Environmental science: atmospheres最新文献

Meteorology can alter bioaerosol properties, potentially enhancing their impact on public health and cloud microphysics. The BioAerosols and Convective Storms (BACS) study was conducted over May-June 2022 and 2023 in Northern Colorado and examines how convective storm processes such as precipitation and cold pools affect bioaerosol concentrations and properties, including pollen, fungal spores and bacterial endotoxin. The two seasons were vastly different climatologically, with drought-like conditions and greater endotoxin concentrations during 2022 and near record rainfall with higher fungal spore concentrations during 2023. Online (fluorescence) and offline (chemical tracer) measurements were used to characterize bioaerosols, alongside collocated measurements of ice-nucleating particles (INPs). Precipitation events generally increased supermicron fluorescent particle concentrations which consisted primarily of fungal spores, as determined from fungal spore counts, chemical tracers, and fluorescent particle types. Storm-generated cold pools had more varied impacts on bioaerosols, sometimes causing depletion and other times enrichment, with peak fluorescent particle concentrations correlating significantly with cold pool strength (r _s = 0.79, p < 0.05, n = 12), indicating that stronger cold pools produce greater increases in local bioaerosol concentrations. Biological INP concentrations in air active at warmer than -15 °C from 1-10 µm in size were enhanced by roughly one order of magnitude in samples collected during convective storms compared to pre-rain samples. Contributions of fungal spores to the enhanced INPs were supported by a significant correlation between large (2.5-10 µm) heat-labile INP concentrations active at -15 °C with mannitol, a fungal spore tracer (r = 0.91, n = 8, p < 0.01). This study found convective storms can greatly increase boundary-layer concentrations of fungal spores and warm-temperature biological INPs, leading to high exposure risks for sensitized populations and the potential for bioaerosols to influence cloud processes.

The impacts of haze on visibility, air quality, and climate are not well quantified due to a lack of understanding of the evolution of the mixing state and phase state of atmospheric particles during haze processing. The variability of the mixing state of atmospheric particles contributes significantly to uncertainties associated with the estimated aerosol radiative forcing. We collected particle samples in January 2018 from the highly polluted Indo-Gangetic plain during hazy conditions to study haze-processed particles. Single particle analysis using multi-modal micro-spectroscopy techniques revealed an abundance (40–70% by number) of potassium-rich sulfate particles from biomass-burning influenced smoke. Tilted view imaging showed that most of the organic particles that had inorganic potassium and sulfate inclusions were liquid-like while those without inclusions were more semi-solid. High-resolution mass spectrometry analysis revealed a significant presence of organosulfates and nitroxy-organosulfates in the morning samples (24%) compared to the afternoon samples (9%), despite higher relative humidity in the afternoon. Overall, our results highlight the significant contribution of both organic and inorganic sulfate to the total particulate sulfur budget during haze processing in winter, when anthropogenic emissions such as household burning, agricultural burning, and vehicular emissions are major contributors to particle mass.

Previous studies reported significant decreases in pollutant emissions across industrialized countries during COVID-19 lockdowns in the spring of 2020. However, high-resolution inverse modeling of satellite observations of nitrogen dioxide (NO₂) by the TROPOMI instrument reveals significant increases in nitrogen oxide (NO_x = NO + NO₂) emissions in some locations despite widespread reductions in economic activity and mobility due to COVID-19 control measures. The NO_x emission increases are associated with supply routes to locked-down cities and urban-to-suburban emission shifts. For example, the total NO_x emissions over the Jiang-Han Plain region, where the supply routes to Wuhan were located, increased by 25% during the lockdown. After the lockdown measures were lifted, NO_x emissions showed uneven recoveries of economic activities. Significant increases in NO_x emissions were observed in the northern part of Jiangsu Province, which has a notable concentration of small-scale or home-based factories, indicating a more rapid resurgence of small enterprises. This research highlights the potential of satellite-based pollutant observations as a valuable tool for assessing socioeconomic activities during pivotal events, such as a pandemic lockdown.

Globally, particulate matter (PM) air pollution is a significant threat to public health. The city of Port Harcourt, Nigeria, is heavily impacted by PM pollution through both natural and anthropogenic sources, including desert dust, vehicular emissions and gas flaring from crude oil processing and refining. Children are especially vulnerable to air pollution, and since they spend a large proportion of their time at school, this microenvironment is critical for their total air pollution exposure. Using low-cost sensors, PM were monitored in three schools in Port Harcourt. The PM_2.5 and PM₁₀ concentrations were, in almost all cases, significantly higher during the dry season compared to the rainy season, up to a factor of 3. Both PM_2.5 and PM₁₀ concentrations were also found to be greater than the annual WHO recommendations throughout the campaign, often exceeding the 24 hour recommendations, in some cases more than 5 times, for both the dry and rainy seasons. Indoor PM₁, PM_2.5 and PM₁₀ concentrations during the school day were significantly higher than outdoor concentrations highlighting the influence of indoor PM sources, in addition to the infiltration of outdoor sources. Source apportionment revealed consistent source patterns across both seasons, showing that outdoor emissions overwhelmingly dominated indoor air quality. Outdoor sources accounted for more than 95% of indoor PM_2.5 and for more than 60% of the indoor PM₁₀. The high PM level exposure during the dry season was significantly influenced by the Harmattan desert dust both inside and outside the schools. In the rainy season, local anthropogenic sources played a more significant role in the absence of the Harmattan effect. These results underscore the urgent need for targeted mitigation strategies within school environments and their surrounding communities to protect children's health and reduce the long-term burden of air pollution in Port Harcourt and other similar urban settings.

Oxidation of hydrofluoroolefins (HFOs) is a source of trifluoroacetic acid (TFA) in the lower atmosphere. TFA is deposited in precipitation and accumulates in water bodies and at land surfaces and concerns have been raised over its environmental impact. The formation and distribution of atmospheric TFA from the gas-phase oxidation of fifteen HFOs were studied. The deposition of TFA associated with regional emissions of HFOs were examined using a global three-dimensional chemical transport model, STOCHEM-CRI, where hypothetical scenarios with annual emissions of 1, 10 and 100 Gg for each of the HFOs were modelled. Globally, between 54 and 78 Gg year⁻¹ of TFA are produced in scenarios using lower and upper limit TFA yields, respectively. The most significant contributors to the TFA formation are found to be HFO-1234yf (9.9 Gg year⁻¹, 13–18%), HFO-1225yeZ (8.5 Gg year⁻¹, 11–16%), HFO-1225yeE (8.6 Gg year⁻¹, 11–16%) and HFO-1216 (7.5 Gg year⁻¹, 10–14%). The tropospheric global burden and lifetime of TFA are found to be 0.54–0.78 Gg and 3.8 days, respectively. Atmospheric levels of TFA from HFO oxidation are highest in northern mid-latitudes, with up to 1.5–2.0 ppt in Europe, 0.5–0.7 ppt in Asia, and 0.5–0.7 ppt in North America during the northern hemispheric summer. TFA is mainly deposited in North America, Europe, and Asia, with deposition rates of up to 0.5 × 10⁻³ Mg km⁻² years⁻¹, 1.0 × 10⁻³ Mg km⁻² years⁻¹, and 1.0 × 10⁻³ Mg km⁻² years⁻¹, respectively. A metric called the TFA deposition potential (TDP) is proposed that quantifies the extent to which different HFOs contribute towards enhanced environmental TFA deposition, relative to that from the oxidation of the most widely used HFO (HFO-1234yf).

Biogenic volatile organic compounds are emitted into the atmosphere where they can oxidize forming compounds with lower volatilities. These low-volatility compounds can participate in the formation of secondary organic aerosols (SOAs) that affect human health and the climate in various ways. We studied the oxidation pathways initiated by the acetyl peroxy radical (APR) of less frequently studied oxygenated monoterpenes (monoterpenoids) using computational methods. The studied reactions included APR-addition, ring-opening reactions and C–C bond scissions. Ring-rearrangement after APR-addition was shown to be significant (43% yield) for one bicyclic monoterpenoid, sabinol. All other studied monoterpenoids will mostly react only with O₂ forming a peroxy radical which will go on to form an alkoxy radical. Alkoxy radical β-scissions lead to different kinds of products depending on the reacting monoterpenoid. Verbenol and α-terpineol will mostly form closed-shell species through alkoxy radical C–C bond scissions leading to low SOA yields. The fate of carveol depends strongly on the stereoisomer. The S-isomer will form a closed-shell species with a 50% yield, whereas the R-isomer will form an alkyl radical with a 100% yield capable of further oxidation. Therefore, a significant SOA yield could be expected for carveol depending on the stereoisomer. For sabinol, umbellulone and carvone, high SOA yields are expected as the majority of them will form an alkyl radical that reacts with O₂ forming a new peroxy radical. In the case of umbellulone and carvone, the formed peroxy radical is an acyl peroxy radical which can undergo rapid unimolecular reactions initiating fast autoxidation. Compared to the monoterpene counterparts of the studied monoterpenoids, significant differences were observed in reaction pathways and SOA yields. While APR-initiated oxidation serves as a minor pathway in the atmosphere, the studied reactions could have an impact on the production of low-volatility compounds.

Modern office infrastructure, furnishings, and traditional cooking practices contribute to air pollution, posing significant health risks, including respiratory issues, cancer, and immune system suppression, especially for vulnerable groups. This review examines recent progress in adsorption, catalytic oxidation, and phytoremediation for reducing volatile organic compounds and fine particulate matter, major air pollutants. Adsorption technologies employ conventional materials like activated carbon and advanced options like metal–organic frameworks and biochars, offering high adsorption capacities due to tunable structures and large surface areas. Catalytic oxidation, including photocatalytic and thermocatalytic methods, effectively degrades pollutants, with composites like nano-ZnO/coke enhancing removal efficiencies. Phytoremediation using household plants like Epipremnum aureum and green walls effectively removes pollutants through enzymatic degradation, stomatal absorption, and microbial synergy. This review assesses integrated strategies' scalability, efficiency, and practicality for comprehensive air quality management, highlighting their potential to enhance public health.

Smoke from the Canadian wildfires in the summer of 2023 spread over seventeen million hectares, traveled across the North American continent, and air quality alerts were issued in 20 states in the United States. Its effects were visible in the Northeast and Mid-Atlantic East Coast regions as the air quality index (AQI) increased to very unhealthy levels. For this work, Particulate Matter (PM) samples were collected during the peak of the pollution event in College Park, Maryland, located more than 1000 miles from the source of the fires. Thus, results of this work provide insights into the molecular-level composition of long-range transported wildfire emissions. Specifically, a non-targeted chemical analysis of aerosols collected during and after the wildfire season is presented. The chemical composition of the water-soluble organic carbon (WSOC) compounds is determined using a Bruker Maxis-II Q-TOF mass spectrometer coupled with a Waters Acquity I-Class PLUS LC system. The results reveal a substantial presence of oxy-hydrocarbons (CHO) and nitrated oxy-hydrocarbons (CHON). Additional compound groups were also detected, incorporating elements such as sulfur, phosphorus, silicon, and various halogens, with chain lengths ranging from C₃ to C₄₁. Our results highlight the prominence of aged water-soluble organic compounds (with O/C ratio ranging from 0.2–0.7) from long-range transported wildfire.

Oxidative potential (OP) is a metric for assessing the potential toxicity of ambient particulate matter (PM). However, it is unclear how the OP of PM relates to the presence of redox-active components, the particle size, or their ability to produce reactive oxygen species (ROS) in aqueous solution. For size-segregated marine PM samples collected during a ship cruise around the Arabian Peninsula, we determined the OP of PM using acellular assays, i.e., dithiothreitol (DTT) depletion and H₂O₂ formation assays. The content of environmentally persistent free radicals (EPFRs) as well as the production of radicals upon dissolution of the PM in water were determined by electron paramagnetic resonance spectroscopy. Generally, sub-micrometer particles contributed more strongly to the particle mass-normalized OP (DTT_m, in units of pmol min⁻¹ µg⁻¹), whereas the production of radicals upon dissolution in water was higher in coarse particles. PM_0.49 (i.e., PM with diameter < 0.49 µm) sampled in the Northern Red Sea showed the highest OP out of all samples. The range of DTT_m is lower than previously observed on both land and sea. The OP assays (DTT, H₂O₂) showed positive correlation with concentrations of both water-soluble transition metals (WSTMs) and water-soluble organic carbon (WSOC), while EPFR content and radical production upon dissolution were significantly correlated with WSTMs only. Overall, the OPs of the marine PM samples investigated in this study were substantial, but below levels reported previously from continental or urban sites.

As a highly reactive atmospheric oxidant, chlorine (Cl) atoms significantly contribute to the oxidation of volatile organic compounds (VOCs) and the formation of secondary organic aerosol (SOA) in coastal and industrial environments. To assess the environmental impacts of SOA generated from Cl-initiated oxidation, elucidating its chemical composition, formation mechanisms, and physicochemical properties under varying atmospheric conditions is of paramount importance. This review summarizes recent research advances on atmospheric chlorine chemistry. We first outline the sources and generation mechanisms of Cl atoms, followed by an analysis of the kinetic characteristics, oxidation mechanisms, and SOA formation potential of Cl-initiated VOC oxidation. Compared to hydroxyl (OH) radicals, Cl atoms exhibit faster reaction rates and reaction pathways that preferentially generate low-volatility products, significantly enhancing SOA formation and demonstrating higher SOA yields. Given the complexity of SOA formation and its strong dependence on environmental conditions, we further discuss the responses of gas-phase chemistry as well as SOA mass yields and composition to the [Cl₂/VOC]₀ ratios, Cl exposure, NO_x levels, and relative humidity. Finally, we outline key experimental challenges and future research priorities.