Investigation of atmospheric hydrogen cyanide: a modelling perspective

2021 ◽  
Author(s):  
Antonio G. Bruno ◽  
Jeremy J. Harrison ◽  
David P. Moore ◽  
Martyn P. Chipperfield ◽  
Richard J. Pope
Keyword(s):  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Hydrogen Cyanide ◽  
Three Dimensional ◽  
Oxidation Reactions ◽  
Loss Mechanism ◽  
Mixing Ratios ◽  
The Individual ◽  
Atmospheric Loss ◽  
Physical And Chemical

<p>Hydrogen cyanide (HCN) is one of the most abundant cyanides present in the global atmosphere, and is a tracer of biomass burning, especially for peatland fires. The HCN lifetime is 2–5 months in the troposphere but several years in the stratosphere. Understanding the physical and chemical mechanisms of HCN variability is important due to its non-negligible role in the nitrogen cycle. The main source of tropospheric HCN is biomass burning with minor contributions from industry and transport. The main loss mechanism of atmospheric HCN is the reaction with the hydroxyl radical (OH). Ocean uptake is also important, while in the stratosphere oxidation by reaction with O(<sup>1</sup>D) needs to be considered.</p><p>HCN variability can be investigated using chemical model simulations, such as three-dimensional (3-D) chemical transport models (CTMs). Here we use an adapted version of the TOMCAT 3-D CTM at a 1.2°x1.2° spatial resolution from the surface to ~60 km for 12 idealised HCN tracers which quantify the main loss mechanisms of HCN, including ocean uptake, atmospheric oxidation reactions and their combinations. The TOMCAT output of the HCN distribution in the period 2004-2020 has been compared with HCN profiles measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) over an altitude grid from 6 to 42 km. HCN model data have also been compared with ground-based measurements of HCN columns from NDACC FTIR stations and with in-situ volume mixing ratios (VMRs) from NOAA ground-based measurement sites.</p><p>The model outputs for the HCN tracer with full treatment of the loss processes generally agree well with ACE-FTS measurements, as long as we use recent laboratory values for the atmospheric loss reactions. Diagnosis of the individual loss terms shows that decay of the HCN profile in the upper stratosphere is due mainly to the O(<sup>1</sup>D) sink. In order to test the magnitude of the tropospheric OH sink and the magnitude of the ocean sink, we also show the comparisons of the model tracers with surface-based observations. The implications of our results for understanding HCN and its variability are then discussed.</p>

scholarly journals A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere

2012 ◽  
Vol 5 (1) ◽  
pp. 947-978 ◽  
Author(s):  
J. L. Ambrose ◽  
Y. Zhou ◽  
K. Haase ◽  
H. R. Mayne ◽  
R. Talbot ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Hydrogen Cyanide ◽  
Regional Scale ◽  
Proton Transfer Reaction ◽  
Mean Value ◽  
Porous Polymer ◽  
Lower Atmosphere ◽  
Atmospheric Conditions ◽  
Mixing Ratios ◽  
And Performance

Abstract. A gas-chromatographic (GC) instrument was developed for measuring hydrogen cyanide (HCN) in the lower atmosphere. The main features of the instrument are (1) a cryogen-free cooler for sample dehumidification and enrichment, (2) a porous polymer PLOT column for analyte separation, (3) a flame thermionic detector (FTD) for sensitive and selective detection and (4) a dynamic dilution system for calibration. We deployed the instrument for a ~4 month period from January–June 2010 at the AIRMAP atmospheric monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of measurements made during 3–31 March is presented here with a detailed description of the instrument features and performance characteristics. The temporal resolution of the measurements was ~20 min, with a 75 s sample capture time. The 1σ measurement precision was <10% and the instrument response linearity was excellent on a calibration scale of 0.10–0.75 ppbv (±5%). The estimated method detection limit (MDL) and accuracy were 0.021 ppbv and 15%, respectively. From 3–31 March 2010, ambient HCN mixing ratios ranged from 0.15–1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared to agree well with tropospheric column measurements reported previously. The GC-FTD HCN measurements were strongly correlated with acetonitrile (CH3CN) measured concurrently with a proton transfer-reaction mass spectrometer (PTR-MS), as anticipated given our understanding that the nitriles share a common primary biomass burning source to the global atmosphere. The nitriles were overall only weakly correlated with CO, which is reasonable considering the greater diversity of sources for CO. However, strong correlations with CO were observed on several nights under stable atmospheric conditions and suggest regional combustion-based sources for the nitriles. These results demonstrate that the GC-FTD instrument is capable of making long term, in-situ measurements of HCN in the lower atmosphere. To date, similar measurements have not been performed, yet they are critically needed to (1) better evaluate the regional scale distribution of HCN in the atmosphere and (2) discern the influence of biomass burning on surface air composition in remote regions.

scholarly journals Hydrogen cyanide in the upper troposphere: GEM-AQ simulation and comparison with ACE-FTS observations

2009 ◽  
Vol 9 (1) ◽  
pp. 2165-2194 ◽  
Author(s):  
A. Lupu ◽  
J. W. Kaminski ◽  
L. Neary ◽  
J. C. McConnell ◽  
K. Toyota ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Atmospheric Chemistry ◽  
Hydrogen Cyanide ◽  
Weather Forecasting ◽  
Boreal Summer ◽  
Air Quality Model ◽  
Quality Model ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
The Tropics

Abstract. We investigate the spatial and temporal distribution of hydrogen cyanide (HCN) in the upper troposphere through numerical simulations and comparison with observations from a space-based instrument. To perform the simulations, we used the Global Environmental Multiscale Air Quality model (GEM-AQ), which is based on the three-dimensional global multiscale model developed by the Meteorological Service of Canada for operational weather forecasting. The model was run for the period 2004–2006 on a 1.5°×1.5° global grid with 28 hybrid vertical levels from the surface up to 10 hPa. Objective analysis data from the Canadian Meteorological Centre were used to update the meteorological fields every 24 h. Fire emission fluxes of gas species were generated by using year-specific inventories of carbon emissions with 8-day temporal resolution from the Global Fire Emission Database (GFED) version 2. The model output is compared with HCN profiles measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) instrument onboard the Canadian SCISAT-1 satellite. High values of up to a few ppbv are observed in the tropics in the Southern Hemisphere; the enhancement in HCN volume mixing ratios in the upper troposphere is most prominent in October. Low upper-tropospheric mixing ratios of less than 100 pptv are mostly recorded at middle and high latitudes in the Southern Hemisphere in May–July. Mixing ratios in Northern Hemisphere peak in the boreal summer. The amplitude of the seasonal variation is less pronounced than in the Southern Hemisphere. Our model results show that in the upper troposphere GEM-AQ performs well globally for all seasons, except at Northern high and middle latitudes in summer, where the model has a large negative bias, and in the tropics in winter and spring, where it exhibits large positive bias. This may reflect inaccurate emissions or possible inaccuracies in the emission profile. The model is able to explain most of the observed variability in the upper troposphere HCN field, including the interannual variations in the observed mixing ratio. The estimated average global emission equals 1.3 Tg N yr−1. The average atmospheric burden is 0.53 Tg N, and the corresponding lifetime is 4.9 months.

scholarly journals Atmospheric pseudohalogen chemistry

2004 ◽  
Vol 4 (5) ◽  
pp. 5381-5405 ◽  
Author(s):  
D. J. Lary
Keyword(s):  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Hydrogen Cyanide ◽  
Lower Stratosphere ◽  
Observational Evidence ◽  
Reactive Nitrogen ◽  
Emission Inventories ◽  
Atmospheric Nitrogen ◽  
Ion Chemistry ◽  
Chemical Decomposition

Abstract. There are at least three reasons why hydrogen cyanide is likely to be significant for atmospheric chemistry. The first is well known, HCN is a product and marker of biomass burning. However, if a detailed ion chemistry of lightning is considered then it is almost certain than in addition to lightning producing NOx, it also produces HOx and HCN. Unlike NOx and HOx, HCN is long-lived and could therefore be a useful marker of lightning activity. Observational evidence is considered to support this view. Thirdly, the chemical decomposition of HCN leads to the production of small amounts of CN and NCO. NCO can be photolyzed in the visible portion of the spectrum yielding N atoms. The production of N atoms is significant as it leads to the titration of nitrogen from the atmosphere via N+N→N2. Normally the only modelled source of N atoms is NO photolysis which happens largely in the UV Schumann-Runge bands. However, NCO photolysis occurs in the visible and so could be involved in titration of atmospheric nitrogen in the lower stratosphere and troposphere. HCN emission inventories are worthy of attention. The CN and NCO radicals have been termed pseudohalogens since the 1920s. They are strongly bound, univalent, radicals with an extensive and varied chemistry. The products of the atmospheric oxidation of HCN are NO, CO and O3. N+CH4 and N+CH3OH are found to be important sources of HCN. Including the pseudohalogen chemistry gives a small increase in ozone and total reactive nitrogen (NOy).

scholarly journals ACE-FTS observations of pyrogenic trace species in boreal biomass burning plumes during BORTAS

2012 ◽  
Vol 12 (12) ◽  
pp. 31629-31661 ◽  
Author(s):  
K. A. Tereszchuk ◽  
G. González Abad ◽  
C. Clerbaux ◽  
J. Hadji-Lazaro ◽  
D. Hurtmans ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Biomass Burning ◽  
Atmospheric Chemistry ◽  
Forest Fires ◽  
Atmospheric Composition ◽  
Fire Season ◽  
Satellite Measurement ◽  
Mixing Ratios ◽  
Trace Species ◽  
The Impact

Abstract. To further our understanding of the effects of biomass burning emissions on atmospheric composition, the Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) campaign was conducted on 12 July to 3 August 2011 during the Boreal forest fire season in Canada. The simultaneous aerial, ground and satellite measurement campaign sought to record instances of Boreal biomass burning to measure the tropospheric volume mixing ratios (VMRs) of short- and long-lived trace molecular species from biomass burning emissions. The goal was to investigate the connection between the composition and the distribution of these pyrogenic outflows and their resulting perturbation to atmospheric chemistry, with particular focus on oxidant species to determine the overall impact on the oxidizing capacity of the free troposphere. Measurements of pyrogenic trace species in Boreal biomass burning plumes were made by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) onboard the Canadian Space Agency (CSA) SCISAT-1 satellite during the BORTAS campaign. Even though most biomass burning smoke is typically confined to the boundary layer, emissions are often injected directly into the upper troposphere via fire-related convective processes, thus allowing space-borne instruments to measure these pyrogenic outflows. An extensive set of 15 molecules, CH3OH, CH4, C2H2, C2H6, C3H6O, CO, HCN, HCOOH, HNO3, H2CO, NO, NO2, OCS, O3 and PAN have been analyzed. Included in this analysis is the calculation of age-dependent sets of enhancement ratios for each of the species.

scholarly journals Hydrogen cyanide in the upper troposphere: GEM-AQ simulation and comparison with ACE-FTS observations

2009 ◽  
Vol 9 (13) ◽  
pp. 4301-4313 ◽  
Author(s):  
A. Lupu ◽  
J. W. Kaminski ◽  
L. Neary ◽  
J. C. McConnell ◽  
K. Toyota ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Atmospheric Chemistry ◽  
Hydrogen Cyanide ◽  
Boreal Summer ◽  
Air Quality Model ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
The Tropics

Abstract. We investigate the spatial and temporal distribution of hydrogen cyanide (HCN) in the upper troposphere through numerical simulations and comparison with observations from a space-based instrument. To perform the simulations, we used the Global Environmental Multiscale Air Quality model (GEM-AQ), which is based on the three-dimensional global multiscale model developed by the Meteorological Service of Canada for operational weather forecasting. The model was run for the period 2004–2006 on a 1.5°×1.5° global grid with 28 hybrid vertical levels from the surface up to 10 hPa. Objective analysis data from the Canadian Meteorological Centre were used to update the meteorological fields every 24 h. Fire emission fluxes of gas species were generated by using year-specific inventories of carbon emissions with 8-day temporal resolution from the Global Fire Emission Database (GFED) version 2. The model output is compared with HCN profiles measured by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) instrument onboard the Canadian SCISAT-1 satellite. High values of up to a few ppbv are observed in the tropics in the Southern Hemisphere; the enhancement in HCN volume mixing ratios in the upper troposphere is most prominent in October. Low upper-tropospheric mixing ratios of less than 100 pptv are mostly recorded at middle and high latitudes in the Southern Hemisphere in May–July. Mixing ratios in Northern Hemisphere peak in the boreal summer. The amplitude of the seasonal variation is less pronounced than in the Southern Hemisphere. The comparison with the satellite data shows that in the upper troposphere GEM-AQ performs well globally for all seasons, except at northern high and middle latitudes in summer, where the model has a large negative bias, and in the tropics in winter and spring, where it exhibits large positive bias. This may reflect inaccurate emissions or possible inaccuracies in the emission profile. The model is able to explain most of the observed variability in the upper troposphere HCN field, including the interannual variations in the observed mixing ratio. A complementary comparison with daily total columns of HCN from two middle latitude ground-based stations in Northern Japan for the same simulation period shows that the model captures the observed seasonal variation and also points to an underestimation of model emissions in the Northern Hemisphere in the summer. The estimated average global emission equals 1.3 Tg N yr−1. The average atmospheric burden is 0.53 Tg N, and the corresponding lifetime is 4.9 months.

scholarly journals A gas chromatographic instrument for measurement of hydrogen cyanide in the lower atmosphere

2012 ◽  
Vol 5 (6) ◽  
pp. 1229-1240 ◽  
Author(s):  
J. L. Ambrose ◽  
Y. Zhou ◽  
K. Haase ◽  
H. R. Mayne ◽  
R. Talbot ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Hydrogen Cyanide ◽  
Regional Scale ◽  
Proton Transfer Reaction ◽  
Mean Value ◽  
Porous Polymer ◽  
Lower Atmosphere ◽  
Atmospheric Conditions ◽  
Mixing Ratios ◽  
And Performance

Abstract. A gas-chromatographic (GC) instrument was developed for measuring hydrogen cyanide (HCN) in the lower atmosphere. The main features of the instrument are (1) a cryogen-free cooler for sample dehumidification and enrichment, (2) a porous polymer PLOT column for analyte separation, (3) a flame thermionic detector (FTD) for sensitive and selective detection, and (4) a dynamic dilution system for calibration. We deployed the instrument for a ∼4 month period from January–June, 2010 at the AIRMAP atmospheric monitoring station Thompson Farm 2 (THF2) in rural Durham, NH. A subset of measurements made during 3–31 March is presented here with a detailed description of the instrument features and performance characteristics. The temporal resolution of the measurements was ~20 min, with a 75 s sample capture time. The 1σ measurement precision was <10% and the instrument response linearity was excellent on a calibration scale of 0.10–0.75 ppbv (±5%). The estimated method detection limit (MDL) and accuracy were 0.021 ppbv and 15%, respectively. From 3–31 March 2010, ambient HCN mixing ratios ranged from 0.15–1.0 ppbv (±15%), with a mean value of 0.36 ± 0.16 ppbv (1σ). The approximate mean background HCN mixing ratio of 0.20 ± 0.04 ppbv appeared to agree well with tropospheric column measurements reported previously. The GC-FTD HCN measurements were strongly correlated with acetonitrile (CH3CN) measured concurrently with a proton transfer-reaction mass spectrometer (PTR-MS), as anticipated given our understanding that the nitriles share a common primary biomass burning source to the global atmosphere. The nitriles were overall only weakly correlated with carbon monoxide (CO), which is reasonable considering the greater diversity of sources for CO. However, strong correlations with CO were observed on several nights under stable atmospheric conditions and suggest regional combustion-based sources for the nitriles. These results demonstrate that the GC-FTD instrument is capable of making long term, in-situ measurements of HCN in the lower atmosphere. To date, similar measurements have not been performed, yet they are critically needed to (1) better evaluate the regional scale distribution of HCN in the atmosphere and (2) discern the influence of biomass burning on surface air composition in remote regions.

Atmospheric Chemistry of Gaseous Oxidized Mercury at a Coastal Site in Atlantic Canada

2019 ◽  
Vol 77 (3) ◽  
pp. 1137-1149
Author(s):  
Irene Cheng ◽  
Leiming Zhang ◽  
Huiting Mao ◽  
Zhuyun Ye ◽  
Robert Keenan
Keyword(s):  
Atmospheric Chemistry ◽  
Liquid Water Content ◽  
Oxidation Reactions ◽  
Air Masses ◽  
Mixing Ratios ◽  
Second Stage ◽  
Chemical Scheme ◽  
Gas Phase Oxidation ◽  
Marine Air ◽  
Gaseous Oxidized Mercury

Abstract A chemistry box model containing a comprehensive suite of mercury (Hg) oxidation mechanisms involving O3, OH, H2O2, Br, BrO, NO2, HO2, and other oxidants was used to simulate the formation of gaseous oxidized mercury (GOM) and understand the chemical processes driving the observed trends in GOM at Kejimkujik, Nova Scotia, Canada. Simulations were conducted using chemical schemes with and without oxidation by O3 and OH. The major oxidants of Hg are O3 and OH (79%), H2O2 (10%), Br with second-stage HgBr oxidation by NO2 (7%), and BrO (3%) in simulations where all GEM oxidation reactions were considered simultaneously. In an alternative chemical scheme without gas-phase oxidation by O3 and OH, the dominant GOM species were HgBrNO2 (58%) and HgBrO (23.5%). Using this chemical scheme, the model reproduced the observed GOM at sub-ppqv Br2 mixing ratios. In the scheme with O3 and OH, the variability in GOM between seasons and between continental and marine air masses was mainly due to the variability in gaseous elemental Hg, O3, OH, and aerosol liquid water content (LWC). LWC governs the partitioning of GOM to the aerosol aqueous phase in the model. In the scheme without O3 and OH, the variability in GOM by season and airmass origin strongly depends on Br and BrO, suggesting that rigorous validation of modeled Br and BrO data are essential for improving the model predictions of GOM in coastal environments.

Semi-automated methods for 3-D reconstruction of macromolecular complexes

1995 ◽  
Vol 53 ◽  
pp. 42-43
Author(s):  
B. Carragher ◽  
M. Whittaker
Keyword(s):  
Three Dimensional ◽  
Time Saving ◽  
Macromolecular Complexes ◽  
Symmetry Properties ◽  
Dimensional Reconstruction ◽  
Experienced Operator ◽  
Projection Images ◽  
The Individual ◽  
Natural Symmetry

Techniques for three-dimensional reconstruction of macromolecular complexes from electron micrographs have been successfully used for many years. These include methods which take advantage of the natural symmetry properties of the structure (for example helical or icosahedral) as well as those that use single axis or other tilting geometries to reconstruct from a set of projection images. These techniques have traditionally relied on a very experienced operator to manually perform the often numerous and time consuming steps required to obtain the final reconstruction. While the guidance and oversight of an experienced and critical operator will always be an essential component of these techniques, recent advances in computer technology, microprocessor controlled microscopes and the availability of high quality CCD cameras have provided the means to automate many of the individual steps.During the acquisition of data automation provides benefits not only in terms of convenience and time saving but also in circumstances where manual procedures limit the quality of the final reconstruction.

Phonetic iconicity in the evaluative morphology of a sample of Indo-European, Niger-Congo and Austronesian languages

2010 ◽  
Vol 3 (2) ◽  
pp. 156-180 ◽  
Author(s):  
Renáta Gregová ◽  
Lívia Körtvélyessy ◽  
Július Zimmermann
Keyword(s):  
Three Dimensional ◽  
Sound Symbolism ◽  
Three Dimensional Model ◽  
Austronesian Languages ◽  
Place Of Articulation ◽  
European Languages ◽  
Phonetic Symbolism ◽  
The Individual ◽  
Core Vocabulary

Universals Archive (Universal #1926) indicates a universal tendency for sound symbolism in reference to the expression of diminutives and augmentatives. The research ( Štekauer et al. 2009 ) carried out on European languages has not proved the tendency at all. Therefore, our research was extended to cover three language families – Indo-European, Niger-Congo and Austronesian. A three-step analysis examining different aspects of phonetic symbolism was carried out on a core vocabulary of 35 lexical items. A research sample was selected out of 60 languages. The evaluative markers were analyzed according to both phonetic classification of vowels and consonants and Ultan's and Niewenhuis' conclusions on the dominance of palatal and post-alveolar consonants in diminutive markers. Finally, the data obtained in our sample languages was evaluated by means of a three-dimensional model illustrating the place of articulation of the individual segments.

Incorporation of spatial variability in modeling non-point source groundwater nitrate pollution

1996 ◽  
Vol 33 (4-5) ◽  
pp. 233-240 ◽  
Author(s):  
F. S. Goderya ◽  
M. F. Dahab ◽  
W. E. Woldt ◽  
I. Bogardi
Keyword(s):  
Spatial Variability ◽  
Point Source ◽  
Three Dimensional ◽  
Nitrate Contamination ◽  
Geostatistical Simulation ◽  
Chemical Measurements ◽  
Spatially Distributed ◽  
Potential Benefits ◽  
Zone Modeling ◽  
Physical And Chemical

A methodology for incorporation of spatial variability in modeling non-point source groundwater nitrate contamination is presented. The methodology combines geostatistical simulation and unsaturated zone modeling for estimating the amount of nitrate loading to groundwater. Three dimensional soil nitrogen variability and 2-dimensional crop yield variability are used in quantifying potential benefits of spatially distributed nitrogen input. This technique, in combination with physical and chemical measurements, is utilized as a means of illustrating how the spatial statistical properties of nitrate leaching can be obtained for different scenarios of fixed and variable rate nitrogen applications.

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