Fugitive emissions from the Bakken shale illustrate role of shale production in global ethane shift

Ethane is the second most abundant atmospheric hydrocarbon, exerts a strong influence on tropospheric ozone, and reduces the atmosphere’s oxidative capacity. Global observations showed declining ethane abundances from 1984 to 2010, while a regional measurement indicated increasing levels since 2009, with the reason for this subject to speculation. The Bakken shale is an oil and gas‐producing formation centered in North Dakota that experienced a rapid increase in production beginning in 2010. We use airborne data collected over the North Dakota portion of the Bakken shale in 2014 to calculate ethane emissions of 0.23 ± 0.07 (2σ) Tg/yr, equivalent to 1–3% of total global sources. Emissions of this magnitude impact air quality via concurrent increases in tropospheric ozone. This recently developed large ethane source from one location illustrates the key role of shale oil and gas production in rising global ethane levels.Key PointsThe Bakken shale in North Dakota accounted for 1–3% total global ethane emissions in 2014These findings highlight the importance of shale production in global atmospheric ethane shiftThese emissions impact air quality and influence interpretations of recent global methane changesPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142509/1/grl54333.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142509/2/grl54333-sup-0001-2016GL068703-SI.pd

Quantifying atmospheric methane emissions from oil and natural gas production in the Bakken shale region of North Dakota

We present in situ airborne measurements of methane (CH4) and ethane (C2H6) taken aboard a NOAA DHC‐6 Twin Otter research aircraft in May 2014 over the Williston Basin in northwestern North Dakota, a region of rapidly growing oil and natural gas production. The Williston Basin is best known for the Bakken shale formation, from which a significant increase in oil and gas extraction has occurred since 2009. We derive a CH4 emission rate from this region using airborne data by calculating the CH4 enhancement flux through the planetary boundary layer downwind of the region. We calculate CH4 emissions of (36 ± 13), (27 ± 13), (27 ± 12), (27 ± 12), and (25 ± 10) × 103 kg/h from five transects on 3 days in May 2014 downwind of the Bakken shale region of North Dakota. The average emission, (28 ± 5) × 103 kg/h, extrapolates to 0.25 ± 0.05 Tg/yr, which is significantly lower than a previous estimate of CH4 emissions from northwestern North Dakota and southeastern Saskatchewan using satellite remote sensing data. We attribute the majority of CH4 emissions in the region to oil and gas operations in the Bakken based on the similarity between atmospheric C2H6 to CH4 enhancement ratios and the composition of raw natural gas withdrawn from the region.Key PointsCH4 emissions from the Bakken region of North Dakota quantifiedFirst emission estimate using in situ CH4 measurementsCH4 sources dominated by oil‐ and gas‐related activitiesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122415/1/jgrd52986.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122415/2/jgrd52986_am.pd

Circadian rhythm of glycoprotein secretion in the vas deferens of the moth, <it>Spodoptera littoralis</it>

<p>Abstract</p> <p>Background</p> <p>Reproductive systems of male moths contain circadian clocks, which time the release of sperm bundles from the testis to the upper vas deferens (UVD) and their subsequent transfer from the UVD to the seminal vesicles. Sperm bundles are released from the testis in the evening and are retained in the vas deferens lumen overnight before being transferred to the seminal vesicles. The biological significance of periodic sperm retention in the UVD lumen is not understood. In this study we asked whether there are circadian rhythms in the UVD that are correlated with sperm retention.</p> <p>Results</p> <p>We investigated the carbohydrate-rich material present in the UVD wall and lumen during the daily cycle of sperm release using the periodic acid-Shiff reaction (PAS). Males raised in 16:8 light-dark cycles (LD) showed a clear rhythm in the levels of PAS-positive granules in the apical portion of the UVD epithelium. The peak of granule accumulation occurred in the middle of the night and coincided with the maximum presence of sperm bundles in the UVD lumen. These rhythms persisted in constant darkness (DD), indicating that they have circadian nature. They were abolished, however, in constant light (LL) resulting in random patterns of PAS-positive material in the UVD wall. Gel-separation of the UVD homogenates from LD moths followed by detection of carbohydrates on blots revealed daily rhythms in the abundance of specific glycoproteins in the wall and lumen of the UVD.</p> <p>Conclusion</p> <p>Secretory activity of the vas deferens epithelium is regulated by the circadian clock. Daily rhythms in accumulation and secretion of several glycoproteins are co-ordinated with periodic retention of sperm in the vas deferens lumen.</p

Airborne measurements from the GEM study

Please see README file for a detailed description of the data.This archive contains airborne measurements from the GEM campaign. Data are archived in association with the following manuscript: Yu, X., D.B. Millet, K.C. Wells, T.J. Griffis, X. Chen, J.M. Baker, S.A. Conley, M.L. Smith, A. Gvakharia, E.A. Kort, G. Plant, and J.D. Wood (2020), Top-down constraints on methane point source emissions from animal agriculture and waste based on new airborne measurements in the US Upper Midwest, J. Geophys. Res., 125, e2019JG005429, doi:10.1029/2019JG005429.NASA (#NNX17AK18G, #80NSSC18K1393

Fugitive emissions from the Bakken shale illustrate role of shale production in global ethane shift

Abstract Ethane is the second most abundant atmospheric hydrocarbon, exerts a strong influence on tropospheric ozone, and reduces the atmosphere&apos;s oxidative capacity. Global observations showed declining ethane abundances from 1984 to 2010, while a regional measurement indicated increasing levels since 2009, with the reason for this subject to speculation. The Bakken shale is an oil and gas-producing formation centered in North Dakota that experienced a rapid increase in production beginning in 2010. We use airborne data collected over the North Dakota portion of the Bakken shale in 2014 to calculate ethane emissions of 0.23 0.07 (2) Tg/yr, equivalent to 1-3% of total global sources. Emissions of this magnitude impact air quality via concurrent increases in tropospheric ozone. This recently developed large ethane source from one location illustrates the key role of shale oil and gas production in rising global ethane levels. Key Points: The Bakken shale in North Dakota accounted for 1-3% total global ethane emissions in 2014 These findings highlight the importance of shale production in global atmospheric ethane shift These emissions impact air quality and influence interpretations of recent global methane change

Top‐Down Constraints on Methane Point Source Emissions From Animal Agriculture and Waste Based on New Airborne Measurements in the U.S. Upper Midwest

Agriculture and waste are thought to account for half or more of the U.S. anthropogenic methane source. However, current bottom‐up inventories contain inherent uncertainties from extrapolating limited in situ measurements to larger scales. Here, we employ new airborne methane measurements over the U.S. Corn Belt and Upper Midwest, among the most intensive agricultural regions in the world, to quantify emissions from an array of key agriculture and waste point sources. Nine of the largest concentrated animal feeding operations in the region and two sugar processing plants were measured, with multiple revisits during summer (August 2017), winter (January 2018), and spring (May–June 2018). We compare the top‐down fluxes with state‐of‐science bottom‐up estimates informed by U.S. Environmental Protection Agency methodology and site‐level animal population and management practices. Top‐down point source emissions are consistent with bottom‐up estimates for beef concentrated animal feeding operations but moderately lower for dairies (by 37% on average) and significantly lower for sugar plants (by 80% on average). Swine facility results are more variable. The assumed bottom‐up seasonality for manure methane emissions is not apparent in the aircraft measurements, which may be due to on‐site management factors that are difficult to capture accurately in national‐scale inventories. If not properly accounted for, such seasonal disparities could lead to source misattribution in top‐down assessments of methane fluxes.Plain Language SummaryKey agricultural methane sources are quantified using new airborne measurements in the U.S. Corn Belt and Upper Midwest. Measurements spanned multiple seasons and targeted nine of the largest concentrated animal feeding operations in the region along with two sugar processing plants. Compared with bottom‐up estimates informed by U.S. Environmental Protection Agency methodology and site‐level animal and management data, top‐down fluxes agree well with bottom‐up estimates for beef but are lower for dairies and sugar plants and suggest a possible mismatch in the timing of emissions.Key PointsWe used aircraft measurements to quantify methane emissions from key agricultural point sources in the Upper Midwest during three seasonsTop‐down methane fluxes are consistent with bottom‐up values for beef facilities but reveal a mismatch for dairies and sugar plantsThese discrepancies point to potential spatial and temporal misattribution of emissions used for atmospheric inverse modelingPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152727/1/jgrg21552.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152727/2/jgrg21552_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152727/3/jgrg21552-sup-0001-2019JG005429-SI.pd

Fossil Versus Nonfossil CO Sources in the US: New Airborne Constraints From ACT‐America and GEM

Carbon monoxide (CO) is an ozone precursor, oxidant sink, and widely used pollution tracer. The importance of anthropogenic versus other CO sources in the US is uncertain. Here, we interpret extensive airborne measurements with an atmospheric model to constrain US fossil and nonfossil CO sources. Measurements reveal a low bias in the simulated CO background and a 30% overestimate of US fossil CO emissions in the 2016 National Emissions Inventory. After optimization we apply the model for source partitioning. During summer, regional fossil sources account for just 9%–16% of the sampled boundary layer CO, and 32%–38% of the North American enhancement—complicating use of CO as a fossil fuel tracer. The remainder predominantly reflects biogenic hydrocarbon oxidation plus fires. Fossil sources account for less domain‐wide spatial variability at this time than nonfossil and background contributions. The regional fossil contribution rises in other seasons, and drives ambient variability downwind of urban areas.Plain Language SummaryCarbon monoxide (CO) is an air pollutant emitted from fossil fuel combustion and from forest and agricultural fires. CO is also produced in the atmosphere through the oxidation of hydrocarbons from both natural and human‐caused sources. US fossil fuel CO emissions have been declining in recent years, and their current importance relative to other regional sources is uncertain. Here, we interpreted a large group of aircraft‐based CO measurements with a high‐resolution atmospheric model to better quantify US fossil and nonfossil fuel CO sources over the eastern half of the US. We find that US fossil fuel CO emissions in the 2016 National Emissions Inventory are overestimated by ∼30%. Furthermore, during summer regional fossil fuel sources account for only a small fraction of the CO over North America compared to the background concentrations already present in air entering North America, and compared to the regional source from natural hydrocarbon oxidation. This complicates the use of CO as a tracer for estimating fossil fuel sources of other pollutants such as carbon dioxide.Key PointsWe interpret an ensemble of airborne measurements with the GEOS‐Chem model to constrain US fossil fuel and nonfossil carbon monoxide (CO) sourcesMeasurements reveal an approximate 30% overestimate of US fossil fuel CO emissions in the National Emissions InventoryDuring summer regional fossil fuel sources account for just 9%–16% of total boundary layer CO over eastern North AmericaPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168306/1/2021GL093361-sup-0001-Supporting_Information_SI-S01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168306/2/grl62480_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168306/3/grl62480.pd