Concentrations Of Organic Compounds Research Articles

Environmental risk assessment methodology for urban tropical lagoons based on feasible lines of evidence under limited resources conditions: Jacarepaguá Lagoon/Brazil.

Determining environmental risk levels posed to different urban lagoon can provide an important overview regarding the relative severity of the environmental degradation of these ecosystems, increasing the risks visibility, which can be used as an important decision-making tool to prioritize investments. Jacarepaguá Lagoon (JPAL) is part of a coastal lagoon system comprising four interconnected lagoons in Rio de Janeiro city, Southeastern Brazil. Real estate speculation and insufficient sanitation infrastructure resulted in untreated sewage discharge into this ecologically sensitive lagoon system. An Environmental Risk Assessment for Jacarepaguá lagoon was carried out integrating three Lines of Evidence (LoE): (i) Water Quality LoE; (ii) Ecotoxicological LoE; (iii) Ecological LoE to estimate an Environmental Risk Index (EnvRI) for this area. Surface water samples were collected during four bimonthly campaigns at five JPAL sampling points as well as an upstream reference area. The Water Quality LoE based on physicochemical parameters was used to estimate the Water Quality Risk Index (WQRI); the Ecotoxicological LoE based on two chronic ecotoxicity bioassays was used to estimate the Ecotoxicological Risk Index (EcotoxRI); and the Ecological LoE based on the richness and the abundance of phytoplankton taxa was used to estimate the Ecological Risk Index (EcoRI). The final EnvRI was then estimated by integrating these three Risk Indices. The WQRI (0.79 ± 0.07), as well as the EcotoxRI (0.80 ± 0.21), and the EcoRI (0.78 ± 0.13), were all in the range classified as very high. The EnvRI for JPAL was consequently also very high (0.81 ± 0.12), which indicates urgent intervention. EnvRI combined with high concentrations of organic compounds directly affected the diversity of phytoplankton species; however, it was observed that the high content of phytoplankton biomass also represents a part of the organic matter in question. The final goal was achieved: a feasible risk assessment tool available for comparison of different aquatic ecosystems, to facilitate decision making establishing priorities of investments under a limited resources scenario.

Ecuadorian Cacao Mucilage as a Novel Culture Medium Ingredient: Unveiling Its Potential for Microbial Growth and Biotechnological Applications

Cacao mucilage is typically disposed of during processing, yet its abundant content of organic compounds, polysaccharides, and nutrients renders it valuable for various applications. This scientific study investigates the suitability of cacao mucilage as an alternative culture medium for Lactiplantibacillus plantarum, Saccharomyces cerevisiae, and Aspergillus niger, aiming to provide a viable alternative to traditional media. Through a mixed-design approach, the powdered mucilage, peptone, and yeast extract ingredients were optimized using the recovery rates of each micro-organism as the response variable. The optimal formulation of the medium, consisting of 49.6% mucilage, 30% yeast extract, and 20.9% peptone, resulted in remarkable microbial recovery rates. L. plantarum achieved an outstanding recovery rate of 98.18%, while S. cerevisiae and A. niger exhibited recovery rates of 90.57% and 89.90%, respectively. Notably, these recovery rates surpassed those obtained using conventional culture mediums. Thus, cacao mucilage emerges as an effective component for formulating a natural culture medium that facilitates the growth of yeasts, lactic acid bacteria, and fungi. The yeast extract peptone mucilage (YPM) medium demonstrated enhanced growth, particularly for yeasts and lactic acid bacteria, with recovery rates exceeding 90%. Conversely, A. niger displayed a relatively lower recovery rate. These findings emphasize the potential of cacao mucilage as a valuable resource for preparing natural culture media that promotes the growth of yeasts, lactic acid bacteria, and fungi, offering promising prospects for various applications in microbiology and biotechnology.

Compositional Changes of Volatile Organic Compounds in Biogases and Biomethanes Depending on the Feedstock in Sweden

Biogas usually contains volatile organic compounds such as terpenes, siloxanes, halogenated hydrocarbons, ketones, alcohols, furans and esters whose presence in the biogas is highly dependent on the feedstock. These trace components can affect the integrity of the materials they come into contact with, e.g., equipment, pipelines and engines, and their presence in the gas may pose health, safety and environmental risks. Understanding the composition of gases is a prerequisite to ensure the correct function of gas infrastructure, appliances and vehicles. This study examined how volatile organic compound (VOC) content in biogas varies depending on the feedstock and evaluated the efficiency of different upgrading processes in removing VOCs. The data, primarily collected in Sweden, include biogases produced in digesters and landfills. The selection of VOCs included in this study was based on extensive analysis of samples collected from numerous biogas and biomethane industrial facilities over an extended period, providing a comprehensive overview of VOC composition. The conducted research is intended to serve as a basis for more systematic studies on the influence of process parameters and feedstock composition on the formation of VOCs. The data have multiple potential uses, including predicting which VOCs would be found in biomethane for a given feedstock and upgrading techniques. Additionally, these data can also be used in standardization discussions to assess the plausibility of the proposed limit values and the need to regulate additional compounds.

Frequency locked whispering evanescent resonator (FLOWER) for biochemical sensing applications.

Sensitive, rapid and label-free biochemical sensors are needed for many applications. In this protocol, we describe biochemical detection using FLOWER (frequency locked optical whispering evanescent resonator)-a technique that we have used to detect single protein molecules in aqueous solution as well as exosomes, ribosomes and low part-per-trillion concentrations of volatile organic compounds. Whispering gallery mode microtoroid resonators confine light for extended time periods (hundreds of nanoseconds). When light circulates within the resonator, a portion of the electromagnetic field extends beyond the cavity, forming an evanescent field. This field interacts with bound analytes resulting in a change in the cavity's effective refractive index, which can be tracked by monitoring shifts in the resonance wavelength. The surface of the microtoroid can be functionalized to respond specifically to an analyte or biochemical interaction of interest. The frequency-locking feature of frequency locked optical whispering evanescent resonator means that the instruments respond to perturbations in the surface by very rapidly finding the new resonant frequency. Here we describe microtoroid fabrication (4-6 h), how to couple light into these devices using tapered optical fibers (20-40 min) and procedures for coupling antibodies as well as G-protein coupled receptors to the microtoroid's surface (from 1 h to 1 d depending on the target analyte). In addition, we describe our liquid handling perfusion system as well as the use of a rotary selector valve and custom fluidic chamber to optimize sample delivery. Step-by-step details on how to perform biosensing experiments and analyze the data are described; this takes 1-2 d.

The chemical assessment of surfaces and air (CASA) study: using chemical and physical perturbations in a test house to investigate indoor processes.

The Chemical Assessment of Surfaces and Air (CASA) study aimed to understand how chemicals transform in the indoor environment using perturbations (e.g., cooking, cleaning) or additions of indoor and outdoor pollutants in a well-controlled test house. Chemical additions ranged from individual compounds (e.g., gaseous ammonia or ozone) to more complex mixtures (e.g., a wildfire smoke proxy and a commercial pesticide). Physical perturbations included varying temperature, ventilation rates, and relative humidity. The objectives for CASA included understanding (i) how outdoor air pollution impacts indoor air chemistry, (ii) how wildfire smoke transports and transforms indoors, (iii) how gases and particles interact with building surfaces, and (iv) how indoor environmental conditions impact indoor chemistry. Further, the combined measurements under unperturbed and experimental conditions enable investigation of mitigation strategies following outdoor and indoor air pollution events. A comprehensive suite of instruments measured different chemical components in the gas, particle, and surface phases throughout the study. We provide an overview of the test house, instrumentation, experimental design, and initial observations - including the role of humidity in controlling the air concentrations of many semi-volatile organic compounds, the potential for ozone to generate indoor nitrogen pentoxide (N2O5), the differences in microbial composition between the test house and other occupied buildings, and the complexity of deposited particles and gases on different indoor surfaces.

POTENCIAL DE FORMAÇÃO DE OZÔNIO NA HOMOLOGAÇÃO VEICULAR NO BAIRRO DE BANGU, RIO DE JANEIRO

OZONE FORMING POTENTIAL FOR VEHICULAR HOMOLOGATION IN THE NEIGHBORHOOD OF BANGU, RIO DE JANEIRO. To control vehicle emissions, the new homologation process must be reported according to the California Maximum Incremental Reactivity (MIR) scale’s procedure to calculate the ozone forming potential (OFP) of each new vehicle. This work calculates an MIR scale suitable for the Brazilian reality. Meteorological and hourly pollutant data from the Bangu Automatic Air Quality Station was inventoried and processed from March to September 2020 to adjust OZIPR Lagrangean model and obtain the MIR scale by making small increments in the concentrations of each volatile organic compounds (VOC) and calculate the ozone increase/decrease. It was found that the VOC that had the greatest impact on ozone formation was 1,2,4-trimethylbenzene, with 2.06 ppb O3 ppbC–1 VOC. The OFP was calculated based on the VOC emissions of a vehicle and it was found a value of 9.421 mg O3 km–1, a much lower value when compared using the California MIR scale of 136.608 mg O3 km–1. It is concluded that meteorological conditions and VOC speciation data in the air mixture in the studied region directly affect the photochemical reactions of ozone formation.

Modelling indoor radical chemistry during the HOMEChem campaign.

In the indoor environment, occupants are exposed to air pollutants originating from continuous indoor sources and exchange with the outdoor air, with the highest concentration episodes dominated by activities performed indoors such as cooking and cleaning. Here we use the INdoor CHEMical model in Python (INCHEM-Py) constrained by measurements from the House Observations of Microbial and Environmental Chemistry (HOMEChem) campaign, to investigate the impact of a bleach cleaning event and cooking on indoor air chemistry. Measurements of the concentrations of longer-lived organic and inorganic compounds, as well as measured photolysis rates, have been used as input for the model, and the modelled hydroxyl (OH) radicals, hydroperoxyl radicals, and nitrous acid (HONO) concentrations compared to the measured values. The peak modelled OH, , and HONO concentrations during cooking and cleaning activities are about 30%, 10%, and 30% higher than the observations, respectively, within experimental uncertainties. We have determined rates for the rapid loss of HONO formed through cooking activities onto a wet surface during the cleaning events and also for the subsequent slow release of HONO from the cleaned surface back into the gas-phase. Using INCHEM-Py we have also predicted peak concentrations of chlorine (Cl) atoms, (0.75-2.3) × 105 atom per cm3 at the time of cleaning. Model predictions of the Cl atom and OH radical reactivities were also explored, showing high Cl atom reactivity throughout the day, peaking around 5000-9000 s-1. The OH reactivity was found to increase from a background value close to urban outdoor levels of 20-40 s-1, to levels exceeding observations in outdoor polluted areas following cooking and cleaning activities (up to 160 s-1). This underlines the high oxidation capacity of the indoor atmospheric environment through determining the abundance of volatile organic compounds.

Design, Synthesis, and Performance of Novel Nano‐CoO/NiO‐loaded and Sulfonation‐Modified ZSM‐5 Composite Catalyst for In Situ Conversion of Oil Shale

ABSTRACTA novel composite catalyst with readily preparation and good catalytic performance was designed and synthesized using sulfonation‐modified zeolite socony mobil‐5 (ZSM‐5) as the carrier and nano‐CoO/NiO as the active components. Compared with traditional in situ conversion, the composite catalyst could effectively reduce the activation energy of catalytic reactions, improve the efficiency of oil and gas conversion, and ameliorate the quality of oil products. When the loading amount of nano‐CoO/NiO was 20 wt% and the silicon/aluminum ratio of ZSM‐5 was 40–50, the required activation energy for oil shale cracking was as low as 43.64 kJ/mol, the yield of oil products was as high as 15.46 wt%, and the content of organic compounds in medium‐/low‐carbon hydrocarbon was as high as 71.50%. The prepared composite catalysts had low preparation cost, environmental friendliness, and significant catalytic effects, providing a feasible approach for the effective exploitation and utilization of oil shale.

Mapping Structure and Rheology of pH-Responsive Resins for Low-VOC Coatings.

In recent years, the paint and coatings industry has shifted away from traditional resin formulations that require high concentrations of volatile organic compounds (VOCs) to achieve the desired rheological performance and sustainability targets. One approach to eliminate or reduce VOCs in paint and coating formulations while maintaining the final performance is to disperse stimuli-responsive polymer latex particles in water. The chemistry and architecture of these particles have been engineered such that the suspension rheology changes in response to the pH changes. The particles can also be swollen with organic solvents to illicit similar rheological changes. To understand how the particle microstructure influences the observed macroscopic properties, we use small-angle neutron scattering and dynamic light scattering to determine that these particles consist of a cross-linked core with long polymer tails that extend into the dispersing medium. Carboxylic acid groups present on the tails deprotonate with increasing pH, and the extension of the polymer chain due to charge repulsion increases the hydrodynamic drag on the particle. We find that adjusting the pH alone has a much more significant effect on the shear dependence of the viscosity of the studied resin than adding organic solvent alone. We also find that this resin architecture is more responsive per mole of pH-responsive group than other architectures of pH-responsive latex particles in the literature.

Sustainable Green Synthesis of ZnO Nanoparticles from Bromelia pinguin L.: Photocatalytic Properties and Their Contribution to Urban Habitability

Aguama (Bromelia pinguin L.), a plant belonging to the Bromeliaceae family, possesses a rich content of organic compounds historically employed in traditional medicine. This research focuses on the sustainable synthesis of ZnO nanoparticles via an eco-friendly route using 1, 2, and 4% of Aguama peel extract. This method contributes to environmental sustainability by reducing the use of hazardous chemicals in nanoparticle production. The optical properties, including the band gap, were determined using the TAUC model through Ultraviolet–Visible Spectroscopy (UV–Vis). The photocatalytic activity was evaluated using three widely studied organic dyes (methylene blue, methyl orange, and rhodamine B) under both solar and UV radiation. The results demonstrated that the ZnO nanoparticles, characterized by a wurtzite-type crystalline structure and particle sizes ranging from 68 to 76 nm, exhibited high thermal stability and band gap values between 2.60 and 2.91 eV. These nanoparticles successfully degraded the dyes completely, with methylene blue degrading in 40 min, methyl orange in 70 min, and rhodamine B in 90 min. This study underscores the potential of Bromelia pinguin L. extract in advancing sustainable nanoparticle synthesis and its application in environmental remediation through efficient photocatalysis.

Gut Microbiota and Related Metabolites in Children With Egg White Sensitization.

We hypothesized that food sensitization in children could be linked to specific gut microbiota. The objective of this study is to assess a group of children with egg white sensitization (ES) from the microbiological and biochemical-metabolic standpoint, applying the microbiota and metabolomics approach to studying the intestinal contents of the feces. Twenty-eight toddlers with ES (mean age 13.08 months) and 24 healthy controls (mean age 12.85 months) were recruited for feces collection, serum IgE measurement, gut microbiota and metabolomics analysis. Individual microbial diversity and composition were analyzed via targeting the 16S rRNA gene hypervariable V3-V5 regions. The metabolite profiles of human feces were explored by 1H nuclear magnetic resonance. Children with ES exhibited relatively high levels of Firmicutes at the phylum level and relatively low levels of Bacteroidetes. Moreover, children with ES exhibited significantly reduced overall gut microbiota diversity and richness compared with healthy children. At the family level, we observed significant increases in the numbers of Clostridiaceae, Lachnospiraceae, Pasteurellaceae and Ruminococcaceae in children with ES. Egg white sensitivity increases orotic acid, nicotinate, methyl succinate, urocanic acid, xanthine, amino acids (tyrosine, lysine, tryptophan, phenylalanine) and short-chain fatty acids (n-butyrate, valerate) levels according to the results of metabolomics analysis. In summary, some specific families and genera (dysbiosis) are enriched in the gut microbiota, and increases in the mean concentrations of organic compounds in the fecal metabolite profile are associated with ES in children. These findings may provide evidence of potential strategies to control the development of ES or other atopies by modifying the gut microbiota.

Delving into Roccaverano PDO cheese: A comprehensive examination of microbial diversity and flavour profiles compared to non-PDO cheeses.

Roccaverano Protected Designation of Origin (PDO) is a fresh soft cheese produced in Roccaverano area (Italy). This study aimed to evaluate Roccaverano PDO microbiota, together with aromatic profile and sensory analysis to be compared with 15 non-PDO cheeses of the same type. Microbiota was evaluated through shotgun metagenomics sequencing, while GC-MS analysis was conducted to study volatile organic compounds (VOCs) presence and concentration. Sensory analyses were conducted through ONAF (Italian National Organization of Cheese Tasters) evaluation parameters followed by flash profile sensory analysis of selected cheeses. The results demonstrated Lactococcus lactis predominance in both non-PDO and PDO cheeses, while Streptococcus thermophilus was more abundant in non-PDO group. A higher abundance of Kluyveromyces lactis was observed in Roccaverano PDO, which exhibited greater fungal diversity compared to non-PDO cheeses. Metagenome-Assembled Genomes of 26 L. lactis and 19 Leuconostoc mesenteroides showed absence of significant differences in terms of average nucleotide identity and pangenomes partitions. The ONAF sensory evaluation demonstrated a higher average score of Roccaverano PDO group. Flash profile analysis demonstrated that lactic aroma/odour, acid, astringent, vegetal odour, exotic fruit and fermented aroma, hazelnut flavour and sweet were associated with high ONAF scores. The concentration of butanoic acid, 2-methyl-, ethyl ester and butanoic acid, 3-methyl- (sweat, acid, rancid related) were higher in PDO cheeses, while reads related to butanoate metabolism were less abundant compared to non-PDO samples. Several fungal species (included K. lactis) were associated with astringents, acid and chalky flavours. Roccaverano PDO demonstrates unique characteristics even maintaining a certain degree of variability between samples.

Identification of the chemical constituents of the Annona muricata L. seeds with coagulating properties on domestic wastewater

In the same vision of the valorization of the species Annona muricata L. (Annonaceae) and with regard to the previous scientific data collected on this plant species, a study was initiated to search for chemical constituents of seeds of this plant which could have the clarifying (coagulant) properties of domestic wastewater. The results obtained show that these seeds contain carbohydrates, proteins, lipids, terpenes and sterols in its almonds and integuments ; flavonoids and tannins in its integuments with significant contents of organic compounds (66.15 %) as well as mineral compounds (00.97 %) and volatile compounds (32.88 %). The vegetable oil (lipids) extracted is 30.56 % in these seeds. The evaluation of the clarifying activity of soursop seeds on samples of domestic wastewater with turbidities of 160 and 259 NTU showed that these seeds have a reduction rate of colloids or suspended matter of 95.40 % with the solution of its almonds and 97.58 % with the solution of its almond cakes at respective doses of 4800 mg powder/L and 3200 mg powder/L in 30 minutes. The results obtained prove that these seeds contain 35.59 % of other organic compounds (proteins, amino acids, carbohydrates and starch) which are responsible for this water clarifying activity. It is important to note that to our knowledge, the indications given on the activity of clarifying wastewater by the seeds of this fruit have not yet been the subject of scientific work making it possible to identify some of the compounds responsible for this activity in these glitches.

Acute and Chronic Health Risk Assessment for Automobile Users Due to Inhalation Exposure to Volatile Organic Compounds and Carbonyl Compounds.

Since automobiles are the primary means of transportation in modern society, the assessment of health effects from acute and chronic exposure to pollutants in automobiles is crucial. In this study, the concentration of volatile organic compounds (VOCs), carbonyl compounds, and odor-including substances in newly manufactured automobiles were analyzed, and exposure factors reflecting automobile user characteristics were selected for health risk assessment. Toluene exhibited the highest concentration (203.5 ± 379.3 μg/m3) among all measured pollutants. The acute and chronic non-carcinogenic health risk assessments indicated that the pollutants did not exceed their standards in any of the automobiles, suggesting no immediate health risks. However, in the chronic carcinogenic health risk assessment, acrylonitrile exceeded its standard value in all automobiles, indicating potential carcinogenic effects from long-term exposure. The findings suggest that careful estimation of lifetime exposure effects to pollutants inside new automobiles is required. Future studies should investigate specific pollutants generated by automotive materials and manufacturing processes to identify pollutant sources and reduce health risks to automobile users.

(Invited) Design of Three-Dimensional Reaction Sites of Solid-Electrolyte Gas Sensors for Sensitive Detection of VOCs

The exhaled breath of patients contains a higher concentration of specific volatile organic compounds (VOCs) than that of healthy peoples, and thus the development of highly sensitive gas sensors for these gases enables the early detection of these diseases. Among the various gas sensors, we focused on solid-electrolyte gas sensors consisting of yttria-stabilized zirconia (YSZ) as an oxide-ion conductor, and we previously reported that the toluene response of YSZ-based gas sensors improved by the addition of CeO2 to the Au sensing electrode (SE) [1].The toluene-response mechanism of the YSZ-based gas sensors is explained on the basis of the mixed potential theory. The sensor output voltage (E) is the potential difference between the SE and the counter electrode (CE). The SE potential of the sensor negatively shifted by the concurrent electrochemical reactions of toluene oxidation (eq. 1) and oxygen reduction (eq. 2) at the interface between YSZ and SE (triple-phase boundaries, TPBs) with the same rate upon exposure to toluene balanced with air.C7H8 + 18O2− → 7CO2 + 4H2O + 36e− (1)2O2− → O2 + 4e− (2)On the other hand, a given amount of toluene is oxidized during gas diffusion in the SE, which decreases the concentration of toluene reaching the TPBs. Since this reduces the toluene response of the sensor, thin-film SEs were fabricated in the thickness range of 30–250 nm by using spin-coating method employing a solution containing Au and Ce components in order to increase toluene concentration at the TPBs. However, the toluene response of the fabricated sensors largely increased with an increase in the SE thickness when the additive amount of CeO2 was relatively high [2–3]. The obtained results suggested that the electrochemical reactions of the toluene proceeded not only at the interface (SE/YSZ/gas) but also at the interface between SE and gas (SE(Au/CeO2)/gas) in the SE, because CeO2 worked as an oxide-ion conductor at elevated temperatures.In this study, we focused on the design of three-dimensional reaction sites of YSZ-based gas sensors for sensitive detection of VOCs. We fabricated Au SEs containing a sufficient amount of CeO2 (n) by spin-coating method. The obtained SEs were denoted as Au-nCeO2(x) SEs (n: an additive amount of CeO2, 24, 32 (wt%), x: the number of spin-coating cycles, 5–15).Figure 1(a) shows the response transient to various concentrations of toluene of the Au-24CeO2(5) sensor in dry air. The E value decreased upon exposure to toluene, and the magnitude of the response (ΔE) negatively increased with an increase in the toluene concentration. Figure 1(b) shows the thickness (spin-coating cycle) dependences of ΔE to 50 ppm toluene of the fabricated sensors in dry air. The ΔE value of the Au-24CeO2(x) sensor increased with a decrease in the SE thickness, and the Au-24CeO2(5) sensor showed the largest response (ca. 256 mV). In contrast, the ΔE of the Au-32CeO2(x) sensor increased with an increase in the SE thickness. In addition, we performed electrochemical impedance measurements in order to quantify the number of TPBs, and we discussed the effects of the number of TPBs on the toluene response. The details of this will be explained in the presentation.

Valorization of Fruit By-Products Through Lactic Acid Fermentation for Innovative Beverage Formulation: Microbiological and Physiochemical Effects.

The increase in food production is accompanied by an increase in waste, particularly agricultural by-products from cultivation and processing. These residues are referred to as agricultural by-products. To address this issue, biotechnological processes can be used to create new applications for these by-products. This study explored the use of LAB strains (Lactiplantibacillus plantarum, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Limosilactobacillus fermentum) on by-products such as white grape pomace, cocoa bean shells, apple pomace, and defatted roasted hazelnut to develop yoghurt-style fruit beverages. Microbial load and pH changes were monitored during a 24 h fermentation and 14-day shelf life at 5 °C. Concentrations of sugars, organic acids, and volatile organic compounds were also analyzed using HPLC and GC-qMS. The results showed that optimizing the matrix led to significant bacterial growth, with viable microbes remaining under refrigeration. In particular, the strain of L. plantarum tested on the cocoa bean shell yielded the most promising results. After 24 h of fermentation, the strain reached a charge of 9.3 Log CFU/mL, acidifying the substrate to 3.9 and producing 19.00 g/100 g of lactic acid. Aromatic compounds were produced in all trials, without off-flavours, and characteristic fermented food flavours developed. Additionally, secondary metabolites produced by lactic acid bacteria may enhance the health benefits of these beverages.

Olfactory Profile and Stochastic Analysis: An Innovative Approach for Predicting the Physicochemical Characteristics of Recycled Waste Cooking Oils for Sustainable Biodiesel Production

The efficient, economical, and sustainable production of biodiesel from waste cooking oils (WCOs) depends on the availability of simple, rapid, and low-cost methods to test the quality of potential feedstocks. The aim of this study was to establish the applicability of stochastic modeling of e-nose profiles in the evaluation of recycled WCO characteristics. Olfactory profiles of 10 WCOs were determined using a Sensigent Cyranose® 320 chemical vapor-sensing device with a 32 sensor-array, and a stepwise multiple linear regression (MLR) analysis was performed to select stochastic parameters (explanatory variables) for inclusion in the final predictive models of the physicochemical properties of the WCOs. The most important model parameters for the characterization of WCOs were those relating to the time of inception of the e-nose signal “plateau” and to the concentration of volatile organic compounds (VOCs) in the sensor region. A comparison of acid values, peroxide values, water contents, and kinematic viscosities predicted by the MLR models with those determined by conventional laboratory methods revealed that goodness of fit and predictor accuracy varied from good to excellent, with all metric values >90%. Combining e-nose profiling with stochastic modeling was successful in predicting the physicochemical characteristics of WCOs and could be used to select suitable raw materials for efficient and sustainable biodiesel production.

Constraining light dependency in modeled emissions through comparison to observed biogenic volatile organic compound (BVOC) concentrations in a southeastern US forest

Abstract. Climate change will bring about changes in meteorological and ecological factors that are currently used in global-scale models to calculate biogenic emissions. By comparing long-term datasets of biogenic compounds to modeled emissions, this work seeks to improve understanding of these models and their driving factors. We compare speciated biogenic volatile organic compound (BVOC) measurements at the Virginia Forest Research Laboratory located in Fluvanna County, VA, USA, for the year 2020 with emissions estimated by the Model of Emissions of Gases and Aerosols from Nature version 3.2 (MEGANv3.2). The emissions were subjected to oxidation in a 0-D box model (F0AM v4.3) to generate time series of modeled concentrations. We find that default light-dependent fractions (LDFs) in the emissions model do not accurately represent observed temporal variability in regional observations. Some monoterpenes with a default light dependence are better represented using light-independent emissions throughout the year (LDFα-pinene=0, as opposed to 0.6), while others are best represented using a seasonally or temporally dependent light dependence. For example, limonene has the highest correlation between modeled and measured concentrations using an LDF =0 for January through April and roughly 0.74–0.97 in the summer months, in contrast to the default value of 0.4. The monoterpenes β-thujene, sabinene, and γ-terpinene similarly have an LDF that varies throughout the year, with light-dependent behavior in summer, while camphene and α-fenchene follow light-independent behavior throughout the year. Simulations of most compounds are consistently underpredicted in the winter months compared to observed concentrations. In contrast, day-to-day variability in the concentrations during summer months are relatively well captured using the coupled emissions–chemistry model constrained by regional concentrations of NOX and O3.

Volatile Organic Compound (VOC) Contamination in Hotel Rooms: A Pilot Study to Understand Sources and Health Risks.

The COVID-19 pandemic drove the use of cleaning products, causing organic solvent contamination in hospitality environments. This pilot study investigated the presence and concentrations of volatile organic compounds (VOCs) in selected hotels in four different US cities with varying star ratings at the end of the pandemic period. Targeting 139 VOCs, 57 were detected across eight groups: alcohols, halocarbons, aromatics, alkanes, terpenes, carbonyls, ethers, and esters, in the indoor air. Alcohols were the most prevalent, especially in lower-rated hotels, suggesting higher use of cleaning supplies. Elevated levels of aromatics were detected in hotels rated under three stars, with a notable disparity compared to higher-rated hotels. Additionally, alkanes and terpenes such as n-tetradecane and d-limonene were consistently detected. Health risk assessment showed concentrations of all VOCs remained below their health criteria for customers. The cumulative cancer risk was 2.25 × 10-6 for hotel workers from chronic occupational exposure to eight carcinogenic VOCs, representing 1/3 of the lifetime risk from these chemicals in the ambient air. Cancer risks from individual VOCs ranged from 0.001 × 10-6 to 1.07 × 10-6, with chloroform accounting for nearly half of the cumulative risk. The findings underscore the need for careful selection and use of furnishings and cleaning supplies and for effective indoor air pollution control and management in hotel indoor environments.

Developing a consistent model for predicting equilibration in polymeric passive samplers across various HOC classes in sediment pore water.

The use of polymeric passive samplers (often polydimethylsiloxane, PDMS, or low-density polyethylene, LDPE) to indicate water concentrations of hydrophobic organic compounds under environmental conditions generally requires two key parameters, a compound-specific polymer-water equilibrium partition coefficient (), and the degree of equilibration achieved in a given environmental exposure scenario. Herein, we have developed model to extrapolate equilibration of performance reference compounds between polymer and pore water across different compound classes that is also dependent upon accurate estimates of . We have also developed quantitative structure-activity relationship (QSAR) models, to estimate for PAHs, PCBs, DDx, and dioxin/furans for the two most common polymeric samplers, PDMS and LDPE. The QSAR models developed in this study provide high accuracy consistent estimates for across the different HOC families. The root mean square error of the QSAR for was 0.226 log units based upon measured values for 159 compounds and 0.184 log units for based upon measured values for 131 compounds.