Fire Aerosols Research Articles

Investigation of sodium fire aerosol diffusiophoresis deposition in concrete gaps during the processes within nuclear power plants

Investigation of sodium fire aerosol diffusiophoresis deposition in concrete gaps during the processes within nuclear power plants

Study on the influence of aerosol atomization by ultrasonic atomization on coal spontaneous combustion

ABSTRACT Influenced by the complex environment and the nature of process materials in goaf, the prevention and control of spontaneous combustion of coal (CSC) in the deep part of goaf were facing many difficulties. To investigate the performance of ultrasonic atomized aerosols, a series of atomization experiments were conducted using a self-developed ultrasonic atomization device. The main conclusions are as follows: under the same atomization conditions, the atomized particle sizes of several inhibitors (except PAS-W) are concentrated in the <8 μm range, with a content of more than 88%, indicating that the aerosol particles produced by ultrasonic atomization are small in size and uniform in distribution. Compared with water and MgCl2 inhibitors, aerosol particles produced by PAS-W are less likely to pass through the voids of the coal body, and have poorer permeability and diffusivity. As the temperature increases, the viscosity and surface tension of the inhibitor decrease, and the percentage of aerosol particles with particle size <8 μm produced by ultrasonic atomization is more than 88%, indicating that the atomization effect is improved. After increasing the temperature, the contact angle between PAS-W inhibitor and coal reduces from 54.7° to 40.8°, and the wettability is better. Compared with raw coal, the final temperature of the PAS-W aerosol treated coal sample is delayed 21.86°C, and has significant retarding property. When the wind speed is 3 m/s, the effect of PAS-W aerosol particle generation, permeability, and particle size distribution is the best. The results of the study are of great significance in improving the ultrasonic atomized aerosol fire prevention technology and realizing large-scale CSC prevention in goaf.

Improvement and validation of discrete-sectional method based code for fast reactor aerosol dynamics

The study of the dynamics of aerosols produced during a severe accident is vital to the safety analysis of a Sodium-cooled Fast Reactor (SFR). Sodium leakage into the containment following a severe accident may result in the production of sodium aerosols along with fission product aerosols. The in-containment radioactive source term depends upon the settling behaviour of fission product aerosols, which co-agglomerate with sodium fire aerosols. Hence, an in-depth understanding of the dynamics and deposition of aerosols within the containment is essential for the safety assessment of an SFR. The current work uses an open-source code based on the Discrete-Sectional (DS) method to solve the simplified form of General Dynamics Equation (GDE) for aerosols relevant to fast reactors. Aerosols of SrO2, CeO2 and sodium are considered in the present work. The DS code has been modified and further improved by including gravitational coagulation, turbulent coagulation, Brownian deposition, gravitational deposition and thermophoretic deposition so that the code can handle the different processes leading to the deposition of aerosols following a sodium fire. The code is also enhanced to account for the effect of relative humidity through the modified Cooper's equation. The improved code is then validated with different experiments conducted in the Aerosol Test Facility (ATF), India; Mini Sodium Fire Facility (MINA), India; and AHMED (Aerosol and Heat Transfer Measurement Device), Finland. Validation from different facilities confirms the applicability of the code to various scenarios. It is found that the modified DS code could predict the decay of suspended mass concentration of aerosols in different enclosures with reasonable accuracy.

Research on the mechanism and extinguishing technology of substation fire

This article utilizes the combustion characteristics of combustible materials to investigate the fire mechanisms and extinguishing technologies in substations. Experimental and simulation analyses have revealed patterns in heat release rates, flame heights, flame temperatures, flame resistance, and particulate ash. A modular solution employing a novel hot aerosol fire suppression system has been introduced. This system integrates independently manufactured alarm devices, initiation devices, sensors, and fire suppression equipment, offering either semi-automatic or fully automatic functionality. It serves both targeted fire suppression and complete immersion scenarios. By developing an integrated fire suppression and database alert system, enhanced intelligent fire protection has been attained, thereby advancing the sophistication of substation fire safety and the digitization of power networks.

Laboratory study on the characteristics of fresh and aged PM1 emitted from typical forest vegetation combustion in Southwest China

The frequency and intensity of forest fires are amplified by climate change. Substantial quantities of PM1 emitted from forest fires can undergo gradual atmospheric dispersion and long-range transport, thus impacting air quality far from the source. However, the chemical composition and physical properties of PM emitted from forest fires and its changes during atmospheric transport remain uncertain. In this study, the evolution of organic carbon (OC), elemental carbon (EC), water-soluble ions, and water-soluble metals in the particulate phase of smoke emitted from the typical forest vegetation combustion in Southwest China before and after photo-oxidation was investigated in the laboratory. Two aging periods of 5 and 9 days were selected. The OC and TC mass concentrations tended to decrease after 9-days aged compared to fresh emissions. OP, OC2, and OC3 in PM1 are expected to be potential indicators of fresh smoke, while OC3 and OC4 may serve as suitable markers for identifying aged carbon sources from the typical forest vegetation combustion in Southwest China. K+ exhibited the highest abundant water-soluble ion in fresh PM1, whereas NO3− became the most abundant water-soluble ion in aged PM1. NH4NO3 emerged as the primary secondary inorganic aerosol emitted from typical forest vegetation combustion in Southwest China. Notably, a 5-day aging period proved insufficient for the complete formation of the secondary inorganic aerosols NH4NO3 and (NH4)2SO4. After aging, the mass concentration of the water-soluble metal Ni in PM1 from typical forest vegetation combustion in Southwest China decreased, while the mean mass concentrations of all other water-soluble metals increased in varying degrees. These findings provide valuable data support and theoretical guidance for studying the atmospheric evolution of forest fire aerosols, as well as contribute to policy formulation and management of atmospheric environment safety and human health.

Effect of Long‐Range Transported Fire Aerosols on Cloud Condensation Nuclei Concentrations and Cloud Properties at High Latitudes

AbstractActive vegetation fires in south‐eastern (SE) Europe resulted in a notable increase in the number concentration of aerosols and cloud condensation nuclei (CCN) particles at two high latitude locations—the SMEAR IV station in Kuopio, Finland, and the Zeppelin Observatory in Svalbard, high Arctic. During the fire episode aerosol hygroscopicity κ slightly increased at SMEAR IV and at the Zeppelin Observatory κ decreased. Despite increased κ in high CCN conditions at SMEAR IV, the aerosol activation diameter increased due to the decreased supersaturation with an increase in aerosol loading. In addition, at SMEAR IV during the fire episode, in situ measured cloud droplet number concentration (CDNC) increased by a factor of ∼7 as compared to non‐fire periods which was in good agreement with the satellite observations (MODIS, Terra). Results from this study show the importance of SE European fires for cloud properties and radiative forcing in high latitudes.

Positive feedback to regional climate enhances African wildfires

Regional climate strongly regulates the occurrence of wildfires partly because drying of fuel load increases fires. The large amounts of aerosols released by wildfires can also strongly affect regional climate. Here we show positive feedback (a seasonal burned area enhancement of 7-17%) due to wildfire aerosol forcing in Africa found in the simulations using the interactive REgion-Specific ecosystem feedback Fire (RESFire) model in the Community Earth System Model (CESM). The positive feedback results partly from the transport of fire aerosols from burning (dry) to wet regions, reducing precipitation and drying fuel load to enhance fires toward the non-burning (wet) region. This internally self-enhanced burning is an important mechanism for the regulation of African ecosystems and for understanding African fire behaviors in a changing climate. A similar mechanism may also help sustain wildfires in other tropical regions.

Conditionally Background Level of Aerosol Pollution of Near-Surface Air in Moscow and One of Its Suburbs: Seasonal Variations

The data of continuous observations of aerosol composition in the near-surface atmosphere in Moscow (in the city center) and in Moscow region (near Zvenigorod, Moscow region) for three years, from autumn 2019 to the end of 2022, are analyzed. The obtained data were compared with the results of observations on the Moscow network stations “Mosecomonitoring”. The concept of conditionally background aerosol pollution of the atmosphere in Moscow is introduced for those days when the average daily concentration of PM10 is less than the MPC value (60 µg/m3). Previously, the authors found that all episodes of increased aerosol pollution in Moscow with daily average PM10 concentration higher than the MPC value, are associated either with the presence of a close local source in the city itself, or with the long-range transport of fire aerosols and/or dust from other territories to the Moscow region. The average daily PM2.5 concentration in the city and the suburb is lower than the MPC (35 µg/m3) all year round. The days corresponding to the introduced conditional background make up more than 91% over three years in the center of Moscow. Such a conditional background is formed by both natural and anthropogenic sources of aerosols, and not only of local, but also of remote origin. It implicitly takes into account the influence of meteorological conditions on sources and sinks of aerosols, as well as advective air mass transport of aerosol to and from the city. Seasonal variations in mass concentration of PM10, PM2.5 particles and individual chemical elements, as well as in the distribution of chemical elements by the size of aerosol particles in near-surface atmosphere under conditionally background pollution are analyzed. The emphasis is placed on the similarity and difference in the conditionally background near-surface aerosol for the city and the suburb in different seasons.

Erratum: Impacts of Amazon fire aerosols on the subseasonal circulations of the mid-high latitudes

Erratum: Impacts of Amazon fire aerosols on the subseasonal circulations of the mid-high latitudes

Carbon emissions and radiative forcings from tundra wildfires in the Yukon–Kuskokwim River Delta, Alaska

Abstract. Tundra environments are experiencing elevated levels of wildfire, and the frequency is expected to keep increasing due to rapid climate change in the Arctic. Tundra wildfires can release globally significant amounts of greenhouse gasses that influence the Earth's radiative balance. Here we develop a novel method for estimating carbon loss and the resulting radiative forcings of gaseous and aerosol emissions from the 2015 tundra wildfires in the Yukon–Kuskokwim Delta (YKD), Alaska. We paired burn depth measurements using two vegetative reference points that survived the fire event – Sphagnum fuscum and Dicranum spp. – with measurements of local organic matter and soil carbon properties to estimate total ecosystem organic matter and carbon loss. We used remotely sensed data on fire severity from Landsat 8 to scale our measured losses to the entire fire-affected area, with an estimated total loss of 2.04 Tg of organic matter and 0.91 Tg of carbon and an average loss of 3.76 kg m−2 of organic matter and 1.68 kg m−2 of carbon in the 2015 YKD wildfires. To demonstrate the impact of these fires on the Earth's radiation budget, we developed a simple but comprehensive framework to estimate the radiative forcing from Arctic wildfires. We synthesized existing research on the lifetime and radiative forcings of gaseous and aerosol emissions of CO2, N2O, CH4, O3 and its precursors, and fire aerosols. The model shows a net positive cumulative mean radiative forcing of 3.67 W m−2 using representative concentration pathway (RCP) 4.5 and 3.37 W m−2 using RCP 8.5 at 80 years post-fire, which was dominated by CO2 emissions. Our results highlight the climate impact of tundra wildfires, which positively reinforce climate warming and increased fire frequency through the radiative forcings of their gaseous emissions.

Fire Aerosols Slow Down the Global Water Cycle

Abstract Fire is an important Earth system process and the largest source of global primary carbonaceous aerosols. Earlier studies have focused on the influence of fire aerosols on radiation, surface climate, air quality, and biogeochemical cycle. The impact of fire aerosols on the global water cycle has not been quantified and related mechanisms remain largely unclear. This study provides the first quantitative assessment and understanding of the influence of fire aerosols on the global water cycle. This is done by quantifying the difference between simulations with and without fire aerosols using the coupled Community Earth System Model (CESM). Results show that present-day fire aerosols weaken the global water cycle significantly. They decrease the continental precipitation, evapotranspiration, and runoff by 4.1 ± 1.8, 2.5 ± 0.5, and 1.5 ± 1.4 ×103 km3 yr−1 as well as ocean evaporation, precipitation, and water vapor transport from ocean to land by 8.1 ± 1.9, 6.6 ± 2.3, and 1.5 ± 1.4 ×103 km3 yr−1. The impacts of fire aerosols are most clearly seen in the tropics and the Arctic-boreal zone. Fire aerosols affect the global water cycle mainly by cooling the surface, which reduces ocean evaporation, land soil evaporation, and plant transpiration. The decreased water vapor load in the atmosphere leads to a decrease in precipitation, which contributes to reduced surface runoff and subsurface drainage.

Data and code for JC paper: Fire aerosols slow down the global water

Data and code for JC paper: Fire aerosols slow down the global water

Fire–climate interactions through the aerosol radiative effect in a global chemistry–climate–vegetation model

Abstract. Fire emissions influence radiation, climate, and ecosystems through aerosol radiative effects. These can drive rapid atmospheric and land surface adjustments which feed back to affect fire emissions. However, the magnitude of such feedback remains unclear on the global scale. Here, we quantify the impacts of fire aerosols on radiative forcing and the fast atmospheric response through direct, indirect, and albedo effects based on the two-way simulations using a well-established chemistry–climate–vegetation model. Globally, fire emissions cause a reduction of 0.565 ± 0.166 W m−2 in net radiation at the top of the atmosphere with dominant contributions by the aerosol indirect effect (AIE). Consequently, terrestrial surface air temperature decreases by 0.061 ± 0.165 ∘C with coolings of &gt;0.25 ∘C over the eastern Amazon, the western US, and boreal Asia. Both the aerosol direct effect (ADE) and AIE contribute to such cooling, while the aerosol albedo effect (AAE) exerts an offset warming, especially at high latitudes. Land precipitation decreases by 0.180 ± 0.966 mm per month (1.78 % ± 9.56 %) mainly due to the inhibition in central Africa by AIE. Such a rainfall deficit further reduces regional leaf area index (LAI) and lightning ignitions, leading to changes in fire emissions. Globally, fire emissions reduce by 2 %–3 % because of the fire-induced fast responses in humidity, lightning, and LAI. The fire aerosol radiative effects may cause larger perturbations to climate systems with likely more fires under global warming.

Potential fire risks in South America under anthropogenic forcing hidden by the Atlantic Multidecadal Oscillation

Fires in South America have profound effects on climate change and air quality. Although anthropogenic forcing has exacerbated drought and fire risks, the fire emissions and aerosol pollution in the southern Amazon and the Pantanal region showed a consistent long-term decrease during the dry season (August–October) between 2003 and 2019. Here, we find that the decreasing trend in fire emissions, mainly located in the non-deforested region, was associated with climatic conditions unfavorable for intensifying and spreading fires, including increased humidity and slower surface wind speed. These climatic trends can be attributed to weakening of the positive phase of the Atlantic Multidecadal Oscillation, which has strengthened the northeast trade winds within the region (3°S–13°N) and the northwest winds east of the Andes that transport more moisture into the southern Amazon and the Pantanal region. Our findings show the mitigating effects of weakening of the positive Atlantic Multidecadal Oscillation phase on human-induced intensification of fire risks in South America and warn of potentially increased risks of fires and aerosol pollution under intensified anthropogenic forcing in the future.

Radiative and microphysical responses of clouds to an anomalous increase in fire particles over the Maritime Continent in 2015

Abstract. The year of 2015 was an extremely dry year for Southeast Asia where the direct impact of a strong El Niño was in play. As a result of this dryness and the relative lack of rainfall, an extraordinary quantity of aerosol particles from biomass burning remained in the atmosphere over the Maritime Continent during the fire season. This study uses the Weather Research and Forecasting model coupled with Chemistry to understand the impacts of these fire particles on cloud microphysics and radiation during the peak biomass burning season in September. Our simulations, one with fire particles and the other without them, cover the entire Maritime Continent region at a cloud-resolving resolution (4 km) for the entire month of September in 2015. The comparison of the simulations shows a clear sign of precipitation enhancement by fire particles through microphysical effects; smaller cloud droplets remain longer in the atmosphere to later form ice crystals, and/or they are more easily collected by ice-phase hydrometeors in comparison to droplets under no fire influences. As a result, the mass of ice-phase hydrometeors increases in the simulation with fire particles, and so does rainfall. On the other hand, the aerosol radiative effect weakly counteracts the invigoration of convection. Clouds are more reflective in the simulation with fire particles as ice mass increases. Combined with the direct scattering of sunlight by aerosols, the simulation with fire particles shows higher albedo over the simulation domain on average. The simulated response of clouds to fire particles in our simulations clearly differs from what was presented by two previous studies that modeled aerosol–cloud interaction in years with different phases of El Niño–Southern Oscillation (ENSO), suggesting a further need for an investigation on the possible modulation of fire–aerosol–convection interaction by ENSO.

The 2019 Raikoke volcanic eruption – Part 2: Particle-phase dispersion and concurrent wildfire smoke emissions

Abstract. Between 27 June and 14 July 2019 aerosol layers were observed by the United Kingdom (UK) Raman lidar network in the upper troposphere and lower stratosphere. The arrival of these aerosol layers in late June caused some concern within the London Volcanic Ash Advisory Centre (VAAC) as according to dispersion simulations the volcanic plume from the 21 June 2019 eruption of Raikoke was not expected over the UK until early July. Using dispersion simulations from the Met Office Numerical Atmospheric-dispersion Modelling Environment (NAME), and supporting evidence from satellite and in situ aircraft observations, we show that the early arrival of the stratospheric layers was not due to aerosols from the explosive eruption of the Raikoke volcano but due to biomass burning smoke aerosols associated with intense forest fires in Alberta, Canada, that occurred 4 d prior to the Raikoke eruption. We use the observations and model simulations to describe the dispersion of both the volcanic and forest fire aerosol clouds and estimate that the initial Raikoke ash aerosol cloud contained around 15 Tg of volcanic ash and that the forest fires produced around 0.2 Tg of biomass burning aerosol. The operational monitoring of volcanic aerosol clouds is a vital capability in terms of aviation safety and the synergy of NAME dispersion simulations, and lidar data with depolarising capabilities allowed scientists at the Met Office to interpret the various aerosol layers over the UK and attribute the material to their sources. The use of NAME allowed the identification of the observed stratospheric layers that reached the UK on 27 June as biomass burning aerosol, characterised by a particle linear depolarisation ratio of 9 %, whereas with the lidar alone the latter could have been identified as the early arrival of a volcanic ash–sulfate mixed aerosol cloud. In the case under study, given the low concentration estimates, the exact identification of the aerosol layers would have made little substantive difference to the decision-making process within the London VAAC. However, our work shows how the use of dispersion modelling together with multiple observation sources enabled us to create a more complete description of atmospheric aerosol loading.

Trace elements and nutrients in wildfire plumes to the southeast of Australia

The unprecedented magnitude of the 2019–20 Australian fires have raised interest in the potential for fire emissions to supply vital nutrients to remote ocean regions. Fire emissions are episodic and unpredictable, making them difficult to investigate. Here we present results from continuous monitoring of the atmospheric composition at the kunanyi/Mount Wellington time-series station, in southeastern Tasmania (Australia) between 2016 and 2020. Characterization of aerosols at the station revealed a striking increase in the atmospheric loading of iron (Fe), nitrate (NO3−), ammonium (NH4+) and manganese (Mn) associated with fire events. High concentrations of mineral dust in fire-impacted aerosols evidenced that strong pyro-convective winds resulted in the erosion and entrainment of soil particles into the atmosphere alongside the fire plume. Enrichment factor (EF) analysis in aerosols suggested that soil dominated the atmospheric loading of Fe and Mn in fire emissions. Lead (Pb) enrichment in fire aerosols (EFPb > 10) was attributed to the resuspension of soil historically contaminated by leaded petrol and mining operations. Finally, atmospheric transport was showed to play a key role in decreasing concentrations of total Fe (TFe) and mineral dust while increasing the aeolian content of bioaccessible Fe (LFe), NO3− and NH4+ in the plume downwind of the fires. As future projections suggest an increase in fire activity worldwide, atmospheric time-series stations such as kunanyi/Mount Wellington are key to better understand future impacts of fire emissions on human health and natural ecosystems.

Environmental inferno- Wildfire emitted aerosols

Wildfire-emitted aerosols could have a huge impact on global climate by disrupting the global radiation balance. The Community Earth Model Of the system with regulated daily smoke aerosol releases is used in this work to evaluate the effects of fire aerosols on global climate, with a focus on climate feedbacks. The total wildfire aerosol thermal influence (RE) is predicted for being 20.78 6 0.29 W m22, with shortwave RE (REaci; 20.70 6 0.20 W m22) accounting for the majority of the RE. The annual global warming shift DT is 20.64 6 0.16 K, with northern hemisphere experiencing the highest change. In the Arctic, where the shortwave REaci is strong, there is a decline. The build-up of Arctic Sea ice is associated to the cooling, which acts to amplify the Arctic cooling through positive ice-albedo feedback. The quick reaction (irrelevant to DT) tends to lower surface latent heat flow into the atmosphere in the tropics to counter compelling smoke black carbon absorbing, which decreases rainfall in tropical land regions (southern Africa and South America). Climate feedback processes (pertaining to DT) result in a significant reduction in surface latent heat flux over global ocean areas, which could account for the vast majority (;80%) of global precipitation reduction. Precipitate is formed in deep tropical latitudes (58N), but rises in the tropical ocean of the Southern Hemisphere, owing to a southern displacement of the inter - tropical convergence transitional zone and a lowering of the Hadley system in the Southern Hemisphere. Through intensifying cross-equator atmospheric heat transport, such changes could partially compensate for the interhemispheric temperature asymmetry induced by boreal forest fire aerosol indirect effects. This paper deals with wildfire aerosols' impact on forest biomass, the global energy budget, and climate, as well as ways to replenish them.

Evaluating Class B Fire Extinguishing Efficacies of Organic Nitro Compounds Based Aerosol Forming Compositions

Every year, increasing fire accidents worldwide have directed our attention towards an effective fire suppression system. For many decades, Halons have been used as effective fire extinguishing agents. Vienna convention (1985) and Montreal protocol (1987) determined Halons as ozone-depleting agents, and subsequently, their manufacturing is banned by the U.S. Environmental Protection Agency. Thus, against the urgent background of this elimination of Halons, aerosol-based extinguisher resulted as one of the significant Halons substitute technology. The Ozone Depletion Potential and Global Warming Potential values of aerosol extinguishing agents are nearly zero. This has provided thrust for various Universities and research institutions for undertaking numerous projects to develop aerosol-forming pyrotechnic composites for fire fighting applications. In the present work, novel fire extinguishing pyrotechnic compositions were fabricated, in which four different organic nitro compounds, 3,5-dinitrosalicylic acid, 3,5-dinitrobenzoic acid, m-nitrobenzenesulphonate and 3-nitrophthalic acid, were used as the reductant. These nitro compounds undergo rapid redox reaction with strong oxidants to produce aerosol fire extinguishing agents, extinguishing 4.57 KW of small scale n-heptane pool fires in 3 seconds. The fire extinguishing efficacy and thermal characteristics of novel compositions were evaluated against potassium nitrate and phenol formaldehyde resin-based conventional pyrotechnic composition.

The influence of forest fire aerosol and air temperature on glacier albedo, western North America

Over the past decade, western North America glaciers experienced strong mass loss. Regional mass loss during the ablation season is influenced by air temperature, but the importance of other factors such as changes in surface albedo remains uncertain. We examine changes in surface albedo for 17 glaciated regions of western North America as documented in a 20-year record (2000 to 2019) of MODIS daily snow albedo (MOD10A1). Trend analysis reveals that albedo declined for 4% to 81% of the albedo grid cells, and the largest negative trends were situated south of 60°N and in the provinces of British Columbia and Alberta. Sen's slope estimates indicate that 15 of 17 regions showed a decline of which the majority of the largest declines occurred within 100 m of glacier median elevation, suggesting that these declines are driven by a rise of the transient snowline. For most regions, albedo correlates strongly to temperature, and albedo trend in the Chugach region of Alaska, the South Coast, Southern Interior and Central and Southern Rockies of Canada show a significant relationship to aerosols optical depth. Temperature is approximately 2–6 times more predictive of the variation in albedo than AOD for the majority of regions, except the Southern Interior and Southern Rockies where albedo shows a greater dependence on AOD. Investigation of broadband albedo (MCD43A3) for snow grid cells above glacier median elevation in the Central and Southern Rockies shows that declines in the visible and near infrared portions of the spectrum are linked to the presence of forest fire generated aerosols. The results of this study indicate that glacier surface mass balance experiences a regional dependence on forest fire generated light absorbing particles.