Concentrations Of Organic Compounds Research Articles

Fundamental insights and recent advances in catalytic oxidation processes using ozone for the control of volatile organic compounds.

The development of technologies for highly efficient treatment of emissions containing low concentrations of volatile organic compounds (VOCs) remains an important challenge. Catalytic oxidation with ozone (catalytic ozonation) is useful for the oxidative decomposition of VOCs, particularly aromatic compounds, under ambient temperature conditions. Only inexpensive transition metal oxides are required as catalysts, and Mn-based catalysts are widely used for catalytic ozonation. This review describes the oxidation reaction mechanisms, reaction pathways of aromatic hydrocarbons, and dependence of the catalytic ozonation activity on the reaction conditions. The reasons why Mn oxides are effective in catalytic ozonation are also explained. The structure of the catalytic active sites and the types of supporting materials contributing to the reaction are also discussed in detail, with the aim of establishing a VOC control technology. In addition, recent progress in catalytic oxidation processes using ozone as an oxidant has been outlined, focusing on catalyst materials and reaction conditions.

Adaptation of Ochrobactrum rhizosphaerae IMV B-7956 Bacteria to the Influence of Copper (II) Chloride

In technologically altered habitats, an increased content of organic compounds, nitrogen, phosphorus, sulfur compounds, antibiotic substances, etc. is found. Therefore, microorganisms that are systematically exposed to various stressors have developed adaptation mechanisms. The strain Ochrobactrum rhizosphaerae IMV B-7956, isolated from the infiltrate lakes of the Lviv solid waste landfill, is resistant to copper, chromium, manganese, and iron in concentrations exceeding the maximum permissible concentrations. The work aimed to study the response of O. rhizosphaerae IMV B-7956 cells to CuCl2 exposure by detecting changes in the content of lipid peroxidation products, products of the oxidative modification of proteins, activity of antioxidant defense system enzymes, and synthesis of extracellular polymers. Methods. To study the effect of CuCl2 on prooxidant indicators and the activity of enzymes of the antioxidant defense system, bacteria were pre-incubated in Tris-HCl buffer containing 2–10 mM CuCl2. After one hour of incubation, the bacterial cells were washed and cultured for 1, 12, 24, and 48 h in metal-free media. The copper content in the bacterial cells was determined by atomic absorption spectrometry. The content of lipid peroxidation indicators, carbonyl groups in proteins, total low-molecular-weight thiols, enzymatic activity, and the content of exopolysaccharides and extracellular proteins were determined photometrically. Results. Within an hour, O. rhizosphaerae IMV B-7956 bacteria accumulated 2.3–7.8 mg Cu/g of biomass. Under these conditions, an increased content of lipid peroxidation products was detected. During the first hour of growth in bacterial cells, enzymes with catalase and peroxidase activity were activated. During further cultivation, an increase in the activity of other antioxidant defense enzymes was detected. Carbonyl groups in proteins are probably formed due to an increase in the content of lipid peroxidation products, as they are formed later. Within 12–48 h of growth, the copper content in the bacterial cells decreases. This leads to the restoration of growth. Conclusions. The main damaging effect of CuCl2 on bacterial cells was detected during the first 24 h of growth. Activation of the enzymes of the antioxidant system and synthesis of exopolysaccharides are among the adaptations that ensure the survival of bacteria under these conditions.

Impact of a minimally processing route for the production of infant formulas on their sensory properties

Infant formulas (IFs), the sole adequate substitute to human milk, undergo several thermal treatments during production that can damage milk proteins and promote the formation of Maillard reaction products, modifying nutritional and sensory properties. The aim of this study was to determine the impact of a minimally processing route based on membrane filtration associated with different levels of heat treatment, on the odor, taste, texture and color attributes of IFs, then to compare with those of commercial milks. Three experimental IFs (produced with membrane filtration associated with low - T-, medium - T+, or high thermal treatments - T+++) were evaluated. Triangular tests conducted with a panel of 50 adults highlighted clear disparities between all the IFs. The same panel applied the Check-All-That-Apply method to evaluate the IFs: the range of variability between T- and T+++ was similar to that between the 2 commercial IFs, and the sensory characteristics of the experimental IFs were not far from the commercial brands for flavor and texture attributes. Analysis performed on the citation frequencies for each descriptor differentiated T-/T+ from T+++, but all the experimental IFs were described with positive sensory characteristics, unlike one commercial IF. Volatile organic compounds (VOCs) content of IFs with low and high thermal treatments were analyzed. Forty VOCs were identified by gas chromatography-mass spectrometry. T- contained a higher quantity of VOCs than T+++, except for benzaldehyde (Maillard reaction product), and aldehydes (oxidation-related products) were the most represented compounds. In conclusion, the processing was associated with sensory differences among IFs, but no marked difference in flavors was found according to CATA and physicochemical analysis. Additionally, no unpleasant sensory descriptors were noted. This shows that the minimally processed route leads to IFs that could fit well within the market from a sensory point of view.

Composition and Transformation of Halogenated Products Contained in Drinking Water Transported through the Urban Water Distribution Network

Analysis of the composition and transformation of organic compounds in water obtained at a surface water intake of a large urban agglomeration (by the example of the city of Ufa) and used to arrange water supply for the population and the industrial sector has been carried out. Using gas and liquid chromatography with various types of detection, more than 250 organic compounds in the supplied water have been determined. It has been revealed that when transporting water, the concentration of organic compounds of technogenic nature (phthalates, polyaromatic hydrocarbons, alkylbenzenes, etc.) does not change. It has been concluded that in remote, dead-end and stagnant zones of the urban water distribution network, the presence of additional organic pollutants not identified in drinking water leaving water treatment facilities, has not been detected.

Are there any differences in the quality of high-mountain green tea before and after the first new leaves unfold? A comprehensive study based on E-sensors, whole metabolomics and sensory evaluation

High-mountain green tea, where the first new leaf hasn't yet unfurled, is prized for perceived superior quality, but this hasn't yet been verified by experimentation. Electronic sensors, whole metabolomics and sensory evaluation were employed to assess the quality of yymj (tea buds with a newly unfurled leaf) and qymj (tea buds without new leaves). The qymj proved to have significant advantages in aroma, color and shape, but still had some shortcomings in umami, bitterness and sourness. Differences in the content of volatile organic compounds (including alcohols, hydrocarbons and lipids) and nonvolatile organic compounds (flavonoids, amino acids, sugars, and phenolic acids) quality of high-mountain green teas with different maturity levels and provides well explained these quality differences. This study establishes a systematic approach to study the quality of high-mountain green tea at different maturity levels, and provides important reference information for consumers, governments and tea farmers.

Development of nickel-based bimetallic catalysts for production of hydrogen-rich syngas via supercritical water gasification of liquid residue from hydrothermal pretreatment of food waste

Hydrothermal carbonization has become increasingly prevalent in the pretreatment of food waste, leading to the generation of substantial volumes of liquid effluent. This hydrothermal liquid effluent from food waste (HLF) contains high content of organic compounds, making it challenging to treat using conventional methods. In this regard, the HLF was considered a potential source for energy production via supercritical water gasification (SCWG). This study aimed to develop effective bimetallic catalysts based on Ni/Al2O3 with four different promoters (Cu, Co, La, and Ce), and investigated their performance in the catalytic SCWG for the treatment of HLF and hydrogen production. Among the tested promoters, the Ce-Ni catalyst was considered the most suitable in terms of its highest H2 yield and H2 selectivity. The optimal Ce content was found to be 5 wt%, with a catalyst dosage of 5 % by weight of HLF. These conditions resulted in the highest H2 selectivity of 1.61 and a relatively high H2 yield of 749.60 mmol/L under SCWG operating conditions of 480 °C and 30 min. Excessive catalyst dosages increased total syngas yield but reduced H2 selectivity. The stability test demonstrated that the Ce promoter contributed to enhancing the catalyst resistance to deactivation by coke deposition. The hydrogen production of 5Ce-Ni decreased by 13.8 % after three reuses, whereas a larger decrease of 26.0 % was observed with Ni/Al2O3. These findings indicate that Ce-Ni catalyst show promise for enhancing H2-rich syngas production in the SCWG of hydrothermal liquid effluent from food waste.

Fermentation Performance Evaluation of Lactic Acid Bacteria Strains for Sichuan Radish Paocai Production.

Fermented vegetable products play a significant role in various cuisines, and understanding the fermentation dynamics of lactic acid bacteria (LAB) strains is essential for optimizing their production and quality. Here, we sought to investigate the fermentation performance of five LAB strains isolated from Sichuan paocai as starters for paocai. Sensory evaluation revealed that the inoculation of radish paocai samples with LAB strains effectively improved the overall liking and sensory satisfaction of participants, increasing the scores to varying degrees in terms of taste, flavor, texture, and coloration. Lactiplantibacillus plantarum and Lacticaseibacillus rhamnosus exhibited a good salt resistance in radish juice and could grow in a medium containing 10% NaCl. Four indicator strains commonly found in contaminated paocai were effectively inhibited by fermented LAB broths, which improved the edibility and safe production of paocai. Compared to spontaneous fermentation (CK), radish paocai inoculated with LAB showed a significantly accelerated acid production rate, shortening the fermentation period by approximately two days. The contents of titratable total acids, organic acids, and free amino acids were higher in the inoculated samples and were enriched in the taste of radish paocai. The content of volatile organic compounds in the inoculated samples was higher than that in CK. Based on OPLS-DA analysis, 31 key indicators of paocai quality were screened and used to rank the fermentation performances of the five strains using the TOPSIS method; here, Lpb. plantarum and Lcb. rhamnosus achieved the highest scores. This study provides a reference for selecting LAB strains as efficient and secure fermentation starters to optimize paocai quality.

Numerical prediction model for long- and short-term concentration of indoor volatile organic compounds from building materials

ABSTRACT Emission models of volatile organic compounds (VOCs) from individual indoor building materials have been developed and validated. However, multiple indoor building materials release VOCs simultaneously, and neither single building material nor multiple building material emission models can predict the entire release cycle of VOCs accurately. This study established a long- and short-term numerical prediction model for indoor VOC concentration. The model includes an attenuation coefficient θ. To describe the decay rate of the total VOC content, which is mainly influenced by time, and by designing experiments and testing in environmental warehouses under different seasonal conditions, the value of θ was first obtained. Then, after successfully plotting the emission curve of indoor pollutant concentration over time through numerical solution and using θ, the VOC content was corrected for various seasonal conditions. On the basis of this model, an exposure dose integration algorithm was proposed to evaluate the environmental health risks, as an application of this model. In comparison with previous research results and experimental data, this model has better predictive performance.

Stable Cd(II)-based coordination polymer as a multifunctional fluorescent sensor for ascorbic acid, acetylacetone and nitrofuran antibiotics

The concentrations of hazardous volatile organic compounds (VOCs), pharmaceutical antibiotics and biomolecules in water systems are closely related with public health and ecological security. Thus, the convenient and accurate detection of these harmful items can not only reflect the state of human health but also evaluate the level of homologous contamination in the environment. To this end, a new Cd(II)-CP ({[Cd3L2(bmoe)]·DMF}n) with excellent luminescence properties was designed by employing the semi-rigid tricarboxylic acid 4-(2′,3′-dicarboxylphenoxy) (H3L) and N-donor ligand 1,1′-bis(1H-benzimidazolyl) oxydiethane (bmoe). The as-prepared Cd-CP features the unique uninodal sql topology. Benefiting from its great stability in the aqueous system, Cd-CP serves as a versatile multifunctional fluorescent sensor for different analytes, ascorbic acid (AA), nitrofuran antibiotics nitrofurantoin (NFT) and nitrofurazone (NFZ) and acetylacetone (ACAC). The established methods are characterized with impressive low detection limits, ultrafast response time, high sensitivity, strong anti-interference ability, as well as reliable reproducibility. Experimental and theoretical calculation reveals that the collaborative effects of Förster resonance energy transfer (FRET), inner-filter effect (IFE) and photoinduced electron transfer (PET) are the most probable causes behind the quenching of the CP's fluorescence signal.

An Assessment of the Contribution of Vehicular Traffic to Ambient Air Quality - A Case Study of Nairobi Expressway Corridor

Abstract In this study, the vehicular air pollution from the Nairobi Expressway corridor was estimated by simulation using AERMOD dispersion model. The Vehicle Kilometer Travelled (VKT), emission factors, and traffic data were used to estimate the pollutants from vehicular traffic.. The highest modelled 24-hour and annual concentrations of PM2.5 were 0.274 µg/m3 and 0.152 µg/m3, whereas the highest 24-hour and annual concentrations of PM10 were 0.405 µg/m3 and 0.225 µg/m3, respectively. The maximum 24-hour and annual concentrations of Total Volatile Organic Compounds (TVOCs) were 20.8 µg/m3 and 11.5 µg/m3, respectively, whereas the maximum 8-hour and annual concentrations of carbon monoxide (CO) were 319 µg/m3 and 177 µg/m3, respectively. The highest modeled 24-hour and annual concentrations of NO2 were 28.2 µg/m3 and 15.7 µg/m3, respectively. The 24-hour average measured TVOCs values showed that Nairobi expressway traffic contributed 3.5 percent to the measured TVOCs concentration value, but CO accounted for 55 percent of the measured value. According to the simulated PM2.5 and PM10 concentration values, Nairobi expressway traffic contributed 1.1 and 1.6 percent, respectively, to the 24-hour average measured concentration levels.

Kombucha beverages made from Camellia nitidissima Chi and Camellia sinensis flowers—physicochemical properties, sensory properties and bioactivity

Recently, various plant materials other than tea have been used as substrates for kombucha beverages. To improve the aroma and other qualities of kombucha, Camellia sinensis and Camellia nitidissima Chi flowers were used as raw materials to prepare novel kombucha beverages (marked as TFK and GFTK), which were systematically compared to traditional kombucha made from black tea. The results revealed that the biomass of kombucha made from TFK increased the most among all samples. TFK had the highest content of organic acids, with 9.03 g/L of acetic acid and 5.57 g/L of gluconic acid. Metabolomic analysis revealed that TFK showed the highest concentration of organic nitrogen compounds, whereas GFTK had the highest concentration of flavonoids. There were 183 kinds of volatile components identified in the 3 kombuchas, only 20 of which were common aroma components. Among the three kombucha beverages, TFK had the highest digestive enzyme inhibitory activity and was also second only to GFTK in terms of anti-oxidant properties. In terms of sensory properties, TFK had a higher fruit score compared to GFTK, but there was no significant difference in floral intensity between these two samples. Therefore, the C. sinensis flower is more suitable for preparing kombucha.

Chemical Analysis of Exhaled Vape Emissions: Unraveling the Complexities of Humectant Fragmentation in a Human Trial Study.

Electronic cigarette smoking (or vaping) is on the rise, presenting questions about the effects of secondhand exposure. The chemical composition of vape emissions was examined in the exhaled breath of eight human volunteers with the high chemical specificity of complementary online and offline techniques. Our study is the first to take multiple exhaled puff measurements from human participants and compare volatile organic compound (VOC) concentrations between two commonly used methods, proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) and gas chromatography (GC). Five flavor profile groups were selected for this study, but flavor compounds were not observed as the main contributors to the PTR-ToF-MS signal. Instead, the PTR-ToF-MS mass spectra were overwhelmed by e-liquid thermal decomposition and fragmentation products, which masked other observations regarding flavorings and other potentially toxic species associated with secondhand vape exposure. Compared to the PTR-ToF-MS, GC measurements reported significantly different VOC concentrations, usually below those from PTR-ToF-MS. Consequently, PTR-ToF-MS mass spectra should be interpreted with caution when reporting quantitative results in vaping studies, such as doses of inhaled VOCs. Nevertheless, the online PTR-ToF-MS analysis can provide valuable qualitative information by comparing relative VOCs in back-to-back trials. For example, by comparing the mass spectra of exhaled air with those of direct puffs, we can conclude that harmful VOCs present in the vape emissions are largely absorbed by the participants, including large fractions of nicotine.

Changes in the Aroma Profile and Phenolic Compound Contents of Different Strawberry Cultivars during Ripening.

Secondary metabolites, namely, phenolic and volatile organic compounds, contribute to the nutritional and organoleptic quality of the strawberry fruit. This study focuses on the changes in the content of phenolic compounds and volatile organic compounds during the ripening, from green to overripe fruit, of five strawberry cultivars ('Asia', 'CIVN 766', 'Aprica', 'Clery', and 'Malwina'). Additionally, these changes are compared with the colour of the fruit and peroxidase and polyphenol oxidase activity. Our results show that the accumulation of secondary metabolites (phenolic and volatile organic compounds) significantly changed during the ripening process for all of the studied cultivars. As for phenolic compounds, flavanols and hydroxybenzoic acid derivatives comprised between 87 and 95% of the total phenolic compound content in unripe green fruit. In contrast, anthocyanins and hydroxycinnamic acid derivatives comprised between 64 and 77% of the total phenolic compound content in overripe fruit, except in the fruit of the cultivar 'CIVN766'. When it comes to the aroma profile, the content of aldehydes decreased by 24-49% as the fruit ripened, and the accumulation of esters increased. Our study also shows that the ripening process differs among cultivars, and it is therefore necessary to define ripening indicators separately for each cultivar.

Application of commercial seaweed extract-based biostimulants to enhance adventitious root formation in ornamental cutting propagation protocols: a review

Despite significant advancements in stem-cutting propagation, insufficient rooting efficiency remains an economic burden for the ornamental nursery industry. IBA and NAA play a critical role in generating adventitious roots (AR) when applied exogenously. In sustainable agriculture, the substitution of chemical inputs, with alternative natural eco-friendly products presents a key challenge. Biostimulants can form part of a solution to mitigate such risks deriving from the use of agrochemicals, they are generally considered to be non-toxic, non-polluting, biodegradable, and non-hazardous. The current knowledge of the use of commercial seaweed extract (SE) products applied to ornamental cutting propagation has not been summarized until now. Therefore, we conducted a systematic review, and we hypothesized that SE-based biostimulant application to ornamental stem cuttings improves AR formation in terms of rooting percentage, root number, and architecture. Moreover, they increase the overall quality of a rooted cutting as dry biomass and organic compound content. The authors chose SE-based biostimulants because they have been proven to have an extremely low carbon footprint; moreover, they are expected to account for more than 33% of the global market for biostimulants and reached a value of 894 million Euros by 2022. This review focuses on (i) SE-based biostimulants, in particular, brown algae; (ii) technical information on five commercial products: Goteo®, Kelpak®, AlgaminoPlant, Bio Rhizotonic, Actiwawe and others, less known, also used as phytoregulators substitutes; (iii) applied protocols, describing dose, application method, number of treatments, cutting type; (iv) effects of applied protocols on rooting rate, root architecture and overall rooted cutting quality. Outcomes show that findings vary based on crops, cuttings, location, raw materials, composition, dose, application number and procedures, and growth environment.

Increase of the indoor concentration of volatile organic compounds after the use of incense and scented candle in studio apartments determined using passive sampling

Burning incenses and scented candles may provide harmful chemicals. Although many studies have evaluated volatile organic chemicals emitted by their use and related health risks, extension of our understanding for guiding appropriate use under various use conditions is necessary. In this study, emission characteristics of commercial incenses and scented candles were evaluated in a laboratory chamber using real-time measurement and the time-weighted average exposure concentrations of monoaromatic compounds and monoterpenes were assessed using passive samplers while volunteers living in a studio apartment use them. After burning incense, the average levels of benzene increased from 1.4 to 100 μg m−3. The presence of a wood core in commercial incense products was the main cause of high benzene emission by burning them although the increase in benzene was also influenced by factors such as the brand of the products, the number of incense sticks burned, the duration of each burning session, and ventilation period. Electrical warming of scented candles increased the levels of monoterpenes by factors of 16–30 on average. Considering the emission characteristics found in this study, exposure to benzene and monoterpenes could be mitigated by cautious use of those products in residential areas.

Tuning of polymeric membranes to mitigate fouling and removal of dissolved compounds for wastewater treatment: a Review

Wastewater, referred to as sewage, has been a byproduct of human settlement since ancient times. An increase in human activities leads to more wastewater effluents, resulting in higher concentrations of organic compounds, which are harmful to all forms of living organisms and drinking water purposes. Traditional methods cannot satisfy this issue for higher concentrations. The advanced membrane process is an alternative to this conventional method for removing organic compounds and various effluents due to its high permeate quality and less toxicity. Moreover, the modification of polymeric membranes by increasing its content led to a higher flux thereby enhancing the fouling property for effective wastewater treatment. The processes, UF, RO, NF, and FO, ion exchange, MD, and pervaporation, were developed for more robust methods to improve the quality of the environment and lead to higher salt rejection. This review provides an overview of the fabrications, methods and modifications of substrates utilized in different processes with varying modules to achieve a higher flux rate, lowering the fouling. We discuss the materials used for various membrane modules in ceramic membranes under different operating circumstances and the methods to enhance the performance of membrane fouling. This review also aims to track the ongoing research works to broaden different process combinations for further research purposes, showcasing better antifouling performance and maximizing water quality in the future.

An integrated uncrewed aerial vehicle platform with sensing and sampling systems for the measurement of air pollutant concentrations

Abstract. In this study, an uncrewed aerial vehicle (UAV) platform with sensing and sampling systems was developed for three-dimensional (3D) measurements of air pollutant concentrations. The sensing system of this platform contains multiple microsensors and Internet of Things devices for determining the 3D distributions of four critical air pollutants and two meteorological parameters in real time. Moreover, the sampling system comprises remote-controllable gas sampling kits, each of which contains a 1 L Tedlar bag for the 3D measurement of volatile organic compound (VOC) concentrations according to the Toxic Organics-15 (TO-15) method of the US Environmental Protection Agency. The performance of the developed UAV platform was verified in experiments where it was used to detect air pollutant emissions from a large industrial zone in Taiwan that included a traditional industrial park, a precision machinery park, and a municipal waste incineration plant. Three locations were selected as field measurement sites according to the prevailing local wind direction. The vertical distributions of four critical air pollutants, the ambient temperature, and the relative humidity were determined from data gathered at the aforementioned sites in March and May 2023. A total of 56 and 72 chemical species were qualitatively and quantitatively analyzed in these two periods, respectively. The experimental results verified the feasibility of using the proposed UAV platform for accurately evaluating the air pollutant concentration distribution and transport in an industrial zone. The sampling system can be used as the sampling part of the TO-15 method, thus extending the method to measure the 3D distribution of VOCs in an area. The UAV platform can serve as a useful tool in the management of and decision-making process for air pollution in industrial areas.

Tofu Liquid Waste Treatment Using Effective Volume of Anaerobic Sequencing Batch Reactor (ASBR)

The tofu industry produces liquid waste containing high organic compounds. Organic compounds in liquid waste can threaten aquatic ecosystems if discharged directly into water bodies. One of the most effective wastewater treatment systems is the treatment using Anaerobic Sequencing Batch Reactor (ASBR). Besides being able to reduce the content of organic compounds, ASBR can produce biogas, and its decomposing microorganisms do not flow into the effluent stream. The purpose of this study was to evaluate the performance of ASBR at an effective reactor volume according to the design. This is because the use of ASBR in previous studies had not reached the operational stage and did not use an effective volume reactor. The stages of waste treatment using ASBR include the seeding, acclimatization, and operation stages. Waste treatment took place at room temperature in the reactor with an effective volume of 6 L. The operating parameters tested were MLVSS, COD, BOD, pH, and cumulative biogas volume. The results obtained show that the seeding process took 56 days, acclimatization took 10 days, and the operation lasted for 17 days. The efficiency of reducing COD concentration was 60%, the efficiency of reducing BOD concentration was 35.65%, and the cumulative volume of biogas produced was 24,120 mL at the operating stage. The use of the ASBR system at an effective volume of 6 L resulted in the successful processing of tofu liquid waste.

Molecular Characterization of Gaseous Organic Acids and Nitrogen‐Containing Compounds From Crop Straw and Wood Burning

AbstractBiomass burning serves as important sources of volatile organic compounds (VOCs), yet our understanding of the molecular characteristics of oxygenated volatile organic compounds (OVOCs) from fresh emissions remains limited. In this study, gaseous organic compounds in fresh smokes from burning typical Chinese crop straws and woods are measured using an iodide time‐of‐flight chemical ionization mass spectrometer. Approximately 750 molecular formulas are identified, with CHO compounds containing carbon, hydrogen and oxygen atoms accounting for 77%–95% of the total. C1–C3 organic acids and dicarboxylic acids dominate the total CHO signal intensities by 27%–48%, while well‐known molecular markers of biomass burning, such as monosaccharide, guaiacol and syringol derivatives, contribute 7%–17%. Notably, crop straw and wood burning emit a higher abundance of guaiacol than syringol derivatives by a factor of 5. Additionally, a variety of nitrogen‐containing compounds (mainly in the CHON group) is identified, including isocyanate, amide, amino acids, and pyridine. The mass spectral profiles of organic compounds are largely similar between crop straw and wood burning fuels, although wood burning produces higher contributions of compounds with carbon atoms numbers >10. The saturation concentrations of organic compounds are estimated using molecular formula‐based volatility parameterization, revealing that semi‐volatile and intermediate VOCs (S/intermediate volatility organic compounds (IVOCs)) predominate smoke releases by 35%–60% and 20%–43%, respectively, with only a small fraction of low‐volatility compounds. Given the widespread nature of biomass burning in winter China, our results may have significant implications for interpreting secondary organic aerosol formation through gas‐particle partitioning or aqueous‐phase reactions.

Determination of emission factors from a landfill through an inverse methodology: Experimental determination of ambient air concentrations and use of numerical modelling

The application of numeric modelling for determining the impact of landfills needs for reliable emission source data. In this study, a methodology for the characterization of the emission profiles of the different sources present in landfills for emission factors determination, applying an indirect methodology, is presented. Ambient air concentrations of volatile organic compounds (VOCs), hydrogen sulphide (H2S) and ammonia (NH3) were determined in three potentially emission sources in Can Mata landfill (Hostalets de Pierola, Catalonia, Spain): dumping areas, pre-closed zone and leachate reservoir as well as in biogas, for the determination of emission factors. Multi-sorbent bed and Tenax TA tubes were used for a wide range of VOCs sampling, and analysis was conducted through TD-GC/MS. H2S and NH3 were sampled and analysed using Radiello passive samplers. The highest total VOC (TVOC) concentrations were found in dumping areas (0.7–3.5 mg m−3), followed by leachate reservoir (0.3–0.6 mg m−3) and pre-closed area (77–165 μg m−3). On the other hand, the highest H2S and NH3 concentrations were found in leachate reservoir, presenting values of 0.8–1.1 mg m−3 and 1.7–1.8 mg m−3, respectively. With the application of odour thresholds to the concentrations obtained, the most critical compounds regarding odour annoyances were determined. The highest odour units (O.U.) were found in leachate reservoir due to H2S concentrations, whereas VOCs contributed mainly to O.U. in the dumping areas. The obtained ambient air concentrations were used for the indirect determination of the emission factors through numerical modelling using a Eulerian dispersion model. The emission factors obtained for the landfill for TVOC, H2S and NH3 were in the range of 0.44–10.9 g s-1, 0.16–1.02 g s−1 and 0.23–1.82 g s−1, respectively, depending on the emission source. Reliable emission factors are crucial to obtain landfill impact maps, which are essential for the correct management of these facilities.