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• CaO has the best performance in the 8-dimensional comparison of 6 conditioners. • Fe/Ca-based conditioners increased 7.5 ∼ 14.8 % char-N and reduced 1.5 ∼ 7 % gas-N. • Fe promoted volatile amine-N cyclization, while Ca promoted it dehydrogenation. • Cl promoted haloalkanes & NO x precursors formation via electrophilic substitution. The nitrogen transformation during sludge pyrolysis is affected by the dewater conditioner. However, the comparative analysis of the conditioner under identical pyrolysis conditions has been previously absent. In this study, Ca-, Fe- and Al-based conditioners were selected as the representatives. A comprehensive evaluation considering the cost of the conditioners and the product characteristics was conducted. Additionally, the in-situ fixation mechanism of the conditioner on nitrogen-containing gas was concurrently revealed. Among the six conditioners, CaO and AlCl 3 were identified as the top performers, ranking first and second, respectively. Furthermore, Fe/Ca-based conditioners reduced NH 3 and HCN release by 1.5 ∼ 5.53 % and 0 ∼ 1.55 %, respectively, by facilitating the conversion of amine-N to a more stable form in condensable fraction. Fe promoted volatile amine-N cyclization, while Ca encouraged its dehydrogenation. Both Fe/Ca-based conditioners increased 7.5 ∼ 14.8 % nitrogen retention in char, by inhibiting the decomposition of protein-N. Al-based conditioners had little effect on NH 3 and HCN, but contributed to 2.3 ∼ 2.8 % production of stabilized nitrogen in char. The introduction of Cl in Fe/Ca/Al chloride conditioners would promote the decomposition of inorganic ammonium salts to produce NH 3 at 30 ∼ 185 °C. And Cl also reacted with volatiles through electrophilic substitution reaction, leading to the formation of halogenated hydrocarbons in condensable fraction and the release of more NH 3 , HCN, and HNCO at 30 ∼ 465 °C. The findings of this study provide a detailed comparative analysis of various conditioners under uniform conditions and reveal the in-situ fixation mechanism of nitrogen-containing gas. This will provide guidance for the sludge conditioning-dewatering-drying integrated treatment and disposal. [ABSTRACT FROM AUTHOR]

The present study reveals the effects of symmetry on how the distribution and flow of energy play out on the decomposition of small halocarbons. Unimolecular decay of the freons CHFCl2 and CF2Cl2 when ionized has been investigated. Mass spectrometric results that encompass isotope effects (peak heights) and energy distribution in the exit channel (peak shapes) are interpreted by computational methods. Non-statistical processes of electronic predissociation and isolated state decay are shown to be directly associated with molecular symmetry. [ABSTRACT FROM AUTHOR]

• Daytime and nighttime dispersion-normalized VOC apportioned profiles were analyzed. • Photochemistry had great impacts on solvent use and biogenic emissions profiles. • Low emissions at nighttime had an important effect on biogenic emissions profile. • Initial data estimation is an effective method for reactive VOCs source analyses. Substantial effects of photochemical reaction losses of volatile organic compounds (VOCs) on factor profiles can be investigated by comparing the differences between daytime and nighttime dispersion-normalized VOC data resolved profiles. Hourly speciated VOC data measured in Shijiazhuang, China from May to September 2021 were used to conduct study. The mean VOC concentration in the daytime and at nighttime were 32.8 and 36.0 ppbv, respectively. Alkanes and aromatics concentrations in the daytime (12.9 and 3.08 ppbv) were lower than nighttime (15.5 and 3.63 ppbv), whereas that of alkenes showed the opposite tendency. The concentration differences between daytime and nighttime for alkynes and halogenated hydrocarbons were uniformly small. The reactivities of the dominant species in factor profiles for gasoline emissions, natural gas and diesel vehicles, and liquefied petroleum gas were relatively low and their profiles were less affected by photochemical losses. Photochemical losses produced a substantial impact on the profiles of solvent use, petrochemical industry emissions, combustion sources, and biogenic emissions where the dominant species in these factor profiles had high reactivities. Although the profile of biogenic emissions was substantially affected by photochemical loss of isoprene, the low emissions at nighttime also had an important impact on its profile. Chemical losses of highly active VOC species substantially reduced their concentrations in apportioned factor profiles. This study results were consistent with the analytical results obtained through initial concentration estimation, suggesting that the initial concentration estimation could be the most effective currently available method for the source analyses of active VOCs although with uncertainty. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, trends in the prediction of acentric factors of halogenated alkanes (HAs) were investigated using two group contribution techniques. The examination of discrepancies between predicted and experimental values for both methods served to delineate the precision and constraints of these prediction techniques. It was observed that while predictions for certain compounds conformed closely to experimental data, others manifested substantial deviations, thereby accentuating the intricacies inherent in predicting acentric factors. The discourse extended to practical implications for applications within the realm of engineering, particularly emphasizing the imperative for the refinement of methods and the conduct of comparative analyses to enrich predictive accuracy. The academic contributions of this investigation are notable for the advancement of predictive methodologies over traditional laboratory procedures in addressing environmental concerns associated with halogenated hydrocarbons. [ABSTRACT FROM AUTHOR]

Volatile halogenated hydrocarbons (VHHs) are annually produced and released into the environment, posing a threat to public health. In this study, a simple, rapid, sensitive and automated method based on headspace and gas chromatography (GC) with electron-capture detection was described for the determination of VHHs in different concentration levels in water samples. The proposed headspace GC method was initially optimized, and the optimum experimental conditions found were 10-mL water sample containing 20% w/v sodium chloride placed in a 20-mL vial and stirred at 60°C for 35 min, and then 14 VHHs were well separated on DB-35 MS capillary column with a split ratio of 12.5: 1. The limits of detection were in the low μg/L level, ranging between 0.01 and 0.6 μg/L. Finally optimized method was applied for determination 14 VHHs in drinking and environmental waters. The total mean concentrations of VHHs were 34.962, 26.183, 3.228 and 647.344 μg/L in tap water, purified water with 1-year-old filter element, seawater and effluents, respectively. However, no VHHs was detected in purified water with a new filter element. The main composition is different among different water matrix, which may be attributed to their different sources. [ABSTRACT FROM AUTHOR]

The present study focuses on a site contaminated with halogenated hydrocarbons, utilizing a detailed inventory of contamination data to achieve the precise characterization of groundwater pollution. Employing MOFLOW-2000 software, a groundwater flow model was established for the study area. In conjunction with MT3DMS, a predictive model was constructed to simulate and forecast the spatiotemporal distribution of contaminant migration and attenuation following site remediation. The simulation area was delineated based on geographical features, with the vertical simulation range of strata also determined. To establish a hydrogeological conceptual model for the target remediation site, comprehensive hydrogeological data were collected, encompassing geological structures, hydrological parameters, and rainfall information. Model calibration was based on the six layers of low-permeability aquifer intervals revealed by geological exploration wells MW1–5, as well as the distribution of groundwater-level contours and rainfall data. Based on data from September 2010, an initial three-dimensional model of tetrachloroethylene (PCE) distribution was generated. Subsequently, a solute transport model for PCE was established, incorporating various enhanced reductive dechlorination (ERD) remediation strategies applied at different times and locations. Calibration against actual monitoring data revealed the presence of unmonitored dense non-aqueous phase liquids (DNAPLs) at the site, contributing to the continuous release and elevation of PCE concentrations. By accounting for DNAPL release, the calibrated transport and attenuation model closely matched observed concentration decay patterns, effectively capturing the actual dynamics of contaminant transport and attenuation within the groundwater system. The modeling approach proposed in this study provides important support for contamination remediation and attenuation at the current site, and it is also applicable to simulating and predicting pollution scenarios at similar sites. [ABSTRACT FROM AUTHOR]

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We describe the discovery of an unspecific peroxygenase (UPO) variant that catalyzes the remote‐site functionalization of halogenated and unsaturated hydrocarbons with high catalytic site‐specificity. UPOs are fungal heme‐thiolate biocatalysts with wide‐ranging oxidative activities, including C─H bond oxygenation, usually with limited regioselectivity. We describe here a wild‐type MroUPO, newly isolated in high yield from a previously uncharacterized strain of Marasmius rotula. This variant, MroUPO‐TN, catalyzes the selective oxygenation of a range of haloalkanes, cyclic haloalkanes and cyclic olefins to generate useful remote‐site haloketones. The regioselectivity for eight‐membered rings reaches 99% with significant enantiomeric excess. Mechanistic studies performed with deuterated substrates and 18O‐labeling experiments have revealed a synergy between intrinsic substrate properties and the highly aliphatic, heme active site. The observed selectivity offers routes to new and useful, bifunctional synthons and pharmacophores, thus providing practical ways to employ these natural and environmentally benign biocatalysts. [ABSTRACT FROM AUTHOR]

To observe the long-term variations in halocarbons in the Yangtze River Delta (YRD) region, this study analyzes halocarbon concentrations and composition characteristics in Shanxi from 2018 to 2020, exploring their origins and the health effects. The total concentration of halocarbons has shown an overall increasing trend, which is driven by both regulated substances (CFC-11 and CFC-113) and unregulated substances, such as dichloromethane, chloromethane and chloroform. The results of the study also reveal that dichloromethane (1.194 ± 1.003 to 1.424 ± 1.004 ppbv) and chloromethane (0.205 ± 0.185 to 0.666 ± 0.323 ppbv) are the predominant halocarbons in Shanxi, influenced by local and northwestern emissions. Next, this study identifies that neighboring cities in Zhejiang Province and other YRD areas are potentially affected by backward trajectory models. Notably, chloroform and 1,2-dichloroethane have consistently surpassed acceptable thresholds, indicating a significant carcinogenic risk associated with solvent usage. This research sheds light on the evolution of halocarbons in the YRD region, offering valuable data for the control and reduction in halocarbon emissions. [ABSTRACT FROM AUTHOR]

We present the synthesis of a novel benzimidazolium-based surface active ionic liquid (SAIL), 3-dodecyl-1H-3λ-benzo[d]imidazole chloride, a SAIL with excellent surface activity and self-aggregation tendency whose aqueous micellar solutions offer exceptional solubilizing capacity and electrocatalytic performance for efficient electrocarboxylation of halocarbons. [ABSTRACT FROM AUTHOR]

To study the impact of volatile organic compounds (VOCs) on air quality, VOCs and related atmospheric pollutants were observed in April 2023 in Daxing District, Beijing, China. The meteorological characteristics of low temperature and relative humidity and wind speed were observed during the observation period. The wind speed occasionally increased, O3 and dust pollution occurred. During the dust pollution period, the concentrations of pollutants such as PM2.5, PM10, NO2, and VOCs significantly increased. The average concentration of VOCs was 20.2 ± 10.7 ppb, with alkanes accounting for the highest percentage, followed by OVOCs, halogenated hydrocarbons, and olefins, aromatic hydrocarbons, alkynes and sulfur dioxide. Calculations based on the ozone generation potential and secondary organic aerosol generation potential indicated that species such as acetaldehyde, ethylene, propylene, propionaldehyde, and toluene were the key VOCs affecting the generation of ozone and secondary particulate matter. The results of the PMF source analysis indicated that the sources with a greater impact on the contribution of VOCs concentrations were liquefied petroleum gas and biomass combustion sources, with 36.8% and 20.8%, respectively, followed by vehicle exhaust, solvent usage, secondary generation and natural sources. The results of this study can provide technical support for a deeper understanding of the characteristics of VOCs in spring of Beijing and effectively formulating of emission reduction measures. [ABSTRACT FROM AUTHOR]

Biochar (BC) is often used as an additive in anaerobic digestion (AD) to increase yield and/or to stabilise the process when the manure content is increased. Unfortunately, BC is rarely described in detail in terms of its raw material sources, production processes, and structural, physical and chemical properties to allow correlation with its effects on AD. It is an open question whether microorganisms from AD can penetrate into different biochar pore types, depending on their wood origin. In this paper, we describe the preparation (temperatures, treatment times, yields) and characterisation shrinkage, density, pore sizes, pore size distribution, specific surface area, ash, volatiles, fixed carbon, elemental composition, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), benzene, toluene, ethyl-toluene, xylene (BTEX) and volatile halogenated hydrocarbons (VHH) of BC cubes of Scots pine (Pinus sylvestris) and common beech (Fagus sylvatica) powder made from this BC in addition to commercial charcoal powder. The pore size distribution determined by mercury porosimetry differs from that determined by 3D-reflected light microscopy. After incubating BC cubes in AD, the cubes were mechanically cleaned and cut into two pieces. Microorganisms were detected inside the cubes by fluorescence microscopy. Particle size and wood source determine the influence of BC on AD. [ABSTRACT FROM AUTHOR]

This study investigates the effects of trifluoromethane (CHF 3) and pentafluoroethane (C 2 HF 5) content on maximum explosion overpressure and maximum rate of pressure rise by changing the equivalence ratio. Then, the critical content of hydrogen explosion inhibition is measured. The inhibition and enhancement mechanisms are analyzed using thermodynamics and reaction kinetics. The results indicate that both sub-inhibitory CHF 3 and C 2 HF 5 enhance hydrogen explosion on the lean and stoichiometric sides, and C 2 HF 5 exhibits stronger enhancement. As the equivalence ratio increases, CHF 3 and C 2 HF 5 directly reduce the maximum explosion overpressure, while C 2 HF 5 shows stronger inhibition. The maximum rate of pressure rise of different equivalence ratios decreases directly with increasing CHF 3 and C 2 HF 5 content. For the same equivalence ratio, the critical content of explosion inhibition of C 2 HF 5 is lower than that of CHF 3. Additionally, R31, R829, R927, and R944 contribute to explosion enhancement by consuming CO, producing [H], or releasing heat, while R824, R830, and R861 for CHF 3 as well as R830, R988, R1097, and R1099 for C 2 HF 5 inhibit hydrogen explosion intensity. • CHF 3 and C 2 HF 5 enhance hydrogen explosions on the lean side. • Production of CO is related to the explosion enhancement caused by CHF 3 and C 2 HF 5. • Critical content of hydrogen explosion inhibition of C 2 HF 5 is lower than that of CHF 3. [ABSTRACT FROM AUTHOR]

114 VOCs were continuously monitored online from January 1st to February 28th, 2021, to analyze the concentration levels and component characteristics of VOCs in Jiaxing, and evaluate ozone formation potential (OFP). The source of VOCs was explored by backward trajectory method and calculation of characteristic species pair ratio. Furthermore, health risk assessment of benzene series was carried out. The results showed that the average volume concentration of VOCs was 38.16x10-9, and the proportion of alkanes, oxygenated volatile organic compounds (OVOCs), halogenated hydrocarbons, olefins, aromatics and alkyns were 31.05%, 20.78%, 19.61%, 13.56%, 12.07% and 2.93%, respectively. The average volume concentration of VOCs during the Spring Festival was 16.82x10-9. The diurnal variation of alkanes, alkenes, aromatic hydrocarbons and halogenated hydrocarbons was consistent with VOCs, while OVOCs showed a fluctuating increase. As shown in OFP results, olefins and aromatic hydrocarbons contributed the most to OFP, and the crucial active species were toluene, propylene, m-p-xylene and ethylene, which were mainly affected by solvent volatilizing. During the Spring Festival, olefins and alkanes contributed the most to OFP, and the crucial active species were propylene, trans-2-butene and cis-2-butene, which were mainly affected by traffic sources. Combining the investigation of characteristic species pair ratio, backward trajectory and potential source contribution function, it can be concluded that VOCs in Jiaxing should be affected by transport and local emission. Among them, alkanes, halogenated hydrocarbons, olefins and aromatic hydrocarbons were jointly affected by regional transport and local emission, and OVOCs and alkynes were mainly local emission. In addition, the non-carcinogenic risk hazard quotient value of benzene series were within the safety threshold, whereas the carcinogenic risk value of benzene and m-xylene/p-xylene were beyond the safety threshold. The above findings can serve as a theoretical foundation for the control of VOCs pollution and the improvement of air quality during winter in Jiaxing. [ABSTRACT FROM AUTHOR]

This study introduces a novel trifluoromethylating reagent, [(bpy)Cu(O2CCF2SO2F)2], notable for not only its practical synthesis from cost-effective starting materials and scalability but also its nonhygroscopic nature. The reagent demonstrates high efficiency in facilitating trifluoromethylation reactions with various halogenated hydrocarbons, yielding products in good yields and exhibiting broad functional group compatibility. The development of [(bpy)Cu(O2CCF2SO2F)2] represents an advancement in the field of organic synthesis, potentially serving as a valuable addition to the arsenal of existing trifluoromethylating agents. [ABSTRACT FROM AUTHOR]

There are no studies investigating the association of chlorinated drinking water with the risk of cardiovascular diseases (CVDs) among young and middle-aged adults. This study was aimed to assess the associations between trihalomethanes (THMs) in drinking water and the risk of CVDs in in the target group in Petropavlovsk, Kazakhstan. 448 dwellers of Petropavlovsk were asked about their demographic, socioeconomic, lifestyle, behavioural characteristics, and drinking water preferences. THMs exposure was assessed to each participant based on their residence address. We used multivariable logistic regression analysis to assess the risk of CVDs in young and middle-aged adults. The results showed that the risk of hypertension in the adjusted logistic regression model was increased by 68% and a 2.7-fold in the second and third THM tertiles, respectively. Participants in the second and third THM exposure tertiles had a 2.3-fold and a 4.8-fold increase in the risk of arrhythmia. [ABSTRACT FROM AUTHOR]

In the Earth's atmosphere, greenhouse gases (GHGs) and reactive trace gases are essential components of chemistry–climate interactions. These trace gases are emitted from both natural and anthropogenic sources over terrestrial and marine regions. Air–sea exchange is the dominant process controlling the distribution of several important trace gases over remote marine regions. Although the ocean–atmosphere interface covers ~70% of the Earth's surface, the quantitative air–sea exchange of reactive trace gases is estimated over the limited oceanic regions. The production and air–sea exchange of trace gases are controlled by physical conditions at both sides of the interface and ocean biogeochemistry. The northern Indian Ocean (NIO) experiences strong seasonal monsoon winds and intense tropical cyclones. Consisting of the Arabian Sea and the Bay of Bengal, it is one of the most biologically productive regimes of the world ocean and home to the intense oxygen minimum zone (OMZ) of the Arabian Sea with dissolved oxygen concentrations. Thus, the NIO offers a unique system to investigate the air–sea exchange processes of reactive trace gases. So far, most of the studies of air–sea exchange of trace gases is focused on the Atlantic and Pacific Oceans, while studies over the northern Indian Ocean are very limited and reported mainly for CH4, CO2 and N2O. Although progress has been made in recent years, studies of air–sea exchange of reactive trace gases such as non-methane hydrocarbon (NMHCs), oxygen-, sulfur- and halogen-containing hydrocarbons remain scarce. This paper addresses the current understanding of air–sea exchange processes and fluxes of reactive trace gases, including NMHCs, dimethyl sulfide (DMS), oxygenated volatile organic compounds (OVOCs), halocarbons, carbon monoxide (CO) and ozone (O3) in the northern Indian Ocean. This review summarizes the studies on the air–sea exchange of trace gases over the northern Indian Ocean and common parametrization approaches used to estimate the air–sea flux of gases. Flux range for ethene (3–10.35 µmol m–2 d–1), isoprene (0.215–0.172 µmol m–2 d–1), acetaldehyde (–6.75–11.35 µmol m–2 d–1), acetone (–9–9 µmol m–2 d–1), DMS (0.03–41.4 µmol m–2 d–1) and CO (1.4–5.4 µmol m–2 d–1) over the NIO were summarized from various in-situ and modelling studies. The paper addresses the importance of the northern Indian Ocean apropos the production and exchange of reactive trace gases, the knowledge gaps and the future scientific scope. Additionally, it emphasizes the need for a multidisciplinary study of oceanic reactive trace gas cycling and its impact on regional atmospheric chemistry over the northern Indian Ocean. [ABSTRACT FROM AUTHOR]

Tyrosinase inhibitors can reduce melanin production for skin whitening, but some existing products may harm the skin. This study discovered six compounds that inhibit tyrosinase in the mushroom Agaricus bisporus by over 50%. Compound 11 displayed strong inhibition (92.2% and 86.7%) for L-tyrosine and L-DOPA substrates, while compound 13 showed high inhibition (96.0% and 62.0%) for both substrates. Molecular docking simulations revealed compounds 11 and 13 bind at the allosteric site of the enzyme. Xanthone derivatives, based on these findings, hold potential as safe skin whitening agents and for pigmentation-related diseases in the cosmetic industry. [ABSTRACT FROM AUTHOR]

Occupational health risk assessments of exposure to VOCs still need to be extensively studied to improve the safety standards in the industry. Based on the monitoring of organic pollutants at various workstations in a truck tire factory in Jiangsu Province, both semi-quantitative and quantitative health risk assessment methods were employed to assess health risk levels. The findings indicated that VOCs were categorized into five classes, which included alkanes, aromatics, halocarbons, carbon disulfide, and oxygenated volatile organic compounds (OVOCs). The highest concentration of total volatile organic compounds (TVOCs) was found in shaping workshop; alkanes were the most abundant class (74.2%), followed by aromatics (24.02%) and OVOCs (1.96%). Although the results of the semi-quantitative risk assessment showed that most of the organic compounds had low R values, various kinds of VOCs were detected; particularly, many harmful organic compounds (such as toluene, ethyl benzene) were detected in all the sampling sites. The quantitative risk in the calendering and vulcanizing workshop exceeded the acceptable level; both the carcinogenic risk of ethylbenzene in the tire-strip storage room, and trichloroethylene and perchloroethylene in the calendering workshop were unacceptable. Thus, the calendering and vulcanizing processes in rubber tire manufacturing should be priority-controlled processes. [ABSTRACT FROM AUTHOR]

In recent years, commercial air transport has increased considerably. However, the compositions and source profiles of volatile organic compounds (VOCs) emitted from aircraft are still not clear. In this study, the characteristics of VOCs (including oxygenated VOCs (OVOCs)) emitted from airport sources were measured at Shenzhen Bao'an International Airport. The results showed that the compositions and proportions of VOC species showed significant differences as the aircraft operating state changed. OVOCs were the dominant species and accounted for 63.17%, 58.44%, and 51.60% of the total VOC mass concentration during the taxiing, approach, and take-off stages. Propionaldehyde and acetone were the main OVOCs, and dichloromethane and 1,2-dichloroethane were the main halohydrocarbons. Propane had the highest proportion among all alkanes, while toluene and benzene were the predominant aromatic hydrocarbons. Compared with the source profiles of VOCs from construction machinery, the proportions of halogenated hydrocarbons and alkanes emitted from aircraft were significantly higher, as were those of propionaldehyde and acetone. OVOCs were still the dominant VOC species in aircraft emissions, and their calculated ozone formation potential (OFP) was much higher than that of other VOC species at all stages of aircraft operations. Acetone, propionaldehyde, formaldehyde, acetaldehyde, and ethylene were the greatest contributors to ozone production. This study comprehensively measured the distribution characteristics of VOCs, and its results will aid in the construction of a source profile inventory of VOCs emitted from aircraft sources in real atmospheric environments. [ABSTRACT FROM AUTHOR]

Online volatile organic compounds (VOCs) were continuous monitored before and after the Omicron policy change at an urban site in polluted Zhengzhou from December 1, 2022, to January 31, 2023. The characteristics and sources of VOCs were explored. The daily average concentration of PM2.5 and total VOCs (TVOCs) ranged from 54 to 239 µg/m3andfrom 15.6 to 57.1 ppbv with an average value of 112 ± 45 µg/m3 and 36.1 ± 21.0 ppbv, respectively during the entire period. The values of PM2.5 and TVOCs in Case 3 (pollution episode after the abolishment of "Nucleic Acid Screening Measures for all staff" policy) were 1.3 and 1.8 times of the values in the Case 1 (pollution episode during "Nucleic Acid Screening Measures for all staff" policy). The concentration of TVOCs in Case 1 and Case 3 were 48.4 ± 20.4 and 67.6 ± 19.6 ppbv, respectively, increased by 63 % and 188 % compared with values during clean days. Alkanes were found to be the most abundant compounds during the entire period. Equivalent volume contribution of halogenated hydrocarbon and oxygenated VOCs (15 %) were found the most in Case 3, followed by alkenes (10 %). Though the volume contributions of aromatics were the lowest (6 % in Case 1 and 7 % in Case 3), the highest increasing ratio was found from clean days to polluted episodes. Positive Matrix Factor model results showed that the main source of VOCs during the observation period was industrial emissions, which accounted for 30 % of the TVOCs, followed by vehicular emission (24 %) and combustion (23 %). The vehicular emission became the largest source during Case 1 (40 %) and Case 3 (29 %), consisting of large numbers of people going out after the blockade. Secondary organic aerosol formation potential (SOAFP) values were 37 and 109 µg/m3, respectively with the highest SOAFP contribution (17–19 μg/m3and 31–51 %) from vehicular emission both in Case 1 and Case 3. Solvent usage sources had the second highest SOAFP value (9 and 16 μg/m3) with the contributions of 23 and 31 % in Case 1 and Case 3 respectively. The control of vehicular emission, and solvent usage should be focused in Zhengzhou, and combustion was also important for the control of PM2.5 pollution in winter. [ABSTRACT FROM AUTHOR]

To investigate the mechanisms of haloalkanes in promoting and inhibiting explosions in methane-air mixtures, the halon alternatives of CHF 3 , C 3 HF 7 , and C 3 H 2 F 6 were selected as inhibitors. Experimental research was conducted in a 20-liter spherical explosion vessel to examine the promotional and inhibitory effects of these haloalkanes on methane-air mixtures. The adiabatic flame temperature, heat release rate, and concentrations of the key radicals were calculated. The results showed that C 3 H 2 F 6 , C 3 HF 7 , and CHF 3 all exhibited a dual effect, initially promoting and subsequently inhibiting explosions in fuel-lean methane-air mixtures. The critical explosion suppression volume fractions of C 3 HF 7 and CHF 3 were 1.5 times and 2.25 times that of C 3 H 2 F 6 , respectively, for the suppression of methane explosion at Φ = 1.2. Furthermore, C 3 HF 7 demonstrated a dual impact on the explosion of stoichiometric methane-air mixtures. From the perspective of reaction kinetics, for fuel-lean methane-air mixture (Φ = 0.8), a small volume of halogenated hydrocarbons led to an increase in the adiabatic flame temperature due to the heat release from critical fluorine-containing elementary reactions, thereby promoting the explosion. Under fuel-lean conditions, the introduction of a small volume of halogenated hydrocarbons led to an increase in the adiabatic flame temperature due to the heat release from critical fluorine-containing elementary reactions, thereby promoting the explosion. Simultaneously, these fluorine-containing reactions scavenged the key free radicals of H, O, and OH inhibiting the explosion process. These two effects competed with each other, ultimately determining the direction of the explosion process. [ABSTRACT FROM AUTHOR]

The study aims to analyze trace gases in the composition of the polythermal glacier on Galindez Island in Maritime Antarctica (65°14' S, 64°16' W) and possible pathways for their abiotic formation in the snowpack and the superimposed or old cold ice. Polythermal glaciers are the most sensitive indicators of climate change. They are ideal for studying chemical post-depositional processes that alter the trace gas composition of the ice core air and the mechanisms involved under the current climate warming. This study is the first attempt to assess the concentration range of a large number of trace gases (except the previously studied O2, N2, Ar, and CO2) in polythermal and temperate glaciers, which are widespread in Greenland, Svalbard, Canadian Arctic, Alaska, Alps, Andes, Tibet, Altai, and Maritime Antarctica. The ice porosity varies from 0.6% to (unique to superimposed ice) 7%. Qualitative analysis by GC-MS was done for more than 200 organic and inorganic trace gases. A quantitative analysis of 27 compounds was performed along the vertical profile of the glacier, including CO2 and N2O, freons, chlorine-based solvents that are prohibited by the Montreal Protocol, F-, Cl-, Br- and I-containing halocarbons, COS, CS2, CH3SCH3, CH3SSCH3, and propene. Statistical data (mean, minimal, and maximum values) for ten horizontal levels of the glacier were calculated for their mixing ratios compared to background air. Most halocarbons, sulfur-containing compounds, and propene are characterized by high enrichment factors. This suggests that the species can be formed in the snowpack and firn of the glacier or its deep bubbling superimposed and old cold ice. Possible pathways of the gases formation include direct and indirect photochemical reactions of the triplet state dissolved organic matter (DOM) in snowpack without or in the presence of X– ions (X = Cl, Br, I), dark redox reactions of Fe3+, Mn4+, Cu2+, O3, H2O2 or radicals HOx (HOx = HO·,HO2·) with DOM in the presence of X–, reactions of HOX with DOM (with the participation of HOx, H2O2 or O3), free radical reactions with alkenes, alkynes, and alkyl radicals, and miscellaneous reactions of methylmethionine and/or S-containing peptides.

To observe the long-term variations in halocarbons in the Yangtze River Delta (YRD) region, this study analyzes halocarbon concentrations and composition characteristics in Shanxi from 2018 to 2020, exploring their origins and the health effects. The total concentration of halocarbons has shown an overall increasing trend, which is driven by both regulated substances (CFC-11 and CFC-113) and unregulated substances, such as dichloromethane, chloromethane and chloroform. The results of the study also reveal that dichloromethane (1.194 ± 1.003 to 1.424 ± 1.004 ppbv) and chloromethane (0.205 ± 0.185 to 0.666 ± 0.323 ppbv) are the predominant halocarbons in Shanxi, influenced by local and northwestern emissions. Next, this study identifies that neighboring cities in Zhejiang Province and other YRD areas are potentially affected by backward trajectory models. Notably, chloroform and 1,2-dichloroethane have consistently surpassed acceptable thresholds, indicating a significant carcinogenic risk associated with solvent usage. This research sheds light on the evolution of halocarbons in the YRD region, offering valuable data for the control and reduction in halocarbon emissions.

BACKGROUND: Endometrial cancer is a hormone-dependent cancer, and estrogens play a relevant role in its etiology. However, little is known about the effects of environmental pollutants that act as xenoestrogens or that influence estrogenic activity through different pathways. OBJECTIVE: We aimed to assess the relationship between the combined estrogenic activity of mixtures of xenoestrogens present in serum samples and the risk of endometrial cancer in the Screenwide case–control study. METHODS: The total effective xenoestrogen burden (TEXB) attributable to organohalogenated compounds (TEXB-a) and to endogenous hormones and more polar xenoestrogens (TEXB-ß) was assessed in serum from 156 patients with endometrial cancer (cases) and 150 controls by combining chemical extraction and separation by high-performance liquid chromatography with the E-SCREEN bioassay for estrogenicity. RESULTS: Median TEXB-a and TEXB-ß levels for cases (0.30 and 1.25 Eeq pM/mL, respectively) and controls (0.42 and 1.28 Eeq pM/mL, respectively) did not significantly differ (??=0.653 and 0.933, respectively). An inverted-U risk trend across serum TEXB-a and TEXB-ß levels was observed in multivariate adjusted models: Positive associations were observed for the second category of exposure in comparison to the lowest category of exposure [odds ratio (OR) = 2.11 (95% CI: 1.13, 3.94) for TEXB-a, and OR=3.32 (95% CI: 1.62, 6.81) for TEXB-ß], whereas no significant associations were observed between the third category of exposure and the first [OR = 1.22 (95% CI: 0.64, 2.31) for TEXB-a, and OR=1.58 (95% CI: 0.75, 3.33) for TEXB-ß]. In mutually adjusted models for TEXB-a and TEXB-ß levels, the association of TEXB-a with endometrial cancer risk was attenuated [OR=1.45 (95% CI: 0.61, 3.47) for the second category of exposure], as well as estimates for TEXB-ß (OR=2.68; 95% CI: 1.03, 6.99). Most of the individual halogenated contaminants showed no associations with both TEXB and endometrial cancer. CONCLUSIONS: We evaluated serum total xenoestrogen burden in relation to endometrial cancer risk and found an inverted-U risk trend across increasing categories of exposure. The use of in vitro bioassays with human samples may lead to a paradigm shift in the way we understand the negative impact of chemical mixtures on human health effects. These results are relevant from a public health perspective and for decision-makers in charge of controlling the production and distribution of chemicals with xenoestrogenic activity. [ABSTRACT FROM AUTHOR]

As "fuel" for atmospheric photochemical reactions, volatile organic compounds (VOCs) play a key role in the secondary generation of ozone (O3) and fine particulate matter (PM2.5, an aerodynamic diameter ≤ 2.5 μm). To determine the characteristics of VOCs in a high-level ozone period, comprehensive monitoring of O3 and its precursors (VOCs and NOx) was continuously conducted in an industrial area in Shanghai from 18 August to 30 September 2021. During the observation period, the average concentration of VOCs was 47.33 ppb, and alkanes (19.64 ppb) accounted for the highest proportion of TVOCs, followed by oxygenated volatile organic compounds (OVOCs) (13.61 ppb), alkenes (6.92 ppb), aromatics (4.65 ppb), halogenated hydrocarbons (1.60 ppb), and alkynes (0.91 ppb). Alkenes were the predominant components that contributed to the ozone formation potential (OFP), while aromatics such as xylene, toluene, and ethylbenzene contributed the most to the secondary organic aerosol production potential (SOAFP). During the study period, O3, NOx, and VOCs showed significant diurnal variations. Industrial processes were the main source of VOCs, and the second largest source of VOCs was vehicle exhaust. While the largest contribution to OFP was from vehicle exhaust, the second largest contribution was from liquid petroleum gas (LPG). High potential source contribution function (PSCF) values were observed in western and southeastern areas near the sampling sites. The results of a health risk evaluation showed that the Hazard Index was less than 1 and there was no non-carcinogenic risk, but 1,3-butadiene, benzene, chloroform, 1,2-dibromoethane, and carbon tetrachloride pose a potential carcinogenic risk to the population. [ABSTRACT FROM AUTHOR]

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) stands as one of the most potent halogenated polycyclic hydrocarbons, known to inflict substantial cytotoxic effects on both animal and human tissues. Its widespread presence and recalcitrance make it an environmental and health concern. Efforts are being intensively channeled to uncover strategies that could mitigate the adverse health outcomes associated with TCDD exposure. In the realm of counteractive agents, boron compounds are emerging as potential candidates. These compounds, which have found applications in a spectrum of industries ranging from agriculture to pharmaceutical and cosmetic manufacturing, are known to modulate several cellular processes and enzymatic pathways. However, the dose–response relationships and protective potentials of commercially prevalent boron compounds, such as boric acid (BA), ulexite (UX), and borax (BX), have not been comprehensively studied. In our detailed investigation, when peripheral blood mononuclear cells (PBMCs) were subjected to TCDD exposure, they manifested significant cellular disruptions. This was evidenced by compromised membrane integrity, a marked reduction in antioxidant defense mechanisms, and a surge in the malondialdehyde (MDA) levels, a recognized marker for oxidative stress. On the genomic front, increased 8-OH-dG levels and chromosomal aberration (CA) frequency suggested that TCDD had the potential to cause DNA damage. Notably, our experiments have revealed that boron compounds could act as protective agents against these disruptions. They exhibited a pronounced ability to diminish the cytotoxic, genotoxic, and oxidative stress outcomes instigated by TCDD. Thus, our findings shed light on the promising role of boron compounds. In specific dosages, they may not only counteract the detrimental effects of TCDD but also serve as potential chemopreventive agents, safeguarding the cellular and genomic integrity of PBMCs. [ABSTRACT FROM AUTHOR]

To acquire a material with simultaneous oil–water emulsion demulsification and oil‐absorbing performance, SiO2 nanoparticles were introduced into the acrylate polymerization system to prepare oil absorbent SiO2/P (SMA‐co‐MMA‐co‐BA) (PSA‐SiO2). PSA‐SiO2 was synthesized from monomers and functional materials, including methyl methacrylate (MMA), butyl acrylate (BA), octadecyl methacrylate (SMA) and SiO2 hydrophobically modified by vinyltrimethoxysilane. The molecular structure of PSA‐SiO2 was characterized by FT‐IR, and its morphology was observed using scanning electron microscopy. In addition, the optimal synthesis conditions for the polymerization system, such as the monomer ratio, the amount of crosslinker and stabilizer and then the particle size and dose of SiO2, were discussed in detail. PSA‐SiO2 had a decent oil absorbency for pure halogenated and aromatic hydrocarbons (49.10, 56.41, 47.32, 43.45, 36.22, and 30.14 g/g for CH2Cl2, CHCl3, CCl4, C2Cl4, toluene and styrene, respectively). Furthermore, SiO2, as a functional material, makes composites that possess excellent demulsification properties for oil‐in‐water emulsions. The oil removal efficiency of CHCl3 in Tween 80‐stabilized and CTAB‐stabilized emulsions were 94.88% and 98.11%, respectively. All results indicated that PSA‐SiO2 had valuable potential for oil removal and emulsion treatment. Highlights: An organic–inorganic composite was synthesized by suspension polymerization.The composite was applied for absorbing pure oil or removing oil form water.By modification, the composite acquired the demulsification ability.The composite accomplished one‐step demulsification and emulsion treatment.The oil absorption and emulsion treatment could achieve at room temperature. [ABSTRACT FROM AUTHOR]

BACKGROUND: In 2015, the U.S. Consumer Product Safety Commission (CPSC) received and then, in 2017, granted a petition under the Federal Hazardous Substances Act to declare certain groups of consumer products as banned hazardous substances if they contain nonpolymeric, additive organohalogen flame retardants (OFRs). The petitioners asked the CPSC to regulate OFRs as a single chemical class with similar health effects. The CPSC later sponsored a National Academy of Sciences, Engineering, and Medicine (NASEM) report in 2019, which ultimately identified 161 OFRs and grouped them into 14 subclasses based on chemical structural similarity. In 2021, a follow-up discussion was held among a group of scientists from both inside and outside of the CPSC for current research on OFRs and to promote collaboration that could increase public awareness of CPSC work and support the class-based approach for the CPSC’s required risk assessment of OFRs. OBJECTIVES: Given the extensive data collected to date, there is a need to synthesize what is known about OFR and how class-based regulations have previously managed this information. This commentary discusses both OFR exposure and OFR toxicity and fills some gaps for OFR exposure that were not within the scope of the NASEM report. The objective of this commentary is therefore to provide an overview of the OFR research presented at SOT 2021, explore opportunities and challenges associated with OFR risk assessment, and inform CPSC’s work on an OFR class-based approach. DISCUSSION: A class-based approach for regulating OFRs can be successful. Expanding the use of read-across and the use of New Approach Methodologies (NAMs) in assessing and regulating existing chemicals was considered as a necessary part of the class-based process. Recommendations for OFR class-based risk assessment include the need to balance fire and chemical safety and to protect vulnerable populations, including children and pregnant women. The authors also suggest the CPSC should consider global, federal, and state OFR regulations. The lack of data or lack of concordance in toxicity data could present significant hurdles for some OFR subclasses. The potential for cumulative risks within or between subclasses, OFR mixtures, and metabolites common to more than one OFR all add extra complexity for class-based risk assessment. This commentary discusses scientific and regulatory challenges for a class-based approach suggested by NASEM. This commentary is offered as a resource for anyone performing class-based assessments and to provide potential collaboration opportunities for OFR stakeholders. [ABSTRACT FROM AUTHOR]

The chemical complexity and toxicity of volatile organic compounds (VOCs) are primarily encountered through intensive anthropogenic emissions in suburban areas. Here, pollution characteristics, impacts on secondary pollution formation, and health risks were investigated through continuous in-field measurements from 1–30 June 2020 in suburban Nanjing, adjacent to national petrochemical industrial parks in China. On average, the total VOCs concentration was 34.47 ± 16.08 ppb, which was comprised mostly by alkanes (41.8%) and halogenated hydrocarbons (29.4%). In contrast, aromatics (17.4%) dominated the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) with 59.6% and 58.3%, respectively. Approximately 63.5% of VOCs were emitted from the petrochemical industry and from solvent usage based on source apportionment results, followed by biogenic emissions of 22.3% and vehicle emissions of 14.2%. Of the observed 46 VOC species, hexachlorobutadiene, dibromoethane, butadiene, tetrachloroethane, and vinyl chloride contributed as high as 98.8% of total carcinogenic risk, a large fraction of which was ascribed to the high-level emissions during ozone pollution episodes and nighttime. Therefore, the mitigation of VOC emissions from petrochemical industries would be an effective way to reduce secondary pollution and potential health risks in conurbation areas. [ABSTRACT FROM AUTHOR]

The paper presents the fabrication and characterization of [CuI(L)][sub n] thin films, where L represents various alkylpyridine ligands including 4-methylpyridine, 3-methylpyridine, 2-methylpyridine, 4-[sup t]butylpyridine, 3,4-dimethylpyridine, and 3,5-dimethylpyridine. The thin films were synthesized by exposing the corresponding ligands to CuI thin films through vapor deposition. The coordination reactions occurring on the films were investigated using PXRD and time-dependent photoluminescence spectroscopy, and a comparison was made between the structures of the thin films and the corresponding powder phases. The films showed primarly blue emission (λem = 457-515 nm) and polymeric structures with excited state lifetimes ranging from 0.6 to 5.5 μs. Significantly, the studied compounds exhibited fast reversible luminescence quenching when exposed to vapors of dichloromethane and dibromomethane (15 and 30 min respectively), and the luminescence was restored upon reexposure to the alkylpyridine ligand (after 20 min). These findings indicate that these thin films hold promise for applications as sensors (with sensitive and reversible detection capability) for volatile halogen-based compounds (VHC). [ABSTRACT FROM AUTHOR]

The surface atmospheric O3 concentration in Kunming shows a significant upward trend, with high values mainly occurring in March–May. Volatile organic compounds (VOCs) are one of the most important precursors of O3. However, the sources of VOCs are complex and difficult to identify. In order to understand the pollution levels, the spatial distribution characteristics, and possible sources of VOCs, we conducted simultaneous offline sampling at representative sites in six different functional areas of Kunming using SUMMA canisters for one week. The VOC samples were analyzed via GC/MS. The VOC data were analyzed (using the feature ratio method, ozone formation potential (OFP), and Positive Matrix Factorization (PMF) model). Some important conclusions were drawn. Firstly, VOCs during the spring in Kunming were mainly derived from oxygenated VOCs, aromatic hydrocarbons, and halogenated hydrocarbons, with significant spatial differences. Secondly, we found that the potential for atmospheric ozone formation is higher in Kunming for aromatic hydrocarbons and oxygenated VOCs. Finally, the results of the Positive Matrix Factorization model (PMF) showed that Kunming's ambient atmospheric VOCs mainly originate from anthropogenic source emissions. These conclusions can provide useful reference information for O3 pollution control in Kunming. [ABSTRACT FROM AUTHOR]

Pharmaceutical product hops are anticompetitive maneuvers that often represent a last-ditch effort by brand manufacturers to preserve market share in the face of generic competition. An integral part of product life cycle management strategies, product hops may offer marginal benefits to patients but can substantially increase costs to payers and patients alike. Industry advocates, however, maintain that product hops represent essential follow-on research and development, resulting in the development of novel products that would otherwise never reach the market. Is there a middle ground between these two diametrically opposed views? Might certain product hops be considered beneficial, perhaps if they furthered important public health interests? Sometimes product hops arise due to safety concerns raised by the U.S. Food and Drug Administration or pressure from other public health agencies. For instance, a push from Congress and the U.S. Environmental Protection Agency to remove chlorofluorocarbons from all consumer and industrial products resulted in a switch from chlorofluorocarbon to hydrofluoroalkane propellants in respiratory inhalers. In another instance, concerns about the opioid crisis fueled the development of abuse-deterrent formulations of opioids as part of a public health response to the crisis. Despite the public health motivations driving each scenario, I find that some public benefit may have been achieved, but at substantial expense to both payers and patients. I explore the potential benefits of a "public health product hop" in more detail using the recent approval of over-the-counter versions of intranasal naloxone as a case study. This Article develops a framework for rewarding product hops that provide a meaningful and quantifiable public health benefit. In these instances, time-limited patent incentives may more equitably reward manufacturers for advancing important public health goals while ending regulatory incentives for purely profit-driven product hops. [ABSTRACT FROM AUTHOR]

• Anthropogenic emissions and air masses with different pollution levels cause seasonal and regional variations of halocarbons in southeastern China. • Industrial activities were the primary sources, accounting for 63.7 % of the total. • CH 2 Cl 2 contributed the most to the total halocarbons, followed by CH 3 Cl and HCFC-22. • It is important to control the rapidly growing unregulated species of halocarbons. • The hotspots in Fujian Province were concentrated in Xiamen, Fuzhou and Sanming. Halocarbons play a vital role in ozone depletion and global warming, and are regulated by the Montreal Protocol (MP) and its amendments. China has been identified as an important contributor to the halocarbon emissions, but the regional sources of halocarbons in China are not yet well comprehended. To investigate the characteristics, emissions, and source profiles, this study conducted a field campaign in Xiamen, a coastal city in southeastern China. Higher enhancements were found in the unregulated halocarbons (CH 3 Cl, CH 2 Cl 2 , CHCl 3) than in the MP eliminated species (CCl 4 , CH 3 Br) and the MP controlled species (HCFCs, HFCs). Many of the measured halocarbons varied seasonally and regionally, depending on the anthropogenic sources and atmospheric transport. Backward trajectory analysis showed that the air masses from inland were polluted over Shandong, Hebei, and northern Fujian in the cold season, while the air masses from the sea in the warm season were clean. Different air masses in two seasons were associated with the halocarbon patterns in the study area. Industrial activities, especially solvent usage, were the primary sources of halocarbons. The emission hot spots in Fujian Province were concentrated in Sanming, Fuzhou, and Xiamen, and the unregulated halocarbons made the largest contribution. This study provides an insight for a deep understanding of the characteristics and potential sources of halocarbons, and for strengthened management of halocarbons in China. [Display omitted] [ABSTRACT FROM AUTHOR]

Phototransformation of free tryptophan (Trp) and Trp complexed with nanodiamond particles (ND–Trp) in the presence of a halocarbon (HC) i.e., chloroform CHCl3), was studied by steady-state spectroscopy. UV irradiation of solutions in the presence of CHCl3 was found to increase the fluorescence intensity of the phototransformation products of Trp (PTT), i.e., kynurenine and its derivatives. The integral intensity of fluorescence with a maximum at ~460 nm increased more significantly in the ND–Trp system than in the system with free Trp. The optimal conditions for this reaction were studied. The applicability of the PTT reaction for the detection of widely used chlorinecontaining hydrocarbons such as Aroclor 1254 (USA standard) and prochloraz, which is part of the combined fungicide Zamir, was demonstrated. A new photometric test system for the detection with high sensitivity (up to 10–6–10–9 M) in the PTT reaction upon irradiation with UV light was proposed. [ABSTRACT FROM AUTHOR]

The aryl hydrocarbon receptors (Ahrs) are evolutionarily conserved ligand‐dependent transcription factors that are activated by structurally diverse endogenous compounds as well as environmental chemicals such as polycyclic aromatic hydrocarbons and halogenated aromatic hydrocarbons. Activation of the Ahr leads to several transcriptional changes that can cause developmental toxicity resulting in mortality. Evidence was assembled and evaluated for two novel adverse outcome pathways (AOPs) which describe how Ahr activation (molecular initiating event) can lead to early–life stage mortality (adverse outcome), via either SOX9‐mediated craniofacial malformations (AOP 455) or cardiovascular toxicity (AOP 456). Using a key event relationship (KER)‐by‐KER approach, we collected evidence using both a narrative search and a systematic review based on detailed search terms. Weight of evidence for each KER was assessed to inform overall confidence of the AOPs. The AOPs link to previous descriptions of Ahr activation and connect them to two novel key events (KEs), increase in slincR expression, a newly characterized long noncoding RNA with regulatory functions, and suppression of SOX9, a critical transcription factor implicated in chondrogenesis and cardiac development. In general, confidence levels for KERs ranged between medium and strong, with few inconsistencies, as well as several opportunities for future research identified. While the majority of KEs have only been demonstrated in zebrafish with 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin as an Ahr activator, evidence suggests that the two AOPs likely apply to most vertebrates and many Ahr‐activating chemicals. Addition of the AOPs into the AOP‐Wiki (https://aopwiki.org/) helps expand the growing Ahr‐related AOP network to 19 individual AOPs, of which six are endorsed or in progress and the remaining 13 relatively underdeveloped. Environ Toxicol Chem 2023;42:2063–2077. © 2023 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Simple Summary: This article aims to explore various ruminant enteric methane mitigation strategies and delve into their underlying modes of action. Furthermore, it addresses the importance of ruminant enteric methane mitigation in the context of climate change and its potential impact on global warming. The article also highlights the need for interdisciplinary research and collaboration to develop comprehensive and practical solutions. By considering the ecological, economic, and social implications of these strategies, policymakers and stakeholders can make informed decisions to reduce methane emissions while ensuring the sustainability of livestock production systems. This review examines the current state of knowledge regarding the effectiveness of different dietary ruminant enteric methane mitigation strategies and their modes of action together with the issues discussed regarding the potential harms/risks and applicability of such strategies. By investigating these strategies, we can enhance our understanding of the mechanisms by which they influence methane production and identify promising approaches for sustainable mitigation of methane emissions. Out of all nutritional strategies, the use of 3-nitrooxypropanol, red seaweed, tannins, saponins, essential oils, nitrates, and sulfates demonstrates the potential to reduce emissions and receives a lot of attention from the scientific community. The use of certain additives as pure compounds is challenging under certain conditions, such as pasture-based systems, so the potential use of forages with sufficient amounts of plant secondary metabolites is also explored. Additionally, improved forage quality (maturity and nutrient composition) might help to further reduce emissions. Red seaweed, although proven to be very effective in reducing emissions, raises some questions regarding the volatility of the main active compound, bromoform, and challenges regarding the cultivation of the seaweed. Other relatively new methods of mitigation, such as the use of cyanogenic glycosides, are also discussed in this article. Together with nitrates, cyanogenic glycosides pose serious risks to animal health, but research has proven their efficacy and safety when control measures are taken. Furthermore, the risks of nitrate use can be minimized by using probiotics. Some of the discussed strategies, namely monensin or halogenated hydrocarbons (as pure compounds), demonstrate efficacy but are unlikely to be implemented widely because of legal restrictions. [ABSTRACT FROM AUTHOR]

Shale gas extraction is increasing worldwide in the context of the energy crisis, yet the associated pollution by this industrial activity is poorly known. Here we analyzed organic contaminants occurring in the effluent of a shale gas wastewater treatment plant from Chongqing, China, using gas chromatography coupled to time of flight mass spectrometry. The toxicological effects of typical iodoalkanes were also evaluated using human liver carcinoma cells. We identified 115 compounds belonging to the classes of alkanes, aromatic hydrocarbons, halogenated hydrocarbons, amines, nitriles, aldehydes, ketones, esters and alcohols in wastewater. Several halogenated hydrocarbons were identified for the first time in shale gas wastewater effluents, notably iodine compounds. Mechanisms of formation of iodoalkanes benzyl bromide and benzyl iodide are discussed. Halogenated N-heterocyclic compounds originate probably from fracturing chemicals. Toxicity evaluation shows that cell growth for iodoalkanes treatments reduced in a dose-dependent manner, especially for diiodoalkane, suggesting that the cytotoxicity may be related to the number of substituted iodine atoms. [ABSTRACT FROM AUTHOR]

The present study has investigated the effects of Metro Vancouver's wastewater treatment plant (WWTP) effluents on English sole (Parophrys vetulus) hepatic gene expression using novel targeted gene expression assays to complement the 2017 Burrard Inlet Ambient Monitoring Program conducted by Metro Vancouver. Seven locations of varying distance to the WWTPs were included. Twelve genes involved in xenobiotic defense (CYP1A, HSP70), thyroid function (DIO1), lipid and glucose metabolism (FABP1, FASN, GLUT2, PPAR δ , PPAR γ), protein synthesis (18S rRNA, RPS4X), and reproduction (ER α , VTG) revealed several differences between these impacted sites. A key finding of the present study was that males exhibited VTG transcript levels either equivalent or exceeding female levels of this gene at all sites investigated, indicating widespread exposure of estrogenic contaminants throughout Burrard Inlet. Furthermore, the induction of hepatic CYP1A was observed due to possible downstream sites being subjected to a larger influx of certain planar halogenated and non-halogenated hydrocarbons from multiple industrial contributors. This study also revealed significant differences between the sites examined and in genes involved in transcriptional regulation and synthesis of proteins, lipids and glucose metabolism, and thyroid hormone metabolism. Collectively, this study demonstrates the potential of molecular biomarkers of urban contaminant exposure in wild caught English sole for use in diagnosing a broader range of adverse health effects when combined with conventional whole organism health indicators. [ABSTRACT FROM AUTHOR]

Many synthesis methods are summarized about ethylene glycol ethers, such as ethylene oxide method, ethylene method, halogenated hydrocarbon method, diethylene glycol method, synthesis gas method, ethylene glycol method, oxalate methocl・ The current status and defects are also evaluated・ The various catalyst application in these synthesis methods and their advantages and disadvantages are also summarized ・ The latest advances of ethylene glycol ethers in industrial as well as domestic applications and technologies are generalized ・ The future development direction and research focus of ethylene glycol ethers are also indicated. [ABSTRACT FROM AUTHOR]

We compiled an experimental database for the surface tension of binary mixtures containing a wide variety of fluids, from the chemical classes (water, alcohols, amines, ketones, linear and branched alkanes, naphthenes, aromatics, refrigerants, and cryogens). The resulting data set includes 65 pure fluids and 154 binary pairs with a total of 8205 points. We used this database to test the performance of a parachor model for the surface tension of binary mixtures. The model uses published correlations to determine the parachors of the pure fluids. The model has a single, constant binary interaction parameter for each pair that was found by fitting experimental mixture data. It can be also used in a predictive mode when the interaction parameters are set to zero. We present detailed comparisons on the performance of the model for both cases. In general, the parachor model in a predictive mode without fitted interaction parameters can predict the surface tension of binary mixtures of non-polar mixtures such as linear and branched alkanes, linear and branched alkanes with naphthenes, aromatics with aromatics, aromatics with naphthenes, and mixtures of linear alkanes of similar sizes with an average absolute percentage deviation of about 3 % or less. Polar mixtures of halocarbons with other halocarbons and also polar/nonpolar mixtures of alkanes with halocarbons could be modeled with an average absolute deviation of less than 0.35 mN·m−1 with the use of a binary interaction parameter. The parachor model even with a fitted binary interaction parameter performs poorly for mixtures of water and organic compounds and is not recommended. [ABSTRACT FROM AUTHOR]

The study aims to analyze trace gases in the composition of the polythermal glacier on Galindez Island in Maritime Antarctica (65°14' S, 64°16' W) and possible pathways for their abiotic formation in the snowpack and the superimposed or old cold ice. Polythermal glaciers are the most sensitive indicators of climate change. They are ideal for studying chemical post-depositional processes that alter the trace gas composition of the ice core air and the mechanisms involved under the current climate warming. This study is the first attempt to assess the concentration range of a large number of trace gases (except the previously studied O2, N2, Ar, and CO2) in polythermal and temperate glaciers, which are widespread in Greenland, Svalbard, Canadian Arctic, Alaska, Alps, Andes, Tibet, Altai, and Maritime Antarctica. The ice porosity varies from 0.6% to (unique to superimposed ice) 7%. Qualitative analysis by GC-MS was done for more than 200 organic and inorganic trace gases. A quantitative analysis of 27 compounds was performed along the vertical profile of the glacier, including CO2 and N2O, freons, chlorine-based solvents that are prohibited by the Montreal Protocol, F-, Cl-, Br- and I-containing halocarbons, COS, CS2, CH3SCH3, CH3SSCH3, and propene. Statistical data (mean, minimal, and maximum values) for ten horizontal levels of the glacier were calculated for their mixing ratios compared to background air. Most halocarbons, sulfur-containing compounds, and propene are characterized by high enrichment factors. This suggests that the species can be formed in the snowpack and firn of the glacier or its deep bubbling superimposed and old cold ice. Possible pathways of the gases formation include direct and indirect photochemical reactions of the triplet state dissolved organic matter (DOM) in snowpack without or in the presence of X- ions (X = Cl, Br, I), dark redox reactions of Fe3+, Mn4+, Cu2+, O3, H2O2 or radicals HOx (HOx = HO·, HO2·) with DOM in the presence of X-, reactions of HOX with DOM (with the participation of HOx, H2O2 or O3), free radical reactions with alkenes, alkynes, and alkyl radicals, and miscellaneous reactions of methylmethionine and/or S-containing peptides. [ABSTRACT FROM AUTHOR]

The concentration of ozone has been in a rising crescendo in the last decade while the fine particles (PM2.5) is gradually decreasing but still at a high level in central China. Volatile organic compounds (VOCs) are the vital precursors of ozone and PM2.5. A total of 101 VOC species were measured in four seasons at five sites from 2019 to 2021 in Kaifeng. VOC sources and geographic origin of sources were identified by the positive matrix factorization (PMF) model and the hybrid single-particle Lagrangian integrated trajectory transport model. The source-specific OH loss rates (LOH) and ozone formation potential (OFP) were calculated to estimate the effects of each VOC source. The average mixing ratios of total VOCs (TVOC) were 43.15 parts per billion (ppb), of which the alkanes, alkenes, aromatics, halocarbons, and oxygenated VOCs respectively accounted for 49%, 12%, 11%, 14%, and 14%. Although the mixing ratios of alkenes were comparatively low, they played a dominant role in the LOH and OFP, especially ethene (0.55 s−1, 7%; 27.11 μg/m3, 10%) and 1,3-butadiene (0.74 s−1, 10%; 12.52 μg/m3, 5%). The vehicle-related source which emitted considerable alkenes ranked as the foremost contributing factor (21%). Biomass burning was probably influenced by other cities in the western and southern Henan and other provinces, Shandong and Hebei. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) as the components of atmospheric pollutants have been potentially harmful to the environment and human health. Swine production, one of the pillar livestock industries, is severely hampered by some air pollution issues, such as the emissions of odor and VOCs. The odor complaints were reported the most, accounting for 12.7% of the whole Chinese livestock industry in 2020, according to the Study "Analysis of National Odor Pollution Complaints in 2018-2020" from the National Ministry of Ecology and Environment. Odor pollution is considered as one of the major environment issues in the large-scale swine production, hindering the sustainable development of the industry. Therefore, it is critical to implement the odor pollution prevention and control measures in the large-scale swine production industry. However, the VOCs, components of the odorous pollutants, vary greatly in the organic molecules in the frequent present of the air, leading to difficulty in mitigation of odor. Generally, the VOCs are the significant precursors of ozone (O3 ) and secondary aerosols (SOA). Once the concentration of VOCs exceeds a certain threshold value, a significant negative impact can be imposed on the environment, as well as human and animal health. Therefore, mitigation measures are essential to reduce the VOC emissions, and their negative impact on the environment and public health. In this review, VOCs emitted from the swine production was introduced from the aspects of characteristics and reduction potential. The types, characteristics, and sources of VOCs from pig farms were elucidated, together with the properties of odor-causing VOCs and detection. The factors that could impact the VOCs concentration were also illustrated, such as ventilation in barn, pig breed and manure cleaning. In addition, different testing methods and standards were selected for the variations in the composition of VOCs. The most common VOCs in swine production were found as the volatile fatty acids (VFA), olefins, alkanes, aromatic hydrocarbons, halogenated hydrocarbons, esters, ethers, phenols, indoles, organic sulfur, aldehydes, and ketones. Among them, the VFA, phenol, indole, and organosulfur were the most common odor-causing substances. The sources of VOCs were then analyzed for the efficient odor management. Manure, indoor air, and dust were the three main sources of VOCs in pig barns, which are considered as the primary risk of the environment and human health. The odor annoyance was found to be directly caused in the neighborhood, leading to the formation of ground-level ozone and secondary aerosols when exposed to the air. The detection methods of VOCs generally consisted of the discrete and continuous approaches. The typical VOCs measurement steps of discrete approaches were the sample collection, pre-treatment, and analysis. The commonly used continuous detection instrument was the proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOF-MS). Finally, the primary VOCs treatment technologies were evaluated from three aspects of VOCs reduction in pig farms: source reduction, process control, and end treatment. Source reduction of VOCs, i.e., adjustments in the feed rations and the additives could improve the physiology and production performance of pigs. Process management of the VOCs reduction was achieved after adjustments in feeding and ventilation systems. The better manure cleaning practices were applied to limit the off-gassing from swine production. End treatment mainly included the VOCs treatment technologies of manure and ambient air treatment. Traditional VOCs treatment technologies were divided into two categories: recycling and degradation treatments. Photocatalytic oxidation, active material adsorption, low temperature plasma technology and degradation methods with the bio filters can be expected to gradually replace the traditional treatments and become the key technologies for the VOCs treatment. The finding can contribute to the more sustainable development in animal husbandry, in order to mitigate the negative environmental and health impacts caused by the VOC emissions. [ABSTRACT FROM AUTHOR]

It is recognized that the combustion of halogenated substances (gas and liquids) may present specific features compared to traditional hydrocarbons. As a matter of facts, the standardized flammability characterization methods referenced by the various regulations (transport, labeling, etc.) do not necessarily take the specific features of these substances into account. Subsequently, this may lead to an underestimation of the risk associated with their use (physical hazard such as explosion). Through two case studies of interest, one concerning a fluorinated liquid, the other focusing on a fluorinated gas, this work reveals technical difficulties that may arise in appraising actual flammability hazards of halogenated hydrocarbons, due to their combustion specific behavior, when applying existing flammability methods without appropriate expert judgement. In the case of the liquid ethoxy-nonafluorobutane (Novec 7200™) this work highlights that this substance can be erroneously considered non-flammable due a clear pitfall of flash point methods, whilst its genuine flammability can be revealed otherwise. Regarding gaseous halogenated species, we show that operating conditions shall be carefully selected to reveal the genuine flammability behavior of such substances. Indeed, this is not necessarily correctly identified in all possible flammability hazard rating standard methods. In this study, the application of European standards allows to confirm that R1234ze(E) is flammable at temperatures below 30 °C, at atmospheric pressure and at a humidity of 50%RH. [ABSTRACT FROM AUTHOR]

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In this study, four typical VOCs emission industries were selected such as automobile manufacturing, textile printing and dyeing, pharmaceutical and chemical industry, pesticide manufacturing in an industrial park in Jingzhou City. The source composition spectrum of localized VOCs in the park was preliminarily established and their environmental impact was analyzed. The results showed that for automobile manufacturing emissions-halogenated hydrocarbons (56.8%), alkanes (19.8%) and aromatic hydrocarbons (14.4%) were the major components. Halogenated hydrocarbons account for a relatively high proportion in spraying and quenching. Textile printing and dyeing mainly emits halogenated hydrocarbons (52.1%) and alkanes (36.1%), among which halogenated hydrocarbon emissions in the shaping and printing links account for a relatively high proportion. Alkane emissions in the singeing and washing links account for a relatively high proportion. Pesticide manufacturing mainly emits halogenated hydrocarbons (39.1%), alkanes (30.0%) and aromatic hydrocarbons (24.5%), pharmaceutical and chemical industries mainly emit alkanes (44.4%), aromatic hydrocarbons (24.1%) and halogenated hydrocarbons (23.7%). Affected by raw and auxiliary materials, production processes, etc., the composition of VOCs in each link is quite different. As for the environmental impact, the OFP and SOAP of the 16 key links are about 0.24-7.25 mg/m3 and 0.68-11.2 mg/m3. VOCs emissions from automobile manufacturing and pharmaceutical and chemical industries contribute greatly to secondary pollution in the park and are industries that need key control. Aromatic hydrocarbons and alkanes contribute highly to O3 and SOA formation and are components that need to be controlled. m-p-xylene, toluene, o-xylene, naphthalene, 1,3,5-trixylene, n-pentane are among the top 15 contributors to OFP and SOAP, mainly from automotive spraying and quenching, textile printing and dyeing shaping, singing, washing links, pesticide manufacturing and pharmaceutical chemical production-which need to be strengthened managed. [ABSTRACT FROM AUTHOR]

A three-model fluorescence "ON–OFF–ON" system, from a tris-bis(urea) anion ligand (LMe) to anionocage 1Me and then to the host–guest complex, in response to anion coordination and halogenated hydrocarbon encapsulation, was established. [ABSTRACT FROM AUTHOR]