution of Phthalate Esters and Plant Metabolites in Carrot by Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry.

The accumulation of organic pollutants in vegetables is a major global food safety issue. The concentrations of pollutants in vegetables usually differ across different tissues because of different transport and accumulation pathways. However, owing to the limitations of conventional methods, in situ localization of typical organic pollutants such as phthalate esters (PAEs) in plant tissues has not yet been studied. Here, we developed a quick and efficient method for in situ detection and imaging of the spatial distribution of PAEs in a typical root vegetable, carrot, using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). The use of a 2,5-dihydroxybenzoic acid matrix with a spray-sublimation coating method led to the successful identification of PAEs ion signals. The IMS results showed that a typical PAE-di-(2-ethylhexyl)phthalate (DEHP) was broadly distributed in the cortex, phloem, and metaxylem, but was barely detectable in the cambium and protoxylem. Interestingly, MALDI-IMS data also revealed for the first time the spatial distribution of sugars and β-carotene in carrots. In summary, the developed method offers a new and practical methodology for the in situ analysis of PAEs and plant metabolites in plant tissues. As a result, it could provide a more intuitive understanding of the movement and transformation of organic pollutants in soil-plant systems.

Investigation of CuCoFe-LDH as an efficient and stable catalyst for the degradation of acetaminophen in heterogeneous electro-Fenton system: Key operating parameters, mechanisms and pathways

Pharmaceuticals, as anthropogenic pollutants in a wide range of water sources, generally require specific treatment methods for degradation. A trimetallic layered double hydroxide (CuCoFe-LDH) was successfully fabricated by coprecipitation and applied as a novel heterogeneous electro-Fenton (EF) catalyst for the degradation of acetaminophen (ACT) from aqueous environments. The EF experiments showed that the CuCoFe-LDH/EF process achieved 100% of ACT degradation efficiency within 60 min at pH = 5, catalyst dosage of 0.50 g/L, current density of 10 mA/cm2 and initial ACT concentration of 20 mg/L. An impressive (>80%) mineralization of ACT was obtained over a wide pH range (pH 3–9) after 180 min. Meanwhile, the role of ·OH and O2.- were certified by radical quenching experiments and electron paramagnetic resonance (EPR) analysis. Through mechanism exploration, the coexistence of Cu and Co on Fe-based LDHs can accelerate the interfacial electron transfer and promote the formation of the reactive oxygen species (ROS), thus facilitating the EF process. Furthermore, the degradation by-products and possible degradation pathways of ACT in the CuCoFe-LDH/EF process were proposed. The reusability test and the treatment of various typical organic pollutants experiments indicated that the CuCoFe-LDH/EF process has excellent stability and broad application prospects. This work provides a valuable reference for the treatment of pharmaceuticals by the heterogeneous EF process in a wide range of pH.

Electrochemical degradation of indigo carmine, P-nitrosodimethylaniline and clothianidin on a fabricated Ti/SnO2–Sb/Co-βPbO2 electrode: Roles of radicals, water matrices effects and performance

In this study, the kinetic degradation of several typical organic pollutants was performed on a synthetic electrode (Ti/SnO2–Sb/Co-βPbO2). The surface structure and the electrochemical properties of the prepared electrode were investigated, confirming the successful preparation of the electrode using an electrochemical deposition method. The outer layer (Co-βPbO2) played an important role in reducing the resistance of the electrode and improving its degradation efficiency. The results showed that indigo carmine (IC), p-nitrosodimethylaniline (RNO), and clothianidin (CLO) were effectively degraded within 20 min of electrolysis. Their degradation in the electrochemical process followed the first-order kinetic model with the degradation rate constant of IC being higher than that of RNO and CLO. This was proved by the difference in the reactivity of the target pollutants toward oxidizing radicals (i.e., •OH, SO4•-, and Cl•). Their second-order rate constant towards radicals were in the range of 109 - 1010 M−1 s−1 with the highest value being that for IC: k·OH,IC = 15.1 × 109 M−1 s−1 and kSO4•−,IC = 7.4 × 109 M−1 s−1. The study calculated the contribution of some oxidizing species, including direct electron transfer (DET), •OH, SO4•-, and other reactive oxygen species (ROS). Solution pH, supporting electrolyte, and water matrix affected the degradation efficiency of pollutants and the contribution of the oxidizing species. Br− and I− ions enhanced the degradation rate of organic pollutants, while Fe2+, HCO3−, and humic acid (HA) reduced it. In addition, the toxicity, total organic carbon (TOC) removal, mineralization current efficiency (MCE), energy consumption, recyclability and stability of the prepared electrode were studied, suggesting that the prepared Ti/SnO2–Sb/Co-βPbO2 is a good candidate for treating organic pollutants using the electrochemical oxidation process.

1α,25-dihydroxyvitamin D3 supplementation alleviates perfluorooctanesulfonate acid-induced reproductive injury in male mice: Modulation of Nrf2 mediated oxidative stress response.

Perfluorooctanesulfonate acid (PFOS) is a typical persistent organic pollutant that widely exists in the environment. To clarify the toxic effects and mechanisms of PFOS and to find effective intervention strategies have been attracted global attention. Here, we investigated the effects of PFOS on the male reproductive system and explored the potential protective role of 1α,25-dihydroxyvitamin D3 (1α,25(OH)2 D3 ). Our results showed that 1α,25(OH)2 D3 intervention significantly improved PFOS-induced sperm quality decline and testicular damage. Moreover, 1α,25(OH)2 D3 aggrandized the total antioxidant capacity. Furthermore, after PFOS exposure, the transcription factor nuclear factor erythroid-related factor 2 (Nrf2) was adaptively increased together with its target genes, such as HO-1, NQO1, and SOD2. Meanwhile, 1α,25(OH)2 D3 ameliorated PFOS-induced augment of Nrf2 and target genes. These findings indicated that 1α,25(OH)2 D3 might attenuate PFOS-induced reproductive injury in male mice via Nrf2-mediated oxidative stress.

The insight into effects of oxygen vacancy on the activation of peroxymonosulfate via MOF-derived magnetic CoFe2O4 for degrading organic contaminants

Herein, MOF-derived magnetic CoFe2O4 with oxygen vacancy was successfully synthesized to activate peroxymonosulfate (PMS) for the effective degradation of emerging organic contaminants. The introduction of oxygen vacancy not only increased the specific surface area of CoFe2O4, but also reduce the charge transfer resistance. The CoFe2O4 with oxygen vacancy showed low charge transfer resistance and oxidation potential. Benefitting from the existence of oxygen vacancy, the PMS could be activated quickly by CoFe2O4 to produce SO4•−. As expected, developed CoFe2O4/PMS oxidation system displayed the excellent degradation ability toward various typical organic pollutants, and the organic pollutant could be mineralized into CO2, H2O and other inorganic molecules. Interestingly, both redox couples of Fe3+/Fe2+ and Co3+/Co2+ played a critical role in the PMS activation process. The SO4•−, OH•, O2•− and 1O2 were major active species in the CoFe2O4/PMS system, which were responsible for the degradation of organic pollutants. Furthermore, proposed CoFe2O4/PMS oxidation system also presented a wide pH range of applicability. The existence of magnetic property was convenient for the recovery of catalyst. All in all, this study provided a promising catalyst for the activation of PMS, and obtained results injected some new insights into the research on advanced oxidation processes (AOPs).

Assessment of factors affecting the diurnal variations of atmospheric PAHs based on a numerical simulation

Atmospheric polycyclic aromatic hydrocarbons (PAHs) are a type of organic pollutants that seriously endanger human health. Obtaining the diurnal variations of PAHs and clarifying their impact mechanisms are significant for the government to formulate targeted prevention and control measures. However, the influencing factors that dominate the diurnal variations of common PAHs are currently unclear. In order to solve this problem, 16 PAHs selected by the United States Environmental Protection Agency (EPA) as priority-controlled pollutants were simulated with high resolution. The simulation results were validated based on diurnal observations in the vertical direction. Although the model underestimated the particle-phase concentrations of most components, it captured their diurnal variations fairly well. In addition, we assessed the factors affecting the diurnal variations of PAHs with sensitivity tests, including chemical reactions and atmospheric diffusion. The results showed that the transforming ratios of PAHs by oxidants were higher during the day than that at night due to the dominant reactions with OH radical. Atmospheric dispersion affected the vertical distribution of PAHs, which resulted in higher day/night ratios at high altitudes than near the ground. We also compared the strength of atmospheric diffusion and chemical reaction on the diurnal trends of PAHs. Near the ground, atmospheric diffusion was the most dominant factor in determining their diurnal trends. At high altitudes, their diurnal trends were determined by a combination of atmospheric diffusion and chemical reactions. These findings can provide a comprehensive understanding of the diurnal variations of common PAHs, which are informative for the prevention and control of PAHs pollution.

Prioritization of micropollutants in municipal wastewater and the joint inhibitory effects of priority organic pollutants on Vibrio qinghaiensis sp.-Q67

Treatment of wastewater in municipal wastewater treatment plants has become a major barrier to organic pollutants entering the aquatic environment. In this study, qualitative screening of organic micropollutants was conducted in a typical municipal wastewater treatment plant (MWWTP) using gas chromatography-mass spectrometry (GC–MS). The identified compounds were prioritized according to their comprehensive scores ranked by detection frequency, semi-quantitative concentration, bioaccumulation, ecotoxicity, and biodegradability. The results showed dibutyl phthalate, antioxidant 2246, methyl stearate, 2,4,6-tri‑tert-butylphenol, and dioctyl phthalate had the top five scores and were ranked as priority organic pollutants in the municipal wastewater. The individual and joint toxicity determinations of the five compounds were carried out by a bioluminescence inhibition assay using Vibrio qinghaiensis sp.-Q67 (V. qinghaiensis). The individual toxicity assay results of these pollutants on V. qinghaiensis demonstrated that the order of the acute toxicity of the five priority organic pollutants was as follows: dioctyl phthalate> dibutyl phthalate> methyl stearate> antioxidant 2246> 2,4,6-tri‑tert-butylphenol. The joint toxicity showed partial addition or antagonism among these pollutants. The prediction results of the mixed toxicity were compared between the concentration addition model and the independent action model, indicating that a single traditional prediction model could not accurately predict the mixed toxicity of different types of organic pollutants, and that a comprehensive application of model prediction could improve the accuracy of mixed toxicity prediction. This method could provide a theoretical basis for systematic screening and toxicity prediction of pollutants in wastewater.