The Experts below are selected from a list of 369 Experts worldwide ranked by ideXlab platform
F C Fehsenfeld - One of the best experts on this subject based on the ideXlab platform.
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Nonmethane Hydrocarbon and oxy Hydrocarbon measurements during the 2002 new england air quality study
Journal of Geophysical Research, 2004Co-Authors: P D Goldan, F C Fehsenfeld, William C Kuster, E J Williams, P C Murphy, J F MeagherAbstract:[1] Nonmethane Hydrocarbons (NMHCs) and oxy Hydrocarbons (oxy HCs) were measured aboard the National Oceanic and Atmospheric Administration research vessel Ronald H. Brown during the New England Air Quality Study from 13 July to 10 August 2002 by an online dual gas chromatographic instrument with two separate analytical columns equipped, respectively, with flame ionization and mass spectrometer detectors. Measurements, taken each half hour, included C2 to C10 alkanes, C2 to C5 alkenes, alcohols and ketones, C6 to C9 aromatics, and biogenic volatile compounds including six monoterpenes, isoprene and its immediate oxidation products methacrolein and methylvinylketone. All compounds have been categorized by their contribution to the OH loss rate calculated for 298K and 1 atm. Large temporal variability was observed for all compounds. Airflow from the Providence, Rhode Island/Boston, Massachusetts, urban corridor northeast to the New Hampshire coast was usually heavily laden with NMHCs and oxy HCs of anthropogenic origin. Comparison of specific compound ratios with automotive tunnel studies suggested that these were predominantly mobile source emissions. When such flow occurred during daylight hours, these urban plumes were accompanied by increases in ozone in the 80 to 120 ppbv range. About equally as often, much less chemically mature NMHC plumes were encountered near the New Hampshire coast. Ozone was titrated out of these latter plumes, and the unusually high mixing ratios of C4 and C5 alkenes suggested that their source was partly gasoline vapor release rather than mobile source emissions. In the New England coastal region explored, in spite of the large anthropogenic NMHC input during periods of offshore flow, OH loss with Hydrocarbons was frequently dominated by compounds of biogenic origin. During periods of cleaner marine air inflow the OH loss rate was dominated by reaction with methane and with oxy HCs, predominantly acetone, formaldehyde, and acetaldehyde.
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correction to Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] In the paper ‘‘Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE): Task 4, ambient air’’ by E. C. Apel, J. G. Calvert, T. M. Gilpin, F. Fehsenfeld, and W. A. Lonneman, a typesetting error appears in section 3.5.2, paragraph [28]. In the sixth sentence, the equation defining di should read as follows: di 1⁄4 participanti NMHC value ð Þ= NCAR NOMHICE referencei NMHC value ð Þ: JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D12, 4359, doi:10.1029/2003JD003783, 2003
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Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to assess the accuracy and comparability of Nonmethane Hydrocarbon (NMHC) measurements from research groups around the globe. This is being accomplished by conducting a series of intercomparisons, called Tasks, of prepared mixtures or collected ambient air. This paper presents results for an ambient air challenge sample as part of the fourth NOMHICE installment (Task 4). Twenty-three laboratories participated in Task 4, and 30 overall analytical results are compared. The air sample provided a wide dynamic range of mixing ratios (parts per trillion by volume (pptv) to parts per billion by volume (ppbv)) as well as large number of compounds (>100). Coelutions of NMHCs with other volatile organic compounds (VOCs) such as oxygenated VOCs are shown to make the analysis of whole air samples more challenging than for prepared standard mixtures. Individual canisters containing the air sample were prepared and analyzed by the NOMHICE group at the National Center for Atmospheric Research (NCAR-NOMHICE), sent to participants for analysis, and reanalyzed upon return to NCAR-NOMHICE. The mixing ratio of propylene increased by 10% (14 pptv) in the canisters with time, and some of the less volatile compounds decreased in the canisters with time; however, the majority of the compounds were stable throughout the experiment. Participants were asked to identify and quantify as many compounds as possible with their analytical techniques and to submit their results to NCAR-NOMHICE scientists. Fifty-four compounds were chosen for the intercomparison. Eight hundred eighty-three measurements were compared overall; the average of the mean ratios of the participants' results to NCAR-NOMHICE results was 1.03. The participants' results were combined and averaged for each individual NMHC measured and compared to the reference results; thirty-three of the 54 compounds agreed to within ±20% of the reference results. Individual analyses from participant laboratories were compared and ranked with respect to agreement with the reference values; the ranking was reconciled with the analytical procedures employed for each analysis. From this, recommendations were derived for preferred analytical techniques and practice. Recommendations include but are not limited to the following: (1) National Institute of Standards and Technology (NIST) standards or NIST-traceable standards should be used and, for mass spectrometric analyses, multicomponent NIST-traceable standards should be used; (2) if solid adsorbents are used for preconcentrating NMHCs, extensive tests should be performed to test for artifact formation and compound losses; and (3) for whole air sampling in canisters, subsequent analyses should be performed as soon as is reasonably possible to avoid the potential for compositional changes.
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the Nonmethane Hydrocarbon intercomparison experiment nomhice task 3
Journal of Geophysical Research, 1999Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, D D Parrish, William A LonnemanAbstract:The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to evaluate current analytical methods used to determine mixing ratios of atmospheric Nonmethane Hydrocarbons (NMHCs). A series of planned experiments, or tasks, were implemented to test the analytical methods in a graduated fashion. Tasks 1 and 2 involved relatively simple standard gas mixtures prepared by the National Institute for Standards and Technology (NIST). Results are presented here for task 3 in which a complex mixture containing 60 commonly observed NMHCs at concentrations of 1-30 parts per billion by volume (ppbv) in nitrogen diluent gas was prepared and distributed for analysis to 29 participating laboratories throughout the world. Reference mixing ratios were determined jointly by scientists from the National Center for Atmospheric Research (NCAR) and from the U. S. Environmental Protection Agency (EPA). Participants were asked to identify and quantify the Hydrocarbons present in the mixture and submit their results to NCAR-NOMHICE scientists. The results were encouraging overall. Some laboratories performed extremely well during this exercise whereas other laboratories experienced problems in either identification or quantification or both. It is evident from the comparison of the NCAR-NOMHICE results with both the EPA analysis and the top 11 analyses in the study that very good agreement is achievable between laboratories for mixtures in this concentration range. Some of the largest analytical discrepancies were from laboratories that used in-house standards for their calibration and/or syringe sample injection techniques. A major conclusion from this study is that the use of high-quality gas phase standards, introduced into the measurement instrument in a similar manner to air samples, is an important prerequisite for an accurate analysis.
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spatial and temporal variability of Nonmethane Hydrocarbon mixing ratios and their relation to photochemical lifetime
Journal of Geophysical Research, 1998Co-Authors: B T Jobson, D. R. Blake, F C Fehsenfeld, P D Goldan, W C Kuster, D D Parrish, N J Blake, H NikiAbstract:The relationship between temporal and spatial variability of C2-C8 Nonmethane Hydrocarbon mixing ratios and their HO lifetimes (τ) is presented for samples collected during the 1993 North Atlantic Regional Experiment (NARE) and from other urban and remote sites. The C2-C4 alkanes, acetylene and benzene typically define a trend of the form slnx = Aτ−b where slnx is the standard deviation of the ln of the mixing ratio. The relationship extended over a wider range of Hydrocarbons in winter. The exponent b ranged in value from 0.28±0.023 for winter urban data where C2-C8 Hydrocarbons defined a strongly correlated trend, to 0.56±0.15 for C2-C4 Hydrocarbons at a coastal site in Nova Scotia during NARE. The trends are significantly different from that given by the Junge relationship [Junge, 1974]. Data from the Azores do not display such a trend and were likely influenced by local emissions. Variance trends are a useful analytical tool for examining the validity of Hydrocarbon measurements.
William A Lonneman - One of the best experts on this subject based on the ideXlab platform.
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summer and winter Nonmethane Hydrocarbon emissions from on road motor vehicles in the midwestern united states
Journal of The Air & Waste Management Association, 2005Co-Authors: Glynis C Lough, William A Lonneman, James J Schauer, Mark K AllenAbstract:Abstract On-road vehicle emission rates of Nonmethane Hydrocarbons (NMHCs) were measured in two tunnels in Milwaukee, WI, in summer 2000 and winter 2001. Seasonal ambient temperatures in the Midwestern United States vary more widely than in locations where most studies of NMHC emissions from vehicle fleets have been conducted. Ethanol is the added fuel oxygenate in the area, and, thus, emissions measured here are of interest as other regions phase out methyl tertiary butyl ether and increase the use of ethanol. Total emissions of NMHCs in three types of tunnel tests averaged 4560 ± 800 mg L−1 fuel burned (average ± standard error). To investigate the impact of cold start on vehicle emissions, samples were collected as vehicles exited a parking structure in subzero temperatures. NMHC emissions in the subzero cold-start test were 8830 ± 190 mg L−1 fuel–nearly double the tunnel emissions. Comparison of ambient data for the Milwaukee area with tunnel emissions showed the impact of seasonal differences in fuel...
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correction to Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] In the paper ‘‘Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE): Task 4, ambient air’’ by E. C. Apel, J. G. Calvert, T. M. Gilpin, F. Fehsenfeld, and W. A. Lonneman, a typesetting error appears in section 3.5.2, paragraph [28]. In the sixth sentence, the equation defining di should read as follows: di 1⁄4 participanti NMHC value ð Þ= NCAR NOMHICE referencei NMHC value ð Þ: JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D12, 4359, doi:10.1029/2003JD003783, 2003
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Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to assess the accuracy and comparability of Nonmethane Hydrocarbon (NMHC) measurements from research groups around the globe. This is being accomplished by conducting a series of intercomparisons, called Tasks, of prepared mixtures or collected ambient air. This paper presents results for an ambient air challenge sample as part of the fourth NOMHICE installment (Task 4). Twenty-three laboratories participated in Task 4, and 30 overall analytical results are compared. The air sample provided a wide dynamic range of mixing ratios (parts per trillion by volume (pptv) to parts per billion by volume (ppbv)) as well as large number of compounds (>100). Coelutions of NMHCs with other volatile organic compounds (VOCs) such as oxygenated VOCs are shown to make the analysis of whole air samples more challenging than for prepared standard mixtures. Individual canisters containing the air sample were prepared and analyzed by the NOMHICE group at the National Center for Atmospheric Research (NCAR-NOMHICE), sent to participants for analysis, and reanalyzed upon return to NCAR-NOMHICE. The mixing ratio of propylene increased by 10% (14 pptv) in the canisters with time, and some of the less volatile compounds decreased in the canisters with time; however, the majority of the compounds were stable throughout the experiment. Participants were asked to identify and quantify as many compounds as possible with their analytical techniques and to submit their results to NCAR-NOMHICE scientists. Fifty-four compounds were chosen for the intercomparison. Eight hundred eighty-three measurements were compared overall; the average of the mean ratios of the participants' results to NCAR-NOMHICE results was 1.03. The participants' results were combined and averaged for each individual NMHC measured and compared to the reference results; thirty-three of the 54 compounds agreed to within ±20% of the reference results. Individual analyses from participant laboratories were compared and ranked with respect to agreement with the reference values; the ranking was reconciled with the analytical procedures employed for each analysis. From this, recommendations were derived for preferred analytical techniques and practice. Recommendations include but are not limited to the following: (1) National Institute of Standards and Technology (NIST) standards or NIST-traceable standards should be used and, for mass spectrometric analyses, multicomponent NIST-traceable standards should be used; (2) if solid adsorbents are used for preconcentrating NMHCs, extensive tests should be performed to test for artifact formation and compound losses; and (3) for whole air sampling in canisters, subsequent analyses should be performed as soon as is reasonably possible to avoid the potential for compositional changes.
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the Nonmethane Hydrocarbon intercomparison experiment nomhice task 3
Journal of Geophysical Research, 1999Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, D D Parrish, William A LonnemanAbstract:The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to evaluate current analytical methods used to determine mixing ratios of atmospheric Nonmethane Hydrocarbons (NMHCs). A series of planned experiments, or tasks, were implemented to test the analytical methods in a graduated fashion. Tasks 1 and 2 involved relatively simple standard gas mixtures prepared by the National Institute for Standards and Technology (NIST). Results are presented here for task 3 in which a complex mixture containing 60 commonly observed NMHCs at concentrations of 1-30 parts per billion by volume (ppbv) in nitrogen diluent gas was prepared and distributed for analysis to 29 participating laboratories throughout the world. Reference mixing ratios were determined jointly by scientists from the National Center for Atmospheric Research (NCAR) and from the U. S. Environmental Protection Agency (EPA). Participants were asked to identify and quantify the Hydrocarbons present in the mixture and submit their results to NCAR-NOMHICE scientists. The results were encouraging overall. Some laboratories performed extremely well during this exercise whereas other laboratories experienced problems in either identification or quantification or both. It is evident from the comparison of the NCAR-NOMHICE results with both the EPA analysis and the top 11 analyses in the study that very good agreement is achievable between laboratories for mixtures in this concentration range. Some of the largest analytical discrepancies were from laboratories that used in-house standards for their calibration and/or syringe sample injection techniques. A major conclusion from this study is that the use of high-quality gas phase standards, introduced into the measurement instrument in a similar manner to air samples, is an important prerequisite for an accurate analysis.
Eric C Apel - One of the best experts on this subject based on the ideXlab platform.
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correction to Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] In the paper ‘‘Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE): Task 4, ambient air’’ by E. C. Apel, J. G. Calvert, T. M. Gilpin, F. Fehsenfeld, and W. A. Lonneman, a typesetting error appears in section 3.5.2, paragraph [28]. In the sixth sentence, the equation defining di should read as follows: di 1⁄4 participanti NMHC value ð Þ= NCAR NOMHICE referencei NMHC value ð Þ: JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D12, 4359, doi:10.1029/2003JD003783, 2003
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Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to assess the accuracy and comparability of Nonmethane Hydrocarbon (NMHC) measurements from research groups around the globe. This is being accomplished by conducting a series of intercomparisons, called Tasks, of prepared mixtures or collected ambient air. This paper presents results for an ambient air challenge sample as part of the fourth NOMHICE installment (Task 4). Twenty-three laboratories participated in Task 4, and 30 overall analytical results are compared. The air sample provided a wide dynamic range of mixing ratios (parts per trillion by volume (pptv) to parts per billion by volume (ppbv)) as well as large number of compounds (>100). Coelutions of NMHCs with other volatile organic compounds (VOCs) such as oxygenated VOCs are shown to make the analysis of whole air samples more challenging than for prepared standard mixtures. Individual canisters containing the air sample were prepared and analyzed by the NOMHICE group at the National Center for Atmospheric Research (NCAR-NOMHICE), sent to participants for analysis, and reanalyzed upon return to NCAR-NOMHICE. The mixing ratio of propylene increased by 10% (14 pptv) in the canisters with time, and some of the less volatile compounds decreased in the canisters with time; however, the majority of the compounds were stable throughout the experiment. Participants were asked to identify and quantify as many compounds as possible with their analytical techniques and to submit their results to NCAR-NOMHICE scientists. Fifty-four compounds were chosen for the intercomparison. Eight hundred eighty-three measurements were compared overall; the average of the mean ratios of the participants' results to NCAR-NOMHICE results was 1.03. The participants' results were combined and averaged for each individual NMHC measured and compared to the reference results; thirty-three of the 54 compounds agreed to within ±20% of the reference results. Individual analyses from participant laboratories were compared and ranked with respect to agreement with the reference values; the ranking was reconciled with the analytical procedures employed for each analysis. From this, recommendations were derived for preferred analytical techniques and practice. Recommendations include but are not limited to the following: (1) National Institute of Standards and Technology (NIST) standards or NIST-traceable standards should be used and, for mass spectrometric analyses, multicomponent NIST-traceable standards should be used; (2) if solid adsorbents are used for preconcentrating NMHCs, extensive tests should be performed to test for artifact formation and compound losses; and (3) for whole air sampling in canisters, subsequent analyses should be performed as soon as is reasonably possible to avoid the potential for compositional changes.
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the Nonmethane Hydrocarbon intercomparison experiment nomhice task 3
Journal of Geophysical Research, 1999Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, D D Parrish, William A LonnemanAbstract:The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to evaluate current analytical methods used to determine mixing ratios of atmospheric Nonmethane Hydrocarbons (NMHCs). A series of planned experiments, or tasks, were implemented to test the analytical methods in a graduated fashion. Tasks 1 and 2 involved relatively simple standard gas mixtures prepared by the National Institute for Standards and Technology (NIST). Results are presented here for task 3 in which a complex mixture containing 60 commonly observed NMHCs at concentrations of 1-30 parts per billion by volume (ppbv) in nitrogen diluent gas was prepared and distributed for analysis to 29 participating laboratories throughout the world. Reference mixing ratios were determined jointly by scientists from the National Center for Atmospheric Research (NCAR) and from the U. S. Environmental Protection Agency (EPA). Participants were asked to identify and quantify the Hydrocarbons present in the mixture and submit their results to NCAR-NOMHICE scientists. The results were encouraging overall. Some laboratories performed extremely well during this exercise whereas other laboratories experienced problems in either identification or quantification or both. It is evident from the comparison of the NCAR-NOMHICE results with both the EPA analysis and the top 11 analyses in the study that very good agreement is achievable between laboratories for mixtures in this concentration range. Some of the largest analytical discrepancies were from laboratories that used in-house standards for their calibration and/or syringe sample injection techniques. A major conclusion from this study is that the use of high-quality gas phase standards, introduced into the measurement instrument in a similar manner to air samples, is an important prerequisite for an accurate analysis.
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the Nonmethane Hydrocarbon intercomparison experiment nomhice tasks 1 and 2
Journal of Geophysical Research, 1994Co-Authors: Eric C Apel, Jack G Calvert, F C FehsenfeldAbstract:The NOMHICE program has been designed to evaluate current methods being used to determine the ambient levels of various atmospheric Nonmethane Hydrocarbons, to identify existing problems in these analyses, to correct these problems, and to help ensure quality control of Hydrocarbon analyses made by atmospheric scientists throughout the world. To accomplish this, a series of planned experiments (tasks) is now under way which involves all the common classes of the atmospheric Hydrocarbons: alkanes, alkenes, alkynes, aromatic Hydrocarbons, and the terpenes. The various tasks of the study have been scheduled in order of increasing complexity so that problems can be addressed as they arise. Preliminary results are presented for task 1 and task 2 of a multitask program. Each laboratory used its own analysis and calibration procedures. The first task of NOMHICE involved the circulation of a two-component, gravimetrically prepared, Hydrocarbon mixture of known composition and unknown concentration to 36 participating scientific groups from laboratories throughout the world. This experiment was planned to check on the reliability of the standards employed by each of the participating groups. Task 2 involved the circulation, to participant laboratories, of a more complex, gravimetrically prepared, 16-component Hydrocarbon mixture (unknown composition and concentration) to determine whethermore » suitable separation, identification, and quantification can be made of the individual Hydrocarbons present in the mixture. Further tasks are described which will be carried out in the future. 16 refs., 12 figs., 3 tabs.« less
Jack G Calvert - One of the best experts on this subject based on the ideXlab platform.
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correction to Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] In the paper ‘‘Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE): Task 4, ambient air’’ by E. C. Apel, J. G. Calvert, T. M. Gilpin, F. Fehsenfeld, and W. A. Lonneman, a typesetting error appears in section 3.5.2, paragraph [28]. In the sixth sentence, the equation defining di should read as follows: di 1⁄4 participanti NMHC value ð Þ= NCAR NOMHICE referencei NMHC value ð Þ: JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D12, 4359, doi:10.1029/2003JD003783, 2003
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Nonmethane Hydrocarbon intercomparison experiment nomhice task 4 ambient air
Journal of Geophysical Research, 2003Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, William A LonnemanAbstract:[1] The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to assess the accuracy and comparability of Nonmethane Hydrocarbon (NMHC) measurements from research groups around the globe. This is being accomplished by conducting a series of intercomparisons, called Tasks, of prepared mixtures or collected ambient air. This paper presents results for an ambient air challenge sample as part of the fourth NOMHICE installment (Task 4). Twenty-three laboratories participated in Task 4, and 30 overall analytical results are compared. The air sample provided a wide dynamic range of mixing ratios (parts per trillion by volume (pptv) to parts per billion by volume (ppbv)) as well as large number of compounds (>100). Coelutions of NMHCs with other volatile organic compounds (VOCs) such as oxygenated VOCs are shown to make the analysis of whole air samples more challenging than for prepared standard mixtures. Individual canisters containing the air sample were prepared and analyzed by the NOMHICE group at the National Center for Atmospheric Research (NCAR-NOMHICE), sent to participants for analysis, and reanalyzed upon return to NCAR-NOMHICE. The mixing ratio of propylene increased by 10% (14 pptv) in the canisters with time, and some of the less volatile compounds decreased in the canisters with time; however, the majority of the compounds were stable throughout the experiment. Participants were asked to identify and quantify as many compounds as possible with their analytical techniques and to submit their results to NCAR-NOMHICE scientists. Fifty-four compounds were chosen for the intercomparison. Eight hundred eighty-three measurements were compared overall; the average of the mean ratios of the participants' results to NCAR-NOMHICE results was 1.03. The participants' results were combined and averaged for each individual NMHC measured and compared to the reference results; thirty-three of the 54 compounds agreed to within ±20% of the reference results. Individual analyses from participant laboratories were compared and ranked with respect to agreement with the reference values; the ranking was reconciled with the analytical procedures employed for each analysis. From this, recommendations were derived for preferred analytical techniques and practice. Recommendations include but are not limited to the following: (1) National Institute of Standards and Technology (NIST) standards or NIST-traceable standards should be used and, for mass spectrometric analyses, multicomponent NIST-traceable standards should be used; (2) if solid adsorbents are used for preconcentrating NMHCs, extensive tests should be performed to test for artifact formation and compound losses; and (3) for whole air sampling in canisters, subsequent analyses should be performed as soon as is reasonably possible to avoid the potential for compositional changes.
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the Nonmethane Hydrocarbon intercomparison experiment nomhice task 3
Journal of Geophysical Research, 1999Co-Authors: Eric C Apel, Jack G Calvert, T M Gilpin, F C Fehsenfeld, D D Parrish, William A LonnemanAbstract:The Nonmethane Hydrocarbon Intercomparison Experiment (NOMHICE) was designed to evaluate current analytical methods used to determine mixing ratios of atmospheric Nonmethane Hydrocarbons (NMHCs). A series of planned experiments, or tasks, were implemented to test the analytical methods in a graduated fashion. Tasks 1 and 2 involved relatively simple standard gas mixtures prepared by the National Institute for Standards and Technology (NIST). Results are presented here for task 3 in which a complex mixture containing 60 commonly observed NMHCs at concentrations of 1-30 parts per billion by volume (ppbv) in nitrogen diluent gas was prepared and distributed for analysis to 29 participating laboratories throughout the world. Reference mixing ratios were determined jointly by scientists from the National Center for Atmospheric Research (NCAR) and from the U. S. Environmental Protection Agency (EPA). Participants were asked to identify and quantify the Hydrocarbons present in the mixture and submit their results to NCAR-NOMHICE scientists. The results were encouraging overall. Some laboratories performed extremely well during this exercise whereas other laboratories experienced problems in either identification or quantification or both. It is evident from the comparison of the NCAR-NOMHICE results with both the EPA analysis and the top 11 analyses in the study that very good agreement is achievable between laboratories for mixtures in this concentration range. Some of the largest analytical discrepancies were from laboratories that used in-house standards for their calibration and/or syringe sample injection techniques. A major conclusion from this study is that the use of high-quality gas phase standards, introduced into the measurement instrument in a similar manner to air samples, is an important prerequisite for an accurate analysis.
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the Nonmethane Hydrocarbon intercomparison experiment nomhice tasks 1 and 2
Journal of Geophysical Research, 1994Co-Authors: Eric C Apel, Jack G Calvert, F C FehsenfeldAbstract:The NOMHICE program has been designed to evaluate current methods being used to determine the ambient levels of various atmospheric Nonmethane Hydrocarbons, to identify existing problems in these analyses, to correct these problems, and to help ensure quality control of Hydrocarbon analyses made by atmospheric scientists throughout the world. To accomplish this, a series of planned experiments (tasks) is now under way which involves all the common classes of the atmospheric Hydrocarbons: alkanes, alkenes, alkynes, aromatic Hydrocarbons, and the terpenes. The various tasks of the study have been scheduled in order of increasing complexity so that problems can be addressed as they arise. Preliminary results are presented for task 1 and task 2 of a multitask program. Each laboratory used its own analysis and calibration procedures. The first task of NOMHICE involved the circulation of a two-component, gravimetrically prepared, Hydrocarbon mixture of known composition and unknown concentration to 36 participating scientific groups from laboratories throughout the world. This experiment was planned to check on the reliability of the standards employed by each of the participating groups. Task 2 involved the circulation, to participant laboratories, of a more complex, gravimetrically prepared, 16-component Hydrocarbon mixture (unknown composition and concentration) to determine whethermore » suitable separation, identification, and quantification can be made of the individual Hydrocarbons present in the mixture. Further tasks are described which will be carried out in the future. 16 refs., 12 figs., 3 tabs.« less
D. R. Blake - One of the best experts on this subject based on the ideXlab platform.
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ambient Nonmethane Hydrocarbon levels along colorado s northern front range acute and chronic health risks
Environmental Science & Technology, 2018Co-Authors: Lisa M. Mckenzie, D. R. Blake, John Hughes, William B. Allshouse, Detlev Helmig, Pam Milmoe, N J Blake, Benjamin D Blair, H S Halliday, John L. AdgateAbstract:Oil and gas (O&G) facilities emit air pollutants that are potentially a major health risk for nearby populations. We characterized prenatal through adult health risks for acute (1 h) and chronic (30 year) residential inhalation exposure scenarios to Nonmethane Hydrocarbons (NMHCs) for these populations. We used ambient air sample results to estimate and compare risks for four residential scenarios. We found that air pollutant concentrations increased with proximity to an O&G facility, as did health risks. Acute hazard indices for neurological (18), hematological (15), and developmental (15) health effects indicate that populations living within 152 m of an O&G facility could experience these health effects from inhalation exposures to benzene and alkanes. Lifetime excess cancer risks exceeded 1 in a million for all scenarios. The cancer risk estimate of 8.3 per 10 000 for populations living within 152 m of an O&G facility exceeded the United States Environmental Protection Agency’s 1 in 10 000 upper thres...
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volatile organic compounds in 43 chinese cities
Atmospheric Environment, 2005Co-Authors: B Barletta, Sherwood F Rowland, Simone Meinardi, C Y Chan, Xinming Wang, Shichun Zou, L Y Chan, D. R. BlakeAbstract:Whole air samples were collected in 43 Chinese cities in January and February 2001, and methane and Nonmethane Hydrocarbon (NMHC) concentrations for those samples are here discussed. In order to identify the main sources of the Hydrocarbons in these cities, cross-correlations with the general combustion tracer ethyne and the gasoline marker i-pentane were investigated. Most of the identified NMHCs correlated with ethyne or i-pentane suggesting that their primary source is combustion or gasoline evaporation. To differentiate between vehicular and other combustion sources, the benzene to toluene ratio characteristic of the Chinese vehicular fleet was calculated using roadside samples (collected in 25 cities). Cities where the main source of the NMHCs was traffic related were identified. The slope resulting from the correlation of selected gases was used to identify the likely sources of the NMHCs measured. Vehicular emissions were found to be an important source of isoprene in some cities. Different VOC mixing ratio distributions throughout the country were also investigated. This paper gives a general overview of urban VOCs in many Chinese cities. Future more rigorous studies will be necessary to further characterize VOC sources in China.
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Nonmethane Hydrocarbon measurements in the north atlantic flight corridor during the subsonic assessment ozone and nitrogen oxide experiment
Journal of Geophysical Research, 2000Co-Authors: Isobel J Simpson, D. R. Blake, N J Blake, Taiyih Chen, B C Sive, Jimena P Lopez, Bruce E Anderson, G W SachseAbstract:Mixing ratios of Nonmethane Hydrocarbons (NMHCs) were not enhanced in whole air samples collected within the North Atlantic Flight Corridor (NAFC) during the fall of 1997. The investigation was conducted aboard NASA's DC-8 research aircraft, as part of the Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (SONEX). NMHC enhancements were not detected within the general organized tracking system of the NAFC, nor during two tail chases of the DC-8's own exhaust. Because positive evidence of aircraft emissions was demonstrated by enhancements in both nitrogen oxides and condensation nuclei during SONEX, the NMHC results suggest that the commercial air traffic fleet operating in the North Atlantic region does not contribute at all or contributes negligibly to NMHCs in the NAFC.
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Nonmethane Hydrocarbon measurements on the north atlantic flight corridor during sonex
1999Co-Authors: Isobel J Simpson, D. R. Blake, N J Blake, B C Sive, T Y Chen, Jimena P Lopez, G W Sachse, S A Vay, Henry E Fuelberg, Y KondoAbstract:Mixing ratios of Nonmethane Hydrocarbons (NMHCS) were not enhanced in whole air samples collected within the North Atlantic Flight Corridor (NAFC) during the fall of 1997. The investigation was conducted aboard NASA's DC-8 research aircraft, as part of the Subsonic Assessment-Ozone and Nitrogen Experiment (SONEX). NMHC enhancements were not detected within the general Organized Tracking System (OTS) of the NAFC, nor during two tail-chases of the DC-8's own exhaust. Because positive evidence of aircraft emissions was demonstrated by enhancements in both nitrogen oxides and condensation nuclei during SONEX, the NMHC results suggest that the commercial air traffic fleet operating in the North Atlantic region does not contribute significantly to NMHCs in the NAFC.
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spatial and temporal variability of Nonmethane Hydrocarbon mixing ratios and their relation to photochemical lifetime
Journal of Geophysical Research, 1998Co-Authors: B T Jobson, D. R. Blake, F C Fehsenfeld, P D Goldan, W C Kuster, D D Parrish, N J Blake, H NikiAbstract:The relationship between temporal and spatial variability of C2-C8 Nonmethane Hydrocarbon mixing ratios and their HO lifetimes (τ) is presented for samples collected during the 1993 North Atlantic Regional Experiment (NARE) and from other urban and remote sites. The C2-C4 alkanes, acetylene and benzene typically define a trend of the form slnx = Aτ−b where slnx is the standard deviation of the ln of the mixing ratio. The relationship extended over a wider range of Hydrocarbons in winter. The exponent b ranged in value from 0.28±0.023 for winter urban data where C2-C8 Hydrocarbons defined a strongly correlated trend, to 0.56±0.15 for C2-C4 Hydrocarbons at a coastal site in Nova Scotia during NARE. The trends are significantly different from that given by the Junge relationship [Junge, 1974]. Data from the Azores do not display such a trend and were likely influenced by local emissions. Variance trends are a useful analytical tool for examining the validity of Hydrocarbon measurements.
