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214 results on '"Collett, Jeffrey L."'

11. Summertime Ozone Production at Carlsbad Caverns National Park, New Mexico: Influence of Oil and Natural Gas Development.

Author

Marsavin, Andrey, Pan, Da, Pollack, Ilana B., Zhou, Yong, Sullivan, Amy P., Naimie, Lillian E., Benedict, Katherine B., Juncosa Calahoranno, Julieta F., Fischer, Emily V., Prenni, Anthony J., Schichtel, Bret A., Sive, Barkley C., and Collett, Jeffrey L.

Subjects
AIR masses, ATMOSPHERIC chemistry, VOLATILE organic compounds, HYDROXYL group, CHEMICAL models
Abstract

Southeastern New Mexico's Carlsbad Caverns National Park (CAVE) has increasingly experienced summertime ozone (O3) exceeding an 8‐hr average of 70 parts per billion by volume (ppbv). The park is located in the western part of the Permian oil and natural gas (O&G) basin, where production rates have increased fivefold in the last decade. We investigate O3–precursor relationships by constraining the F0AM box model to observations of nitrogen oxides (NOx = NO + NO2) and a suite of volatile organic compounds (VOCs) collected at CAVE during summer 2019. O&G‐related VOCs dominated the calculated VOC reactivity with hydroxyl radicals (OH) on days when O3 concentrations were primarily controlled by local photochemistry. Radical budget analysis showed that NOx levels were high enough to impose VOC sensitivity on O3 production in the morning hours, while subsequent NOx loss through photochemical consumption led to NOx‐sensitive conditions in the afternoon. Maximum daily O3 was responsive to both NOx and O&G‐related VOC reductions, with NOx reductions proving most effective. The model underestimated observed O3 during a 5‐day high O3 episode that was influenced by photochemically aged O&G emissions, as indicated by back‐trajectory analysis, low i‐/n‐pentane ratios, enhanced secondary VOCs, and low ratios of NOx to total reactive oxidized nitrogen (NOy). Model‐observation agreement was improved by constraining model NOx with observed NOy, which approximates NOx at the time of emission, indicating that a large fraction of O3 during this episode was formed nonlocally. Plain Language Summary: New Mexico's Carlsbad Caverns National Park has faced an increase in ground‐level ozone pollution. Summertime southeasterly winds place the park directly downwind of the Permian basin, one of the largest and most productive oil and natural gas (O&G) basins in the US. Our study, conducted using measurements collected in the park during summer 2019 and an air quality model, investigates how emissions from O&G activities affect ozone production. We find that local ozone production is sensitive to changes in both nitrogen oxides and volatile organic compound levels, but more significant reductions in ozone can be achieved by preferentially lowering nitrogen oxides. While the Permian is the closest O&G basin to the park, controlling ozone pollution may require emission reductions from other basins and shale plays in the region, as the park is sometimes impacted by aged air masses that transport ozone from farther upwind. Key Points: 8‐hr ozone concentrations frequently exceed 70 parts per billion by volume at Carlsbad Caverns National ParkA box modeling analysis indicates that local ozone production is most sensitive to nitrogen oxide levelsA subset of high ozone days was influenced by photochemically aged air masses carrying ozone from upwind oil and gas production regions [ABSTRACT FROM AUTHOR]

Published
2024
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27. Increasing importance of ammonia emission abatement in PM2.5 pollution control

Author

Xu, Wen, Zhao, Yuanhong, Wen, Zhang, Chang, Yunhua, Pan, Yuepeng, Sun, Yele, Ma, Xin, Sha, Zhipeng, Li, Ziyue, Kang, Jiahui, Liu, Lei, Tang, Aohan, Wang, Kai, Zhang, Ying, Guo, Yixin, Zhang, Lin, Sheng, Lifang, Zhang, Xiuming, Gu, Baojing, Song, Yu, Van Damme, Martin, Clarisse, Lieven, Coheur, Pierre-François, Collett, Jeffrey L., Jr, Goulding, Keith, Zhang, Fusuo, He, Kebin, and Liu, Xuejun

Published
2022
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47. Interfacing microchip electrophoresis to a growth tube particle collector for semicontinuous monitoring of aerosol composition

Author

Noblitt, Scott D., Lewis, Gregory S., Liu, Yah, Hering, Susanne V., Collett, Jeffrey L., Jr., and Henry, Charles S.

Subjects
Electrophoresis -- Usage, Aerosols -- Composition, Aerosols -- Research, Integrated circuits -- Usage, Semiconductor chips -- Usage, Standard IC, Chemistry
Abstract

Semicontinuous monitoring of aerosol chemical composition has continually increased in demand because of the high spatial and temporal variability of atmospheric particles and the effects these aerosols have on human health and the environment. To address this demand, we describe the preliminary development of a semicontinuous aerosol composition analyzer consisting of a growth tube particle collector coupled to a microfluidic device for chemical analysis. The growth tube enlarges particles through water condensation in a laminar flow, permitting inertial collection into the microchip sample reservoir. Analysis is done by electrophoresis with conductivity detection. To avoid hydrodynamic interference from the sampling pressure, the microchip was operated isobarically by sealing the buffer reservoirs from the atmosphere and interconnecting all the reservoirs with air ducts. The collector samples at 1 L [min.sup.-1] and deposits particles into 30 [micro]L of solution. Sample accumulates with time, and sequential injections are performed as aerosol concentration increases. For extended analyses, a sample rinsing system flushes the sample collection reservoir periodically. For inorganic anions, temporal resolution of 1 min and estimated detection limits of 70-140 ng [m.sup.-3] min were obtained. The system was used to measure sulfate and nitrate, and results were compared to a particle-into-liquid-sampler running in parallel. Results indicate that the prototype growth tube-microchip system (termed aerosol chip electrophoresis, ACE) could provide a useful complement to existing aerosol monitoring technologies, especially when less expensive and/or rapid analyses are desired. 10.1021/ac901903m

Published
2009

48. Integrated membrane filters for minimizing hydrodynamic flow and filtering in microfluidic devices

Author

Noblitt, Scott D., Kraly, James R., VanBuren, Jaimie M., Hering, Susanne V., Collett, Jeffrey L., Jr., and Henry, Charles S.

Subjects
Electrophoresis -- Equipment and supplies, Membrane filters -- Composition, Membrane filters -- Properties, Polycarbonates -- Properties, Chemistry
Abstract

Microfluidic devices have gained significant scientific interest due to the potential to develop portable, inexpensive analytical tools capable of quick analyses with low sample consumption. These qualities make microfluidic devices attractive for point-of-use measurements where traditional techniques have limited functionality. Many samples of interest in biological and environmental analysis, however, contain insoluble particles that can block microchannels, and manual filtration prior to analysis is not desirable for point-of-use applications. Similarly, some situations involve limited control of the sample volume, potentially causing unwanted hydrodynamic flow due to differential fluid heads. Here, we present the successful inclusion of track-etched polycarbonate membrane filters into the reservoirs of poly(dimethylsiloxane) capillary electrophoresis microchips. The membranes were shown to filter insoluble particles with selectivity based on the membrane pore diameter. Electrophoretic separations with membrane-containing microchips were performed on cations, anions, and amino acids and monitored using conductivity and fluorescence detection. The dependence of peak areas on head pressure in gated injection was shown to be reduced by up to 92%. Results indicate that separation performance is not hindered by the addition of membranes. Incorporating membranes into the reservoirs of microfluidic devices will allow for improved analysis of complex solutions and samples with poorly controlled volume.

Published
2007

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