Global tropospheric halogen (Cl, Br, I) chemistry and its impact on oxidants

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(18), P. 13973 - 13996

Published: Sept. 21, 2021

Abstract. We present an updated mechanism for tropospheric halogen (Cl + Br I) chemistry in the GEOS-Chem global atmospheric chemical transport model and apply it to investigate radical cycling implications oxidants. Improved representation of HOBr heterogeneous its pH dependence our simulation leads less efficient recycling mobilization bromine radicals enables include mechanistic sea salt aerosol debromination without generating excessive BrO. The resulting mean BrO mixing ratio is 0.19 ppt (parts per trillion), lower than previous versions GEOS-Chem. Model shows variable consistency biases comparison surface aircraft observations marine air, which are often near or below detection limit. underestimates daytime measurements Cl2 BrCl from ATom campaign over Pacific Atlantic, if correct would imply a very large missing primary source chlorine radicals. IO highest boundary layer uniform free troposphere, with 0.08 ppt, observations. modeled concentration Cl atoms 630 cm−3, contributing 0.8 % oxidation methane, 14 ethane, 8 propane, 7 higher alkanes. Halogen decreases burden ozone by 11 %, NOx 6 OH 4 %. Most decrease driven iodine-catalyzed loss. unbiased Southern Hemisphere but too low Northern Hemisphere.

Language: Английский

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Updated World Health Organization Air Quality Guidelines Highlight the Importance of Non-anthropogenic PM_2.5

Environmental Science & Technology Letters, Journal Year: 2022, Volume and Issue: 9(6), P. 501 - 506

Published: June 6, 2022

The World Health Organization recently updated their air quality guideline for annual fine particulate matter (PM2.5) exposure from 10 to 5 μg m-3, citing global health considerations. We explore if this is attainable across different regions of the world using a series model sensitivity simulations 2019. Our results indicate that >90% population exposed PM2.5 concentrations exceed m-3 and only few sparsely populated (largely in boreal North America Asia) experience average <5 m-3. find even under an extreme abatement scenario, with no anthropogenic emissions, more than half world's would still exposures above (including >70% >60% African Asian populations, respectively), largely due fires natural dust. demonstrate large heterogeneity composition highlight how sensitive reductions emissions. thus suggest use speciated aerosol guidelines help facilitate region-specific management decisions improve health-burden estimates exposure.

Language: Английский

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Separating Daily 1 km PM_2.5 Inorganic Chemical Composition in China since 2000 via Deep Learning Integrating Ground, Satellite, and Model Data

Environmental Science & Technology, Journal Year: 2023, Volume and Issue: 57(46), P. 18282 - 18295

Published: April 28, 2023

Fine particulate matter (PM2.5) chemical composition has strong and diverse impacts on the planetary environment, climate, health. These effects are still not well understood due to limited surface observations uncertainties in model simulations. We developed a four-dimensional spatiotemporal deep forest (4D-STDF) estimate daily PM2.5 at spatial resolution of 1 km China since 2000 by integrating measurements species from high-density observation network, satellite retrievals, atmospheric reanalyses, Cross-validation results illustrate reliability sulfate (SO42-), nitrate (NO3-), ammonium (NH4+), chloride (Cl-) estimates, with high coefficients determination (CV-R2) ground-based 0.74, 0.75, 0.71, 0.66, average root-mean-square errors (RMSE) 6.0, 6.6, 4.3, 2.3 μg/m3, respectively. The three components secondary inorganic aerosols (SIAs) account for 21% 20% 14% (NH4+) total mass eastern China; we observed significant reductions 40-43% between 2013 2020, slowing down 2018. Comparatively, ratio SIA increased 7% across except Beijing nearby areas, accelerating recent years. SO42- been dominant component China, although it was surpassed NO3- some e.g., Beijing-Tianjin-Hebei region 2016. SIA, accounting nearly half (∼46%) mass, drove explosive formation winter haze episodes North Plain. A sharp decline concentrations an increase SIA-to-PM2.5 ratios during COVID-19 lockdown were also revealed, reflecting enhanced oxidation capacity particles.

Language: Английский

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Rapid rise in premature mortality due to anthropogenic air pollution in fast-growing tropical cities from 2005 to 2018

Science Advances, Journal Year: 2022, Volume and Issue: 8(14)

Published: April 8, 2022

Tropical cities are experiencing rapid growth but lack routine air pollution monitoring to develop prescient quality policies. Here, we conduct targeted sampling of recent (2000s 2010s) observations pollutants from space-based instruments over 46 fast-growing tropical cities. We quantify significant annual increases in nitrogen dioxide (NO 2 ) (1 14%), ammonia (2 12%), and reactive volatile organic compounds 11%) most cities, driven almost exclusively by emerging anthropogenic sources rather than traditional biomass burning. estimate urban population exposure 1 18% for fine particles (PM 2.5 23% NO 2005 2018 attribute 180,000 (95% confidence interval: −230,000 590,000) additional premature deaths (62% increase relative 2005) this exposure. These predicted reach populations up 80 million people 2100, so regulatory action targeting is urgently needed.

Language: Английский

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Vehicular Emissions Enhanced Ammonia Concentrations in Winter Mornings: Insights from Diurnal Nitrogen Isotopic Signatures

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(3), P. 1578 - 1585

Published: Jan. 20, 2022

A general feature in the diurnal cycle of atmospheric ammonia (NH3) concentrations is a morning spike that typically occurs around 07:00 to 10:00 (LST). Current hypotheses explain this morning's NH3 increase remain elusive, and there still no consensus whether traffic emissions are among major sources urban NH3. Here, we confirmed pulse Beijing universal feature, with an annual occurrence frequency 73.0% rapid growth rate (>20%) winter. The stable nitrogen isotopic composition (δ15N–NH3) winter also exhibited significant variation obvious peak at (−18.6‰, mass-weighted mean), higher than other times day (−26.3‰). This pattern suggests large fraction originated from nonagricultural sources, for example, power plants, vehicles, coal combustion tend have δ15N–NH3 emission signatures relative agricultural emissions. In particular, contribution vehicular increased 18% (00:00 07:00) 40% (07:00 10:00), while fertilizer was reduced 15.8% 00:00 5.2% 10:00. We concluded mornings were indeed enhanced by vehicle emissions, which should be considered air pollution regulations.

Language: Английский

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In situ ozone production is highly sensitive to volatile organic compounds in Delhi, India

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(17), P. 13609 - 13630

Published: Sept. 13, 2021

Abstract. The Indian megacity of Delhi suffers from some the poorest air quality in world. While ambient NO2 and particulate matter (PM) concentrations have received considerable attention city, high ground-level ozone (O3) are an often overlooked component pollution. O3 can lead to significant ecosystem damage agricultural crop losses, adversely affect human health. During October 2018, speciated non-methane hydrocarbon volatile organic compounds (C2–C13), oxygenated (o-VOCs), NO, NO2, HONO, CO, SO2, O3, photolysis rates, were continuously measured at urban site Old Delhi. These observations used constrain a detailed chemical box model utilising Master Chemical Mechanism v3.3.1. VOCs NOx (NO + NO2) varied test their impact on local production P(O3), which revealed VOC-limited regime. When only reduced, increase P(O3) was observed; thus, VOC co-reduction approaches must also be considered pollution abatement strategies. Of examined this work, mean morning rates most sensitive monoaromatic compounds, followed by monoterpenes alkenes, where halving led 15.6 %, 13.1 12.9 % reduction respectively. not direct changes aerosol surface area but very may influenced future PM concentrations. divided into emission source sectors, as described Emissions Database for Global Atmospheric Research (EDGAR) v5.0 Air Pollutant EDGAR v4.3.2_VOC_spec inventories, allowing individual sources investigated. Reducing road transport emissions only, common strategy strategies worldwide, found even when removed its entirety. Effective achieved reducing along with combustion manufacturing process emissions. Modelled reduced ∼ 20 ppb h−1 these combined halved. This study highlights importance parallel

Language: Английский

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Ammonium Chloride Associated Aerosol Liquid Water Enhances Haze in Delhi, India

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(11), P. 7163 - 7173

Published: April 28, 2022

The interaction between water vapor and atmospheric aerosol leads to enhancement in content, which facilitates haze development, but its concentrations, sources, impacts remain largely unknown polluted urban environments. Here, we show that the Indian capital, Delhi, tops list of capital cities, also experiences highest yet reported worldwide. This high promotes secondary formation aerosols worsens air pollution. We report severe pollution events are commonly associated with enhances light scattering reduces visibility by 70%. Strong suppresses boundary layer height on winter mornings inhibiting dispersal pollutants further exacerbating morning peaks. provide evidence ammonium chloride is largest contributor making up 40% average, highlight regulation chlorine-containing precursors should be considered mitigation strategies.

Language: Английский

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Hitchhiking into the Deep: How Microplastic Particles are Exported through the Biological Carbon Pump in the North Atlantic Ocean

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(22), P. 15638 - 15649

Published: Oct. 27, 2022

Understanding residence times of plastic in the ocean is a major knowledge gap pollution studies. Observations report large mismatch between load estimates from worldwide production and disposal actual plastics floating at sea surface. Surveys water column, surface to deep sea, are rare. Most recent work, therefore, addressed "missing plastic" question using modeling or laboratory approaches proposing biofouling degradation as main removal processes ocean. Through organic matrices, can affect biogeochemical microbial cycling carbon nutrients. For first time, we provide situ measured vertical fluxes microplastics deploying drifting sediment traps North Atlantic Gyre 50 m down 600 depth, showing that through biogenic polymers be embedded into rapidly sinking particles also known marine snow. We furthermore show contained represent up 3.8% total downward flux particulate carbon. Our results shed light on important pathways regulating transport systems potential interactions with cycle, suggesting microplastic "biological pump".

Language: Английский

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Global Emissions of Hydrogen Chloride and Particulate Chloride from Continental Sources

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(7), P. 3894 - 3904

Published: March 23, 2022

Gaseous and particulate chlorine species play an important role in modulating tropospheric oxidation capacity, aerosol water uptake, visibility degradation, human health. The lack of recent global continental emissions has hindered modeling studies the atmosphere. Here, we develop a comprehensive emission inventory gaseous HCl Cl– (pCl), including 35 sources categorized six source sectors based on published up-to-date activity data factors. These are gridded at spatial resolution 0.1° × for years 1960 to 2014. estimated pCl 2014 2354 (1661–3201) 2321 (930–3264) Gg Cl a–1, respectively. Emissions mostly from open waste burning (38%), biomass (19%), energy residential (13%) sectors, major classified by fuel type combustion (43%), (32%), coal (25%). biofuel (29%) processes (44%). sectoral distributions very heterogeneous along study period, temporal trends mainly driven changes factors, intensity, economy, population.

Language: Английский

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Rapid night-time nanoparticle growth in Delhi driven by biomass-burning emissions

Nature Geoscience, Journal Year: 2023, Volume and Issue: 16(3), P. 224 - 230

Published: March 1, 2023

Language: Английский

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