ACS ES&T Air最新文献

The impact of detailed spatial and temporal allocation of unconventional oil and gas development (UOGD) NOx emissions on predicted ozone formation was examined using hydraulic fracturing emissions in the Eagle Ford Shale region of Texas as a case study. Hydraulic fracturing occurs at specific well sites, lasting only 1–2 weeks prior to production. Four scenarios for spatial and temporal allocation of hydraulic fracturing NOx emissions were developed. In one scenario, NOx emissions were evenly distributed to all active wells in the Eagle Ford region, with continuous emissions throughout the year. In other scenarios, NOx emissions from hydraulic fracturing engines in Karnes County were allocated only to fractured wells, with durations ranging from 2 days to 2 weeks. In the month of August, predicted daily maximum of 8 h average (MDA8) O₃ concentrations were consistently 6, 8, and 10 ppb higher over wide regions for the two-week, one-week, and two-day emission periods, respectively, compared to the annual county level distribution, demonstrating that detailed spatial and temporal allocation of NOx emissions in regions like the Eagle Ford Shale, with abundant biogenic VOCs, impacts predicted ozone formation.

Allocating certain emissions from unconventional oil and gas development to specific point sources at the times that the emissions are active can significantly impact predicted ozone formation in some regions.

Due to the increased prevalence of plastic pollution globally, atmospheric deposition of microplastics (MPs) is a significant issue that needs to be better understood to identify potential consequences for human health. This study is the first to quantify and characterize atmospheric MP deposition in the Eastern United States. Passive sampling was conducted at two locations within the Eastern United States, specifically in remote South Central Appalachia, from March to September 2023. Each location had five sampling periods, with collections over a 21 day period. Samples were processed to remove biological material, and the presence of MPs was confirmed using Raman spectroscopy to match particles based on polymer similarity. The relative average atmospheric MP deposition in South Central Appalachia was determined to be 68 MPs m^-2 d^-1. Most verified MPs were fibers, and the most abundant polymer type identified was poly(ethylene terephthalate) PETE. This study's average MP deposition rate is qualitatively comparable to rates reported in other studies that employed a similar methodology in a similar landscape. Scaling up our measured deposition rate to all of South Central Appalachia, an area of over 94,000 km² and home to five million people, suggests a yearly MP deposition of approximately 321 metric tonnes. Our study highlights the prevalence of MP deposition in the Eastern United States, providing baseline data for future work to further assess routes of MP introduction.

Due to the increased prevalence of plastic pollution globally, atmospheric deposition of microplastics (MPs) is a significant issue that needs to be better understood to identify potential consequences for human health. This study is the first to quantify and characterize atmospheric MP deposition in the Eastern United States. Passive sampling was conducted at two locations within the Eastern United States, specifically in remote South Central Appalachia, from March to September 2023. Each location had five sampling periods, with collections over a 21 day period. Samples were processed to remove biological material, and the presence of MPs was confirmed using Raman spectroscopy to match particles based on polymer similarity. The relative average atmospheric MP deposition in South Central Appalachia was determined to be 68 MPs m^–2 d^–1. Most verified MPs were fibers, and the most abundant polymer type identified was poly(ethylene terephthalate) PETE. This study’s average MP deposition rate is qualitatively comparable to rates reported in other studies that employed a similar methodology in a similar landscape. Scaling up our measured deposition rate to all of South Central Appalachia, an area of over 94,000 km² and home to five million people, suggests a yearly MP deposition of approximately 321 metric tonnes. Our study highlights the prevalence of MP deposition in the Eastern United States, providing baseline data for future work to further assess routes of MP introduction.

There is currently no research on the atmospheric deposition of microplastics in the Eastern United States. This study quantifies and characterizes atmospheric microplastic deposition at two locations in South Central Appalachia.

The Marshall Fire was a wildland urban interface (WUI) fire that destroyed more than 1000 structures in two communities in Colorado. High winds carried smoke and ash into an unknown number of buildings that, while not incinerated, were significantly damaged. We aimed to understand whether smoke or ash damage to one's home was associated with physical health impacts of the fire event for people living in and around the fire zone whose homes were not completely destroyed. We analyzed data collected from participants who responded to Wave 1 (six months postfire; N = 642) or Wave 2 (one-year postfire; N = 413) of the Marshall Fire Unified Research Survey. We used self-reported exposure to smells and ash in their homes as measures of exposure and also created spatial exposure measures based on proximity to destroyed structures. Reporting a headache was statistically significantly associated with all exposure metrics (self-reported and spatial proximity), and reporting a strange taste in one's mouth was also significantly associated with having more destroyed buildings within 250 m of the home. Study findings can inform response planning for future WUI fires to protect the health of residents of smoke-damaged homes.

The Marshall Fire was a wildland urban interface (WUI) fire that destroyed more than 1000 structures in two communities in Colorado. High winds carried smoke and ash into an unknown number of buildings that, while not incinerated, were significantly damaged. We aimed to understand whether smoke or ash damage to one’s home was associated with physical health impacts of the fire event for people living in and around the fire zone whose homes were not completely destroyed. We analyzed data collected from participants who responded to Wave 1 (six months postfire; N = 642) or Wave 2 (one-year postfire; N = 413) of the Marshall Fire Unified Research Survey. We used self-reported exposure to smells and ash in their homes as measures of exposure and also created spatial exposure measures based on proximity to destroyed structures. Reporting a headache was statistically significantly associated with all exposure metrics (self-reported and spatial proximity), and reporting a strange taste in one’s mouth was also significantly associated with having more destroyed buildings within 250 m of the home. Study findings can inform response planning for future WUI fires to protect the health of residents of smoke-damaged homes.

People with smoke or ash damaged homes reported more physical health symptoms six months postfire than those in nondamaged homes.

We identified fugitive methane (CH₄) leaks within natural gas transmission and distribution pipeline rights of way (ROWs) around Pittsburgh, PA, and Baltimore, MD, by means of a walking survey while measuring ambient methane and ethane (C₂ H₆) mixing ratios. We used the methane time series to determine discrete leaks using a simple algorithm and verified that the methane was fossil in origin via the methane-to-ethane ratio. For transmission ROWs, we found an average of 23 leaks (range of 12 to 47) over 20.1 total km, corresponding to an activity factor (AF) of 1.1 leaks/km (range 0.60 to 2.3 leaks/km). We also quantified total methane emissions for a subset (N = 5) of the identified leaks using a soil flux measurement chamber. The mean leak emission rate (ER) was 172 g/h/leak (range 17 to 452 g/h/leak). Our AF is higher than the Environmental Protection Agency’s Greenhouse Gas Inventory (GHGI) estimate for transmission pipelines, which is 0.02 leaks/km. Our mean ER is also larger than the GHGI estimate for protected steel pipelines (44 g/h/leak). This study provides a model for making AF and ER measurements in vegetated environments with difficult terrain and suggests fugitive emissions from transmission pipelines may be a more significant source of atmospheric methane than is currently outlined in the GHGI.

This study presents activity (leaks per km) and emission rates (grams per hour per leak) measurements from natural gas transmission pipelines, which have received very little attention as a source of fugitive methane compared to distribution and gathering pipelines. Our results indicate that transmission pipelines may be a more substantial source of fugitive methane than is suggested by current inventories.

Wildfires at the wildland–urban interface (WUI) have been increasing in frequency over recent decades due to increased human development and shifting climatic patterns. The work presented here focuses on the impacts of a WUI fire on indoor air using field measurements of volatile organic compounds (VOCs) by Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS). We found a slow decrease in VOC mixing ratios over the course of roughly 5 weeks starting 10 days after the fire, and those levels decreased to ∼20% of the initial indoor value on average. The VOC composition could be described by a combination of biomass burning emissions and indoor air composition. Comparisons were made between polycyclic aromatic hydrocarbon (PAH) distributions in the gas phase and ash, with differences observed in their distribution between each other and when compared to fresh fuel inventory measurements. Mitigation tests were conducted running air cleaners with activated carbon and opening windows to promote indoor–outdoor air exchange, with both methods showing a decrease greater than 50% for average VOC levels indoors while active. We compare our results with simulated smoke impact experiments that show the slow decline in VOCs must be understood in the context of indoor reservoirs, beyond just on surfaces, leading to the slow release of VOCs to indoor air.

This study reports on the smoke impacts of a fire at the wildland−urban interface on the VOC composition of indoor air. Work was also done to investigate mitigation strategies using ventilation and filtration boxes.

Wildfires at the wildland-urban interface (WUI) have been increasing in frequency over recent decades due to increased human development and shifting climatic patterns. The work presented here focuses on the impacts of a WUI fire on indoor air using field measurements of volatile organic compounds (VOCs) by Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS). We found a slow decrease in VOC mixing ratios over the course of roughly 5 weeks starting 10 days after the fire, and those levels decreased to ∼20% of the initial indoor value on average. The VOC composition could be described by a combination of biomass burning emissions and indoor air composition. Comparisons were made between polycyclic aromatic hydrocarbon (PAH) distributions in the gas phase and ash, with differences observed in their distribution between each other and when compared to fresh fuel inventory measurements. Mitigation tests were conducted running air cleaners with activated carbon and opening windows to promote indoor-outdoor air exchange, with both methods showing a decrease greater than 50% for average VOC levels indoors while active. We compare our results with simulated smoke impact experiments that show the slow decline in VOCs must be understood in the context of indoor reservoirs, beyond just on surfaces, leading to the slow release of VOCs to indoor air.

Here, we investigate the vertical distribution of ammonia (NH₃) and its nitrogen isotopic composition (δ¹⁵N-NH₃) at nine heights along the Shanghai Tower (632 m a.g.l.), the world’s highest in situ research platform in urban areas that we recently established. Both the NH₃ levels and δ¹⁵N-NH₃ values, at all heights, were highly responsive to China’s COVID-19 shutdown, and N isotopic shifts were consistent with the shutdown-associated reduction of combustion-related NH₃ emissions in early 2020. Despite the fact that the NH₃ source partitioning did not greatly change along the vertical transect, we observed that the abundance of NH₃ continuously increased from the ground to the upper mixing layer (∼570 m). Supported by chemical transport-model simulations and auxiliary field measurements, our data indicate that vertical transport of urban NH₃ emissions represents an important modulating control with regards to the observed vertical pattern of NH₃ concentrations and δ¹⁵N-NH₃.

Air pollution causes more than 8.34 million premature deaths worldwide. Most of these deaths occur in the Global South, particularly in Africa. However, the means of observing this air pollution in these countries are lacking. Knowledge of pollutant concentration levels and their distribution in time and space is inadequate or nonexistent in most African countries. This study focuses on the temporal and spatial distribution of PM_2.5 in Burkina Faso, a country of more than 22 million residents yet with very scarce air pollution literature. The study used Clarity low-cost sensors. The sensors were placed at 19 sites throughout the country, including 13 in Ouagadougou, the capital, and three in Bobo-Dioulasso and three in Koudougou, the second and third largest cities in Burkina Faso, respectively. The measurements were taken over a one year period (November 2021 to November 2022). The data was corrected using a Gaussian Mixture Regression trained on a 2-month colocation of a TEOM with a Clarity monitor in Ouagadougou. The corrected mean daily concentrations measured at all of the sites ranged from 17 to 68 μg/m³, with an overall daily average of 46.7 μg/m³. The city averages are 48.5 μg/m³ for Ouagadougou, 46.9 μg/m³ for Bobo-Dioulasso, and 38.7 μg/m³ for Koudougou. These concentrations are significantly higher than the World Health Organization’s recommended safe daily guideline, 15 μg/m³. Measurement values are highest during the dry season, which is dominated by the Harmattan winds from the Sahara desert. At all sites, between 61% and 87% of the measured days exceeded the WHO daily guidelines for PM_2.5. These measurements show the need to undertake an action plan to reduce air pollution in general in Burkina Faso in order to better protect the population health.