Carbon-Centered Free Radicals in Particulate Matter Emissions from Wood and Coal Combustion.
Ontology highlight
ABSTRACT:
SUBMITTER: Tian L
PROVIDER: S-EPMC2700017 | biostudies-other | 2009 May
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Direct household use of unprocessed raw coals for cooking and heating without any air pollution control device has caused serious indoor and outdoor environment problems by emitting particulate matter (PM) and gaseous pollutants. This study examined household emission reduction by switching from unprocessed bituminous and anthracite coals to processed semi-coke briquettes. Two typical stoves were used to test emission characteristics when burning 20 raw coal samples commonly used in residential heating activities and 15 semi-coke briquette samples which were made from bituminous coals by industrial carbonization treatment. The carbonization treatment removes volatile compounds from raw coals which are the major precursors for PM formation and carbon emission. The average emission factors of primary PM2.5, elemental carbon, organic carbon, and carbon monoxide for the tested semi-coke briquettes are much lower than those of the tested raw coals. Based on the current coal consumption data in China, switching to semi-coke briquettes can reduce average emission factors of these species by about 92%, 98%, 91%, and 34%, respectively. Additionally, semi-coke briquette has relatively lower price and higher burnout ratio. The replacement of raw coals with semi-coke briquettes is a feasible path to reduce pollution emissions from household activities.
| S-EPMC4726058 | biostudies-literature
Project description:Catechol is speculated to be a potential precursor of environmentally persistent free radicals (EPFRs) in the atmosphere. EPFRs absorbed on PM2.5 have attracted public attention because their toxicity is similar to cigarette smoke. In this study, we found that catechol could produce EPFRs, which were oxygen-centered phenoxy and semiquinone radicals. These free radical species had half-lives of up to 382 days. CaO, CuO, and Fe2O3 markedly promoted EPFR formation from catechol. The valence states of Cu and Fe changed during the photochemical reactions of catechol but no valence state changed for Ca. Alkaline nature of CaO is possibly the key for promoting the free radical formations through acid-base reactions with catechol. In addition to hydroxyl free radicals, hydrogen free radicals and superoxide anions formed from the photochemical reactions of catechol were first discovered. This is of concern because of the adverse effects of these free radicals on human health.
| S-EPMC7920856 | biostudies-literature
Project description:Wood burning contributes to indoor and ambient particulate matter (PM) pollution and has been associated with increased morbidity and mortality. Here, we present an integrated methodology that allows to generate, sample, and characterize wood smoke derived from different moisture contents and representative combustion conditions using pine wood as a model. Flaming, smoldering, and incomplete combustion were assessed for low-moisture pine, whereas both low-moisture pine and high-moisture pine were investigated under flaming conditions. Real-time monitoring of carbon monoxide, volatile organic compounds, and aerosol number concentration/size in wood smoke was performed. The PM was size-fractionated, sampled, and characterized for elemental/organic carbon, organic functional groups, and inorganic elements. Bioactivity of PM was assessed by measuring the sterile alpha motif (SAM) pointed domain containing ETS (E-twenty-six) transcription factor (SPDEF) gene promoter activity in human embryonic kidney 293 (HEK-293T) cells, a biomarker for mucin gene expression. Findings showed that moisture content and combustion condition significantly affected the organic and inorganic elemental composition of PM0.1 as well as its bioactivity. Also, for a given moisture and combustion scenario, PM chemistry and bioactivity differed considerably with PM size. Importantly, PM0.1 from flaming combustion of low-moisture pine contained the highest abundance of the oxygenated saturated aliphatic functional group [H-C-O] and was also biologically most potent in stimulating SPDEF promoter activity, suggesting the role of organic compounds such as carbohydrates and sugar alcohols (that contain [H-C-O]) in driving mucus-related respiratory outcomes. Our platform enables further well-controlled parametric studies using a combination of in vitro and in vivo approaches to link wood burning parameters with acute and chronic inhalation health effects of wood smoke.
| S-EPMC9491341 | biostudies-literature
Project description:Published emission factors (EFs) often vary significantly, leading to high uncertainties in emission estimations. There are few reliable EFs from field measurements of residential wood combustion in China. In this study, 17 wood fuels and one bamboo were combusted in a typical residential stove in rural China to measure realistic EFs of particulate matter (PM), organic carbon (OC), and elemental carbon (EC), as well as to investigate the influence of fuel properties and combustion conditions on the EFs. Measured EFs of PM, OC, and EC (EF(PM), EF(OC), and EF(EC), respectively) were in the range of 0.38-6.4, 0.024-3.0, and 0.039-3.9 g/kg (dry basis), with means and standard derivation of 2.2 ± 1.2, 0.62 ± 0.64, and 0.83 ± 0.69 g/kg, respectively. Shrubby biomass combustion produced higher EFs than tree woods, and both species had lower EFs than those of indoor crop residue burning (p < 0.05). Significant correlations between EF(PM), EF(OC), and EF(EC) were expected. By using a nine-stage cascade impactor, it was shown that size distributions of PM emitted from tree biomass combustions were unimodal with peaks at a diameter less than 0.4 ?m (PM(0.4)), much finer than the PM from indoor crop residue burning. Approximately 79.4% of the total PM from tree wood combustion was PM with a diameter less than 2.1 ?m (PM(2.1)). PM size distributions for shrubby biomasses were slightly different from those for tree fuels. On the basis of the measured EFs, total emissions of PM, OC, and EC from residential wood combustion in rural China in 2007 were estimated at about 303, 75.7, and 92.0 Gg.
| S-EPMC3352236 | biostudies-literature
Project description:Environmentally persistent free radicals (EPFRs) have been shown to form on the surfaces of various types of transition metal-containing particulate matter (PM), and it has been demonstrated they are capable of initiating adverse health impacts. Following sonification and solvent extraction for chemical analysis, they are partially converted to molecular species. Alcoholic solvents extracted the EPFRs with near 100% efficiency, while nonpolar hydrocarbon solvents exhibited <20% efficiency and dichloromethane exhibited 20-55% efficiency. The extracted radicals reacted in solution to form multiple molecular reaction products including catechol, hydroquinone, phenol, chlorinated phenols, dibenzo-p-dioxin, and dibenzofuran. This suggests that EPFRs in environmental samples are indistinguishable from molecular pollutants and are subject to misidentification as molecular adsorbates when traditional extraction and chemical analysis methods are employed. On the basis of these findings, the origin of the toxicity of particulate matter contaminated with toxic organic compounds should be considered for re-evaluation to include the possibility that EPFRs may be a significant contributor, and the impact of some molecular pollutants may have been overestimated.
| S-EPMC4315178 | biostudies-literature
Project description:BackgroundThe atmosphere has become a major transport corridor for free radicals and particulate matter from combustion events. The motivation behind this study was to determine the nature of particulate emissions and surface bound radicals formed during the thermal degradation of diesel blends in order to assess the health and environmental hazards of binary transport fuels.MethodologyAccordingly, this contribution explored the interactions that occur when Croton megalocarpus biodiesel and fossil diesel in the ratio of 1:1 by weight were co-pyrolyzed in a quartz reactor at a residence time of 0.5 s under an inert flow of nitrogen at 600 °C. The surface morphology of the thermal char formed were imaged using a Feld emission gun scanning electron microscope (FEG SEM) while Electron paramagnetic resonance spectrometer (EPR) was used to explore the presence of free radicals on the surface of thermal char. Molecular functional groups adsorbed on the surface of thermal char were explored using Fourier transform infrared spectroscopy (FTIR).ResultsFTIR spectrum showed that the major functional groups on the surface of the char were basically aromatic and some methylene groups. The particulate emissions detected in this work were ultrafine (~ 32 nm). The particulates are consistent with the SEM images observed in this study. Electron paramagnetic resonance results gave a g-value of 2.0027 characteristic of carbon-based radicals of aromatic nature. Spectral peak-to-peak width (∆Hp-p) obtained was narrow (4.42 G).ConclusionsThe free radicals identified as carbon-based are medically notorious and may be transported by various sizes of particulate matter on to the surface of the human lung which may trigger cancer and pulmonary diseases. The nanoparticulates determined in this work can precipitate severe biological health problems among humans and other natural ecosystems.
| S-EPMC6081488 | biostudies-literature
Project description:We employed an in vivo assay system of Caenorhabditis elegans to determine if and which microRNAs (miRNAs) were dysregulated upon exposure to coal combustion related fine particulate matter (PM2.5) by profiling the miRNAs using SOLiD sequencing. From this, expression of 25 miRNAs was discovered to become dysregulated by exposure to PM2.5. Using the corresponding C. elegans deletion mutants, 5 miRNAs (mir-231, mir-232, mir-230, mir-251 and mir-35) were found to be involved in the control of PM2.5 toxicity. Furthermore, mutation of mir-231 or mir-232 induced a resistance to PM2.5 toxicity, whereas mutation of mir-230, mir-251, or mir-35 induced a susceptibility to PM2.5 toxicity. SMK-1, an ortholog of the mammalian SMEK protein, was identified as a molecular target for mir-231 in the regulation of PM2.5 toxicity. In addition, the genes of sod-3, sod-4 and ctl-3, which are necessary for protection against oxidative stress, were determined to be important downstream targets of smk-1 in the regulation of PM2.5 toxicity. The triggering of this mir-231-SMK-1-SOD-3/SOD-4/CTL-3 signaling pathway may be a critical molecular basis for the role of oxidative stress in the induction of coal combustion related PM2.5 toxicity.
| S-EPMC6062267 | biostudies-literature
Project description:BackgroundIn vitro studies with monocultures of human alveolar cells shed deeper knowledge on the cellular mechanisms by which particulate matter (PM) causes toxicity, but cannot account for mitigating or aggravating effects of cell-cell interactions on PM toxicity.MethodsWe assessed inflammation, oxidative stress as well as cytotoxic and genotoxic effects induced by PM from the combustion of different types of wood logs and softwood pellets in three cell culture setups: two monocultures of either human macrophage-like cells or human alveolar epithelial cells, and a co-culture of these two cell lines. The adverse effects of the PM samples were compared between these setups.ResultsWe detected clear differences in the endpoints between the mono- and co-cultures. Inflammatory responses were more diverse in the macrophage monoculture and the co-culture compared to the epithelial cells where only an increase of IL-8 was detected. The production of reactive oxygen species was the highest in epithelial cells and macrophages seemed to have protective effects against oxidative stress from the PM samples. With no metabolically active cells at the highest doses, the cytotoxic effects of the PM samples from the wood log combustion were far more pronounced in the macrophages and the co-culture than in the epithelial cells. All samples caused DNA damage in macrophages, whereas only beech and spruce log combustion samples caused DNA damage in epithelial cells. The organic content of the samples was mainly associated with cytotoxicity and DNA damage, while the metal content of the samples correlated with the induction of inflammatory responses.ConclusionsAll of the tested PM samples induce adverse effects and the chemical composition of the samples determines which pathway of toxicity is induced. In vitro testing of the toxicity of combustion-derived PM in monocultures of one cell line, however, is inadequate to account for all the possible pathways of toxicity.
| S-EPMC5821343 | biostudies-literature
Project description:Organic radicals, which have unique doublet spin-configuration, provide an alternative method to overcome the efficiency limitation of organic light-emitting diodes (OLEDs) based on conventional fluorescent organic molecules. Further, they have made great breakthroughs in deep-red and near-infrared OLEDs. However, it is difficult to extend their fluorescence into a short-wavelength region because of the natural narrow bandgap of the organic radicals. Herein, we significantly expand the scope of luminescent radicals by showing a new platform of carbon-centered radicals derived from N-heterocyclic carbenes that produce blue to green emissions (444-529 nm). Time-dependent density functional theory calculations and experimental investigations disclose that the fluorescence originates from the high-energy excited states to the ground state, demonstrating an anti-Kasha behavior. The present work provides an efficient and modular approach toward a library of carbon-centered radicals that feature anti-Kasha's rule emission, rendering them as potential new emitters in the short-wavelength region.
| S-EPMC9470563 | biostudies-literature
Project description:Few studies have examined particulate matter (PM) exposure from self-reported use of wood stoves and other indoor combustion sources in urban settings in developed countries. We measured concentrations of indoor PM < 2.5 microns (PM2.5) for one week with the MicroPEM™ nephelometer in 36 households in the greater Oslo, Norway metropolitan area. We examined indoor PM2.5 levels in relation to use of wood stoves and other combustion sources during a 7 day monitoring period using mixed effects linear models with adjustment for ambient PM2.5 levels. Mean hourly indoor PM2.5 concentrations were higher (p = 0.04) for the 14 homes with wood stove use (15.6 μg/m3) than for the 22 homes without (12.6 μg/m3). Moreover, mean hourly PM2.5 was higher (p = 0.001) for use of wood stoves made before 1997 (6 homes, 20.2 μg/m3), when wood stove emission limits were instituted in Norway, compared to newer wood stoves (8 homes, 11.9 μg/m3) which had mean hourly values similar to control homes. Increased PM2.5 levels during diary-reported burning of candles was detected independently of concomitant wood stove use. These results suggest that self-reported use of wood stoves, particularly older stoves, and other combustion sources, such as candles, are associated with indoor PM2.5 measurements in an urban population from a high income country.
| S-EPMC5113953 | biostudies-literature