Search

Phenolic compounds, which are significant emissions from biomass burning (BB), undergo rapid photochemical reactions in both gas and aqueous phases to form secondary organic aerosol, namely, gasSOA and aqSOA, respectively. The formation of gasSOA and aqSOA involves different reaction mechanisms, leading to different product distributions. In this study, we investigate the gaseous and aqueous reactions of guaiacol-a representative BB phenol-to elucidate the compositional differences between phenolic aqSOA and gasSOA. Aqueous-phase reactions of guaiacol produce higher SOA yields than gas-phase reactions (e.g., roughly 60 vs 30% at one half-life of guaiacol). These aqueous reactions involve more complex reaction mechanisms and exhibit a more gradual SOA evolution than their gaseous counterparts. Initially, gasSOA forms with high oxidation levels (O/C > 0.82), while aqSOA starts with lower O/C (0.55-0.75). However, prolonged aqueous-phase reactions substantially increase the oxidation state of aqSOA, making its bulk chemical composition closer to that of gasSOA. Additionally, aqueous reactions form a greater abundance of oligomers and high-molecular-weight compounds, alongside a more sustained production of carboxylic acids. AMS spectral signatures representative of phenolic gasSOA have been identified, which, together with tracer ions of aqSOA, can aid in the interpretation of field observation data on aerosol aging within BB smoke. The notable chemical differences between phenolic gasSOA and aqSOA highlighted in this study also underscore the importance of accurately representing both pathways in atmospheric models to better predict the aerosol properties and their environmental impacts.

Environmentally persistent free radicals (EPFRs) play an important role in aerosol effects on air quality and public health, but their atmospheric abundance and sources are poorly understood. We measured EPFRs contained in PM2.5 collected in Fairbanks, Alaska, in winter 2022. We find that EPFR concentrations were enhanced during surface-based inversion and correlate strongly with incomplete combustion markers, including carbon monoxide and elemental carbon (R2 > 0.75). EPFRs exhibit moderately good correlations with PAHs, biomass burning organic aerosols, and potassium (R2 > 0.4). We also observe strong correlations of EPFRs with hydrocarbon-like organic aerosols, Fe and Ti (R2 > 0.6), and single-particle mass spectrometry measurements reveal internal mixing of PAHs, with potassium and iron. These results suggest that residential wood burning and vehicle tailpipes are major sources of EPFRs and nontailpipe emissions, such as brake wear and road dust, may contribute to the stabilization of EPFRs. Exposure to the observed EPFR concentrations (18 ± 12 pmol m-3) would be equivalent to smoking ∼0.4-1 cigarette daily. Very strong correlations (R2 > 0.8) of EPFR with hydroxyl radical formation in surrogate lung fluid indicate that exposure to EPFRs may induce oxidative stress in the human respiratory tract.

The post-monsoon agricultural biomass burning activities in Northwest India have been recognized as a significant socio-environmental problem in recent years, primarily due to their severe impacts on air quality degradation across a wide area, including the capital New Delhi. Although these biomass burning activities have been extensively studied from an air quality perspective, their potential impacts on the climate system, particularly through their influences on cloud and radiation fields, have been largely overlooked. In this study, we aim to address this research gap by analyzing fire, meteorological parameters, aerosol, cloud, and radiation data spanning nearly two decades (2002–2021), obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Aqua satellite, Modern-Era Retrospective Analysis Research and Applications, Version 2 (MERRA-2), and the Fifth Generation of European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA5). Our analysis reveals a notable increase in agricultural biomass burning intensity in Northwest India over the past two decades, contributing significantly to air quality degradation. Our analysis further indicates a delay in peak burning time (day of the year) and a shortening of the period of intense burning, reflecting changes in farming practices and agricultural biomass burning in Northwest India over the past two decades. These agricultural biomass burning activities substantially elevate total and light-absorbing aerosols, thereby affecting cloud properties and altering the radiation budget. The intensification of these burning activities can cause an increase in cloud droplet size and a decrease in cloud optical thickness, suggesting an enhancement of the cloud droplet collision-coalescence process during the period of intense burning. Similarly, the intensification of burning activities leads to increased cooling effects at the surface and top-of-the-atmosphere across shortwave and longwave spectral ranges, while inducing a heating effect within the atmosphere. These findings highlight the potential impacts of agricultural biomass burning activities on the regional climate system and hydrological cycle, emphasizing the need for more detailed studies in the future. [ABSTRACT FROM AUTHOR]

An exergy analysis of maize cob gasification in a concentric tube fixed-bed reactor was conducted to define the relationship between biomass in the combustion and gasification zones. Biomass exergy was estimated based on its elemental composition, and syngas was treated as an ideal gas. The results show a linear correlation between temperature and the mass ratio in both the combustion and gasification zones. The optimum exergy efficiency was 68.2% at a mass ratio of 2. Most irreversibilities were found in the combustion zone, with 42.9 kJ/kg destroyed, compared to 33.7 kJ/kg in the gasification zone. It is concluded that the allothermal gasification of biomass in two-zone gasifiers with concentric tubes improves the syngas LHV, demonstrating good reactor performance. [ABSTRACT FROM AUTHOR]

To explore air contamination resulting from special biomass combustion and suspended dust in Lhasa, the present study focused on the size distribution and chemical characteristics of particulate matter (PM) emission resulting from 7 types of non-fossil pollution sources. We investigated the concentration and size distribution of trace elements from 7 pollution sources collected in Lhasa. Combining Lhasa's atmospheric particulate matter data, enrichment factors (EFs) have been calculated to examine the potential impact of those pollution sources on the atmosphere quality of Lhasa. The highest mass concentration of total elements of biomass combustion appeared at PM 0.4 , and the second highest concentration existed in the size fraction 0.4–1 µm; the higher proportion (12 %) of toxic metals was produced by biomass combustion. The elemental composition of suspended dust and atmospheric particulate matter was close (except for As and Cd); the highest concentration of elements was all noted in PM 2.5-10 (PM 3-10). Potassium was found to be one of the main biomass markers. The proportion of Cu in suspended dust is significantly lower than that of atmospheric particulate matter (0.53 % and 3.75 %), which indicates that there are other anthropogenic sources. The EFs analysis showed that the Cr, Cu, Zn, and Pb produced by biomass combustion were highly enriched (EFs > 100) in all particle sizes. The EFs of most trace elements increased with decreasing particle size, indicating the greater influence of humanfactors on smaller particles. [ABSTRACT FROM AUTHOR]

Smoke particles from biomass burning events are typically assumed to be spherical despite previous observations of non-spherical smoke. As such, large uncertainties exist in some physical and optical parameters used in lidar aerosol retrievals, including depolarization and lidar ratio of non-spherical smoke aerosols. In this analysis, using NASA's Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data during the biomass burning season over Africa from 2015 to 2017, we studied the frequency and distribution of non-spherical smoke particles to compare with findings of smoke particle non-sphericity from the Cloud-Aerosol Transport System (CATS) lidar. A supplemental smoke aerosol typing algorithm was developed to identify aerosol layers containing non-spherical smoke particles, which might otherwise be misclassified as desert dust, polluted dust, or dusty marine by the CALIOP standard aerosol typing algorithm. Then, the relationships between smoke particle sphericity, lidar ratio, and relative humidity are analyzed for CATS and CALIOP observations over Africa. Approximately 18% of smoke layers observed by CALIOP over Africa are non-spherical (depolarization ratio > 0.075) and agree with spatial distributions of non-spherical smoke found in CATS observations. A dependance of lidar ratio on relative humidity was found for layers of spherical smoke over Africa in both CATS and CALIOP data; however, no such dependance was evident for the depolarization ratio and layer relative humidity. While the supplemental smoke aerosol typing algorithm presented in this analysis was targeted only for specific biomass burning regions during biomass burning seasons and is not meant for global operational use, it presents one potential method for improved backscatter lidar aerosol typing. These results suggest that a dynamic lidar ratio, based on layer-relative humidity for spherical smoke, could be used to reduce uncertainties in smoke aerosol extinction retrievals for future backscatter lidars. [ABSTRACT FROM AUTHOR]

Previous studies have estimated the sources of particulate matter in the atmosphere. Among these, studying the sources of secondary aerosols harmful to human health is important. However, there is a lack of research on ammonia (NH3), a precursor to secondary aerosol formation. This study uses positive matrix factorization (PMF) model and conditional bivariate probability function (CBPF) model to estimate the sources of particulate matter and ammonia. The results showed that about 40% of the PM2.5 mass at both sites was attributable to secondary aerosol. To estimate the emission sources of ammonia that contribute to the generation of secondary aerosols, CBPF was utilized to model and compare the emission characteristics of categorized pollution sources and ammonia, and it was found that SMA had similar emission trends to industry, road dust, oil combustion, and biomass combustion, while GRA had similar emission trends to oil combustion and vehicle (diesel). Considering the results from these two regions, ammonia in the metropolitan area is more likely to be emitted from daily activities than from long distances. The study results demonstrate the major role of secondary aerosols on ambient PM2.5 concentrations and can help develop effective management strategies and policies for air pollution mitigation. [ABSTRACT FROM AUTHOR]

Burning agricultural biomass in the field significantly contributes to air pollution, particularly in the Indian context, where numerous cities have consistently ranked among the world's most polluted over the past few decades. The investigation endeavors to examine the potential utilization of cotton stalks as an environmentally friendly and sustainable energy source. During the investigation, biochar was generated through pyrolysis at temperatures of 300, 500, and 700 ˚C for 4 h, while hydrochars were produced via hydrothermal carbonization (HTC) at 180, 210, and 240 ˚C for the same duration. The findings revealed that hydrochar exhibited higher mass and energy yields, with mass yields of 60 ± 7% compared to 41 ± 10% for biochar, and energy yields of 87 ± 1% compared to 63 ± 5% for biochar. Elemental analysis results indicated an increase in carbon percentage with rising process temperatures, with carbon content increasing from 59% at 300 ˚C to 78% at 700 ˚C for pyrolysis, and from 49% at 180 ˚C to 63% at 240 ˚C for HTC. The biochar synthesized at 700 ˚C demonstrated the highest measured high heating value (HHVm) of 29.83 MJ/kg, whereas for HTC, the HHVm of 25.88 MJ/kg was reported for hydrochar synthesized at 240 ˚C. From the computed thermal kinetic parameters, it is evident that the biochars are more thermally stable than hydrochars and raw cotton. According to the Van Krevelen diagram, both biochar and hydrochar products exhibited improved fuel properties. The cumulative evidence suggests a ground-breaking potential for utilizing these char products as sustainable solid fuel alternatives. [ABSTRACT FROM AUTHOR]

To explore the efficient application of biomass pellet fuel in Lijiang tobacco growing areas, using low-cost tobacco sticks with large and stable yield and easy collection in this region as the main material, designing different auxiliary materials for biomass pellet fuel formulas in Liji, the aim is to screen out high-quality biomass fuel formulas. The results showed that the biomass fueled barn had better cost saving, economic benefits, combustion performance, appearance quality of tobacco leaves and baking curve time than the traditional coal-fueled barn. Among them, the “75% tobacco stick and 25% sawdust” and “50% tobacco stick and 50% sawdust” had better comprehensive effects, which was beneficial for the accumulation of flavor substances in tobacco leaves. In addition, the emissions of SO2 and particulate pollutants from biomass fuel were lower than those of traditional coal, while the emissions of NOn were higher than those of traditional coal. This study preliminarily screened out suitable fuel formulas for biomass-fueled barn, and further proved that biomass-fueled barn was superior to traditional coal-fueled barn. This provides positive reference for further improving biomass-fueled barn and optimizing biomass fuel formulas. [ABSTRACT FROM AUTHOR]

Amazon forests play a significant role in the global C cycle by assimilating large amounts of CO2 through photosynthesis and by storing C largely as biomass and soil organic matter. To evaluate the net budget of C in the Amazon, we must also consider the amplitude and timing of losses of C back to the atmosphere through respiration and biomass burning. One useful timescale metric that integrates such information in terrestrial ecosystems is the transit time of C, defined as the time elapsed between C entering and leaving the ecosystem; the transit time is equivalent to the age of C exiting the ecosystem, which occurs mostly through respiration. We estimated the mean transit time of C for a central Amazon forest based on the C age during ecosystem respiration (ER), taking advantage of the large variations in CO2 in the atmosphere below the forest canopy to estimate the radiocarbon signature of mean ER (Δ14CER) using Keeling and Miller–Tans mixing models. We collected air samples to evaluate changes in the isotopic signature of the main ER sources by estimating the δ13CER. We collected air samples in vertical profiles in October 2019 and December 2021 at the Amazon Tall Tower Observatory (ATTO) in the central Amazon. Air samples were collected in a diel cycle from two heights below the canopy (4 and 24 m above ground level (a.g.l.)). Afternoon above-canopy samples (79 and 321 m a.g.l.) were collected as the background. For the campaign of October 2019, the mean Δ14CER ranged from 24 ‰ to 41 ‰ with both Keeling and Miller–Tans methods. In December 2021, mean Δ14CER ranged from 53 ‰ to 102 ‰. The δ13CER showed a smaller variation, being -27.8 ‰ ± 0.3 ‰ in October 2019 and -29.0 ‰ ± 0.5 ‰ in December 2021. The Δ14CER estimates were compared with the record of atmospheric radiocarbon from the bomb period, providing estimates of mean transit time of 6 ± 2 years for 2019 and 18 ± 4 years for 2021. In contrast to steady-state carbon balance models that predict constant mean transit times, these results suggest an important level of variation in mean transit times. We discuss these results in the context of previous model-based estimates of mean transit time for tropical forests and the Amazon region. In addition, we discuss previous studies that indicate that approximately 70 % of assimilated carbon is respired as autotrophic respiration in the central Amazon. Our results suggest that newly fixed carbon in this terra firme tropical forest is respired within 1 to 2 decades, implying that only a fraction of assimilated C can act as a sink for decades or longer. [ABSTRACT FROM AUTHOR]

Reports on the composition of ultrafine particles (<100 nm in diameter) in the Amazon are scarce, due in part to the fact that new-particle formation has rarely been observed near ground level. Ultrafine particles near the surface have nevertheless been observed, leaving open questions regarding the sources and chemistry of their formation and growth, particularly as these vary across seasons. Here, we present measurements of the composition of ultrafine particles collected in the Tapajós National Forest (2.857° S, 54.959° W) during three different seasonal periods: 10–30 September 2016 (SEP), 18 November–23 December 2016 (DEC), and 22 May–21 June 2017 (JUN). Size-selected (5–70 nm) particles were collected daily (for 22 h each day) using an offline sampler. Samples collected during the three time periods were compiled and analyzed using liquid chromatography coupled with Orbitrap high-resolution mass spectrometry. Our findings suggest a sustained influence of isoprene organosulfate chemistry on ultrafine particles from the different periods. We present chemical evidence that indicates that biological-spore fragmentation impacted ultrafine-particle composition during the late wet season (JUN), while chemical markers for biomass burning and secondary chemistry peaked during the dry season (SEP and DEC). Higher oxidation states and degrees of unsaturation were observed for organics in the dry season (SEP and DEC), suggesting greater extents of aerosol aging. Finally, applying a volatility parameterization to the observed compounds suggests that organic sulfur species are likely key drivers of new-particle growth in the region due to their low volatility compared to other species. [ABSTRACT FROM AUTHOR]

We present a global climatology of upper-tropospheric hydrogen cyanide (HCN), carbon monoxide (CO), acetylene (C2H2), ethane (C2H6), peroxyacetyl nitrate (PAN), and formic acid (HCOOH) obtained from observations of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board the Environmental Satellite (Envisat) between 2002 and 2012. At northern midlatitudes and high latitudes, the biomass burning tracer HCN, but also CO, PAN, and HCOOH, exhibit maxima during spring and/or summer and minima during winter. On the contrary, maximum northern extratropical C2H2 and C2H6 amounts were measured during winter and spring, and minimum values were measured during summer and fall. In the tropics and subtropics, enhanced amounts of all pollutants were observed during all seasons, especially widespread and up to southern midlatitudes during austral spring. Other characteristic features are eastward transport of anthropogenic C2H6 and of biogenic HCOOH from Central and North America in boreal summer, accumulation of pollutants in the Asian monsoon anticyclone (AMA), and enhanced C2H2 over southeastern Asia in boreal winter. Clear indication of biogenic release of HCOOH was also found above tropical South America and Africa. A global correlation analysis of the other pollutants with HCN corroborates common release by biomass burning as a source of the widespread southern hemispheric pollution during austral spring. Furthermore, high correlation with HCN points to biomass burning as a major source of tropical and subtropical C2H2 and PAN during most of the year. In the northern extratropics, there are generally low correlations with HCN during spring and early summer, indicating the influence of anthropogenic and biogenic sources. However, in August, there are stronger correlations above Siberia and boreal North America, which points to common release by boreal fires. This is confirmed by the respective enhancement ratios (ERs). The ERs measured above northeastern Africa fit well to the emission ratios of the dominant local fire type (savanna burning) for C2H2 , while those for CO, C2H6 , and HCOOH rather indicate tropical forest fires or additional anthropogenic or biogenic sources. The southern hemispheric ΔC2H6/ΔHCN ERs obtained during August to October are in good agreement with the emission ratio for savanna fires. The same applies for ΔC2H2/ΔHCN in August and for ΔHCN/ΔCO and ΔHCOOH/ΔHCN in October. [ABSTRACT FROM AUTHOR]

Global chemistry–climate models (CCMs) play an important role in assessing the climate and air pollution implications of aerosols and chemically reactive gases. Evaluating these models under past conditions and constraining historical sources and sinks necessitate reliable records of atmospheric mixing ratios spanning preindustrial times. Such precious records were recently obtained for carbon monoxide (CO), documenting for the first time the evolution of this reactive compound over the industrial era. In this study, we compare the simulated atmospheric surface CO mixing ratios ([CO]) from two different sets of chemistry–climate models and emissions within the frameworks of CMIP5 and of CMIP6 (Coupled Model Intercomparison Project Phases 5 and 6) to recent bipolar ice archive reconstructions for the period spanning 1850 to the present. We analyse how historical (1850–2014) [CO] outputs from 16 ACCMIP (Atmospheric Chemistry and Climate Model Intercomparison Project) models and 7 AerChemMIP (Aerosol Chemistry Model Intercomparison Project) models over Greenland and Antarctica are able to capture both absolute values and trends recorded in multi-site ice archives. While most models underestimate [CO] at northern high latitudes, a reduction in this bias is observed between the ACCMIP and the AerChemMIP exercise. Over the 1980–2010 CE period (common era; all subsequent years in the paper are reported in CE), trends in ice archive and firn air observations and AerChemMIP outputs align remarkably well at northern and southern high latitudes, indicating improved quantification of anthropogenic CO emissions and the main CO sink (OH oxidation) compared to ACCMIP. From 1850 to 1980, AerChemMIP models and observations consistently show increasing [CO] in both the Northern Hemisphere (NH) and Southern Hemisphere (SH), suggesting a robust understanding of the CO budget evolution. However, a divergence in the [CO] growth rate emerges in the NH between models and observations over the 1920–1980 period, attributed to uncertainties in CO emission factors (EFs), particularly EFs for the RCO (residential, commercial, and other) and transportation sectors, although we cannot totally rule out the possibility that the CO record based on the Greenland ice archives may be biased high by CO chemical production processes occurring in the ice prior to the measurements (i.e. in situ CO production). In the Southern Hemisphere, AerChemMIP models simulate an increase in atmospheric [CO] from 1850 to 1980 that closely reproduces the observations (22 ± 10 ppb and 13 ± 7 ppb, respectively). Such agreement supports CMIP6 biomass burning CO emission inventories, which do not reveal a peak in CO emissions in the late 19th century. Furthermore, both SH models and observations reveal an accelerated growth rate in [CO] during 1945–1980 relative to 1850–1945, likely linked to increased anthropogenic transportation emissions. [ABSTRACT FROM AUTHOR]

The pristine Himalayas are sensitive to pollutants from different source regions, including its foothills that have adverse effects on air quality and climate. Despite this, there are no observations of aromatic hydrocarbons in the central Himalayas. Thus, online observations of aromatics (C6-C8, defined here as BTEX) were conducted for the first time at the mountain site (Nainital, 1958 m) in the central Himalayas during January 2017-December 2022 period. Additionally, observations were made at a foothill site in the Indo-Gangetic Plain (Haldwani, 554 m) to assess the source features. The diurnal variations at the mountain site were characterised by daytime higher BTEX (~ 6 ppbv), in-contrast the IGP foothill site exhibited nighttime elevated levels (~ 19 ppbv). Higher values were exhibited in spring and autumn at the mountain site, while values were higher in winter at the IGP foothill site. These variations were primarily influenced by the transport of diverse air masses to the mountain site, while the role of local emissions was found at the IGP foothill site. The boundary layer processes play a role at both sites, but differently. Xylene was the most abundant (60–65%) at both sites, suggesting the influence of emissions from the IGP region. This contrasts with the composition used in emission inventories for this region. The toluene to benzene ratio at mountain (4.5) and IGP foothill (5.3) sites and ternary plots indicated the dominance of industrial/vehicular sources, with some contributions from biomass burning. The estimated OH reactivity, ozone formation potential and secondary organic aerosol formation potential were found to be 4–6 times greater at the IGP foothill site than those at the mountain site. Xylene played a significant role in these processes at both sites. Furthermore, benzene played a dominant role in the hazard ratio and the lifetime cancer risk (LCR) at both sites. The LCR at both sites crossed the probable risk limit. [ABSTRACT FROM AUTHOR]

The 'Third Pole', home to numerous glaciers, serves as vital water reserves for a significant portion of the Asian population and has garnered global attention within the context of climate change due to their highly vulnerable nature. While a general decline in global glacial extent has been observed in recent decades, the pronounced regional imbalances across the Third Pole present a perplexing anomaly. To assess the impact of glacier mass changes in the Gangotri basin, we conducted a comprehensive analysis using remote sensing data to estimate spatially resolved mass changes from 2000 to 2023. Our glacier mass balance estimates were based on empirical models and the digital elevation model difference method. We also examine the relationship between glacier retreat and the variability of albedo and aerosols in the glacier ice. Analysis of the geodetic mass balance indicates that the glacier surface has decreased by 8.12 m, a loss of 0.49 m of water equivalent per annum (m.w.e. a−1) between 2000 and 2014. The estimates and results revealed from the accumulation area ratio (AAR) mass balance, and ice velocity measurements indicate a negative mass balance of − 0.28 m.w.e. a−1 for Gangotri between 2000 and 2023. Our analyses highlight both climatological and anthropogenic factors responsible for the accelerated rate of mass loss. Regional mass loss during the ablation season is primarily influenced by land surface temperature, yet the role of other factors, such as changes in surface albedo and light-absorbing impurities (LAIs), remains uncertain. Our analysis investigated temporal variations in mass balance values, while also considering changes in surface albedo and LAIs like black carbon (BC), organic carbon (OC) and dust concentrations. This analysis reveals that LAIs have an inverse relationship with albedo, where an increase in LAI concentration results in reduced albedo over the glacier. Consequently, as albedo decreases, the surface mass balance of the glacier also declines, which is further validated by the findings of this study. While this study highlights the detrimental effects of light-absorbing pollutants on the health of glacier, further investigation is necessary to comprehensively establish their role in reducing the albedo of the glacier surface and influencing associated mass loss. [ABSTRACT FROM AUTHOR]

Road traffic is one of the main sources of particulate matter in the urban environment, emitting particulate organic and elemental carbon compounds and metal-rich particles through combustion and brakes and tires wear. In Western Africa, the carbon and metal composition of airborne particles is also influenced by additional sources linked to biomass combustion and recent industrialization. Here, we investigated the impact of combustion-related and non-combustion-related emissions on the distribution of carbonaceous fractions and iron-rich particles in two urban environments in France and Senegal. The supermicron fraction ( D a > 1 µm) showed a significantly higher isothermal remanent magnetization (SIRM) than finer fractions, accounting for 79% in France and 81% in Senegal of the total SIRM. In the submicron fraction ( D a < 1 µm), we noted significantly higher concentrations of total carbon (TC) and elemental carbon (EC) than for other fractions, both accounting for 71% in France and 68% and 75% in Senegal of the total and elemental particulate carbon concentration, respectively. Electron microscope observations revealed the presence of iron-rich particles for D a < 0.2 µm, however, associated with a weak SIRM. Such iron particles may be produced by combustion or abrasion while we suspect that emissions by the abrasion process produce larger particles. [ABSTRACT FROM AUTHOR]

For a given solar elevation, the levels of solar ultraviolet radiation at the Earth's surface are determined by the amounts of ozone, aerosols, and clouds, as well as by the reflectivity of the surface. Here, we study the evolution of these factors for three selected decades in the period 1950–2100 using results from simulations with Earth-System models (ESMs) participating in the 6th phase of the Coupled Model Intercomparison Project (CMIP6). The simulations for the future are based on three Shared Socioeconomic Pathways: SSP1–2.6, SSP3–7.0, and SSP5–8.5. The models were grouped according to whether they use prescribed ozone fields or interactive chemistry schemes for ozone, revealing significant differences in the absolute levels and variability of total ozone column between the two groups of models. From mid-twenty-first century onward, the ozone recovery is evident in both groups under SSP3–7.0 and SSP5–8.5, but not under SSP1–2.6. The changes in the aerosol optical depth show distinct geographical patterns that are related to their sources, either natural (i.e., dust, biomass burning) or anthropogenic (industrial activities). The aerosols are generally more abundant in 1990–2000 compared to 1950–1960, particularly over regions with industrial activity, with a reversal of this pattern in 2090–2100. Most of these patterns are present in all three pathways, but with different signs compared to 1990–2000 in some regions (i.e., Europe, North America). Over areas with strong natural sources, the aerosol optical depth (AOD) in 2090–2100 increases further under all pathways. The changes in surface reflectivity are important mainly at the end of the twenty-first century and occur predominantly at the high and polar latitudes of both hemispheres, with reductions relative to 1950–1960 of up to 45% due to sea ice retreat. The alterations in the attenuation of shortwave solar radiation by changing cloudiness (expressed in the form of the cloud modification factor, CMF) are more evident at high latitudes, with decreases in 2090–2100 over the Arctic ranging from –5% (SSP1–2.6) to –13% (SSP5–8.5) and smaller decreases of up to –5% in the vicinity of the Antarctic coast. The simulations of ozone, aerosols, surface reflectivity, and clouds for the recent past (2003–2012) were compared to the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis data, showing for total ozone better agreement to models with interactive ozone chemistry. The model-derived AOD shows significant differences from CAMS in various regions worldwide, with up to 0.2 higher values across the northern hemisphere. Finally, the comparisons for surface reflectivity and cloud effects οn this decadal scale reveal a general agreement between models and observations over most of the globe. Thus, we conclude that the projected changes have a good basis in the recent past, suggesting they are realistic estimates of how factors influencing solar ultraviolet radiation may differ under climate change. [ABSTRACT FROM AUTHOR]

Nevertheless, there is a lot to know about air pollutants in Mexico's largest cities, like San Luis Potosi City, which is one of the 12 most crowded cities and is expected to grow in the next years; however, there is little information about air pollutant levels mainly particulate matter in their regulated size fractions (PM10 or PM2.5), and its main component of the Organic fraction: Black Carbon (BC), which is especially important because of its chemical properties and their effects on human health, air pollution, and climate change. This work presents a one-year BC monitoring in the northern part of the city (2018–2019) and another one-year BC monitoring in the southern area (2019–2020) during the health contingency situation due to the SARX-CoV-2 virus to obtain direct equivalent black carbon (eBC) concentrations and their main fractions related to fossil fuel and biomass burning using aethalometer AE-33, as well as other air pollutants concentrations measured at the same periods by the governmental local monitoring network (SEGAM). At the North, BC mass annual average concentration was (1.11 µg m−3), divided into seasonal stations, the cold season was the highest with (1.44 µg m−3), followed by the dry season (1.23 µg m−3), rainy season (0.94 µg m−3) and finally warm dry season (0.83 µg m−3). In the south, BC annual average concentration was (1.96 µg m−3); divided into seasons, the highest was the dry season with (2.73 µg m−3), followed by the cold season (2.37 µg m−3), dry warm season (1.61 µg m−3) and the rainy season (1.28 µg m−3). One of the main findings was the dominance of annual mean concentrations of BC originating from fossil fuels (BCff) on the north site in the city was 0.97 and on the south site (BCff) was 0.91 due to some forest fires during the monitoring period. This study presented information from two zones of a growing city in Mexico to generate new air pollutant indicators to have a better understanding of pollutant interactions in the city, to decrease the emission precursor sources, and reduce the health risks in the population. [ABSTRACT FROM AUTHOR]

Bioenergy production generates huge amounts of ash from biomass combustion. One of the attempts to utilize them is to use them in agriculture as fertilizers. The response to this challenge is a three-year field experiment (2018–2021) where the effect of fertilization with ash from forest biomass (approx. 70%) and agricultural biomass (approx. 30%), and soil type (Gleyic Chernozem and Haplic Luvisol), on the fatty acid (FA) profile of winter rape seeds (Brassica napus L. ssp. oleifera Metzg) was studied. Environmental factors modified the accumulation of fatty acids in winter oilseed rape seeds to the greatest extent and included all labelled unsaturated and saturated fatty acids from C12:0 to C24:0, with exceptions. In warm and dry years, C18:1n9c, C18:2n9c and C18:3n6 accumulated more, while cooler and humid years promoted an increase in the content of, among others, C20:2, C24:1, C18:3n3, C20:4 and C22:2. Cultivation of plants in Gleyic Chernozem soil promoted the accumulation of unsaturated fatty acids C18:3n3 and C18:3n6 in winter rape seeds—important from the nutritional point of view. The soil type Haplic Luvisol influenced a larger number of saturated acids and promoted an increase in their content to a greater extent than the Gleyic Chernozem soil type. Among unsaturated fatty acids, fertilization had an effect only on C18:3n3 with mineral fertilization (variant D1) and a very high K dose (variant D5) and C24:1 with the highest K dose (variant D6). No negative changes in the proportions of FAs, including omega-3 and omega-6, were demonstrated under the influence of BA application. [ABSTRACT FROM AUTHOR]

Combustion is the most advanced and proven method on the market for using agricultural by-product residues and waste from the agri-food industry. Currently, a wide range of combustion technologies is used to produce heat and electricity in low-power heating devices (>50 kW) using various types of biofuels from biomass (woody biomass, herbaceous biomass, waste and residues from the agri-food industry). Combustion of biomass fuels, especially those of wood origin, causes lower carbon dioxide (CO2) and sulfur oxides (SOx) emissions into the atmosphere compared to coal combustion. The growing interest in solid biofuels has contributed to intensive activities on improving the combustion process and energy devices enabling effective and economic conversion of chemical energy contained in biomass into other usable forms such as heat, electricity. Having good quality fuel, it is necessary to ensure an appropriate, clean combustion technique, which allows to achieve the highest thermal efficiency of the heating device and at the same time the lowest emission of pollutants. The article presents issues related to the theory, characteristics of the combustion process and problems related to the formation of harmful chemical compounds nitrogen oxides (NOx), SOx, carbon monoxide (CO), particulate matter (PM) emitted to the atmosphere during the combustion process in low-power heating devices. The analysis indicates the possibility of minimizing undesirable phenomena during the combustion of these biofuels related to ash sintering, the formation of deposits, corrosion and improving the amount of condensable solid particles formed and therefore reducing the emission of gaseous products to the environment. [ABSTRACT FROM AUTHOR]

ABSTRACT: Introduction: Chronic respiratory symptoms (dyspnoea, coughing, sputum production) associated with abnormalities of the airways (bronchitis, bronchiolitis) and/or alveoli (emphysema) that result in persistent, frequently progressive airflow obstruction are the hallmarks of COPD, a diverse lung illness. The current investigation aimed to establish a clinical profile of patients with recently diagnosed COPD who present to a healthcare facility in Vadodara. Materials and Methods: The Department of Respiratory Medicine conducted an observational cross-section study on individuals with recently discovered COPD. The study comprised records of 50 participants, from September 2022 to January 2024. Along with the spirometry results, pertinent clinical data were gathered. Results: The study's patient population presented with an average age of 61.52 years. The fact that every patient in the research was over 40 years old suggests that COPD is becoming more common in people over 40. There was a male majority among the 50 patients, with 40 (80%) male and 10 (20%) female. Most common age group was smokers accounted for 80% of the total cases, suggesting that their incidence of COPD is greater. Average FEV1 at presentation was 41 L/min for 50 patients. Among 50 patients, 6% falls under mild, 28% under moderate, 42% under severe, and 24% under very severe according to GOLD grading and severity of airflow obstruction. Conclusion: Despite the fact that tobacco smoke is thought to be the main cause of COPD. Indoor and outdoor air pollution are major issues in many nations, including India. One of the main risk factors for COPD is smoke from activities such as burning wood or biomass fuels in addition to work exposure. The ageing of the global population and ongoing exposure to COPD risk factors are expected to contribute to a rise in the prevalence and burden of COPD in the ensuing decades. The fact that most newly diagnosed patients in this research were older and more symptomatic and that most identified individuals had moderate to severe COPD, indicates the importance of spirometry programs in primary care for the early detection of COPD. Our findings suggest that a new campaign requiring patients to undergo spirometry and routine follow-up may be able to identify a sizable proportion of patients with undiagnosed COPD and perhaps improve their quality of life. [ABSTRACT FROM AUTHOR]