Atmospheric Compounds Research Articles

Technical note: Towards atmospheric compound identification in chemical ionization mass spectrometry with pesticide standards and machine learning

Technical note: Towards atmospheric compound identification in chemical ionization mass spectrometry with pesticide standards and machine learning

Unveiling emerging polycyclic aromatic compounds in the urban atmospheric particulate matter.

Despite the ubiquity and complexity of atmospheric polycyclic aromatic compounds (PACs), many of these compounds are largely unknown and lack sufficient toxicity data for comprehensive risk assessments. In this study, nontarget screening assisted by in-house and self-developed spectra databases was, therefore, employed to identify PACs in atmospheric particulate matter collected from multiple outdoor settings. Additionally, absorption, distribution, metabolism, excretion, and toxicity properties were evaluated to indicate PAC's overall abilities to cause adverse outcomes and incorporated into a novel health risk assessment model to assess their inhalation risks. Here, except for target PACs, 98 PAC analogues across eight categories were identified in the outdoor samples of atmospheric particulate matter. Their concentrations were source-specific and correlated to that of the total 16 priority polycyclic aromatic hydrocarbons (PAHs). Virtual high-throughput screening results suggested that metabolism disruption and endocrine disruption might be significant non-carcinogenic effects caused by the PACs. However, PAHs and oxygenated PAHs exhibited stronger overall abilities to induce non-carcinogenic adverse outcomes in human body when compared to the other PACs. Among PACs, total PAHs exhibited the highest carcinogenic and non-carcinogenic risks, while emerging PAHs accounted for 47% and 27% of total carcinogenic and non-carcinogenic risks, respectively. This study advances our understanding of the potential harmful effects of PACs and provides insights into mitigating the inhalation risks from complex PAC exposures based on classified risk levels.

Unraveling a Novel Formation Pathway of Hydroxymethanesulfonate (HMS) in the Marine Atmosphere

AbstractHydroxymethanesulfonate (HMS, CH2(OH)SO3−) is an important contributor to organosulfates with the potential to impact the biogeochemical sulfur cycle and global climate. However, its characteristics in the marine atmosphere have rarely been investigated. This study investigated the abundances of HMS over the Yellow and East China Seas based on island and cruise observations, showing weak seasonal variations but significant spatial patterns. Aerosol pH was diagnosed as the limiting factor governing the production rates of HMS via the traditional aqueous processing. However, the disparities between the theoretical formation rates and observed concentrations implied the possibility of a new formation mechanism for HMS. Strong correlations were found between methanesulfonate (MSA) and HMS, with machine learning simulation indicating MSA as the most pivotal contributor. Through the density functional theory calculations, HMS can be generated by gas‐phase organic reactions between the •OOCH2SO3H radical (formed from the isomerization of methylsulfonoxyl radical (CH3SO3•) and oxidation) and NO or CH3OO• radical, leading to the cogeneration of HMS and MSA. The HMS production rate via the gas phase process was 3.7–55 times larger than that of aqueous processing, which extends the understanding of formation mechanisms of atmospheric organosulfur compounds.

Effect of Storage Conditions on the Corrosion Resistance of Laser-Treated Al Surfaces Discussed in Terms of Adhesive Bond Strength

In the automotive industry, structures and components are becoming increasingly multi-material. Materials such as steel, aluminum, and carbon fiber composite materials, among others, are used in a composite manner to improve the mechanical utility and performance of each component.The most traditional technique for assembling dissimilar materials is mechanical fastening. However, mechanical fastening requires numerous manufacturing processes, affects the inherent mechanical properties of the base material, and increases weight due to extra metal parts. Adhesive bonding is increasingly being used in more and more industrial fields as a method that avoids the above drawbacks.One disadvantage of adhesive bonding is the long-life durability of the joint when exposed to harsh conditions such as the presence of water or corrosive environments[1]. To ensure this long-life durability of the joint, surface pretreatment of the material is always necessary. Among the many surface pretreatments, laser surface treatment is an efficient method that corrects both the physical and chemical properties of the surface at once, with numerous advantages such as requiring only electrical energy, being easy to integrate into the production process, and not using chemicals.Laser surface treatment of aluminum alloys has been shown to improve the durability of joints through the formation of passivation oxide films and roughening of the material surface[2,3,4]. The laser-treated aluminum alloy surfaces are expected to undergo physicochemical changes over time due to absorption of moisture and organic compounds in the storage atmosphere as well as storage temperature, and the above anticorrosion effects of laser treatment are expected to change as well. In industry, material surfaces are subjected to a certain storage period after laser treatment before they are joined, but the effects of storage methods on the corrosion of treated surfaces and joint interfaces have not yet been fully investigated.In this study, laser-treated aluminum alloys were stored in a high-temperature, high-humidity environment, then joined and DCB tests were performed to investigate how the corrosion protection effect on the material surface given by the laser treatment changed during storage and how it affected joint strength. The storage period was varied from none to one month, and the results of indoor storage are also shown for comparison. Through the above, the appropriate storage environment and storage period after laser treatment will be discussed.This presentation is based on results obtained from a project, JPNP2005, commissioned by the New Energy and Industrial Technology Development Organization (NEDO).[1] Johannes M. C. Mol, “Interface strength and degradation of adhesively bonded porous aluminum oxides,” npj Materials Degradation, Volume 1, Article number 8, 2017, DOI: 10.1038/s41529-017-0007-0[2] Elisabeth Stammen, “Surface Modification with Laser: Pretreatment of Aluminium Alloys for Adhesive Bonding,” Tenth International Conference on Plasma Surface Engineering (PSE2006), Volume 4, Issue S1, Pages S39-S43, 2007, DOI: 10.1002/ppap.200730303[3] Rico Rechner, “Influence on the strength and aging resistance of aluminium joints by laser pre-treatment and surface modification,” International Journal of Adhesion and Adhesives, Volume 30, Issue 7, Pages 595-601, 2010, DOI: 10.1016/j.ijadhadh.2010.05.009[4] Jianping Lin, Junying Min, “Effect of laser ablation treatment on corrosion resistance of adhesive-bonded Al alloy joints,” Surface and Coatings Technology, Volume 345, Pages 13-21, 2018, DOI: 10.1016/j.surfcoat.2018.03.087

Application of tree cores to investigate the historical pollution trends of atmospheric polycyclic aromatic compounds: A case study in a typical coal-contaminated region of China

In this study, 76 polycyclic aromatic compounds (PACs) were detected in air, soil, and tree core samples from Huainan, a typical coal-contaminated region of China. Concentrations of ΣPACs in soil and air samples were 2400 ± 5100 ng/g and 150 ± 63 ng/m3, respectively. Priority PAHs were predominant in both air and soil samples, contributing over 50 % of ΣPACs. Source analysis indicated that PAC contamination in Huainan primarily originated from local coal-related activities. The benzo[a]pyrene (BaP)-toxic equivalent concentrations (TEQBaP) of PACs in the air samples (5.6 ± 5.3 ng/m3) exceeded the threshold of 1 ng/m3. Some PACs, such as benzo[e]pyrene (BeP) and Alk-BaPs, demonstrated significant toxicity and are recommended for consideration as priority pollutants. The historical pollution trends of atmospheric PACs were obtained based on the tree core samples. PAC concentrations in tree core segments showed a strong correlation with atmospheric PM10 levels in Huainan. As air quality has improved in recent years, the PACs concentrations in tree core segments have also decreased. Historical fluctuations of atmospheric PACs were largely attributed to the changes in the gas treatment systems of a nearby coal-fired power plant and adjustments in environmental policies. By integrating trends observed in tree core segments with air concentrations, the historical atmospheric PAC concentrations were extrapolated. The extrapolated results showed similar concentration levels and trends when compared with historical data from other studies in China. Thus, tree cores can not only reflect the historical trends of atmospheric PACs with high temporal precision but also are feasible for extrapolating historical concentrations of airborne PACs.

Mining of dynamic traffic-meteorology-atmospheric pollutant association rules based on Eclat method

With the rapid increase of urban vehicles, the atmospheric compound pollutants, notably PM2.5 and O3, have significantly increased and seriously affected public health. Traffic and meteorological conditions are the primary influencing factors of pollutant concentrations, and their spatial and temporal changes affect the dispersion of pollutants. Increasing use of high-resolution big data offers opportunities to explore these correlations. More extensive quantitative studies are essential for effective air pollution control. This study presents an Eclat algorithm to quantitatively reveal the relationship between traffic, meteorology and pollutants with hourly and 5-minute scale data in the urban area of Guangzhou. We establish a research framework covering temporal pollution analysis, multifactor rule mining, and spatial effects. The results show that PM2.5 and O3 exhibit coordinated trends on the daily scale influenced by traffic flow and meteorology conditions, but on the hourly scale, they are negatively correlated. At the 5-minute scale, synchronized variations occur only during specific periods. This finer scale better identifies association rules for high-concentration pollutant scenarios, and non-roadside sites outperform roadside sites in mining these associations. For example, when humidity is below 37%, atmospheric pressure is 1016.2–1020.3 Pa, wind speed is 1.7–2.6 m/s, and the traffic volume on Jiefang North Road exceeds 635 vehicles every 5 min, there is a 92.86% probability that the PM2.5 concentration at GYQ (a non-roadside monitoring site) will exceed 127 μg/m3. These findings enhance our understanding of how dynamic traffic and meteorological conditions impact atmospheric pollutants and provide a scientific basis for regional collaborative pollution prevention.

Review of the Mechanisms of Liquid-Phase Transformation of Atmospheric Phenolic Compounds: Implications for Air Quality and Environmental Health

Review of the Mechanisms of Liquid-Phase Transformation of Atmospheric Phenolic Compounds: Implications for Air Quality and Environmental Health

Evolution Characteristics of PM2.5 and O3 and Their Synergistic Effects on Atmospheric Compound Pollution in Tangshan

The concentrations of atmospheric pollutants PM2.5, O3, SO2, NO2, and CO together with the meteorological factors of temperature （T）, relative humidity （RH）, wind speed, and other relevant data in Tangshan from 2015 to 2021 were collected to study the variation characteristics of PM2.5 and O3 at different periods in Tangshan City in the past seven years and their influencing factors, to discuss the contributions of air mass transport to PM2.5 and O3 pollution, and to reveal the synergistic influence mechanism of PM2.5 and O3 on atmospheric compound pollution by using correlation analysis and backward trajectory cluster analysis techniques. The results showed that PM2.5 concentrations in Tangshan decreased year by year from 2015 to 2021, whereas O3 concentration showed a unimodal trend, with the peak appearing in 2017. Both PM2.5 and O3 concentrations showed obvious seasonal variation trends； PM2.5 was characterized by the highest concentration in winter and the lowest concentration in summer, whereas O3 was characterized by the highest concentration in summer and the lowest concentration in winter. In addition, the diurnal variation in PM2.5 showed a bimodal distribution, with the peak occurring during the morning and evening on weekdays, and O3 showed a unimodal distribution, with the peak value appearing during the period with strong ultraviolet radiation in the afternoon. PM2.5 had a significant positive correlation with SO2, NO2, and CO, whereas O3 had a significant positive correlation with radiation and temperature. Under the different pollution conditions, PM2.5 and O3 were affected by air mass transports from different directions. Being impacted by various factors, the synergistic effect of PM2.5 and O3 on atmospheric compound pollution showed an obvious negative effect in winter, whereas there was an obvious positive effect in spring, summer, and autumn. Under the backgrounds of different pollutions, when the concentration of PM2.5 exceeded 150 μg·m-3, the synergistic effect of PM2.5 and O3 showed an obvious negative effect.

Enhancing long-term trend simulation of the global tropospheric hydroxyl (TOH) and its drivers from 2005 to 2019: a synergistic integration of model simulations and satellite observations

Abstract. The tropospheric hydroxyl (TOH) radical is a key player in regulating oxidation of various compounds in Earth's atmosphere. Despite its pivotal role, the spatiotemporal distributions of OH are poorly constrained. Past modeling studies suggest that the main drivers of OH, including NO2, tropospheric ozone (TO3), and H2O(v), have increased TOH globally. However, these findings often offer a global average and may not include more recent changes in diverse compounds emitted on various spatiotemporal scales. Here, we aim to deepen our understanding of global TOH trends for more recent years (2005–2019) at 1×1°. To achieve this, we use satellite observations of HCHO and NO2 to constrain simulated TOH using a technique based on a Bayesian data fusion method, alongside a machine learning module named the Efficient CH4-CO-OH (ECCOH) configuration, which is integrated into NASA's Goddard Earth Observing System (GEOS) global model. This innovative module helps efficiently predict the convoluted response of TOH to its drivers and proxies in a statistical way. Aura Ozone Monitoring Instrument (OMI) NO2 observations suggest that the simulation has high biases for biomass burning activities in Africa and eastern Europe, resulting in a regional overestimation of up to 20 % in TOH. OMI HCHO primarily impacts the oceans, where TOH linearly correlates with this proxy. Five key parameters, i.e., TO3, H2O(v), NO2, HCHO, and stratospheric ozone, can collectively explain 65 % of the variance in TOH trends. The overall trend of TOH influenced by NO2 remains positive, but it varies greatly because of the differences in the signs of anthropogenic emissions. Over the oceans, TOH trends are primarily positive in the Northern Hemisphere, resulting from the upward trends in HCHO, TO3, and H2O(v). Using the present framework, we can tap the power of satellites to quickly gain a deeper understanding of simulated TOH trends and biases.

Insights into the catalytic effect of atmospheric organic trace species on the hydration of Criegee intermediates

The bimolecular reactions between Criegee intermediates (CIs) and atmospheric trace species have been extensively investigated, with a particular focus on the reaction with water, while the catalytic role of atmospheric organic compounds in hydration reactions was often neglected. In this study, we employed quantum chemical calculations and Born-Oppenheimer molecular dynamics (BOMD) simulations to investigate the catalytic effects of atmospheric organic amines, organic acids, and alcohols on the hydration reactions of CIs in the gas phase and at the gas-liquid interface. The catalytic reactions were found to follow a cyclic catalytic structure and a stepwise reaction mechanism. Gas-phase studies revealed that organic acids exhibited stronger catalytic effects compared to amines and alcohols, and the catalytic efficiency of amines and alcohols was similar to those of single water molecule. In addition, the catalytic reaction barriers of organic acids and alcohols were positively correlated with their gas-phase acidity (R2 = 0.94 to 0.97). A negative correlation was observed between the catalytic reaction barrier of amines and their gas-phase basicity (R2 = 0.84 to 0.90) and proton affinity (R2 = 0.84 to 0.92). At the gas-liquid interface, organic acids promoted the formation of hydroxyethyl hydroperoxide (HEHP, CH3CH(OH)(OOH)), organic acid ions, and H3O+, whereas the catalytic hydration of CIs by organic amines resulted in the formation of CH3CH(OH)OO and amine ions. Both HEHP and CH3CH(OH)OO can be further decomposed to form OH and HO2, or participate in new particles formation as precursors. This study complements the research gap on the reaction of CIs with water, providing valuable insights into the atmospheric sources of HEHP and HOx as well as the formation of secondary organic aerosols (SOAs).

Resolving the overlooked photochemical nitrophenol transformation mechanism induced by nonradical species under visible light

Nitrophenols present on the surface of particulates are ubiquitous in the atmosphere. However, its atmospheric photochemical transformation pathway remains unknown, for which the crucial effect of visible light is largely overlooked, resulting in an incomplete understanding of the effects of nitrophenols in the atmospheric environment. This study delves into the photolysis mechanism of 4-nitrophenol (4NP), one of the most abundant atmospheric nitrophenol compounds, on the surface of photoactive particulates under visible light irradiation. Unexpectedly, the nonradical species (singlet oxygen, 1O2) was identified as a dominant factor in driving the visible photolysis of 4NP. The pathways of HONO and p-benzoquinone (C6H4O2) generation were clarified by acquiring direct evidence of C-N and O-H bond breakage in the nitro (-NO2) and hydroxyl (-OH) groups of 4NP. The further decomposition of HONO results in the generation of NO and hydroxyl radicals, which could directly contribute to atmospheric oxidizing capacity and complicate the PM2.5 composition. Significantly, the behavior of 1O2-induced visible photolysis of 4NP was universal on the surface of common particulates in the atmosphere, such as A1 dust and Fe2O3. This work advances the understanding of the photochemical transformation mechanism of particulate-phase atmospheric nitrophenols, which is indispensable in elucidating the role of nitrophenols in atmospheric chemistry.

Characterization of atmospheric nitroaromatic compounds in Southwest China by direct injection liquid chromatography-tandem mass spectrometry analysis of aerosol extracts

Nitroaromatic compounds (NACs) in ambient particles are of great concern due to their adverse effects on human health and climate. However, investigations on the characteristics and potential sources of NACs in Southwest China are still scarce. In this study, a field sampling campaign was carried out in the winter of 2022 at a suburban site in Mianyang, Southwest China. A direct injection liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to rapidly determine 10 NACs in fine particulate matter (PM2.5) extracts. The method was sensitive for the quantification of the NACs, with a limit of quantification (LOQ) in the range of 0.092–0.52 ng mL−1. Then, the developed method was applied to determine the concentrations of nitrophenols (NPs), nitrocatechols (NCs), nitrosalicylic acids (NSAs), and nitronaphthol in PM2.5 in Mianyang. The average concentration of total NACs was 78.2 ± 31.2 ng m−3, with daily concentrations ranging from 20.7 to 127.9 ng m−3. Among the measured NACs, 4-nitrocatechol was the most abundant, accounting for 57.8% of the NACs in winter. The five NPs compounds together contributed to 14% of the NACs, which was lower than in other Chinese cities due to the warm climate in winter in Southwest China. NSAs and nitronaphthol each accounted for less than 5% of the NACs. Three major sources of NACs were identified based on the principal component analysis, including vehicle emissions, biomass burning, and secondary formation. The significant correlation between individual NACs and NO2 supported their secondary formation sources. The good correlation between NPs and cloud amount further suggested that gas-phase oxidation was the possible NPs formation mechanism. Our findings revealed the important role of nitrocatechols in NACs in Southwest China, implying that more measures should be taken to control biomass burning and aromatic volatile organic compounds emissions to reduce the level of NACs.

Effect of fertilizer deep placement and nitrification inhibitor on N2O, NO, HONO, and NH3 emissions from a maize field in the North China Plain

Fertilized soil is an essential source of atmospheric gaseous nitrogen compounds (GNC, including N2O, NO, HONO, and NH3) that play important roles in global warming and regional air pollution. However, there is still a lack of comprehensive research on the exchange fluxes of these gases between soil and the atmosphere, let alone exploration of mitigation measures. Herein, the fluxes of N2O, NO, HONO, and NH3 under different fertilization treatments (surface fertilization (SF), deep fertilization (DF), DF with added nitrification inhibitor (DN), and control (CK, non-fertilization)) were comparatively investigated by open-top dynamic chambers in a maize field in the North China Plain (NCP) in 2022. The results showed that fertilization significantly promoted soil GNC emissions under SF and DF treatments, while there was no significant increase in GNC emissions except for NH3 under the DN treatment after fertilization. In comparison to the SF treatment, the cumulative emissions under the DF treatment exhibited a significant reduction, amounting to 80.8% for N2O, 89.4% for NO, 88.3% for HONO, 84.8% for NH3, and 83.9% for the total emissions of these four gases. These results emphasize the effect of fertilizer deep placement in mitigating soil GNC emissions, and further reductions were observed when using nitrification inhibitors like dicyandiamide (DCD). Compared with the cumulative emissions under the SF treatment, the DN treatment showed reductions exceeding 95% for N2O, NO, and HONO, and 77.1% for NH3 due to the inhibition of ammonia oxidation by DCD, resulting in an overall reduction of 88.8% for the four gases. Therefore, we advocate deep placement of fertilizer with or without nitrification inhibitors during crop cultivation to achieve a comprehensive reduction in GNC emissions and improve regional air quality.

Evaporation-Induced Transformations in Volatile Chemical Product-Derived Secondary Organic Aerosols: Browning Effects and Alterations in Oxidative Reactivity.

Volatile chemical products (VCPs) are increasingly recognized as significant sources of volatile organic compounds (VOCs) in urban atmospheres, potentially serving as key precursors for secondary organic aerosol (SOA) formation. This study investigates the formation and physicochemical transformations of VCP-derived SOA, produced through ozonolysis of VOCs evaporated from a representative room deodorant air freshener, focusing on the effects of aerosol evaporation on its molecular composition, light absorption properties, and reactive oxygen species (ROS) generation. Following aerosol evaporation, solutes become concentrated, accelerating reactions within the aerosol matrix that lead to a 42% reduction in peroxide content and noticeable browning of the SOA. This process occurs most effectively at moderate relative humidity (∼40%), reaching a maximum solute concentration before aerosol solidification. Molecular characterization reveals that evaporating VCP-derived SOA produces highly conjugated nitrogen-containing products from interactions between existing or transformed carbonyl compounds and reduced nitrogen species, likely acting as chromophores responsible for the observed brownish coloration. Additionally, the reactivity of VCP-derived SOA was elucidated through heterogeneous oxidation of sulfur dioxide (SO2), which revealed enhanced photosensitized sulfate production upon drying. Direct measurements of ROS, including singlet oxygen (1O2), superoxide (O2•-), and hydroxyl radicals (•OH), showed higher abundances in dried versus undried SOA samples under light exposure. Our findings underscore that drying significantly alters the physicochemical properties of VCP-derived SOA, impacting their roles in atmospheric chemistry and radiative balance.

A cluster-of-functional-groups approach for studying organic enhanced atmospheric cluster formation

Abstract. The role of organic compounds in atmospheric new particle formation is difficult to disentangle due to the myriad of potentially important oxygenated organic molecules (OOMs) present in the atmosphere. Using state-of-the-art quantum chemical methods, we here employ a novel approach, denoted the “cluster-of-functional-groups” approach, for studying the involvement of OOMs in atmospheric cluster formation. Instead of the usual “trial-and-error” approach of testing the ability of experimentally identified OOMs to form stable clusters with other nucleation precursors, we here study which, and how many, intermolecular interactions are required in a given OOM to form stable clusters. In this manner we can reverse engineer the elusive structure of OOM candidates that might be involved in organic enhanced atmospheric cluster formation. We calculated the binding free energies of all combinations of donor and acceptor organic functional groups to investigate which functional groups most preferentially bind with each other and with other nucleation precursors such as sulfuric acid and bases (ammonia, methyl-, dimethyl- and trimethylamine). We find that multiple carboxyl groups lead to substantially more stable clusters compared to all other combinations of functional groups. Employing cluster dynamics simulations, we investigate how a hypothetically OOM composed of multiple carboxyl groups can stabilize sulfuric acid–base clusters and provide recommendations for potential atmospheric multi-carboxylic acid tracer compounds that should be explicitly studied in the future. The presented “cluster-of-functional-groups” approach is generally applicable and can be employed in many other applications, such as ion-induced nucleation and potentially in elucidating the structural patterns in molecules that facilitate ice nucleation.

Distribution of volatile organic compounds (VOCs) in the urban atmosphere of Hangzhou, East China: Temporal variation, source attribution, and impact on the secondary formations of ozone and aerosol

Distribution of volatile organic compounds (VOCs) in the urban atmosphere of Hangzhou, East China: Temporal variation, source attribution, and impact on the secondary formations of ozone and aerosol

Impact of Deforestation on Regional Climate Patterns in Japan

Purpose: To aim of the study was to analyze impact of deforestation on regional climate patterns. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Research on the impact of deforestation in Japan reveals significant alterations in regional climate patterns. Deforested areas experience changes in precipitation, often leading to decreased rainfall and potential drought conditions. Additionally, deforestation contributes to higher temperatures, exacerbating the urban heat island effect and altering local weather dynamics. Modifications in atmospheric circulation patterns further compound these effects, potentially increasing the frequency of extreme weather events. Unique Contribution to Theory, Practice and Policy: Theory of land surface-atmosphere interaction, bio geophysical feedback hypothesis & theory of atmospheric circulation changes may be used to anchor future studies on impact of deforestation on regional climate patterns. Implement sustainable land management practices and reforestation initiatives to mitigate the adverse effects of deforestation on regional climate patterns. Enact and enforce policies that promote sustainable forestry practices, including forest protection, sustainable logging, and forest restoration measures.

Application of Satellite Observation and GIS in Mapping Greenhouse Gases in Part Delta State, Nigeria

The present study aimed to apply satellite observation and Geographic Information System (GIS) to map GHGs in Delta State, Nigeria. Carbon monoxide (CO), nitrous oxide (N O), and sulfur dioxide (SO ) constituted the main GHGs studied. The2 2 datasets covering January 2019 to December 2022 were sourced from the archive of Copernicus Atmosphere Monitoring Service Emissions of Atmospheric Compound and Compilation of Ancillary Data. The Google Earth Engine framework, the inverse distance weighting interpolation algorithm in ArcGIS 10.8 software, and Microsoft Excel were deployed in data analyses. In general, the results showed remarkable seasonal oscillation in the mean concentration of CO, with peak values in January and February, while the lowest mean concentration was observed in October. Higher values of NO were observed2 from November to February and the lowest values in July. July also recorded the highest SO values, with the lowest mean2 observable atmospheric concentrations in August, in addition to remarkable insignificant values in 2020–2022. Besides, the 12 geospatial models (maps) also depicted the spatio-temporal distribution of CO, NO , and SO concentrations from 2019 to2 2 2022 for easy visualization and facilitation of workable policies towards global warming mitigation. The paper recommended the establishment of well-equipped and functional ground-based GHG observatories with early warning systems across the state. This will facilitate real-time GHG monitoring, early warning forecasts, and stimulate scholarship on global warming and climate change.

Seasonal estimates of ozone and secondary organic aerosol formation from volatile organic compounds in a rural atmosphere of India

Volatile Organic Compounds (VOCs) serve as precursors for tropospheric ozone (O3) and Secondary Organic Aerosol (SOA) formation. The formation of O3 and SOA are the indicators of the oxidative capacity specific to a given chemical environment. The current study investigates the oxidative capacity of the relatively less explored tropical rural atmosphere. This study is accomplished by measuring the concentrations of various VOCs and combining them with OH loss rates to estimate the potentials for O3 and SOA formation (OFP and SOAP, respectively). Continuous diel VOC measurement data from Gadanki (13.5°N, 79.2°E), Peninsular India, encompassing four distinct seasons and comprising over 4000 samples, have been utilized to estimate OFP and SOAP and their variations across different seasons. Additionally, efforts have been made to comprehend the contribution of different VOC sources to O3 and SOA formation. The results indicate that, 1, 3, 6-trimethyl benzene (20.09 %) among the VOCs and aromatics (44.37%) among the VOC groups exhibit the highest OFP at the observational site. Among seasons, the post-monsoon period exhibits the highest OFP (31.94%). The increased presence of biogenic VOCs, such as ethylene, propylene, and 1-butene during monsoon, likely due to the increased vegetation cover can be attributed for the elevated OFP. Similarly, n-dodecane (43.22%) and the VOC group of alkanes (50.79%) show the highest SOAP. The summer season has the highest SOAP (29.7%), owing to the enhanced concentrations and photochemistry initiated by OH radicals. Within the PMF-modelled sources, biomass-burning VOCs make a substantial contribution to both OFP and SOAP, distinguishing the rural atmosphere from its urban counterpart, where traffic emissions predominantly influence OFP and SOAP.

Contribution of intermediate-volatility organic compounds from on-road transport to secondary organic aerosol levels in Europe

Abstract. Atmospheric organic compounds with an effective saturation concentration (C∗) at 298 K between 103 and 106 µg m−3 are called intermediate-volatility organic compounds (IVOCs), and they have been identified as important secondary organic aerosol (SOA) precursors. In this work, we simulate IVOCs emitted from on-road diesel and gasoline vehicles over Europe with a chemical transport model (CTM), utilizing a new approach in which IVOCs are treated as lumped species that preserve their chemical characteristics. This approach allows us to assess both the overall contribution of IVOCs to SOA formation and the role of specific compounds. For the simulated early-summer period, the highest concentrations of SOA formed from the oxidation of on-road IVOCs (SOA-iv) are predicted for major European cities, like Paris, Athens, and Madrid. In these urban environments, on-road SOA-iv can account for up to a quarter of the predicted total SOA. Over Europe, unspeciated cyclic alkanes in the IVOC range are estimated to account for up to 72 % of the total on-road SOA-iv mass, with compounds with 15 to 20 carbons being the most prominent precursors. The sensitivity of the predicted SOA-iv concentrations to the selected parameters of the new lumping scheme is also investigated. Active multigenerational aging of the secondary aerosol products has the most significant effect as it increases the predicted SOA-iv concentrations by 67 %.