Search Results (26)

In January 2025, multiple wildfires erupted across the Los Angeles region, fueled by prolonged dry conditions and intense Santa Ana winds. Southern California has faced increasingly frequent and severe wildfires in recent years, driven by prolonged drought, high temperatures, and the expanding wildland–urban interface. These fires have caused major loss of life, extensive property damage, mass evacuations, and severe air-quality decline in this densely populated, high-risk region. This study integrates passive and active satellite observations to characterize the spatiotemporal and vertical distribution of wildfire emissions and assesses their impact on air quality. TROPOMI (Sentinel-5P) and the recently launched TEMPO geostationary instrument provide hourly high temporal-resolution mapping of trace gases, including nitrogen dioxide (NO₂), carbon monoxide (CO), formaldehyde (HCHO), and aerosols. Vertical column densities of NO₂ and HCHO reached 40 and 25 Pmolec/cm², respectively, representing more than a 250% increase compared to background climatological levels in fire-affected zones. TEMPO’s unique high-frequency observations captured strong diurnal variability and secondary photochemical production, offering unprecedented insights into plume evolution on sub-daily scales. ATLID (EarthCARE) lidar profiling identified smoke layers concentrated between 1 and 3 km altitude, with optical properties characteristic of fresh biomass burning and depolarization ratios indicating mixed particle morphology. Vertical profiling capability was critical for distinguishing transported smoke from boundary-layer pollution and assessing radiative impacts. These findings highlight the value of combined passive–active satellite measurements in capturing wildfire plumes and the need for integrated monitoring as wildfire risk grows under climate change. Full article

Energy production from burning biomass in bioheat plants involves the production of biomass fly ash (BFA). Due to its rich chemical composition, in the era of a circular economy, it should be reused, for example, for environmental purposes as a secondary raw material containing valuable macro- and micronutrients. Due to its alkaline nature, it can also be an alternative to commercial agricultural lime (CAL) for neutralizing the acidic reaction of agricultural soils. The basis for the presented research was a pot experiment with corn (Zea mays L.) as a test plant and increasing doses of BFA (16.20, 32.40, and 48.60 g pot⁻¹), which is equal to 6.99, 13.98, and 20.97 g of CAL pot⁻¹. The above doses were determined based on the neutralization value (NV) of BFA and CAL, calculated to neutralize the hydrolytic acidity of the soil (Hh) to 0.5, 1.0, and 1.5 Hh. The study analyzed the effect of BFA on the leaf greenness index (SPAD), plant height, yield, and chemical composition of corn, as well as macronutrient content. The observations indicate that BFA application positively modified the yield of both fresh mass and dry mass of corn and height of plants, and reduced the dry matter content compared to the effect obtained after CAL use. BFA caused a decrease in the total N and Ca content and a significant increase in P, K, and Na compared to the CAL-fertilized treatments. BFA significantly contributed to a narrowing of the Ca:P, Ca:Mg ratios, and a widening of the K:(Ca + Mg), and K:Ca ratios compared to the ionic balance observed in the CAL-fertilized corn. The obtained results allow us to conclude that fly ash from biomass combustion can be a valuable alternative to conventional soil deacidification agents used till now in agriculture. Full article

This study describes a quite special and interesting atmospheric event characterized by the simultaneous presence of fresh and aged smoke layers. These peculiar conditions occurred on 16 July 2024 at the CNR-IMAA atmospheric observatory (CIAO) in Potenza (Italy), and represent an ideal case for the evaluation of the impact of aging and transport mechanisms on both the optical and microphysical properties of biomass burning aerosol. The fresh smoke was originated by a local wildfire about 2 km from the measurement site and observed about one hour after its ignition. The other smoke layer was due to a wide wildfire occurring in Canada that, according to backward trajectory analysis, traveled for about 5–6 days before reaching the observatory. Synergetic use of lidar, ceilometer, radar, and microwave radiometer measurements revealed that particles from the local wildfire, located at about 3 km a.s.l., acted as condensation nuclei for cloud formation as a result of high humidity concentrations at this altitude range. Optical characterization of the fresh smoke layer based on Raman lidar measurements provided lidar ratio (LR) values of 46 ± 4 sr and 34 ± 3 sr, at 355 and 532 nm, respectively. The particle linear depolarization ratio (PLDR) at 532 nm was 0.067 ± 0.002, while backscatter-related Ångström exponent (AEβ) values were 1.21 ± 0.03, 1.23 ± 0.03, and 1.22 ± 0.04 in the spectral ranges of 355–532 nm, 355–1064 nm and 532–1064 nm, respectively. Microphysical inversion caused by these intensive optical parameters indicates a low contribution of black carbon (BC) and, despite their small size, particles remained outside the ultrafine range. Moreover, a combined use of CIAO remote sensing and in situ instrumentation shows that the particle properties are affected by humidity variations, thus suggesting a marked particle hygroscopic behavior. In contrast, the smoke plume from the Canadian wildfire traveled at altitudes between 6 and 8 km a.s.l., remaining unaffected by local humidity. Absorption in this case was higher, and, as observed in other aged wildfires, the LR at 532 nm was larger than that at 355 nm. Specifically, the LR at 355 nm was 55 ± 2 sr, while at 532 nm it was 82 ± 3 sr. The AEβ values were 1.77 ± 0.13 and 1.41 ± 0.07 at 355–532 nm and 532–1064 nm, respectively and the PLDR at 532 nm was 0.040 ± 0.003. Microphysical analysis suggests the presence of larger, yet much more absorbent particles. This analysis indicates that both optical and microphysical properties of smoke can vary significantly depending on its origin, persistence, and transport in the atmosphere. These factors that must be carefully incorporated into future climate models, especially considering the frequent occurrences of fire events worldwide. Full article

The production of biomass fly ash has been increasing every year in Europe, reaching 5.5 million tons in 2020. Fly ash produced by burning biomass is not yet accepted in the standards as a substitute material for cement in mortar and concrete. In a first approach, the substitution limit of biomass ash is determined by comparing the mechanical strengths (among others, compressive strength), fresh state properties and hardened properties of mortars produced with fly ash with those of mortars produced with coal fly ash (EN 450-1 and ASTM C618). Masonry and rendering mortars have been designed with different substitution rates of fly ashes from wood combustion in thermal power plants. Although there is an overall decrease in performance, mortars made with biomass ash retain properties that make them suitable for use in masonry (loss of 13% compressive strength for masonry mortars with 10% substitution rate after 90 days) or rendering (loss of 20% compressive strength for rendering mortars with 10% substitution rate after 90 days). Water absorption and porosity (24.1 and 23.7% for masonry and rendering mortars, respectively) are, however, not significantly modified, which potentially contributes to good durability properties. Full article

Basil (Ocimum species) represents an extraordinary group of aromatic plants that have gained considerable economic importance, primarily due to their essential oils, which have applications in medicine, culinary, and perfumery. The Ocimum genus encompasses more than 60 species of herbs and shrubs originally native to tropical regions. This genus stands out for its remarkable diversity, displaying a wide spectrum of variations in phenotype, chemical composition, and genetic makeup. In addition to genetic factors, the growth, development, and essential oil production of basil are also influenced by environmental conditions, ontogeny, and various other factors. Consequently, the primary objective of this study was to explore the diversity in both the morphological characteristics and essential oil composition among basil genotypes preserved within the gene bank of the Hungarian University of Agriculture and Life Sciences’ Department of Medicinal and Aromatic Plants. The investigation involved the assessment of fifteen basil genotypes, representing four distinct species: Ocimum basilicum (including ‘Anise’, ‘Clove’, ‘Fino Verde’, ‘Licorice’, ‘Mammoth’, ‘Mrs. Burns’, ‘Thai tömzsi’, ‘Thai hosszú’, and ‘Vietnamese basil’), Ocimum sanctum (green holy basils), Ocimum citrodora (Lemon basil), and Ocimum gratissimum (African and Vana holy basil). The genotypes exhibited significant variations in their morphological growth, essential oil content (EOC), and composition. African basil produced more biomass (408.3 g/plant) and showed robust growth. The sweet basil cultivars clove, licorice, Thai tömzsi, and Thai hosszú also exhibited similar robust growth trends. Vietnamese basil, on the other hand, displayed the lowest fresh biomass of 82.0 g per plant. Both holy basils showed EOC levels below 0.5%, while Mrihani basil stood out with the highest EOC of 1.7%. The predominant constituents of the essential oil among these genotypes comprised estragole, thymol, methyl cinnamate, linalool, and eugenol. In conclusion, this study showed that the genotypes of basil stored in the department’s gene bank exhibit a wide range of variability, both within and between species. Full article

Insufficient data on the chemical composition of PM_2.5 and its emission sources in the southwestern (SW) Mediterranean area has been identified. Ambient PM_2.5 samples were collected in an urban area of Tetouan city, northern Morocco. Chemical mass closure calculations and positive matrix factorization were performed for the comprehensive dataset of PM_2.5 chemical analyses. Mass closure improved when multipliers (1.2 and 0.23, respectively) were used for the conversion of organic carbon (OC) and calcium ion (Ca²⁺) into particulate organic matter (POM) and mineral dust masses, respectively. The mass closure model performed well in this SW Mediterranean region, with a significant correlation (r² = 0.97) obtained between gravimetrically measured and chemically determined PM_2.5 mass. The one-year average concentration of PM_2.5 was 17.96 μg/m³, and the major chemical components were POM (34%), secondary inorganic aerosol (SIA) (28%), and black carbon (18%), while unidentified mass was 4%. The mass concentration and most of the chemical components of PM_2.5 showed clear seasonal variations, with a summer-high and winter-low pattern for SIA, dust, and BC. In the winter months, POM was the dominant component. Source apportionment analysis revealed that PM_2.5 emission sources, regarding their typical tracers, were ammonium sulfate (SO₄²⁻, NH₄⁺, K⁺, NO₃⁻), road traffic and biomass burning emissions (OC, BC), fresh sea salt (Cl⁻, K⁺, NO₃⁻), aged sea salt (Mg²⁺, Na⁺, Ca²⁺), and oxalate-rich (oxalate, NO₃⁻) factors. Further, it is hoped that these findings help to improve the scientific understanding of SW Mediterranean aerosols. Full article

In this paper, characterization of the optical and microphysical properties of extremely fresh biomass burning aerosol is presented. This work aims to characterize, for the first time to our knowledge, freshly formed smoke particles observed only a few minutes after they were emitted from a nearby forest fire. The smoke particles were detected by combining passive (sun-photometer) and active (Raman lidar) techniques. On 14 August 2021, an EARLINET (European Aerosol Research Lidar Network) multi-wavelength Raman lidar and a co-located AERONET sun-photometer in Potenza, South Italy, observed an extremely fresh smoke plume. The lidar measurements, carried out from 22:27 to 02:16 UTC, revealed a thick biomass burning layer below 2.7 km. The particle depolarization ratio at 532 nm was 0.025, and lidar ratios at 355 and 532 nm were, respectively, 40 and 38 sr. The mean value of the Ångström exponent was 1.5. The derived size distribution was bimodal with a peak at 0.13 µm, an effective radius mean value of 0.15 µm, and a single scattering albedo of 0.96 at all wavelengths. The real part of the refractive index was 1.58 and the imaginary was 0.006. The AERONET measurements at 5:34 UTC confirmed the lidar measurements. Full article

The chimney effect taking place in biomass cooking stoves results from a conversion process between thermal and mechanical energy. The efficiency of this conversion is assessed with the stove loss coefficient. The derivation of this quantity in cooking stove modelling is still uncertain. Following fluid mechanics, this loss coefficient refers to an overall pressure drop through stove geometry by performing an energy balance according to the first law of thermodynamics. From this approach, heat-transfer processes are quite ignored yet they are important sources of irreversibilities. The present work takes a fresh look at stove loss coefficient assessment relying on the second law of thermodynamics. The purpose in this paper is to identify the influence of operating firepower level on flow dynamics in biomass natural convection-driven cooking stoves. To achieve that, a simplified analytical model of the entropy-generation rate in the flow field is developed. To validate the model, experiments are conducted first on a woodburning stove without cooking pot to better isolate physical processes governing the intrinsic behaviour of the stove. Then, for the practical case of a stove operating with a cooking pot in place, data from published literature have served for validation. In particular, mass-flow rate and flue gas temperature at different firepower levels have been monitored. It turns out that losses due to viscous dissipations are negligible compared to the global process dissipation. Exergy analysis reveals that the loss coefficient should rather be regarded from now as the availability to generate flow work primarily associated with the heat-transfer Carnot factor. In addition, the energy flux applied as flow work has to be considered as pure exergy that is lost through consecutive energy-transfer components comprising the convective heat transfer to the cooking pot. Finally, this paper reports a satisfactory agreement that emerged between the exergy Carnot factor and the experimental loss coefficient at different fuel-burning rates. Full article

The weather in the high latitudes of China is cold in winter. The pollution caused by the burning of biomass fuels used in rural individual heating is a great threat to human health. This study finds that the amounts of CO₂, CO, PM_2.5, and PM₁₀ in the bedroom exceed the standard and the temperature does not meet the standard based on indoor air measurements in rural residential buildings in Liaoning Province in winter. In this study, a mechanical ventilation method which uses flue gas to preheat fresh air is proposed, for the purpose of simultaneously improving the indoor air quality and the thermal environment of rural houses. The flue gas–fresh air heat exchange (FGFAHE) experiment shows that biomass combustion flue gas can increase the outdoor air temperature by 23.7 °C on average. The ventilation experiment shows that the method of mechanical ventilation combined with external window penetration can increase the dilution rate of indoor CO by more than 1 times. The simulation results of six different ventilation schemes show that the ventilation mode of the diagonal opposite side upper air supply and lower exhaust air (DOUSLE) has the best effect on indoor CO prevention and control, and the mode of median air supply is the most beneficial to the indoor thermal environment. Full article

Cairpol and Aeroqual air quality sensors measuring CO, CO₂, NO₂, and other species were tested on fresh biomass burning plumes in field and laboratory environments. We evaluated the sensors by comparing 1 min sensor measurements to collocated reference instrument measurements. The sensors were evaluated based on the coefficient of determination (r²) between the sensor and reference measurements, as well as by the accuracy, collocated precision, root mean square error (RMSE), and other metrics. In general, CO and CO₂ sensors performed well (in terms of accuracy and r² values) compared to NO₂ sensors. Cairpol CO and NO₂ sensors had better sensor-versus-sensor agreement (i.e., collocated precision) than Aeroqual CO and NO₂ sensors of the same species. Tests of other sensors (e.g., NH₃, H₂S, VOC, and NMHC) provided more inconsistent results and need further study. Aeroqual NO₂ sensors had an apparent O₃ interference that was not observed in the Cairpol NO₂ sensors. Although the sensor accuracy lags that of reference-level monitors, with location-specific calibrations they have the potential to provide useful data about community air quality and personal exposure to smoke impacts. Full article

Carbonaceous aerosols emitted from biomass burning influence radiative forcing and climate change. Of particular interest are emissions from high-latitude peat burning because amplified climate change makes the large carbon mass stored in these peatlands more susceptible to wildfires and their emission can affect cryosphere albedo and air quality after undergoing transport. We combusted Siberian peat in a laboratory biomass-burning facility and characterized the optical properties of freshly emitted combustion aerosols and those photochemically aged in an oxidation flow reactor (OFR) with a three-wavelength photoacoustic instrument. Total particle count increased with aging by a factor of 6 to 11 while the total particle volume either changed little (<8%) for 19 and 44 days of equivalent aging and increased by 88% for 61 days of equivalent aging. The aerosol single-scattering albedo (SSA) of both fresh and aged aerosol increased with the increasing wavelength. The largest changes in SSA due to OFR aging were observed at the shortest of the three wavelengths (i.e., at 405 nm) where SSA increased by less than ~2.4% for 19 and 44 days of aging. These changes were due to a decrease in the absorption coefficients by ~45%, with the effect on SSA somewhat reduced by a concurrent decrease in the scattering coefficients by 20 to 25%. For 61 days of aging, we observed very little change in SSA, namely an increase of 0.31% that was caused a ~56% increase in the absorption coefficients that was more than balanced by a somewhat larger (~71%) increase in the scattering coefficients. These large increases in the absorption and scattering coefficients for aging at 7 V are at least qualitatively consistent with the large increase in the particle volume (~88%). Overall, aging shifted the absorption toward longer wavelengths and decreased the absorption Ångström exponents, which ranged from ~5 to 9. Complex refractive index retrieval yielded real and imaginary parts that increased and decreased, respectively, with the increasing wavelength. The 405 nm real parts first increased and then decreased and imaginary parts decreased during aging, with little change at other wavelengths. Full article

Vertical profiling of aerosol particles was performed during the PANhellenic infrastructure for Atmospheric Composition and climatE chAnge (PANACEA) winter campaign (10 January 2020–7 February 2020) over the city of Ioannina, Greece (39.65° N, 20.85° E, 500 m a.s.l.). The middle-sized city of Ioannina suffers from wintertime air pollution episodes due to biomass burning (BB) domestic heating activities. The lidar technique was applied during the PANACEA winter campaign on Ioannina city, to fill the gap of knowledge of the spatio-temporal evolution of the vertical mixing of the particles occurring during these winter-time air pollution episodes. During this campaign the mobile single-wavelength (532 nm) depolarization Aerosol lIdAr System (AIAS) was used to measure the spatio-temporal evolution of the aerosols’ vertical profiles within the Planetary Boundary Layer (PBL) and the lower free troposphere (LFT; up to 4 km height a.s.l.). AIAS performed almost continuous lidar measurements from morning to late evening hours (typically from 07:00 to 19:00 UTC), under cloud-free conditions, to provide the vertical profiles of the aerosol backscatter coefficient (b_aer) and the particle linear depolarization ratio (PLDR), both at 532 nm. In this study we emphasized on the vertical profiling of very fresh (~hours) biomass burning (BB) particles originating from local domestic heating activities in the area. In total, 33 out of 34 aerosol layers in the lower free troposphere were characterized as fresh biomass burning ones of local origin, showing a mean particle linear depolarization value of 0.04 ± 0.02 with a range of 0.01 to 0.09 (532 nm) in a height region 1.21–2.23 km a.s.l. To corroborate our findings, we used in situ data, particulate matter (PM) concentrations (PM_2.5) from a particulate sensor located close to our station, and the total black carbon (BC) concentrations along with the respective contribution of the fossil fuel (BC_ff) and biomass/wood burning (BC_wb) from the Aethalometer. The PM_2.5 mass concentrations ranged from 5.6 to 175.7 μg/m³, while the wood burning emissions from residential heating were increasing during the evening hours, with decreasing temperatures. The BC_wb concentrations ranged from 0.5 to 17.5 μg/m³, with an extremely high mean contribution of BC_wb equal to 85.4%, which in some cases during night-time reached up to 100% during the studied period. Full article

Due to its unique natural conditions and agricultural tradition, northeast China (NEC) has formed a distinctive open biomass burning habit with local-specific biomass burning aerosol features. In this research, with the help of a newly optimized biomass burning aerosol identification method, which combines satellite aerosol and fire observational products with the HYSPLIT model forward trajectories, a systematic and quantitative analysis of aerosol emitted from open biomass burning in the NEC region are conducted to determine in detail its local-specific features, such as influence region, aging characteristics, and seasonal variation. During the 72-h aging process after biomass burning emission, aerosol particle size growth found with the Angstrom exponent declines from 1.6 to 1.54. Additionally, the volume fraction of black carbon decreases from 4.5% to 3.1%, leading to the Single Scattering Albedo (SSA) increasing from the fresh state of 0.84 to the aged state of 0.89. The cooling effect at TOA, due to the existence of aerosol, is enhanced by more than 70%, indicating its severe and dynamic influence on climate change. The average AOD in spring is 0.63, which is higher than autumn’s value of 0.52, indicating that biomass burning is more intensive in spring. Compared to autumn, aerosols emitted from spring biomass burning in the NEC region have lower sphere fraction, smaller particle size, higher volume fraction of black carbon, higher absorbability, and weaker cooling effect at TOA, which can be partly explained by the drier ambient environment and lower water content of the burned crop straw in spring. Full article

Soil water repellency (hydrophobicity) prevents water from wetting or infiltrating soils, triggering changes in the ecosystems. This physical property is directly correlated to the erodibility grade of a soil. Wildfire events may develop, enhance, or destroy soil hydrophobicity, modifying the erodibility grade of a soil and increasing the loss of its most reactive layer (organic matter). To assess the main organic family of compounds (biomarkers) surrogates to fire-induced water repellency, a study was carried out on a fire-affected soil under eucalyptus canopy at two depths (0–2 and 2–5 cm) from Portugal. The potential soil water repellency was measured using the water drop penetration time (WDPT) test. The molecular characterization of hydrophobic biomarkers was carried out using analytical pyrolysis (Py-GC/MS) in combination with multivariate statistical analysis (PCA, MLR). The upper burned soil layer (0–2 cm) displayed a significant contribution of fresh biomass (lignin and polysaccharides), while the deepest (2–5 cm) one showed more humified organic matter (lipids). The soil hydrophobicity was directly correlated to non-polar organic compounds, such as lipids and polycyclic aromatic hydrocarbons (PAHs), and inversely to unspecific aromatic compounds. The combination of mass spectrometry techniques and chemometric analysis allowed obtaining a preliminary forecast model of hydrophobicity degree in fire-affected soil samples under eucalyptus canopy. This analytical approach opens the door to developing more sensitive mathematical models using molecular organic compounds to predict the alteration of hydrophobicity and other soil physical properties induced by fires. Full article

Port cities are affected by a wide array of emissions, including those from the shipping, road transport, and residential sectors; therefore, the characterization and apportionment of such sources in a high temporal resolution is crucial. This study presents measurements of fine aerosol chemical composition in Piraeus, one of the largest European ports, during two monthly periods (winter vs. summer) in 2018–2019, using online instrumentation (Aerosol Chemical Speciation Monitor—ACSM, 7-λ aethalometer). PMF source apportionment was performed on the ACSM mass spectra to quantify organic aerosol (OA) components, while equivalent black carbon (BC) was decomposed to its fossil fuel combustion and biomass burning (BB) fractions. The combined traffic, shipping and, especially, residential emissions led to considerably elevated submicron aerosol levels (22.8 μg m⁻³) in winter, which frequently became episodic late at night under stagnant conditions. Carbonaceous compounds comprised the major portion of this submicron aerosol in winter, with mean OA and BC contributions of 61% (13.9 μg m⁻³) and 16% (3.7 μg m⁻³), respectively. The contribution of BB to BC concentrations was considerable and spatially uniform. OA related to BB emissions (fresh and processed) and hydrocarbon-like OA (from vehicular traffic and port-related fossil fuel emissions including shipping) accounted for 37% and 30% of OA, respectively. In summer, the average PM₁ concentration was significantly lower (14.8 μg m⁻³) and less variable, especially for the components associated with secondary aerosols (such as OA and sulfate). The effect of the port sector was evident in summer and maintained BC concentrations at high levels (2.8 μg m⁻³), despite the absence of BB and improved atmospheric dispersion. Oxygenated components yielded over 70% of OA in summer, with the more oxidized secondary component of regional origin being dominant (41%) despite the intensity of local sources, in the Piraeus environment. In general, with respect to local sources that can be the target of mitigation policies, this work highlights the importance of port-related activities but also reveals the extensive wintertime impact of residential wood burning. While a separation of the BB source is feasible, more research is needed on how to disentangle the short-term effects of different fossil-fuel combustion sources. Full article