Combustion Of Organic Matter Research Articles

Highly selective ethanol gas sensor based on CdS/Ti3C2T x MXene composites.

Sensing of hazardous gases has an important role in ensuring safety in a variety of industries as well as environments. Mainly produced by the combustion of fossil fuels and other organic matter, ethanol is a dangerous gas that endangers human health and the environment. Stability and sensing sensitivity are major considerations when designing gas sensors. Here, a superior ethanol sensor with a high response and fast recovery was synthesized by "wrapping" CdS nanoparticles on metallic Ti3C2T x MXene using a simple method. CdS nanoparticles were uniformly covered on the Ti3C2T x MXene surface, forming a "rice crust"-like heterostructure. The sensor displayed good detection of ethanol gas at room temperature. Response signals up to 31% were obtained for ethanol molecules (20 ppm) with quick recovery (41 s). The performance of the ethanol sensor was evaluated across a range of concentrations (5-100 ppm) and relative humidity (60% and 90% RH) at room temperature. Our method could open up a new strategy for the development of ethanol sensors.

Polycyclic Aromatic Hydrocarbons (PAHs): Environmental Persistence and Human Health Risks

Polycyclic aromatic hydrocarbons (PAHs) are a class of organic compounds generated during the incomplete combustion of organic materials, such as coal, oil, and biomass. PAHs are highly persistent in the environment and pose significant health risks due to their genotoxic, mutagenic, and carcinogenic properties. This review provides an overview of PAH formation, environmental accumulation, and the main human exposure pathways, including inhalation, ingestion, and dermal contact. It highlights the toxicological effects of PAHs on various systems of the human body, such as the nervous, respiratory, reproductive, immune, and cardiovascular systems. Acute exposure to PAHs can cause symptoms such as eye irritation, nausea, vomiting, and diarrhea, while chronic exposure is associated with cancer, cardiovascular diseases, respiratory issues, and reproductive dysfunction. Although most research relies on animal studies, the findings suggest that PAHs may cause severe harm to humans through mechanisms like DNA damage. Due to the limitations of extrapolating animal-based studies to human health, future researches should more thoroughly explore the specific mechanisms by which PAHs affect human health to address the challenges posed by PAH pollution.

Metabolic syndrome prevalence in Mexican individuals exposed to polycyclic aromatic hydrocarbons and their association with an increased risk of cardiovascular events

Polycyclic aromatic hydrocarbons (PAHs) are an organic chemical family produced during incomplete combustion of organic materials. Besides, PAHs are associated with different detrimental health effects. Therefore, this research was aimed to assess the association between PAHs exposure, metabolic syndrome (MetS) prevalence, and cardiovascular risk in a Mexican population. Urinary 1-hydroxypyrene (1-OHP) was the exposure biomarker quantified. MetS prevalence was defined using the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) and the International Diabetes Federation (IDF) criteria. Also, we used the atherogenic index of plasma (AIP) as a cardiovascular risk biomarker. The mean urinary 1-OHP level quantified was 2.50 ± 1.25 µmol/mol creatinine. The MetS prevalence found was 35% (n = 222) and 31% (n = 197) using NCEP ATP III and IDF criteria, respectively. The mean AIP value was 0.32 ± 0.15. Furthermore, the data analysis showed robust associations between PAH exposure (urinary 1-OHP concentrations), MetS prevalence, and cardiovascular risk (AIP). The real significance of the findings in this study needs to be clarified completely, as MetS and cardiovascular diseases represent a critical challenge in contaminated zones of developing countries such as Mexico.

TG-MS Analysis for Elemental Composition of Organic Matters and Their Structural Properties.

A novel approach for determining the elemental content of organic matter through thermal gravimetric analysis coupled online with a mass spectrometer (TG-MS) is disclosed. This method not only yields results equivalent to ASTM analysis but also provides insight into the covalent bond structure within the sample. The principle of this technique consists of the combustion of organic matter in an oxygen-enriched environment within the thermogravimetric (TG) system. The gases generated during combustion, including carbon-containing gases such as CO2 and CO, hydrogen-containing gases such as H2O, nitrogen-containing gases such as NO2 and NO, and sulfur-containing gases such as SO2, are then analyzed using online MS. Quantitative analysis of these gases is accomplished via an external standard method, facilitating the determination of the elemental content of the organic matters. The experiment employed a temperature-programmed heating rate of 10 °C/min, a carrier gas flow rate of 100 mL/min, and an oxygen concentration of 50% by volume. We conducted tests on a range of 23 samples, including coal, heavy oil, oil shale, and biomass. The results for coal, oil shale, and biomass samples were consistent with ASTM standards, while the heavy oil samples demonstrated slightly lower values compared with ASTM methods. Furthermore, we probed into the mass loss and gas generation processes that occur during the combustion of samples, and these results enhance the understanding of the mechanism of organic matter combustion as well as that of the covalent bond structure of organic matters.

Advances in the Degradation of Polycyclic Aromatic Hydrocarbons by Yeasts: A Review

Polycyclic aromatic hydrocarbons (PAHs) are toxic organic compounds produced during the incomplete combustion of organic materials and are commonly found in the environment due to anthropogenic activities such as industrial and vehicular emissions as well as natural sources, mainly volcanic eruptions and forest fires. PAHs are well known for their bioaccumulative capacity and environmental persistence, raising concerns due to their adverse effects on human health, including their carcinogenic potential. In recent years, bioremediation has emerged as a promising, effective, and sustainable solution for the degradation of PAHs in contaminated environments. In this context, yeasts have proven to be key microorganisms in the degradation of these compounds, owing to their ability to metabolize them through a series of enzymatic pathways. This review explores the advancements in yeast-mediated degradation of PAHs, with a particular focus on the role of enzymes such as cytochrome P450 (CYPs), epoxide hydrolases (EHs), and glutathione S-transferases (GSTs), which facilitate the breakdown of these compounds. The review also discusses the applications of genetic engineering to enhance the efficiency of yeasts in PAH degradation and the use of omics technologies to predict the catabolic potential of these organisms. Additionally, it examines studies addressing the degradation of benzo[a]pyrene (BaP) by yeasts such as Debaryomyces hansenii, and the potential future implications of omics sciences for developing new bioremediation.

Genome-modified Caenorhabditis elegans expressing the human cytochrome P450 (CYP1A1 and CYP1A2) pathway: An experimental model for environmental carcinogenesis and pharmacological research.

Polycyclic aromatic hydrocarbons (PAHs), including the Group 1 human carcinogen benzo[a]pyrene (BaP), are produced by the incomplete combustion of organic matter and thus are present in tobacco smoke, charbroiled food and diesel exhaust. The nematode Caenorhabditis elegans is an established model organism, however it lacks the genetic components of the classical mammalian cytochrome P450 (CYP)-mediated BaP-diol-epoxide metabolism pathway. We therefore introduced human CYP1A1 or CYP1A2 together with human epoxide hydrolase (EPHX) into the worm genome by Mos1-mediated Single Copy Insertion (MosSCI) and evaluated their response to BaP exposure via toxicological endpoints. Compared to wild-type control, CYP-humanised worms were characterised by an increase in pharyngeal pumping rate and a decrease in volumetric surface area. Furthermore, BaP exposure reduced reproductive performance, as reflected in smaller brood size, which coincided with the downregulation of the nematode-specific major sperm protein as determined by transcriptomics (RNAseq). BaP-mediated reproductive toxicity was exacerbated in CYP-humanised worms at higher exposure levels. Collagen-related genes were downregulated in BaP-exposed animals, which correlate with the reduction in volumetric size. Whole genome DNA sequencing revealed a higher frequency of T>G (A>C) base substitution mutations in worms expressing human CYP1A1;EPHX which aligned with an increase in DNA adducts identified via an ELISA method (but not classical 32P-postlabelling). Overall, the CYP-humanised worms provided new insights into the value of genome-optimised invertebrate models by identifying the benefits and limitations within the context of the (3Rs) concept which aims to replace, reduce and refine the use of animals in research.

Dose-Related Mutagenic and Clastogenic Effects of Benzo[b]fluoranthene in Mouse Somatic Tissues Detected by Duplex Sequencing and the Micronucleus Assay.

Polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants that originate from the incomplete combustion of organic materials. We investigated the clastogenicity and mutagenicity of benzo[b]fluoranthene (BbF), one of 16 priority PAHs, in MutaMouse males after a 28 day oral exposure. BbF causes robust dose-dependent increases in micronucleus frequency in peripheral blood, indicative of chromosome damage. Duplex sequencing (DS), an error-corrected sequencing technology, reveals that BbF induces dose-dependent increases in mutation frequencies in bone marrow (BM) and liver. Mutagenicity is increased in intergenic relative to genic regions, suggesting a role for transcription-coupled repair of BbF-induced DNA damage. At higher doses, the maximum mutagenic response to BbF is higher in liver, which has a lower mitotic index but higher metabolic capacity than BM; however, mutagenic potency is comparable between the two tissues. BbF induces primarily C:G > A:T mutations, followed by C:G > T:A and C:G > G:C, indicating that BbF metabolites mainly target guanines and cytosines. The mutation spectrum of BbF correlates with cancer mutational signatures associated with tobacco exposure, supporting its contribution to the carcinogenicity of combustion-derived PAHs in humans. Overall, BbF's mutagenic effects are similar to benzo[a]pyrene, a well-studied mutagenic PAH. Our work showcases the utility of DS for effective mutagenicity assessment of environmental pollutants.

Slow post-fire carbon balance recovery despite increased net uptake rates in Alaskan tundra

Abstract Increasing wildfire occurrence and intensity have immediate effects on northern ecosystems due to combustion of aboveground vegetation and belowground soil organic matter. These immediate impacts have indirect and longer term effects, including deepening of the active layer, changes in soil decomposition rates, and shifts in plant community composition. Despite the increasing fire impacts across the tundra region, the implications of wildfire on ecosystem carbon balance are not well understood. Using paired eddy covariance towers in unburned and burned tundra, we examined the effects of a 2015 wildfire on carbon dioxide and methane fluxes in a wetland tundra ecosystem in the Yukon–Kuskokwim Delta, Alaska, from 2020 to 2022. Wildfire increased the amplitude and variability of carbon uptake and release on seasonal and annual timescales and increased the temperature sensitivity of soil respiration. Seven years post fire, there was annual net uptake in both unburned and burned tundra based on net ecosystem exchange, with the sink strength of burned tundra exceeding that of the unburned tundra by 1.18–1.64 times. However, when considering emissions, it would take approximately 86 years to recover the carbon lost from the wildfire itself. Soil moisture was a dominant driver of fluxes and positively associated with higher rates of carbon dioxide uptake and release and methane release. This study underscores the importance of understanding the effects of wildfire-induced shifts on tundra carbon cycling, allowing better predictions of long-term landscape-scale climate feedbacks as the climate continues to warm.

Effects of Fire on Physical and Chemical Properties of Soil in Fwangnin Bokkos District, Nigeria

Background: Vegetation burning, a common agricultural practice, has both positive and negative effects on soil fertility. Soil quality, which is critical for ecosystems, shapes biodiversity and productivity, while increased temperatures from vegetation burning can alter conditions for seed germination by reducing nutrient availability. Objectives: The study aims to assess the impacts of vegetation burning on soil fertility in Fwangnin, Bokkos, Nigeria, through experimental investigation of the effects of burning on both the chemical and physical properties of soil. The results are expected to contribute to the development of adaptive fire management strategies in land use, and the results will also help monitor soil changes in order to maintain long-term soil fertility. Methods: Using purposive sampling, four 500-gram soil samples were taken from 0 – 15 cm depth in burned and unburned areas. The samples were analysed for pH, electrical conductivity (EC), organic carbon (OC), organic matter (OM), nitrogen (N), phosphorus (P), and cation exchange capacity (CEC). Traditional well-proven methods were used for the analysis. Results: It was found that the pH of the burnt soil samples ranged from 6.10 to 5.90, while that of the unburnt samples ranged from 5.73 to 5.81; a significant increase in pH occurs at higher combustion temperatures, which increases the alkalinity of the soil due to the alkaline properties of ash. The electrical conductivity value for the samples in the burnt areas was significantly higher (0.08 mS/cm and 0.10 mS/cm) compared to the healthy soil (0.07 mS/cm and 0.09 mS/cm), which can be explained by the release of mineral ions due to the combustion of organic matter. The study found a decrease in organic carbon content in the burnt soil, a significant deficiency of nitrogen and a decrease in the cation exchange capacity, which contributes to the depletion of the fertile layer and a decrease in the ability of the soil to retain essential nutrients. Increased levels of organic phosphorus were also found in burnt soils, which contributes to improved crop growth and increased yields in the short term. Conclusion: The current study has filled the gap in deep understanding of the impact of vegetation burning on the fertile properties of agricultural soils. Namely, it has been experimentally established and confirmed by the results of similar studies and statistical analysis that while vegetation burning remains a common agricultural practice in Fwangnin, the long-term implications for soil fertility, structure, and ecosystem health are significant. The soil degradation observed in this study suggests that continued reliance on burning as a land-clearing method may undermine agricultural productivity and environmental integrity over time.

Satellite derived air pollution climatology over India and its neighboring regions: Spatio-temporal trends and insights

This study examines the spatial and temporal variations of key air pollutants, including Nitrogen Dioxide (NO₂), Carbon Monoxide (CO), Tropospheric Ozone (O₃), Sulfur Dioxide (SO₂), Aerosol Optical Depth (AOD), and Formaldehyde (HCHO) over India and neighboring regions, using satellite data from 2005 to 2022. Peak NO₂ (∼11–13 × 101⁵molecules/cm2) occurs in pre-monsoon and winter, mainly over urban centers, thermal plants, and crop-burning areas, emphasizing anthropogenic emissions. High CO levels (2.0–2.3 × 101⁸molecules/cm2) during summer dominate in Indo-Gangetic Plains (IGP), Eastern India, and Northeastern region, linked to the incomplete combustion of organic matter (e.g., natural forest fires and biofuel-based household cooking). Stable CO trends reflect effective government policies promoting cleaner fuels. Tropospheric O₃ shows a spatial gradient, with higher values in northern and coastal regions influenced by sunlight, humidity, and precursor emissions. Seasonal peaks in summer are governed by solar intensity, while the December peak over the northern region is likely due to dynamical transport from O₃-rich areas. SO₂ hotspots in IGP, central and eastern India, especially during winter (∼1.3–1.9 × 101⁵molecules/cm2), are attributed to local anthropogenic emissions and fossil fuel combustion such as coal. Long-term trends reveal rising SO₂ levels. AOD hotspots occur over IGP, Central and Southern India, with particularly high values during the pre-monsoon (0.5–0.6) and winter seasons. HCHO shows hotspots in the IGP, west coast, eastern, and northeastern regions, peaking in summer (7.5–8.5 × 101⁵molecules/cm2) due to biogenic VOC emissions. This study underscores the need for integrated policies to mitigate emissions, improve air quality, and protect public health.

Nanomaterial-mediated strategies for enhancing bioremediation of polycyclic aromatic hydrocarbons: A systematic review

Polycyclic aromatic hydrocarbons (PAHs) are pervasive organic pollutants in the environment that are formed as an outcome of partial combustion of organic matter. PAHs pose a significant threat to ecological systems and human health due to their cytotoxic and genotoxic effects. Therefore, an immediate need for effective PAH remediation methods is crucial. Although nanomaterials are effective for remediation of PAHs, concerns regarding environmental compatibility and sustainability remains. Therefore, this study emphasizes integration of nanomaterials with bioremediation methods, which might offer a more sustainable and ecofriendly approach to PAHs remediation. A systematic search was conducted through scholarly databases from 2013 to 2023. A total of 360 articles were scrutinized, among which 26 articles were selected that resonated with the application of nano-bioremediation. These literatures comprise both comparative analysis of bioremediation only as well as nano-bioremediation. There is an elevation of 18.9 % in PAHs removal of liquid-phase samples, when comparing bioremediation (52.2 %) with nano-bioremediation (71.1 %). A consistent trend was observed in soil samples, with bioremediation and nano-bioremediation that successfully remove PAHs, with 60.8 % and 75.1 % respectively, indicating a 14.3 % improvement. Furthermore, the review elaborated on the various features of nanomaterials that led to their efficiency in the bioremediation of PAH. The review also discussed the strategies of nano-bioremediation namely nanomaterial-assisted microbial degradation, nanomaterial-assisted enzyme-enhanced microbial activity, nanomaterial-immobilized microbial cells, nanomaterial-facilitated electron transfer, and even some eco-green approaches to remediate PAHs, like biogenic nanomaterial for PAHs.

Effects of fire and fire-induced changes in soil properties on post-burn soil respiration

Abstract Background Boreal forests cover vast areas of land in the northern hemisphere and store large amounts of carbon (C) both aboveground and belowground. Wildfires, which are a primary ecosystem disturbance of boreal forests, affect soil C via combustion and transformation of organic matter during the fire itself and via changes in plant growth and microbial activity post-fire. Wildfire regimes in many areas of the boreal forests of North America are shifting towards more frequent and severe fires driven by changing climate. As wildfire regimes shift and the effects of fire on belowground microbial community composition are becoming clearer, there is a need to link fire-induced changes in soil properties to changes in microbial functions, such as respiration, in order to better predict the impact of future fires on C cycling. Results We used laboratory burns to simulate boreal crown fires on both organic-rich and sandy soil cores collected from Wood Buffalo National Park, Alberta, Canada, to measure the effects of burning on soil properties including pH, total C, and total nitrogen (N). We used 70-day soil incubations and two-pool exponential decay models to characterize the impacts of burning and its resulting changes in soil properties on soil respiration. Laboratory burns successfully captured a range of soil temperatures that were realistic for natural wildfire events. We found that burning increased pH and caused small decreases in C:N in organic soil. Overall, respiration per gram total (post-burn) C in burned soil cores was 16% lower than in corresponding unburned control cores, indicating that soil C lost during a burn may be partially offset by burn-induced decreases in respiration rates. Simultaneously, burning altered how remaining C cycled, causing an increase in the proportion of C represented in the modeled slow-cycling vs. fast-cycling C pool as well as an increase in fast-cycling C decomposition rates. Conclusions Together, our findings imply that C storage in boreal forests following wildfires will be driven by the combination of C losses during the fire itself as well as fire-induced changes to the soil C pool that modulate post-fire respiration rates. Moving forward, we will pair these results with soil microbial community data to understand how fire-induced changes in microbial community composition may influence respiration.

SOURCE APPORTIONMENT OF ATMOSPHERIC AND SEDIMENTARY PAHS FROM KOLKATA, INDIA USING COMPOUND-CLASS-SPECIFIC RADIOCARBON ANALYSIS (CCSRA)

ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are major air pollutants that are ubiquitously produced by the combustion of organic materials, and it is extremely important to identify their pollution sources. In this study, molecular fingerprinting and compound class-specific radiocarbon dating (CCSRA) were performed on PAHs from canal sediments and air samples collected in Kolkata, India’s third largest city (population approximately 16 million), where PAHs pollution has been a serious problem. Average PAH (Σ12-parent PAHs) concentrations in air samples were 65.1 ng m–3 in summer and 70.9 ng m–3 in winter and in canal sediments were 32.7 µg g–1, which are classified as “very high-level” pollution. Molecular fingerprinting using methyl-PAH/PAH (MPAHs/PAHs) ratios and isomer pair ratios with molecular weights of 178, 202, 228, and 276 suggested that wood and coal combustion were the dominant sources of PAHs in the sediment, and that atmospheric PAHs were influenced by oil combustion in addition to them. The fraction of contemporary carbon (ƒC) of sedimentary PAHs (0.056–0.100), together with the extremely low MPAHs/PAHs ratio results, lead to the conclusion that the major source of the high concentration of PAHs in the canals is from coal combustion. On the other hand, the ƒC of atmospheric PAHs (0.272–0.369) was close to the share of biomass fuels in India’s domestic fuel consumption in 2011 (about 35%). Furthermore, the observed ƒC-discrepancy between atmospheric and sedimentary PAHs in the same urban environment was interpreted to give an insight into the loading pathway of PAHs to canal sediments in Kolkata.

Exploring naphthalene vapor biofiltration: performance and microbial community dynamics with diverse inoculums

AbstractBackgroundNaphthalene is a polycyclic aromatic hydrocarbon, highly dangerous for human health. It is produced as a byproduct of incomplete combustion of organic material and is frequently present in the air. Biofilters offer an effective alternative for its treatment. The aim of this work was to study the treatment of naphthalene vapors through biofiltration using two biofilters: one inoculated with a consortium composed of Fusarium solani and Rhodococcus erythropolis (BF1), and the other inoculated with a consortium of microbial isolates obtained from a previous biofilter eliminating naphthalene vapors.ResultsThe results demonstrate that inoculating a biofilter with a reconstructed consortium of microbial isolates from a naphthalene vapor‐eliminating biofilter allowed a reduction of the startup time from 35 to 5 days, while maintaining a consistent removal capacity (6 g m−3 h−1, equivalent to 80% removal efficiency). It was also observed that the biofilter inoculated with the reconstructed consortium exhibited comparable robustness to a biofilter previously operated for 4 months with naphthalene, with a maximum removal capacity of 14 g m−3 h−1 for a naphthalene inlet load of 17 g m−3 h−1. The study of microbial communities indicates an increase in the bacterial variability, while fungal variability remains low, with Fusarium solani being predominant at 97%.ConclusionsResults obtained during the startup of both biofilters and by challenging biofilters to increasing naphthalene concentrations or decreasing empty bed residence time showed that startup time can be reduced sevenfold by selecting the microbial consortium. An equivalent performance, in the long run, was achieved for both biofilters. © 2024 Society of Chemical Industry (SCI).

A vortex-assisted MSPD method for the extraction of Polycyclic Aromatic Hydrocarbons from shrimp with determination by GC-MS/MS

Polycyclic Aromatic Hydrocarbons (PAHs) are organic compounds with two or more condensed aromatic rings, formed from incomplete organic matter combustion. PAHs pose potential health risks due to their carcinogenic and mutagenic properties, accumulating in edible tissues of aquatic organisms, such as shrimp, which is extensively produced in the southern region of Rio Grande do Sul state (Brazil) and it is the most consumed seafood globally. Therefore, this study aimed to optimize and validate an analytical method for extracting 16 priority PAHs from shrimp samples using Vortex-Assisted Matrix Solid-Phase Dispersion (VA-MSPD) with determination by Gas Chromatography Tandem Mass Spectrometry (GC-MS/MS). The optimized method, which uses a reused solid support, was validated according to INMETRO and SANTE guidelines. PAHs demonstrated adequate linearity with correlation coefficients > 0.99. The matrix effect was assessed, and 12 out of the 16 PAHs showed a matrix effect of less than ±20%. The method's quantification limits ranged from 6.67 to 33.35 ng g-1. Accuracy and precision showed recovery values ranging from 55 to 115% with relative standard deviation (RSD) lower than 17% for all PAHs. In the applicability, 11 PAHs were detected, such as benzo[a]pyrene and benzo[b]fluoranthene, and the ∑PAHs ranged from 25.14 to 79.52 ng g-1, confirming the environmental contamination in the region and the need for monitoring these contaminants in shrimp destined for human consumption.

Synergistic Toxicity of Pollutant and Ultraviolet Exposure from a Mitochondrial Perspective.

Ultraviolet (UV) exposure and atmospheric pollution are both independently implicated in skin diseases such as cancer and premature aging. UVA wavelengths, which penetrate in the deep layers of the skin dermis, exert their toxicity mainly through chromophore photosensitization reactions. Benzo[a]pyrene (BaP), the most abundant polycyclic aromatic hydrocarbon originating from the incomplete combustion of organic matter, could act as a chromophore and absorb UVA. We and other groups have previously shown that BaP and UVA synergize their toxicity in skin cells, which leads to important oxidation. Even if mitochondria alterations have been related to premature skin aging and other skin disorders, no studies have focused on the synergy between UV exposure and pollution on mitochondria. Our study aims to investigate the combined effect of UVA and BaP specifically on mitochondria in order to assess the effect on mitochondrial membranes and the consequences on mitochondrial activity. We show that BaP has a strong affinity for mitochondria and that this affinity leads to an important induction of lipid peroxidation and membrane disruption when exposed to UVA. Co-exposure to UVA and BaP synergizes their toxicity to negatively impact mitochondrial membrane potential, mitochondrial metabolism and the mitochondrial network. Altogether, our results highlight the implication of mitochondria in the synergistic toxicity of pollution and UV exposure and the potential of this toxicity on skin integrity.

SIMULATION THE PROCESSES OF ORGANIC MATERIALS DESTRUCTION AND COMBUSTION PROCESSES CONDITION OF FIRE INTENSEICATION

Problem statement. The rapid occurrence and development of fires are caused by the occurrence of combustible materials and structures in their focus. This complicates, and in some cases makes impossible, effective firefighting, evacuation, and rescue of people and property. In order to correctly assess fire resistance, effectively increase fire resistance, and change the flammability of materials, it is necessary to study the materials burning process. The purpose of the article. To study of the combustion of easily dispersible substances and the development of gaseous reactions and their combination using the example of wood combustion. Methods. We use mathematical modeling of combustion and destructive processes under the high temperatures, taking into account the rules of thermodynamics. Research results. The conducted analysis showed that the selection of the main stages in the simulation of wood combustion is much less developed than in the case of the combustion of gas systems. It is especially difficult to do this to describe the combustion of wood, on the surface of which there is an interaction of masses (and heat) during the combustion of individual components, and the size of the front surface per unit cross-section of the sample may also change over time. Therefore, the definition of the main stage in wood burning should be used mainly in the qualitative analysis of the process, and quantitative models of wood burning should be built, if possible, taking into account all the determining factors characterizing the phenomena. Scientific novelty. For the first time, on the basis of the modeling of organic material combustion is proposed. We determine the patterns of destructive processes, which, depending on the temperature, have common patterns of qualitative and quantitative characteristics. The chemical phasing and its connection with the physical phasing of the transformation of combustible organic materials dispersed in the surface layer with the overall thermal effect of the combustion wave were determined. Practical value. The identification of stages during the wave burning of wood allows for a qualitative display of processes depending on the spatial zone and its distance from the gas zone, which allows predicting the development of protective means of organic materials against combustion.

Polycyclic aromatic compounds in a northern freshwater ecosystem: Patterns, sources, and the influences of environmental factors

Polycyclic aromatic compounds (PACs) - a large group of organic chemicals naturally present in petroleum deposits (i.e., petrogenic) or released into the environment by incomplete combustion of organic materials (i.e., pyrogenic) - represent a potential risk to the health of aquatic ecosystems. In high latitude freshwater ecosystems, concentrations of PACs may be increasing, yet there are limited studies in such systems to assess change and to understand threats. Using 10 years of contemporary data from passive samplers deployed across five regions (n = 43 sites) in the Mackenzie River Basin, we (i) describe baseline levels of PACs, (ii) assess spatiotemporal patterns, and (iii) evaluate the extent to which environmental factors (fire, snowmelt, and proximity to oil infrastructure) influence concentrations in this system. Measured concentrations were low, relative to those in more southern systems, with mixtures primarily being dominated by non-alkylated, low molecular weight compounds. Concentrations were spatially consistent, except for two sites near Norman Wells (an area of active oil extraction) with increased levels. Similarly, observed annual variation was minimal, with 2014 having generally higher levels of PACs. We did not detect effects of fire, snowmelt, or oil infrastructure on concentrations. Taken together, our findings suggest that PACs in the Mackenzie River are currently at low levels and are primarily petrogenic in origin. They further indicate that ongoing monitoring and testing of environmental drivers (especially at finer spatial scales) are needed to better predict how ecosystem change will influence PAC levels in the basin and in other northern systems.

Clustered Carbon Monoxide Poisoning Cases: Accidental Poisoning In A Vehicle

Carbon monoxide (CO) is a product of combustion of organic matter in the presence of inadequate supply of oxygen. Common sources are burning fuel, engine exhaust, burning of animal dung, heater emissions and gas geyser. It is a toxic, clear, colorless and tasteless gas. The clinical presentation runs a spectrum, ranging from headache and dizziness to coma and death. Here we report three cases that presented to us in the month of November 2023 with history, sign & symptoms suggestive of CO poisoning. Bangladesh Crit Care J March 2024; 12 (1): 72-74

Assessment of PAH exposure and health risks among South Korean firefighters based on urinary PAH metabolites

Polycyclic aromatic hydrocarbons (PAHs) comprise a group of compounds resulting from the incomplete combustion of organic matter. Firefighters engaged in fire suppression are highly exposed to PAHs. This study centered on evaluating the exposure levels and health risks of PAHs in South Korean firefighters involved in firefighting activities. The concentrations of 10 PAH metabolites in the urine of firefighters were measured immediately after, and two weeks post their engagement in extinguishing a large tire factory fire. The levels of OH-PAHs in urine samples immediately after fire suppression were elevated by a factor of 1.01–1.84 compared to urine samples from non-exposed period. The median concentration of total PAH metabolites (OH-PAHs) was higher in urine samples immediately after fire suppression (5910 ng/g creatinine) than in urine samples from non-exposed periods (5020 ng/g creatinine). However, the ∑OH-PAH levels in firefighters’ urine were related to personal habits such as smoking. The concentrations of all individual OH-PAHs in the urine samples of nonsmokers exhibited a substantial increase, ranging from 1.37 to 2.3 times, clearly demonstrating that firefighting activities were a substantial source of PAH exposure. The calculated values associated with the health risks stemming from exposure to PAHs, including carcinogenic risk, total estimated daily intake (TEDI), and hazard quotients/index (HQs/HI), all fell within acceptable limits, indicating negligible risk. However, the HQ/HI values and TEDI for individual and total PAH exposures, except those for naphthalene, were 1.36–2.00 times higher in firefighters' samples taken after firefighting operations compared to those during regular duty. This underscores the need for more comprehensive investigations to comprehend the singular impact of firefighting activities due to the diverse sources of PAH emissions in the environment.