ACS ES&T Air最新文献

Over the past decade, Delhi has implemented various air quality control measures, but their effectiveness remains unclear. The present study addresses this gap by employing multimodal analysis to quantify the contribution of various sources to ambient PM_2.5 and evaluate their spatiotemporal distribution. Isotopic analysis (δ¹³C and δ¹⁵N) reveals that PM_2.5 in Delhi comprises a mix of sources, including coal combustion, crop residue burning, residential solid biofuel, vehicle emissions, and unidentified contributors. Moreover, positive matrix factorization (PMF) quantified the mixed combustion, and secondary aerosols (MCSAs) contributed the highest loading (34%), followed by vehicular emissions (26.7%), soil dust (28.9%), industries (6.6%), and solid waste burning (2.9%) from 2017 to 2019. The contribution of different sources varies throughout the year. Dust dominated during warm seasons, while MCSAs and vehicles, during cold seasons. The major sources are spread relatively uniform across Delhi and neighboring cities. Compared to 2013–2016, a decline in the contribution of MCSA_SWB [MCSA with solid waste burning] (∼15%) and industries (∼4%) were observed during 2017–2019. However, this is counterbalanced by a rise in vehicle emissions (∼10%) and construction dust (∼8%), highlighting the need for multifaceted strategies. The present study provides valuable insights for developing future air quality management strategies in Delhi to achieve the National Clean Air Programme target and contribute to sustainable development goals. Furthermore, the analysis paves the way for assessing the impact of control measures in other megacities worldwide.

The 2017 and 2018 wildfire seasons in British Columbia (BC), Canada were unprecedented. Among all the pollutants in wildfire smoke, fine particulate matter (PM_2.5) poses the most significant risk to human health. There is limited research on prenatal wildfire smoke exposure and its impacts on infant health. We used a population-based nested case-control design to assess the association between daily PM_2.5 exposures during specific developmental windows and the occurrence of otitis media or lower respiratory infections by age 1 year, including infections associated with dispensations of the antibiotic amoxicillin. We observed the strongest association between per 10 μg/m³ increase in PM_2.5 exposure and otitis media during the fourth window of eustachian tube development (weeks 19-28) with an OR [95% confidence interval] of 1.31 [1.22, 1.41]. Similarly, the canalicular stage of lower respiratory tract development (weeks 18-27) was associated with the highest odds of lower respiratory infections, with an OR of 1.21 [1.15, 1.28]. Measures to reduce wildfire smoke exposure during pregnancy are warranted.

The 2017 and 2018 wildfire seasons in British Columbia (BC), Canada were unprecedented. Among all the pollutants in wildfire smoke, fine particulate matter (PM_2.5) poses the most significant risk to human health. There is limited research on prenatal wildfire smoke exposure and its impacts on infant health. We used a population-based nested case-control design to assess the association between daily PM_2.5 exposures during specific developmental windows and the occurrence of otitis media or lower respiratory infections by age 1 year, including infections associated with dispensations of the antibiotic amoxicillin. We observed the strongest association between per 10 μg/m³ increase in PM_2.5 exposure and otitis media during the fourth window of eustachian tube development (weeks 19–28) with an OR [95% confidence interval] of 1.31 [1.22, 1.41]. Similarly, the canalicular stage of lower respiratory tract development (weeks 18–27) was associated with the highest odds of lower respiratory infections, with an OR of 1.21 [1.15, 1.28]. Measures to reduce wildfire smoke exposure during pregnancy are warranted.

This study suggests that wildfire smoke exposure during specific developmental windows can affect respiratory health in early life. Public health practitioners and healthcare providers should work to protect pregnant people and their children from the detrimental effects of wildfire smoke.

Wildfires are increasingly frequent and intense, leading to substantial production of biomass burning (BB)-derived organic aerosol (BBOA). BBOA adversely affects public health and perturbs the climate. Although African fires account for over 50% of worldwide BB-derived organic emissions, few studies have systematically analyzed molecular tracers of BBOA in fresh versus photochemically aged BB emissions representative of African fires. Therefore, by using gas chromatography interfaced to electron ionization quadrupole mass spectrometry (GC/EI-MS), we chemically characterized aerosol filter samples collected from both fresh and photochemically aged BB emissions of six biomass fuels found in Sub-Saharan Africa (Cordia africana, Baikiaea plurijuga, Acacia erioloba, Colophospermum mopane, cow dung, and a fuel mixture). BB emissions were generated from a furnace mimicking smoldering combustion and subsequently injected into a humidified laboratory chamber (70% ± 3% RH). Seventeen known BBOA tracer compounds (e.g., levoglucosan, mannosan, coniferyl alcohol, catechol, and palmitic acid) were targeted, quantified, and compared between fresh and photochemically aged BB emissions. Furthermore, total-suspended atmospheric particulate matter (PM) samples collected from Botswana during the fire season were also analyzed by GC/EI-MS. We identified laboratory-generated BBOA constituents that were also found in Botswana PM that could plausibly serve as unique tracers (e.g., D-pinitol) for African BBOA during future field studies.

Aldehydes, including formaldehyde and acetaldehyde, are commonly observed as amine solvent degradation products in carbon capture systems. These degradation products have the potential to cause environmental consequences if they migrate to the flue gas and are emitted from CO₂ capture systems. A better understanding of the Henry’s volatility coefficients of these compounds is needed to estimate the gas-phase partitioning of these compounds from the amine solvent and to aid in the development of proper mitigation strategies that can be implemented within CO₂ capture systems. This work highlights the experimental determination of the dimensionless Henry’s volatility coefficient of acetaldehyde from unloaded and CO₂ loaded amine solvents using headspace solid-phase microextraction with on-fiber derivatization and gas chromatography mass spectrometry detection. The experimental dimensionless Henry’s volatility coefficient was significantly higher from the amine solvent when compared to acetaldehyde’s partitioning coefficient from water due to a “salting out” effect from increases in ionic strength with CO₂ loaded amine solutions. A linear temperature and CO₂ loading dependency of the Henry’s volatility coefficient was observed with acetaldehyde from the amine solvent. The experimental Henry’s coefficient was then used to estimate gas-phase concentrations from carbon capture systems based on measured process temperatures, CO₂ loading in the solvent, and acetaldehyde liquid concentration values all measured from a pilot CO₂ capture system.

Fires at the wildland-urban interface (WUI) are increasing in magnitude and frequency, emitting organic aerosol (OA) with unknown composition and atmospheric impacts. In this study, we investigated the chemical composition of OA produced through the 600 °C pyrolysis of ten urban materials in nitrogen, which were subsequently aged under UV light for 2 h. The analysis utilized ultrahigh-performance liquid chromatography (UHPLC) separation, coupled with a photodiode array (PDA) detector and a high-resolution mass spectrometer (HRMS) for molecular characterization. Hierarchical clustering analysis demonstrated that lumber-derived OA was the most diverse and distinct in composition. Unaged and aged OA (for each urban material) did not significantly differ in chemical identities. Potential aromatic brown carbon (BrC) chromophores (based on their degree of unsaturation) constituted 13-42% of all assigned compounds. PDA chromatograms revealed multiple BrC chromophoric species that were either enhanced or degraded as a result of UV aging, providing insights into specific BrC chromophores responsible for photobleaching and photoenhancement of the overall absorption coefficient. Thirty-six BrC chromophores were identified across the ten OA types, and their structures were confirmed using reference standards. Components of plasticizers and resins, such as phthalic and terephthalic acids, were structurally confirmed in the samples. We present potential species for WUI fires as components of resins, epoxies, dyes, and adhesives commonly used in manufacturing urban materials. Photolysis did not significantly impact the chemical composition of OA emitted from the burning of specific WUI materials.

Fires at the wildland–urban interface (WUI) are increasing in magnitude and frequency, emitting organic aerosol (OA) with unknown composition and atmospheric impacts. In this study, we investigated the chemical composition of OA produced through the 600 °C pyrolysis of ten urban materials in nitrogen, which were subsequently aged under UV light for 2 h. The analysis utilized ultrahigh-performance liquid chromatography (UHPLC) separation, coupled with a photodiode array (PDA) detector and a high-resolution mass spectrometer (HRMS) for molecular characterization. Hierarchical clustering analysis demonstrated that lumber-derived OA was the most diverse and distinct in composition. Unaged and aged OA (for each urban material) did not significantly differ in chemical identities. Potential aromatic brown carbon (BrC) chromophores (based on their degree of unsaturation) constituted 13–42% of all assigned compounds. PDA chromatograms revealed multiple BrC chromophoric species that were either enhanced or degraded as a result of UV aging, providing insights into specific BrC chromophores responsible for photobleaching and photoenhancement of the overall absorption coefficient. Thirty-six BrC chromophores were identified across the ten OA types, and their structures were confirmed using reference standards. Components of plasticizers and resins, such as phthalic and terephthalic acids, were structurally confirmed in the samples. We present potential species for WUI fires as components of resins, epoxies, dyes, and adhesives commonly used in manufacturing urban materials. Photolysis did not significantly impact the chemical composition of OA emitted from the burning of specific WUI materials.

Organic aerosol from pyrolyzed urban materials contains compounds different from those found in wood smoke. They evolve upon exposure to UV radiation, reflecting the dynamic nature of urban fire smoke.

Dust storms in arid regions transport desert salts and dust, affecting geochemical processes, atmospheric chemistry, climate, and human health. This study examines how the gas–salt interface composition of desert salt changes with varying relative humidity (RH), using ambient pressure X-ray photoelectron spectroscopy (APXPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and molecular dynamics (MD) simulations. Ion chromatography analysis of desert salt indicates it is predominantly composed of sulfate, sodium, and magnesium ions, with traces of calcium, chloride, nitrate, and potassium ions. APXPS and NEXAFS surface analyses show that, at 0% RH, the gas–salt interface primarily features Na₂SO₄, with smaller amounts of MgSO₄ and a trace of NaCl on the top layers. As humidity increases, the composition at the gas–salt interface changes, notably with Mg²⁺ binding to SO₄^2– ions and a dominant NaCl formation throughout the studied surface depth. This shift indicates a transition from a sulfate- to a chloride-rich surface as humidity increases, contradicting MD simulations that predicted that on salt crystals covered by a submonolayer of water with electrolytes, chloride ions migrate toward the liquid–solid interface. This discrepancy indicates that other factors, like enhanced ionic mobility at grain boundaries, might drive the accumulation of chloride ions at the gas interface. The study emphasizes the crucial role of adsorbed water in ion migration and surface composition transformation of desert salts, affecting geochemical processes in arid regions.

Water adsorption-driven transformation of Gobi Desert salts, leading to surface sodium chloride formation, with potential implications for atmospheric chemistry in dust storm-affected regions.

Dust storms in arid regions transport desert salts and dust, affecting geochemical processes, atmospheric chemistry, climate, and human health. This study examines how the gas-salt interface composition of desert salt changes with varying relative humidity (RH), using ambient pressure X-ray photoelectron spectroscopy (APXPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and molecular dynamics (MD) simulations. Ion chromatography analysis of desert salt indicates it is predominantly composed of sulfate, sodium, and magnesium ions, with traces of calcium, chloride, nitrate, and potassium ions. APXPS and NEXAFS surface analyses show that, at 0% RH, the gas-salt interface primarily features Na₂SO₄, with smaller amounts of MgSO₄ and a trace of NaCl on the top layers. As humidity increases, the composition at the gas-salt interface changes, notably with Mg²⁺ binding to SO₄ ^2- ions and a dominant NaCl formation throughout the studied surface depth. This shift indicates a transition from a sulfate- to a chloride-rich surface as humidity increases, contradicting MD simulations that predicted that on salt crystals covered by a submonolayer of water with electrolytes, chloride ions migrate toward the liquid-solid interface. This discrepancy indicates that other factors, like enhanced ionic mobility at grain boundaries, might drive the accumulation of chloride ions at the gas interface. The study emphasizes the crucial role of adsorbed water in ion migration and surface composition transformation of desert salts, affecting geochemical processes in arid regions.