scholarly journals The isotopic composition of atmospheric nitrous oxide observed at the high-altitude research station Jungfraujoch, Switzerland

2020 ◽  
Author(s):  
Anonymous
Keyword(s):  
Nitrous Oxide ◽  
Isotopic Composition ◽  
High Altitude ◽  
Research Station

scholarly journals The isotopic composition of atmospheric nitrous oxide observed at the high-altitude research station Jungfraujoch, Switzerland

2020 ◽  
Vol 20 (11) ◽  
pp. 6495-6519 ◽  
Author(s):  
Longfei Yu ◽  
Eliza Harris ◽  
Stephan Henne ◽  
Sarah Eggleston ◽  
Martin Steinbacher ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Isotopic Composition ◽  
High Altitude ◽  
High Precision ◽  
Large Scale ◽  
Late Summer ◽  
Site Preference ◽  
Research Station ◽  
N2o Production ◽  
Mixing Ratios

Abstract. Atmospheric nitrous oxide (N2O) levels have been continuously growing since preindustrial times. Mitigation requires information about sources and sinks on the regional and global scales. Isotopic composition of N2O in the atmosphere could contribute valuable constraints. However, isotopic records of N2O in the unpolluted atmosphere remain too scarce for large-scale N2O models. Here, we report the results of discrete air samples collected weekly to biweekly over a 5-year period at the high-altitude research station Jungfraujoch, located in central Switzerland. High-precision N2O isotopic measurements were made using a recently developed preconcentration and laser spectroscopy technique. The measurements of discrete samples were accompanied by in situ continuous measurements of N2O mixing ratios. Our results indicate a pronounced seasonal pattern with minimum N2O mixing ratios in late summer, associated with a maximum in δ15Nbulk and a minimum in intramolecular 15N site preference (δ15NSP). This pattern is most likely due to stratosphere–troposphere exchange (STE), which delivers N2O-depleted but 15N-enriched air from the stratosphere into the troposphere. Variability in δ15NSP induced by changes in STE may be masked by biogeochemical N2O production processes in late summer, which are possibly dominated by a low-δ15NSP pathway of N2O production (denitrification), providing an explanation for the observed seasonality of δ15NSP. Footprint analyses and atmospheric transport simulations of N2O for Jungfraujoch suggest that regional emissions from the planetary boundary layer contribute to seasonal variations of atmospheric N2O isotopic composition at Jungfraujoch, albeit more clearly for δ15NSP and δ18O than for δ15Nbulk. With the time series of 5 years, we obtained a significant interannual trend for δ15Nbulk after deseasonalization (-0.052±0.012 ‰ a−1), indicating that the atmospheric N2O increase is due to isotopically depleted N2O sources. We estimated the average isotopic signature of anthropogenic N2O sources with a two-box model to be -8.6±0.6 ‰ for δ15Nbulk, 34.8±3 ‰ for δ18O and 10.7±4 ‰ for δ15NSP. Our study demonstrates that seasonal variation of N2O isotopic composition in the background atmosphere is important when determining interannual trends. More frequent, high-precision and interlaboratory-compatible measurements of atmospheric N2O isotopocules, especially for δ15NSP, are needed to better constrain anthropogenic N2O sources and thus the contribution of biogeochemical processes to N2O growth on the global scale.

scholarly journals The isotopic composition of atmospheric nitrous oxide observed at the high-altitude research station Jungfraujoch, Switzerland

2019 ◽  
Author(s):  
Longfei Yu ◽  
Eliza Harris ◽  
Stephan Henne ◽  
Sarah Eggleston ◽  
Martin Steinbacher ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Isotopic Composition ◽  
High Altitude ◽  
High Precision ◽  
Large Scale ◽  
Late Summer ◽  
Site Preference ◽  
Research Station ◽  
N2o Production ◽  
Mixing Ratios

Abstract. Atmospheric nitrous oxide (N2O) levels have been continuously growing since preindustrial times. Mitigation requires information about sources and sinks on the regional and global scales. Isotopic composition of N2O in the atmosphere could contribute valuable constraints. However, isotopic records of N2O in the unpolluted atmosphere remain too scarce for large-scale N2O models. Here, we report the results of discrete air samples collected weekly to bi-weekly over a five-year period at the high-altitude research station Jungfraujoch, located in central Switzerland. High-precision N2O isotopic measurements were made using a recently developed preconcentration-laser spectroscopy technique. The measurements of discrete samples were accompanied by in situ continuous measurements of N2O mixing ratios. Our results indicate a pronounced seasonal pattern with minimum N2O mixing ratios in late summer, associated with a maximum in δ15Nbulk and a minimum in intramolecular 15N site preference (δ15NSP). This pattern is most likely due to stratosphere-troposphere exchange (STE), which delivers N2O-depleted but 15N-enriched air from the stratosphere into the troposphere. Variability in δ15NSP induced by changes in STE may be masked by biogeochemical N2O production processes in late summer, which are possibly dominated by a low-δ15NSP pathway of N2O production (denitrification), providing an explanation for the observed seasonality of δ15NSP. Footprint analyses and atmospheric transport simulations of N2O for Jungfraujoch suggest that regional emissions from the planetary boundary layer contribute to seasonal variations of atmospheric N2O isotopic composition at Jungfraujoch, albeit more clearly for δ15NSP and δ18O than for δ15Nbulk. With the time-series of five years, we obtained a significant interannual trend for δ15Nbulk after deseasonalization (−0.052±0.012 ‰ a−1), indicating that the atmospheric N2O increase is due to isotopically depleted N2O sources. We estimated the average isotopic signature of anthropogenic N2O sources with a two-box model to be −8.6±0.6 ‰ for δ15Nbulk, 34.8±3 ‰ for δ18O and 10.7±4 ‰ for δ15NSP. Our study demonstrates that seasonal variation of N2O isotopic composition in the background atmosphere is important when determining interannual trends. More frequent, high-precision and inter-laboratory compatible measurements of atmospheric N2O isotopocules, especially for δ15NSP, are needed to better constrain anthropogenic N2O sources, and thus the contribution of biogeochemical processes to N2O growth on the global scale.

Changes in alveolar and arterial gas tensions as related to altitude and age

1964 ◽  
Vol 19 (1) ◽  
pp. 21-24 ◽  
Author(s):  
James W. Terman ◽  
Jerry L. Newton
Keyword(s):  
High Altitude ◽  
Pulmonary Ventilation ◽  
Research Station ◽  
Age Changes ◽  
Altitude Acclimatization ◽  
Ventilation Perfusion Ratio ◽  
Early Phases ◽  
Chilean Andes

In the summer of 1962 at the White Mountain Research Station the early phases of altitude acclimatization were studied in six of the surviving eight members of the 1935 expedition to the Chilean Andes; they were from 58 to 71 years of age. Alveolar and arterial Po2 and Pco2 were determined for each man a few hours after arrival at 3,093 m and at 3,800 and 4,343 m over the next few days. The effects of age were superimposed on the classical responses to high altitude. The arterial and alveolar Pco2 values showed no significant gradient; the alveolar Pco2 was found to be lower for a given altitude than 27 years before. For example, their average alveolar Pco2 at 4,700 m in 1935 was 27.7 mm Hg as opposed to 25.1 mm Hg at 4,343 m in 1962. The case of Hall was exceptional: his alveolar Pco2 ranged from 21 to 24 mm Hg regardless of altitude for his sojourn of 22 days. In 1935 these six men had a mean A-a Po2 gradient of +3.0 mm Hg at 4,700 m, while in 1962 the gradient over the three altitudes was +12.4 mm Hg. These findings would likely be explained partially by age changes in the pulmonary ventilation-perfusion ratio. acclimatization; pulmonary ventilation-perfusion ratio; alveolar-arterial Po2 and Pco2 gradients; alveolar hyperventilation; aging and altitude Submitted on February 19, 1963

Inversion Approach to Validate Mercury Emissions Based on Background Air Monitoring at the High Altitude Research Station Jungfraujoch (3580 m)

2017 ◽  
Vol 51 (5) ◽  
pp. 2846-2853 ◽  
Author(s):  
Basil Denzler ◽  
Christian Bogdal ◽  
Stephan Henne ◽  
Daniel Obrist ◽  
Martin Steinbacher ◽  
...  
Keyword(s):  
High Altitude ◽  
Air Monitoring ◽  
Research Station ◽  
Mercury Emissions ◽  
Background Air

Source identification of aerosol chemical composition in the Atlas region of North Africa.

2021 ◽  
Author(s):  
Nabil Deabji ◽  
Khanneh Wadinga Fomba ◽  
Eduardo José dos Santos Souza ◽  
Hartmut Herrmann
Keyword(s):  
High Altitude ◽  
Complex Mixture ◽  
Saharan Dust ◽  
Atmospheric Composition ◽  
Urban Site ◽  
Chemical Components ◽  
Research Station ◽  
African Region ◽  
Aerosol Composition ◽  
The Impact

<p>Aerosol particles are important constituents of the atmosphere due to their role in controlling climate-related processes. In addition, their impacts on air quality and human health make it essential to study. However, the characterization and the identification of natural and anthropogenic atmospheric particles can be challenging due to the complex mixture occurring during atmospheric transport. Background locations such as high-altitude sites provide valuable infrastructure for obtaining representative data for understanding various pathways for aerosol interactions useful in assessing atmospheric composition. However, information about aerosol characteristics at high-altitude in the African regions and their relation to urban aerosol composition is still not well understood. In the present study, PM<sub>10</sub> and PM<sub>2.5</sub> particulate matter was characterized at two different sites in the North African region of Morocco. A background site located at the newly established AM5 research station in the Middle Atlas region at an altitude of 2100 m and an urban site situated in a polluted city, Fez. The goal was to determine chemical components, evaluate Saharan dust’s role on the PM10 concentrations between the sites, and assess the impact of urban pollution on background aerosol composition. The results indicate that the background aerosol composition is influenced by both regional and trans-regional transport. Despite the site's proximity to the Sahara Desert, the deserts influence on the atmospheric composition was observed for only 22% of the time and this was mainly seasonal. Marine air masses were more dominant with a mixture of sea salt and polluted aerosol from the coastal regions especially during wintertime. Furthermore, high concentrations of mineral dust were observed during the daytime due to the resuspension of road dust. At the same time, an increase of PAHs and anthropogenic metals such as Pb, Ni, and Cu were found during the nighttime because of the boundary layer variation. The Fez's urban site is characterized by a high contribution of elemental carbon (6%) and organic biomass tracers (3%) such as Levoglucosane and 4-nitrophenol.</p>

The effectiveness of dicyandiamide in reducing nitrous oxide emissions from a cattle-grazed, winter forage crop in Southland, New Zealand

2008 ◽  
Vol 48 (2) ◽  
pp. 160 ◽  
Author(s):  
L. C. Smith ◽  
C. A. M. de Klein ◽  
R. M. Monaghan ◽  
W. D. Catto
Keyword(s):  
Nitrous Oxide ◽  
New Zealand ◽  
Nitrous Oxide Emissions ◽  
N2o Emissions ◽  
Research Station ◽  
Forage Crops ◽  
N Losses ◽  
Forage Crop ◽  
Spring Period ◽  
Simulated Grazing

A study was conducted in Southland, New Zealand to: (i) measure nitrous oxide (N2O) emissions and nitrate (NO3–-N) leaching losses from a cattle-grazed, winter forage crop; and (ii) quantify the effect of dicyandiamide (DCD) in reducing these losses. Drainage losses were measured for 12 months (December 2005–November 2006) from a December-sown kale crop using 12 hydrologically isolated drainage plots at the Woodlands Research Station. N2O emissions were measured for 6 months (June–November) following simulated grazing of the crop in mid-June. N2O emissions from the bare ground following grazing of the crop amounted to 3.6 kg nitrogen (N)/ha for the winter–spring period. This figure is higher than that measured for pasture on the same soil type over a similar period. DCD application significantly reduced N2O emissions for the whole crop area by 25% over this period and reduced the N2O emission factor for urine by 54%. DCD application increased the length of time mineral N (0–10 cm soil depth) was maintained in the ammonium form and significantly reduced soil NO3–-N levels for 6 weeks following the simulated grazing. Annual NO3–-N losses in drainage under this winter forage crop were relatively high at 79 kg N/ha.year, with the majority of this (67%) being lost over the wet summer months (December–January rainfall 434 mm or 200% of normal) during crop growth. The application of DCD following the grazing resulted in a 47% decrease in NO3–-N leached over the winter–spring period (26 kg N/ha v. 14 kg N/ha) with this equating to a 29% decrease over the full 12-month measurement period. This study suggested that winter forage crops are major contributors to N losses from livestock farming systems in Southland and that DCD application following the grazing of such crops by cattle can significantly reduce N2O emissions and leaching N losses.

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