Residue Burning Research Articles

Transitions to crop residue burning have multiple antecedents in Eastern India

Far removed from the agricultural fire “hotspots” of Northwestern India, rice residue burning is on the rise in Eastern India with implications for regional air quality and agricultural sustainability. The underlying drivers contributing to the increase in burning have been linked to the adoption of mechanized (combine) harvesting but, in general, are inadequately understood. We hypothesize that the adoption of burning as a management practice results from a set of socio-technical interactions rather than emerging from a single factor. Using a mixed methods approach, a household survey (n = 475) provided quantitative insights into landscape and farm-scale drivers of burning and was complemented by an in-depth qualitative survey (n = 36) to characterize decision processes and to verify causal inferences derived from the broader survey. For communities where the combine harvester is present, our results show that rice residue burning is not inevitable. The decision to burn appears to emerge from a cascading sequence of events, starting with the following: (1) decreasing household labor, leading to (2) decreasing household livestock holdings, resulting in (3) reduced demands for residue fodder, incentivizing (4) adoption of labor-efficient combine harvesting and subsequent burning of loose residues that are both difficult to collect and of lower feeding value than manually harvested straw. Local demand for crop residues for livestock feeding plays a central role mediating transitions to burning. Consequently, policy response options that only consider the role of the combine harvester are likely to be ineffective. Innovative strategies such as the creation of decentralized commercial models for dairy value chains may bolster local residue demand by addressing household-scale labor bottlenecks to maintaining livestock. Secondary issues, such as timely rice planting, merit consideration as part of holistic responses to “bend” agricultural burning trajectories in Eastern India towards more sustainable practices.

Seasonal occurrence and ecological risk assessment of polycyclic aromatic hydrocarbons in the sediments and water in the left-bank canals of Indus River, Pakistan.

This study investigated a pressing environmental concern: the presence, distribution, sources, and ecological implications of sixteen polycyclic aromatic hydrocarbons (PAHs) in the left-bank canals of Kotri barrage-Akram, Pinyari, and Phuleli of the Indus River in Pakistan. These vital waterways, crucial for industrial, domestic, and agricultural activities, are experiencing contamination threats from anthropogenic sources, particularly PAHs. The study collected three water and two sediment samples from each canal in pre-monsoon and post-monsoon seasons. Then the EPA's liquid-liquid extraction method and gas chromatography determined the concentrations of PAHs. The findings of this study reveal alarming contamination levels, with pre-monsoon concentrations ranging from 22.256 to 836.455ng/L in water and 1,459.941 to 43,179.243ng/g in sediments. The post-monsoon concentrations ranged from 60.352 to 5663.058ng/L in water and 2976.770 to 15,238.335ng/g in sediments. The diagnostic ratios and principal component analysis (PCA) identified multiple sources of contamination, including industrial and domestic wastewater discharge, solid waste burning, vehicular emissions, biomass combustion, and petroleum residues. Furthermore, the assessment of the toxic equivalency factor (TEF) underscored the heightened carcinogenic potential of certain PAHs, notably benzo(a)pyrene and benzo(a)anthracene. Thus, the high levels of PAH contamination pose severe health risks to both human populations and aquatic ecosystems, emphasizing the urgency of addressing this issue. Stricter regulations governing industrial and domestic waste discharge, advocacy for cleaner fuel technologies, and the implementation of effective waste management practices must be initiated as crucial strategies in safeguarding the environmental integrity of the left-bank canals and the health of the surrounding communities.

Effect of environmental factors on seed germination and seedling emergence of weedy rice (Oryza sativa f. spontanea) in China

Abstract Weedy rice (Oryza sativa f. spontanea Auct. ex Backer) is a troublesome annual weed from the Gramineae family and infests rice (Oryza sativa L.) fields globally, with a notable presence in China. However, limited information is available regarding the effects of diverse environmental factors on its germination and emergence. A better understanding of the seed biology and ecology of weedy rice is crucial for developing effective weed management strategies. Experiments were conducted to evaluate the effects of temperature, light, soil burial depth, wheat (Triticum aestivum L.) crop residue amount, salt stress, osmotic stress, and radiant heat on the germination and seedling emergence of weedy rice. Weedy rice exhibited robust germination (>98%) when exposed to varying day/night temperatures (20/15 to 35/30 C) and remained unaffected by light conditions. Seedling emergence was not influenced within the top 5-cm soil layer, where 100% of the seedlings emerged. However, emergence decreased as the soil burial depth increased, eventually resulting in no emergence from a burial depth of 11 cm. The soil burial depth required for 50% of the maximum emergence was 8.3 cm. Seedling emergence ranged from 97% to 100% across different amounts of the wheat straw residue cover (0 to 10,000 kg ha−1). The sodium chloride concentration and osmotic potential required for 50% were 230.8 mM and −0.5 MPa, respectively. No germination was observed when weedy rice seeds were exposed to >110 C pretreatment (radiant heat for 5 min), indicating that residue burning could reduce infestation of weedy rice. The insights gained from this study contribute valuable knowledge to enhance the integrated management of weedy rice in China.

Lignin-derived core-shell flame retardants for fire-safety rigid polyurethane (RPU) insulations

How to ensure the fire safety of rigid polyurethane (RPU) insulation materials remains a challenge. Herein, alkali lignin (AL) and 4,4'-diphenylmethane diisocyanate (MDI) were used as raw materials to construct bio-based cross-linked polyurethane structures on the surface of ammonium polyphosphate (APP) to obtain APP@AL flame retardants. APP@AL was combined with expandable graphite (EG) in varying proportions and applied to rigid polyurethane (RPU) foam to modify its flame retardancy and physico-mechanical characteristics. Compared with untreated RPU, the high interfacial compatibility increased the compressive strength of the flame-retardant RPUs by 10.8%, and the thermal insulation coefficient reached 22.8mW·m−1·K−1. The addition of flame retardant for each flame-retardant RPU was 30wt% of the polymethylene polyphenyl isocyanate. Owing to the P/C/O hybridized char layer in the combustion residues and the capture of gas by EG after expansion, APP@AL/EG not only reached the limiting oxygen index (LOI) of 27.1% but reduced the mean heat release rate and smoke release rate by 70.3% and 58.9%, respectively. This work presented a novel approach to designing environmentally friendly flame retardants for RPU foams with enhanced fire safety and superior overall performance. Additionally, it offers a novel strategy for the high-value conversion of lignin.

Effect of PTFE content on the laser-induced ignition and combustion characteristics of Al@PTFE composite fuels

This paper prepared aluminum@polytetrafluoroethylene (Al@PTFE) composite fuels with different PTFE contents and evaluated the effect of PTFE content on the thermal and combustion characteristics via multiple characterization methods. The scanning electron microscopy (SEM) and thermogravimetry–differential scanning calorimetry (TG-DSC) results showed that the PTFE was well coated on the surface, and the higher the PTFE content, the faster the oxidation reaction rate. Al@PTFE_8% fuel demonstrated more stable thermal performance and higher weight gain. Al@PTFE_15% had a weak endothermic peak at 337.2 °C, while the other two fuels did not appear. The nanosecond pulsed laser-induced plasma ignition (LIPI) test showed that compared to pure Al counterpart, Al@PTFE fuels could effectively shorten the ignition delay and promote the energy release, for Al@PTFE_8% with a reduction of 41.9% in ignition delay and an increase by 17.1 % in combustion temperature. The self-sustaining burn time decreased as the PTFE content increased. The gas-phase combustion of Al@PTFE fuels were more pronounced, and their AlO spectral signal intensity were stronger. The Al@PTFE combustion residues showed lots of cracks and holes, and the mass fraction of O was increased from 22.96 % (Al) to 30.53 % (Al@PTFE_8%). The proposed combustion mechanism reveals that PTFE destroyed the alumina film that hindered combustion, significantly promoting the combustion of Al particles. This study provides guidance for laser-induced plasma ignition of this material under ultrahigh heating rates.

Precise fabrication and superior combustion properties of n-B pomegranate microspheres based on a new dissolution-dispersion-coating method

To enhance the reactivity and combustion efficacy of boron powders, a new dissolution-dispersion-coating (DDC) method of fabricating nano-boron (n-B) pomegranate microspheres were developed. Metal nanoparticles were uniformly encapsulated within n-B microspheres, which varied in size from 2 to 500 μm. The spheroidization mechanism of microsphere structure was investigated. Subsequently, the ignition and combustion performance of the prepared pomegranate microspheres were evaluated by combustion tests at 0.2 and 0.5 MPa, respectively. The results demonstrated that the n-B microspheres of F5 (75 wt% n-B@17 wt% NC@8 wt% n-Ti) exhibited superior performances, achieving the largest flame area, minimal ignition delay time and combustion time. The combustion thermal value and combustion residue analysis indicated that the content of available boron in the F5 microspheres exceeded 72.6 % and the combustion was complete. This study provides a novel approach to enhance the ignition and combustion efficiency of n-B powders.

Imprints of Soil Microbial Activity Accredited to Residue-Management and Tillage Practices for Boosting Rice and Wheat Production

The sustainable productivity of rice–wheat cropping systems relies on soil health, and soil health can be positively influenced by treating previous crop residues using conservation tillage practices. The present study examined the impact of three rice residue-management practices under zero-tilled wheat (ZTW) and conventionally tilled wheat (CTW), along with two rice-sowing practices, during rice cultivation on soil functional microbial diversity, physiological profiling, and grain yields of rice and wheat. Anchored residues (ARs) under ZTW exhibited significantly (p ≤ 0.05) high average well color development—31.43% more than CTW with no residue (NR). CTW with residue burning (BUR) showed a 5.42% increase in the Shannon diversity index compared to CTW-NR. Substrate richness was 10.02% higher in CTW-BUR compared to CTW-NR. CTW-BUR demonstrated the highest 17.98% increase in the Shannon evenness index compared to CTW-NR. The direct-seeded rice (DSR) system generally surpassed puddled transplanted rice (PTR) in most indices, except for the Shannon evenness index values. ZTW-AR exhibited the highest utilization of amino acids, carboxylic acids, and phenolic compounds, while CTW-BUR exhibited the highest utilization of carbohydrates and polymers utilization, and ZTW with no-residue (NR) exhibited the highest utilization of amines. Rice and wheat grain yields were highest with full residue in ZTW and lowest in CTW-NR. PTR supported higher rice yields, while DSR was superior for wheat. These findings highlight the favorable role of residue retention with no tillage during wheat cultivation in the maintenance of soil quality and rice–wheat productivity.

The Prospects of Controlling Open Burning of Crop Residues in Thailand: A Quantitative Assessment of Implementation Barriers and Costs

The open burning of agricultural crop residues poses a sizable threat to Southeast Asia’s near-term prosperity and long-term sustainability. Though Southeast Asia’s policymakers have adopted burning bans and other solutions to curb this threat, few studies have systematically assessed their implementation prospects. This study offers a novel data-driven assessment of those prospects in Thailand. More concretely, it estimates how much economic, technological, institutional, and social barriers could slow the implementation of burning restrictions featured in Thailand’s PM2.5 control plan. This study finds that institutional/social barriers delay implementation more than technical/economic barriers, resulting in about twice the level of PM2.5 emissions relative to an effectively implemented policy scenario over a 10- to 20-year period. This study also demonstrates that the costs of overcoming social/institutional barriers are approximately 14 million US dollars annually over a ten-year period. This figure is equivalent to about a 70% increase on the 21 million US dollars planned for controlling burning in 2026 in Thailand. The approach employed in this study—though not free of imperfections—can also be used for finer-grained comparison of the barriers/costs of managing different crop residues in Thailand and beyond.

Thermogravimetric Analysis of Combustion of Semi-Coke Obtained from Coniferous Wood and Mixtures on Their Basis

Coal remains one of the most used solid fuels for heat and electricity generation but burning coal releases large amounts of CO2 into the urban atmosphere in addition to harmful substances. In order to reduce the consumption of solid fossil fuels, it is necessary to search for fuels capable of replacing coal in terms of its thermal and environmental characteristics. One of the best alternative fuels is biomass, which is considered carbon neutral, but its thermal characteristics are worse than those of solid fossil fuels. In this work, an alternative to coal was studied for the first time, which was semi-coke, obtained by gasification at a temperature of 700–900 °C, the heat of combustion of which turned out to be higher than that of biomass before thermal treatment by 75%. We also studied fuel mixtures based on the resulting semi-coke. The aim of the work is to determine the main characteristics of combustion of semi-coke obtained from coniferous wood and mixtures based on them. The method of thermogravimetric analysis in oxidising medium at a heating rate of 20 °C/min was applied for the research. According to the results of this analysis, the ignition and burnout temperatures were determined, the combustion index was determined, the duration of coke residue combustion was determined, and synergetic interactions between the mixture components influencing the combustion characteristics were established. It was found that the ignition temperature of semi-coke is more than 50% higher than that of biomass and the burnout temperature is 10% higher. Adding 50% of biomass to semi-coke increases the combustion index by more than 30% and decreases the ignition temperature and burnout temperature. The mixture components synergistically interact with each other during combustion to reduce the value of maximum mass loss rate. It was found that the atomic ratios of O/C and H/C in semi-coke are lower than in biomass before gasification.

Bureaucrat incentives reduce crop burning and child mortality in South Asia.

Air pollution in South Asia is a health emergency, responsible for 2 million deaths every year1. Crop residue burning accounts for 40-60% of peak pollution during the winter harvest months2,3. Despite being illegal, this practice remains widespread4,5. Any solution to curb the problem necessitates government action at scale. Here we study whether leveraging the incentives of bureaucrats tasked with controlling burning can mitigate this phenomenon. Using a decade of wind, fire and health data from satellites and surveys from theDemographic and Health Surveys Program, we show that crop burning responds to bureaucrat incentives: fires increase by 15% when wind is most likely to direct pollution to neighbouring jurisdictions, and decrease by 14.5% when it pollutes their own. These effects intensify with stronger bureaucratic incentives and capacity. We also find that bureaucrat action against burning deters future polluters, further reducing fires by 13%. Finally, using an atmospheric model, we estimate that one log increase in in utero exposure to pollution from burning raises child mortality by 30-36 deaths per 1,000 births, underscoring the importance of bureaucrat action. Contrary to the growing beliefs that the problem of crop burning is intractable6,7, these findings highlight specific ways in which existing bureaucrats, when properly incentivized, can improve environmental management and public health outcomes.

Spatiotemporal Analysis of Open Biomass Burning in Guangxi Province, China, from 2012 to 2023 Based on VIIRS

Open biomass burning has significant adverse effects on regional air quality, climate change, and human health. Extensive open biomass burning is detected in most regions of China, and capturing the characteristics of open biomass burning and understanding its influencing factors are important prerequisites for regulating open biomass burning. The characteristics of open biomass burning have been widely investigated at the national scale, with regional studies often focusing on northeast China, but few studies have examined regional discrepancies in spatiotemporal variations over a long timescale in Guangxi province. In this study, we used the Visible Infrared Imaging Radiometer Suite (VIIRS) 375 m active fire product (VNP14IMG), combined with land cover data and high-resolution remote sensing images, to extract open biomass burning (crop residue burning and forest fire) fire points in Guangxi province from 2012 to 2023. We explored the spatial density distribution and temporal variation of open biomass burning using spatial analysis methods and statistical methods, respectively. Furthermore, we analyzed the driving forces of open biomass burning in Guangxi province from natural (topography, climate, and plant schedule), policy, and social (crop production and cultural customs) perspectives. The results show that open biomass burning is concentrated in the central, eastern, and southern parts of the study area, where there are frequent agricultural activities and abundant forests. At the city level, the highest numbers of fire points were found in Baise, Yulin, Wuzhou, and Nanning. The open biomass burning fire points exhibited large annual variation, with high levels from 2013 to 2015 and a remarkable decrease from 2016 to 2020 under strict control measures; however, inconsistent enforcement led to a significant rebound in fire points from 2021 to 2023. Forest fires are the predominant type of open biomass burning in the region, with forest fires and crop residue burning accounting for 76.82% and 23.18% of the total, respectively. The peak period for crop residue burning occurs in the winter, influenced mainly by topography, planting schedules, crop production, and policies, while forest fires predominantly occur in the winter and spring, primarily influenced by topography, climate, and cultural customs. The results indicate that identifying the driving forces behind spatiotemporal variations is essential for the effective management of open biomass burning.

The “Archeology of the Light”: A multiproxy, interdisciplinary and experimental approach to Paleolithic subterranean activities.

Background The "Archeology of the Light" (A-Light) project aims to improve our knowledge of paleolithic cave activities through an interdisciplinary methodology applied to rarely-studied remains: the residues of Paleolithic light from lamps, fireplaces and torches (specially, charcoal and soot). Methods The methodology includes different stages such as: 1. Work in caves and sampling, 2 Laboratory analyses (multi-analytical approach adapted to the type of combustion residue analysed, including Anthracology, C14 dating, Bayesian analysis, SEM-EDX, TEM.EDX, Raman…), 3. Ethnographic review of firelight, 4. Experimental reproduction and monitoring of Palaeolithic firelight. Results This approach contributes multifaceted data about the Paleolithic activities inside the caves (lighting systems selected, fuel used, chronology and intensity of visits, paleo-paths...). Besides, experimental reproductions have enabled evaluation of their lighting potential, and provide essential information for research the visibility and the accessibility of Rock Art from GIS, and allow to more realistic virtual simulation. Conclusions In short, these data demonstrate that the Archaeology of the Light is here to stay and that it is an essential approach for a holistic understanding of Palaeolithic caves.

Burning fields, fading memories: exploring the effects of sugarcane burning on air quality and cognitive functioning – A case study in Northeast Thailand

This study assessed the relationship between PM2.5 concentration and the working memory of sugarcane farmers (n = 444) in Khon Kaen Province, one of the largest sugarcane producers in the Northeast region of Thailand. The relationship between the ambient PM2.5 concentrations and the working memory of sugarcane farmers was evaluated using two working memory outcomes. These outcomes included a working memory difficulty score derived from self-report of difficulty in daily tasks that require working memory and an objective memory test score consisting of a set of number recall exercises. The PM2.5 concentration data in this study were obtained from air quality monitoring stations located in the vicinity of the study locations, ensuring both precision and relevance to local air conditions. The regression results showed that farmers in the low-burn farming zone had less difficulty with working memory and better performance on number recall exercises, compared to farmers in the high-burn farming zones, even after controlling for health and socio-economic factors. Our findings highlight the potential impacts of PM2.5 exposure on the cognitive functions of farmers who burn sugarcane residues in Thailand. Our study supports the need for the government of Thailand or health agencies to establish an effective policy to reduce sugarcane residue burning in Thailand.

Performance Study of Eco‐Friendly and Safe Pyrotechnics for Fireworks

AbstractThe combustion of traditional pyrotechnics will pose great risks to the environment and human health. Although sulfur‐free pyrotechnics prepared from metals or expired military gunpowder have been used to solve this problem, the high sensitivity of them has resulted in insufficient safety. Therefore, new eco‐friendly and safe pyrotechnics are urgently needed. In this study, we prepared novel metal‐free pyrotechnic compositions for fireworks based on 5‐amino tetrazole. The optimized formulations are proposed by calculation. Particle size effects on thermal stability and kinetics are tested. Then, the sensitivity tests, moisture absorption, and burst temperature test were analyzed and compared. The combustion heat and specific volume were also measured. The Py‐GCMS and PM2.5 were used to clarify the composition of gas products and confirm their environmental‐friendly performance. The findings revealed that the novel pyrotechnics has a small amount of combustion residue, greater safety performance, and less PM2.5 concentration. The novel pyrotechnics could generate 564.9 mL/g clean and non‐toxic gas composed of 93.2% N2, H2O, and CO2 without any NOx or SO2 vapor. The test results suggest that the new pyrotechnics can effectively increase gas production and reduce the content of CO and PM2.5. So, it has great potential in application.

Spatiotemporal variations of farmland crop residue burning in China from 2013 to 2022

Farmland crop residue burning (FCRB) significantly impacts air quality, necessitating understanding its spatiotemporal variations to evaluate control measures and guide future policies. This study analyzes FCRB across China from 2013 to 2022 using remote sensing technology and spatiotemporal analysis. Results indicate that the first phase (2013–2017) of the “Clean Air Action” control measures has been proven ineffective, with a 30.9 % increase in FCRB. Effective measures implemented in the second phase (2018–2020) resulted in a reduction of 41.4 % and led to a decrease of 34.3 % in 2022 compared to 2013. FCRB exhibits significant seasonal and regional variations, with a 69 % decrease in autumn and a 23 % increase in spring. While the variations in FCRB across regions are found to be significantly negatively correlated with the stringency of control measures, there is a 61.2 % reduction in the central region, 42.4 % in the western region, 29.7 % in the eastern region with the highest intra-regional disparities, and only 4.5 % in the northeastern region, which is attributed to the high FCRB in Heilongjiang province. FCRB demonstrates the “club convergence” phenomenon and the spillover effects of adjacent provinces, leading to high-high clusters in the northeastern region, emphasizing the need for region-specific control measures (e.g., Heilongjiang province in the northeastern) and the implementation of similar control measures in adjacent areas. Additionally, it is necessary to avoid the rebound phenomenon determined by the analysis of the kernel density estimation curve. Our findings underscore the importance of tailored strategies in managing FCRB and improving air quality in critical areas.

A char removal protocol to visualize fiber cross‐sections of carbon/epoxy composites subjected to flame

AbstractPost‐crash fires obscure or destroy critical fracture surfaces needed to determine the origin of aircraft structural failures. Our goal is to eliminate combustion residue from carbon fiber‐reinforced polymer composites to enable fractographic examination during aviation accident investigations. In this work, combustion residues were removed from burned Hexcel SGP370‐8H/8552 woven‐fabric carbon/epoxy specimens by nitric/sulfuric acid oxidations. Scanning electron microscopy identified various types of char obscuring the fiber ends. For char removal, the burned specimens were immersed in a nitric acid/sulfuric acid/water solution (0.18 wt.%, 96.25 wt.%, 3.57 wt.%) at elevated temperatures (75–150°C). Higher temperatures enhanced nitric acid decomposition in this highly acidic, low‐water environment, accelerating char oxidation and progressively enhancing the extent of char removal. At lower temperatures (T < 100°C), char deposits were partially oxidized after 60 mins. At 125 and 150°C, the char was removed within 30 mins of immersion. The epoxy matrix both chemically decomposed and oxidized and the char oxidized during these oxidation treatments. Gas evolution and soluble products dissolved in the HNO3/H2SO4 media. The damage morphology created by the sawing action on the fiber ends, created before flame exposure, remained clearly visible after the acid oxidations. This occurs because oxidation rates at the carbon fiber ends are much slower than the char oxidation in these acid treatments. If the acid treatment temperature raised above 185°C, then this sawing‐induced fiber damage morphology will also be destroyed. This preliminary understanding can be applied to develop a comprehensive forensic analysis procedure for post‐crash fire investigations.Highlights Flame exposure of sawed specimen cross‐sections leads to char formation, obscuring fiber damage morphologies. HNO3/H2SO4 oxidations at elevated temperatures (75–150°C) resulted in char removal from fiber ends. Higher temperatures (T = 125 and 150°C) accelerated char oxidation. The sawing of carbon/epoxy composites caused extensive fiber damage and ply delamination. Residual decomposed resin matrix and char oxidized faster than the carbon fibers and the fiber sawing‐induced fiber damage morphologies created before flame exposure and were preserved after char removal.

Investigation the Thermal Behavior of Lemon and Orange Peels Composite Fuel Diesel

Background: The aim of this research is to investigate the thermal behavior of a composite fuel prepared by mixing diesel fuel with citrus peel powder in the presence of activators and combustion accelerators. The study focused on utilizing abundant citrus waste, such as lemon and orange peels, as sustainable bioresources to reduce environmental pollution and optimize fuel efficiency. The research explored the thermal properties of the composite fuel and compared it with pure diesel through combustion experiments conducted at atmospheric pressure and combustion pressure in the engine. Methods: The study set the limits of the investigation to various proportions of lemon and orange peel powder mixed with diesel, ranging from 5% to 15% by mass of the total fuel composite. Two catalysts, sodium hydroxide (NaOH) and sulfuric acid (H2SO4), along with calcium oxide (CaO) powder were incorporated into the mixtures as activators to enhance combustion efficiency. The composite fuel characterization included thermogravimetric analysis (TGA) and thermographmetric station experiments to observe the combustion processes and assess the thermal behavior of the composite fuel. Results: The results revealed four distinct phases of combustion during the burning time of 60 seconds: volatile combustion, liquid combustion, combustion of solid materials, and the interaction of active substances with combustion residues. Using activators and catalysts significantly enhanced combustion efficiency and minimized the amount of residue produced during the process, resulting in thermal behavior that is more similar to that of pure diesel. Lemon peel powder with activators demonstrates better thermal behavior compared to orange peel powder. Conclusions: Based on the findings, some recommendations are proposed for further development such as the optimization of activator ratios, exploration of different proportions of lemon and orange peel powder, and investigation of other catalysts. Real-world engine performance tests and emission profile analysis can validate the thermal behavior results obtained from combustion experiments.

Gaseous and aerosol emissions from open burning of tree pruning and hedge trimming residues: Detailed composition and toxicity

Gaseous and PM10 samples were collected during the open burning of pruning residues (olive branches and garden waste) and characterised by distinct analytical techniques to obtain comprehensive chemical emission profiles. Oxidative potential (dithiothreoitol and ascorbic acid assays) and cell viability tests were also performed with the aim of evaluating aerosol toxicity. Emission factors (EFs) were as follows (g kg−1 biofuel, dry basis): 1537–1672 for CO2, 41.9–80 for CO, 2.74–6.6 for CH4, 0.89–3.51 for ethane, 0.79–1.78 for ethylene and 0.56–3.47 for formaldehyde. Emissions of PM10, organic carbon (OC) and elemental carbon (EC) were in the ranges 8–41, 3–18, and 0.4–1.5 g kg−1 biofuel, dry basis, respectively. OC accounted for 35–45% of the total PM10 mass, while EC contributed between around 3% and 5%. WSOC/OC ratios varied from 0.4 to 0.6, revealing that a substantial portion of the carbon emitted was hydrosoluble. Water soluble ions constituted around 8–21% of the PM10 mass, with potassium and chloride as the most abundant ions in all samples. Levoglucosan, widely used a reliable biomass burning tracer, was found in significant amounts in all samples (up to 1.2% of the PM10 mass). Retene, generally pointed out as a biomass combustion biomarker, was the predominant PAH. WSOC and some PAHs showed significant positive correlations with the intrinsic OP measured with the DTT assay, while the OPAA was significantly correlated with some trace metals, such as Fe or Ni. All samples significantly reduced the viability of alveolar epithelial cells.

Assessing environmental issues and possible remedies for the burning of crop residue in Northern India

Assessing environmental issues and possible remedies for the burning of crop residue in Northern India

Elucidating the impacts of aerosol radiative effects for mitigating surface O3 and PM2.5 in Delhi, India during crop residue burning period

Atmospheric aerosol radiative effects regulate surface air pollution (O3 and PM2.5) via both the aerosol–photolysis effect (APE) and the aerosol–radiation feedback (ARF) on meteorology. Here, we elucidate the roles of APE and ARF on surface O3 and PM2.5 in the heavily polluted megacity, Delhi, India by using a regional model (WRF-Chem) with constraints from limited surface observations. While APE reduces surface O3 (by 6.1%) and PM2.5 concentrations (by 2.4% via impeding the secondary aerosol formations), ARF contributes to a 2.5% and 17.5% increase in surface O3 and PM2.5, respectively. The ARF from smoke enhances PM2.5 (by 8%), black carbon (by 10%), and primary organic aerosol (by 18%) during late autumn when crop residue burning is significant. The synergistic APE and ARF have a negligible impact on the total concentrations of O3 and PM2.5. Hence, the reduction of PM2.5 may lead to O3 escalation due to weakened APE. Sensitivity experiments indicate the need and effectiveness of reducing VOC emission for the co-benefits of mitigating both O3 and PM2.5 concentrations in Delhi.