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Atmospheric Environment (v.45, #23)
Source apportionment of fine particulate matter measured in an industrialized coastal urban area of South Texas by Saritha Karnae; Kuruvilla John (pp. 3769-3776).
Corpus Christi is a growing industrialized urban airshed in South Texas impacted by local emissions and regional transport of fine particulate matter (PM2.5). Positive matrix factorization (PMF2) technique was used to evaluate particulate matter pollution in the urban airshed by estimating the types of sources and its corresponding mass contributions affecting the measured ambient PM2.5 levels. Fine particulate matter concentrations by species measured during July 2003 through December 2008 at a PM2.5 speciation site were used in this study. PMF2 identified eight source categories, of which secondary sulfates were the dominant source category accounting for 30.4% of the apportioned mass. The other sources identified included aged sea salt (18.5%), biomass burns (12.7%), crustal dust (10.1%), traffic (9.7%), fresh sea salt (8.1%), industrial sources (6%), and a co-mingled source of oil combustion & diesel emissions (4.6%). The apportioned PM mass showed distinct seasonal variability between source categories. The PM levels in Corpus Christi were affected by biomass burns in Mexico and Central America during April and May, sub-Saharan dust storms from Africa during the summer months, and a continental haze episode during August and September with significant transport from the highly industrialized areas of Texas and the neighboring states. Potential source contribution function (PSCF) analysis was performed and it identified source regions and the influence of long-range transport of fine particulate matter affecting this urban area.► PMF2 was used to evaluate particulate pollution levels in Corpus Christi, Texas. ► Eight sources were apportioned with major contribution from secondary sulfates. ► Local impact from industrial sources, traffic and marine aerosols was observed. ► Long-range transport of PM2.5 due to haze, biomass burns and dust storms evaluated. ► Seasonal variability in the apportioned sources and its impact were observed.
Keywords: Fine particulate matter (PM; 2.5; ); Long-range transport; Positive matrix factorization (PMF); Potential source contribution function (PSCF) analysis
Source apportionment of fine particulate matter measured in an industrialized coastal urban area of South Texas by Saritha Karnae; Kuruvilla John (pp. 3769-3776).
Corpus Christi is a growing industrialized urban airshed in South Texas impacted by local emissions and regional transport of fine particulate matter (PM2.5). Positive matrix factorization (PMF2) technique was used to evaluate particulate matter pollution in the urban airshed by estimating the types of sources and its corresponding mass contributions affecting the measured ambient PM2.5 levels. Fine particulate matter concentrations by species measured during July 2003 through December 2008 at a PM2.5 speciation site were used in this study. PMF2 identified eight source categories, of which secondary sulfates were the dominant source category accounting for 30.4% of the apportioned mass. The other sources identified included aged sea salt (18.5%), biomass burns (12.7%), crustal dust (10.1%), traffic (9.7%), fresh sea salt (8.1%), industrial sources (6%), and a co-mingled source of oil combustion & diesel emissions (4.6%). The apportioned PM mass showed distinct seasonal variability between source categories. The PM levels in Corpus Christi were affected by biomass burns in Mexico and Central America during April and May, sub-Saharan dust storms from Africa during the summer months, and a continental haze episode during August and September with significant transport from the highly industrialized areas of Texas and the neighboring states. Potential source contribution function (PSCF) analysis was performed and it identified source regions and the influence of long-range transport of fine particulate matter affecting this urban area.► PMF2 was used to evaluate particulate pollution levels in Corpus Christi, Texas. ► Eight sources were apportioned with major contribution from secondary sulfates. ► Local impact from industrial sources, traffic and marine aerosols was observed. ► Long-range transport of PM2.5 due to haze, biomass burns and dust storms evaluated. ► Seasonal variability in the apportioned sources and its impact were observed.
Keywords: Fine particulate matter (PM; 2.5; ); Long-range transport; Positive matrix factorization (PMF); Potential source contribution function (PSCF) analysis
Source apportionment of fine particulate matter measured in an industrialized coastal urban area of South Texas by Saritha Karnae; Kuruvilla John (pp. 3769-3776).
Corpus Christi is a growing industrialized urban airshed in South Texas impacted by local emissions and regional transport of fine particulate matter (PM2.5). Positive matrix factorization (PMF2) technique was used to evaluate particulate matter pollution in the urban airshed by estimating the types of sources and its corresponding mass contributions affecting the measured ambient PM2.5 levels. Fine particulate matter concentrations by species measured during July 2003 through December 2008 at a PM2.5 speciation site were used in this study. PMF2 identified eight source categories, of which secondary sulfates were the dominant source category accounting for 30.4% of the apportioned mass. The other sources identified included aged sea salt (18.5%), biomass burns (12.7%), crustal dust (10.1%), traffic (9.7%), fresh sea salt (8.1%), industrial sources (6%), and a co-mingled source of oil combustion & diesel emissions (4.6%). The apportioned PM mass showed distinct seasonal variability between source categories. The PM levels in Corpus Christi were affected by biomass burns in Mexico and Central America during April and May, sub-Saharan dust storms from Africa during the summer months, and a continental haze episode during August and September with significant transport from the highly industrialized areas of Texas and the neighboring states. Potential source contribution function (PSCF) analysis was performed and it identified source regions and the influence of long-range transport of fine particulate matter affecting this urban area.► PMF2 was used to evaluate particulate pollution levels in Corpus Christi, Texas. ► Eight sources were apportioned with major contribution from secondary sulfates. ► Local impact from industrial sources, traffic and marine aerosols was observed. ► Long-range transport of PM2.5 due to haze, biomass burns and dust storms evaluated. ► Seasonal variability in the apportioned sources and its impact were observed.
Keywords: Fine particulate matter (PM; 2.5; ); Long-range transport; Positive matrix factorization (PMF); Potential source contribution function (PSCF) analysis
Characterization of PAHs within PM10 fraction for ashes from coke production, iron smelt, heating station and power plant stacks in Liaoning Province, China by Shaofei Kong; Jianwu Shi; Bing Lu; Weiguang Qiu; Baosheng Zhang; Yue Peng; Bowen Zhang; Zhipeng Bai (pp. 3777-3785).
Polycyclic aromatic hydrocarbons within PM10 fraction of ashes from two coke production plants, one iron smelt plant, one heating station and one power plant were analyzed with GC–MS technique in 2009. The sum of 17 selected PAHs varied from 290.20 to 7055.72 μg/g and the amounts of carcinogenic PAHs were between 140.33 and 3345.46 μg/g. The most toxic ash was from the coke production plants and then from the iron smelt plant, coal-fired power plant and heating station according to BaP-based toxic equivalent factor (BaPeq) and BaP-based equivalent carcinogenic power (BaPE). PAHs profile of the iron smelt ash was significantly different from others with coefficient of divergence value higher than 0.40. Indicatory PAHs for coke production plants, heating station and coal-fired power plant were mainly 3-ring species such as Acy, Fl and Ace. While for iron smelt plant, they were Chr and BbF. Diagnostic ratios including Ant/(Ant + Phe), Flu/(Flu + Pyr), BaA/Chr, BbF/BkF, Ind/BghiP, IND/(IND + BghiP), BaP/BghiP, BaP/COR, Pyr/BaP, BaA/(BaA + Chr), BaA/BaP and BaP/(BaP + Chr) were calculated which were mostly different from other stacks for the iron smelt plant.► PAHs levels and profiles were analyzed for fly ashes from five industrial plants. ► The most toxic ash was found from the coke production plant. ► Specific indicators and diagnostic ratios were calculated. ► PAHs profile of the iron smelt ash was significantly different from others.
Keywords: Polycyclic aromatic hydrocarbons; Ash; Industrial stacks; PM; 10; Profile characteristic; Diagnostic ratios
Characterization of PAHs within PM10 fraction for ashes from coke production, iron smelt, heating station and power plant stacks in Liaoning Province, China by Shaofei Kong; Jianwu Shi; Bing Lu; Weiguang Qiu; Baosheng Zhang; Yue Peng; Bowen Zhang; Zhipeng Bai (pp. 3777-3785).
Polycyclic aromatic hydrocarbons within PM10 fraction of ashes from two coke production plants, one iron smelt plant, one heating station and one power plant were analyzed with GC–MS technique in 2009. The sum of 17 selected PAHs varied from 290.20 to 7055.72 μg/g and the amounts of carcinogenic PAHs were between 140.33 and 3345.46 μg/g. The most toxic ash was from the coke production plants and then from the iron smelt plant, coal-fired power plant and heating station according to BaP-based toxic equivalent factor (BaPeq) and BaP-based equivalent carcinogenic power (BaPE). PAHs profile of the iron smelt ash was significantly different from others with coefficient of divergence value higher than 0.40. Indicatory PAHs for coke production plants, heating station and coal-fired power plant were mainly 3-ring species such as Acy, Fl and Ace. While for iron smelt plant, they were Chr and BbF. Diagnostic ratios including Ant/(Ant + Phe), Flu/(Flu + Pyr), BaA/Chr, BbF/BkF, Ind/BghiP, IND/(IND + BghiP), BaP/BghiP, BaP/COR, Pyr/BaP, BaA/(BaA + Chr), BaA/BaP and BaP/(BaP + Chr) were calculated which were mostly different from other stacks for the iron smelt plant.► PAHs levels and profiles were analyzed for fly ashes from five industrial plants. ► The most toxic ash was found from the coke production plant. ► Specific indicators and diagnostic ratios were calculated. ► PAHs profile of the iron smelt ash was significantly different from others.
Keywords: Polycyclic aromatic hydrocarbons; Ash; Industrial stacks; PM; 10; Profile characteristic; Diagnostic ratios
Characterization of PAHs within PM10 fraction for ashes from coke production, iron smelt, heating station and power plant stacks in Liaoning Province, China by Shaofei Kong; Jianwu Shi; Bing Lu; Weiguang Qiu; Baosheng Zhang; Yue Peng; Bowen Zhang; Zhipeng Bai (pp. 3777-3785).
Polycyclic aromatic hydrocarbons within PM10 fraction of ashes from two coke production plants, one iron smelt plant, one heating station and one power plant were analyzed with GC–MS technique in 2009. The sum of 17 selected PAHs varied from 290.20 to 7055.72 μg/g and the amounts of carcinogenic PAHs were between 140.33 and 3345.46 μg/g. The most toxic ash was from the coke production plants and then from the iron smelt plant, coal-fired power plant and heating station according to BaP-based toxic equivalent factor (BaPeq) and BaP-based equivalent carcinogenic power (BaPE). PAHs profile of the iron smelt ash was significantly different from others with coefficient of divergence value higher than 0.40. Indicatory PAHs for coke production plants, heating station and coal-fired power plant were mainly 3-ring species such as Acy, Fl and Ace. While for iron smelt plant, they were Chr and BbF. Diagnostic ratios including Ant/(Ant + Phe), Flu/(Flu + Pyr), BaA/Chr, BbF/BkF, Ind/BghiP, IND/(IND + BghiP), BaP/BghiP, BaP/COR, Pyr/BaP, BaA/(BaA + Chr), BaA/BaP and BaP/(BaP + Chr) were calculated which were mostly different from other stacks for the iron smelt plant.► PAHs levels and profiles were analyzed for fly ashes from five industrial plants. ► The most toxic ash was found from the coke production plant. ► Specific indicators and diagnostic ratios were calculated. ► PAHs profile of the iron smelt ash was significantly different from others.
Keywords: Polycyclic aromatic hydrocarbons; Ash; Industrial stacks; PM; 10; Profile characteristic; Diagnostic ratios
The effect of slurry treatment including ozonation on odorant reduction measured by in-situ PTR-MS by Dezhao Liu; Anders Feilberg; Anders P.S. Adamsen; Kristoffer E.N. Jonassen (pp. 3786-3793).
The emission of odorous compounds from intensive pig production facilities is a nuisance for neighbors. Slurry ozonation for odor abatement has previously been demonstrated in laboratory scale. In this study, the effect of slurry ozonation (combined with solid–liquid pre-separation and acidification) on emissions of odorous compounds was tested in an experimental full-scale growing pig facility using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) for online analysis of odorants. The measurements were performed to gain a better understanding of the effects of ozone treatment on emissions odorous compounds and to identify potential options for optimization of ozone treatment. The compounds monitored included volatile sulfur compounds, amine, carboxylic acids, ketones, phenols and indoles. Measurements were performed during nearly a one-month period in summertime. The compounds with the highest concentrations observed in the ventilation exhaust duct were acetic acid, hydrogen sulfide, propanoic acid and butanoic acid. The compounds with the highest removal efficiencies were hydrogen sulfide, 3-methyl-indole, phenol and acetic acid. Based on odor threshold values, methanethiol, butanoic acid, 4-methylphenol, hydrogen sulfide and C5 carboxylic acids are estimated to contribute significantly to the odor nuisance. Emissions of odorous compounds were observed to be strongly correlated with temperature with the exception of hydrogen sulfide. Emission peaks of sulfur compounds were seen during slurry handling activities. Discharging of the slurry pit led to reduced hydrogen sulfide emissions, but emissions of most other odorants were not affected. The results indicate that emissions of odorants other than hydrogen sulfide mainly originate from sources other than the treated slurry, which limits the potential for further optimization. The PTR-MS measurements are demonstrated to provide a quantitative, accurate and detailed evaluation of ozone treatment for emission reduction.► Effect of slurry ozonation on odor emissions was tested by PTR-MS. ► Hydrogen sulfide achieved the highest removal by slurry ozonation. ► Key odors are methanethiol, butanoic acid, 4-methyphenol and hydrogen sulfide. ► Emission of hydrogen sulfide mainly originates from slurry. ► Emissions of other odorants mainly originate from other sources.
Keywords: Ozonation; Odorants; Mass spectrometry; Slurry; In-situ
The effect of slurry treatment including ozonation on odorant reduction measured by in-situ PTR-MS by Dezhao Liu; Anders Feilberg; Anders P.S. Adamsen; Kristoffer E.N. Jonassen (pp. 3786-3793).
The emission of odorous compounds from intensive pig production facilities is a nuisance for neighbors. Slurry ozonation for odor abatement has previously been demonstrated in laboratory scale. In this study, the effect of slurry ozonation (combined with solid–liquid pre-separation and acidification) on emissions of odorous compounds was tested in an experimental full-scale growing pig facility using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) for online analysis of odorants. The measurements were performed to gain a better understanding of the effects of ozone treatment on emissions odorous compounds and to identify potential options for optimization of ozone treatment. The compounds monitored included volatile sulfur compounds, amine, carboxylic acids, ketones, phenols and indoles. Measurements were performed during nearly a one-month period in summertime. The compounds with the highest concentrations observed in the ventilation exhaust duct were acetic acid, hydrogen sulfide, propanoic acid and butanoic acid. The compounds with the highest removal efficiencies were hydrogen sulfide, 3-methyl-indole, phenol and acetic acid. Based on odor threshold values, methanethiol, butanoic acid, 4-methylphenol, hydrogen sulfide and C5 carboxylic acids are estimated to contribute significantly to the odor nuisance. Emissions of odorous compounds were observed to be strongly correlated with temperature with the exception of hydrogen sulfide. Emission peaks of sulfur compounds were seen during slurry handling activities. Discharging of the slurry pit led to reduced hydrogen sulfide emissions, but emissions of most other odorants were not affected. The results indicate that emissions of odorants other than hydrogen sulfide mainly originate from sources other than the treated slurry, which limits the potential for further optimization. The PTR-MS measurements are demonstrated to provide a quantitative, accurate and detailed evaluation of ozone treatment for emission reduction.► Effect of slurry ozonation on odor emissions was tested by PTR-MS. ► Hydrogen sulfide achieved the highest removal by slurry ozonation. ► Key odors are methanethiol, butanoic acid, 4-methyphenol and hydrogen sulfide. ► Emission of hydrogen sulfide mainly originates from slurry. ► Emissions of other odorants mainly originate from other sources.
Keywords: Ozonation; Odorants; Mass spectrometry; Slurry; In-situ
The effect of slurry treatment including ozonation on odorant reduction measured by in-situ PTR-MS by Dezhao Liu; Anders Feilberg; Anders P.S. Adamsen; Kristoffer E.N. Jonassen (pp. 3786-3793).
The emission of odorous compounds from intensive pig production facilities is a nuisance for neighbors. Slurry ozonation for odor abatement has previously been demonstrated in laboratory scale. In this study, the effect of slurry ozonation (combined with solid–liquid pre-separation and acidification) on emissions of odorous compounds was tested in an experimental full-scale growing pig facility using Proton-Transfer-Reaction Mass Spectrometry (PTR-MS) for online analysis of odorants. The measurements were performed to gain a better understanding of the effects of ozone treatment on emissions odorous compounds and to identify potential options for optimization of ozone treatment. The compounds monitored included volatile sulfur compounds, amine, carboxylic acids, ketones, phenols and indoles. Measurements were performed during nearly a one-month period in summertime. The compounds with the highest concentrations observed in the ventilation exhaust duct were acetic acid, hydrogen sulfide, propanoic acid and butanoic acid. The compounds with the highest removal efficiencies were hydrogen sulfide, 3-methyl-indole, phenol and acetic acid. Based on odor threshold values, methanethiol, butanoic acid, 4-methylphenol, hydrogen sulfide and C5 carboxylic acids are estimated to contribute significantly to the odor nuisance. Emissions of odorous compounds were observed to be strongly correlated with temperature with the exception of hydrogen sulfide. Emission peaks of sulfur compounds were seen during slurry handling activities. Discharging of the slurry pit led to reduced hydrogen sulfide emissions, but emissions of most other odorants were not affected. The results indicate that emissions of odorants other than hydrogen sulfide mainly originate from sources other than the treated slurry, which limits the potential for further optimization. The PTR-MS measurements are demonstrated to provide a quantitative, accurate and detailed evaluation of ozone treatment for emission reduction.► Effect of slurry ozonation on odor emissions was tested by PTR-MS. ► Hydrogen sulfide achieved the highest removal by slurry ozonation. ► Key odors are methanethiol, butanoic acid, 4-methyphenol and hydrogen sulfide. ► Emission of hydrogen sulfide mainly originates from slurry. ► Emissions of other odorants mainly originate from other sources.
Keywords: Ozonation; Odorants; Mass spectrometry; Slurry; In-situ
Long-term aerosol particle flux observations. Part II: Particle size statistics and deposition velocities by I. Mammarella; Ü. Rannik; P. Aalto; P. Keronen; T. Vesala; M. Kulmala (pp. 3794-3805).
Aerosol particle dry deposition is driven by meteorological conditions as well as by strong functional dependence on particle size. The current study aims to understand seasonal differences in size-integrated deposition velocities over a pine forest. Long period of measurements was used to study dependence of particle deposition velocities on size from 10nm to 1μm. Particle fluxes have been obtained by eddy covariance (EC) technique applied together with condensational particle counter. Size differentiation is performed by means of statistical analysis and modelling approach utilising the concurrent particle size spectra measurements. Theoretical particle deposition model including Brownian diffusion, interception and turbophoresis mechanisms was applied to analyse the results. In addition, empirical representation of collection velocity was considered. The empirically determined power factor for deposition dependence on Schmidt number in Brownian diffusion regime was observed to be larger in absolute value than expected from theory. Minimum of deposition velocity occurred at around 200nm and steep increase at larger sizes was observed. Winter-time observations were dominated by bi-modal size distributions and deposition velocities were qualitatively well described by model while the quantitative difference of 30% remained on seasonal average level. It appeared that larger than 200nm particles contributed to elevated average deposition values in winter. In autumn, significant deviation between modelled and measured deposition velocities was observed. We also showed that, in case of size-integrated flux measurements, using geometric mean diameter to characterise the particle size distribution can lead to biased interpretation of size dependence of deposition velocities. Further research is needed to understand seasonally different driving variables for deposition velocities preferably involving direct size-resolved flux measurements.► Seasonal differences in deposition explained by differences in size distribution. ► Winter higher deposition velocities explained by prevailing bi-modal distributions. ► The use ofD pg can lead to biased interpretation of size-dependence deposition rate.
Keywords: Aerosol particle deposition; Eddy covariance; Particle deposition model; Particle size distribution; Long-term observations; Pine forest
Long-term aerosol particle flux observations. Part II: Particle size statistics and deposition velocities by I. Mammarella; Ü. Rannik; P. Aalto; P. Keronen; T. Vesala; M. Kulmala (pp. 3794-3805).
Aerosol particle dry deposition is driven by meteorological conditions as well as by strong functional dependence on particle size. The current study aims to understand seasonal differences in size-integrated deposition velocities over a pine forest. Long period of measurements was used to study dependence of particle deposition velocities on size from 10nm to 1μm. Particle fluxes have been obtained by eddy covariance (EC) technique applied together with condensational particle counter. Size differentiation is performed by means of statistical analysis and modelling approach utilising the concurrent particle size spectra measurements. Theoretical particle deposition model including Brownian diffusion, interception and turbophoresis mechanisms was applied to analyse the results. In addition, empirical representation of collection velocity was considered. The empirically determined power factor for deposition dependence on Schmidt number in Brownian diffusion regime was observed to be larger in absolute value than expected from theory. Minimum of deposition velocity occurred at around 200nm and steep increase at larger sizes was observed. Winter-time observations were dominated by bi-modal size distributions and deposition velocities were qualitatively well described by model while the quantitative difference of 30% remained on seasonal average level. It appeared that larger than 200nm particles contributed to elevated average deposition values in winter. In autumn, significant deviation between modelled and measured deposition velocities was observed. We also showed that, in case of size-integrated flux measurements, using geometric mean diameter to characterise the particle size distribution can lead to biased interpretation of size dependence of deposition velocities. Further research is needed to understand seasonally different driving variables for deposition velocities preferably involving direct size-resolved flux measurements.► Seasonal differences in deposition explained by differences in size distribution. ► Winter higher deposition velocities explained by prevailing bi-modal distributions. ► The use ofD pg can lead to biased interpretation of size-dependence deposition rate.
Keywords: Aerosol particle deposition; Eddy covariance; Particle deposition model; Particle size distribution; Long-term observations; Pine forest
Long-term aerosol particle flux observations. Part II: Particle size statistics and deposition velocities by I. Mammarella; Ü. Rannik; P. Aalto; P. Keronen; T. Vesala; M. Kulmala (pp. 3794-3805).
Aerosol particle dry deposition is driven by meteorological conditions as well as by strong functional dependence on particle size. The current study aims to understand seasonal differences in size-integrated deposition velocities over a pine forest. Long period of measurements was used to study dependence of particle deposition velocities on size from 10nm to 1μm. Particle fluxes have been obtained by eddy covariance (EC) technique applied together with condensational particle counter. Size differentiation is performed by means of statistical analysis and modelling approach utilising the concurrent particle size spectra measurements. Theoretical particle deposition model including Brownian diffusion, interception and turbophoresis mechanisms was applied to analyse the results. In addition, empirical representation of collection velocity was considered. The empirically determined power factor for deposition dependence on Schmidt number in Brownian diffusion regime was observed to be larger in absolute value than expected from theory. Minimum of deposition velocity occurred at around 200nm and steep increase at larger sizes was observed. Winter-time observations were dominated by bi-modal size distributions and deposition velocities were qualitatively well described by model while the quantitative difference of 30% remained on seasonal average level. It appeared that larger than 200nm particles contributed to elevated average deposition values in winter. In autumn, significant deviation between modelled and measured deposition velocities was observed. We also showed that, in case of size-integrated flux measurements, using geometric mean diameter to characterise the particle size distribution can lead to biased interpretation of size dependence of deposition velocities. Further research is needed to understand seasonally different driving variables for deposition velocities preferably involving direct size-resolved flux measurements.► Seasonal differences in deposition explained by differences in size distribution. ► Winter higher deposition velocities explained by prevailing bi-modal distributions. ► The use ofD pg can lead to biased interpretation of size-dependence deposition rate.
Keywords: Aerosol particle deposition; Eddy covariance; Particle deposition model; Particle size distribution; Long-term observations; Pine forest
Impact of galactic cosmic rays on Earth’s atmosphere and human health by A.K. Singh; Devendraa Siingh; R.P. Singh (pp. 3806-3818).
The galactic cosmic rays (GCRs) originating from astrophysical sources and traversing through the interstellar/interplanetary medium reach the terrestrial atmosphere and produce complex dynamic changes in it. The flow rate of GCRs incident on the Earth’s upper atmosphere is varied by the solar wind and the geomagnetic field. Striking correlations between the cloud cover and GCR fluxes on long time scale are observed whereas on short time scale no significant correlation is found. These observations are directly related to climate variations on short term as well as long term. In the present paper, we have reviewed and attempted to provide an overview of cosmic ray effects on terrestrial processes such as electrical phenomena, lightning discharges cloud formation and cloud coverage, temperature variation, space weather phenomena, Earth’s climate and the effects of GCRs on human health. It is shown that CRs control long term variations of some of the above mentioned physical processes, which in turn control short term and long term variations in climate. It is also pointed out that there are many basic phenomena which need further study and require new and long term data set.► Review of present understanding of cosmic rays impact on Earth’s atmosphere. ► Effect of cosmic rays on Earth’s electrical environments. ► Effects of galactic cosmic rays on space weather and human health. ► Cosmic rays and their effects on cloud and climate. ► We have addressed some unresolved problems.
Keywords: Cosmic rays; Atmosphere; Clouds; Climate; Space weather; Human health
Impact of galactic cosmic rays on Earth’s atmosphere and human health by A.K. Singh; Devendraa Siingh; R.P. Singh (pp. 3806-3818).
The galactic cosmic rays (GCRs) originating from astrophysical sources and traversing through the interstellar/interplanetary medium reach the terrestrial atmosphere and produce complex dynamic changes in it. The flow rate of GCRs incident on the Earth’s upper atmosphere is varied by the solar wind and the geomagnetic field. Striking correlations between the cloud cover and GCR fluxes on long time scale are observed whereas on short time scale no significant correlation is found. These observations are directly related to climate variations on short term as well as long term. In the present paper, we have reviewed and attempted to provide an overview of cosmic ray effects on terrestrial processes such as electrical phenomena, lightning discharges cloud formation and cloud coverage, temperature variation, space weather phenomena, Earth’s climate and the effects of GCRs on human health. It is shown that CRs control long term variations of some of the above mentioned physical processes, which in turn control short term and long term variations in climate. It is also pointed out that there are many basic phenomena which need further study and require new and long term data set.► Review of present understanding of cosmic rays impact on Earth’s atmosphere. ► Effect of cosmic rays on Earth’s electrical environments. ► Effects of galactic cosmic rays on space weather and human health. ► Cosmic rays and their effects on cloud and climate. ► We have addressed some unresolved problems.
Keywords: Cosmic rays; Atmosphere; Clouds; Climate; Space weather; Human health
Impact of galactic cosmic rays on Earth’s atmosphere and human health by A.K. Singh; Devendraa Siingh; R.P. Singh (pp. 3806-3818).
The galactic cosmic rays (GCRs) originating from astrophysical sources and traversing through the interstellar/interplanetary medium reach the terrestrial atmosphere and produce complex dynamic changes in it. The flow rate of GCRs incident on the Earth’s upper atmosphere is varied by the solar wind and the geomagnetic field. Striking correlations between the cloud cover and GCR fluxes on long time scale are observed whereas on short time scale no significant correlation is found. These observations are directly related to climate variations on short term as well as long term. In the present paper, we have reviewed and attempted to provide an overview of cosmic ray effects on terrestrial processes such as electrical phenomena, lightning discharges cloud formation and cloud coverage, temperature variation, space weather phenomena, Earth’s climate and the effects of GCRs on human health. It is shown that CRs control long term variations of some of the above mentioned physical processes, which in turn control short term and long term variations in climate. It is also pointed out that there are many basic phenomena which need further study and require new and long term data set.► Review of present understanding of cosmic rays impact on Earth’s atmosphere. ► Effect of cosmic rays on Earth’s electrical environments. ► Effects of galactic cosmic rays on space weather and human health. ► Cosmic rays and their effects on cloud and climate. ► We have addressed some unresolved problems.
Keywords: Cosmic rays; Atmosphere; Clouds; Climate; Space weather; Human health
Wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992–2008 by Eric van der Swaluw; Willem A.H. Asman; Hans van Jaarsveld; Ronald Hoogerbrugge (pp. 3819-3826).
We present measurements of wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992–2008. These data series are obtained from the Dutch National Precipitation Chemistry Monitoring Network which consists of 11 monitoring stations which are homogeneously spread over the Netherlands. These long-term measurements allow for a trend analysis over this period, which are to a large extent not influenced by the year to year variations in meteorological circumstances. It is shown that the downward trend of ammonium, nitrate and sulfate wet deposition over the period 1992–2008 are statistically significant: the wet deposition in the Netherlands decreased in the period 1992–2008 by 37% for ammonium, 28% for nitrate and 59% for sulfate. A comparison between the measurements and emissions are made in order to check whether the emissions show similar downward trends. Subsequently a comparison is made between measured and calculated wet deposition fluxes. These calculation results were performed with the Operational Priority Substances (OPS-model). The trends in both the emissions and the calculated wet deposition fluxes show good agreement for all three measured components. It is therefore concluded that the downward trends of the wet deposition fluxes are a direct effect of the decrease of emissions. Finally, it is shown that the relative downward trend of the wet deposition fluxes of sulfate in the Netherlands shows a large-scale structure with a gradient running from east to west. A similar pattern is seen in the simulations performed with the OPS-model.► Wet deposition levels of sulfur and nitrogen in the Netherlands are presented. ► Both components have a downward trend over the period 1992–2008. ► These downward trends are statistically significant. ► The downward trends are the result of emission reduction of the precursors.
Keywords: Wet deposition; Monitoring network; Ammonium; Sulfate; Nitrate; Modeling
Wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992–2008 by Eric van der Swaluw; Willem A.H. Asman; Hans van Jaarsveld; Ronald Hoogerbrugge (pp. 3819-3826).
We present measurements of wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992–2008. These data series are obtained from the Dutch National Precipitation Chemistry Monitoring Network which consists of 11 monitoring stations which are homogeneously spread over the Netherlands. These long-term measurements allow for a trend analysis over this period, which are to a large extent not influenced by the year to year variations in meteorological circumstances. It is shown that the downward trend of ammonium, nitrate and sulfate wet deposition over the period 1992–2008 are statistically significant: the wet deposition in the Netherlands decreased in the period 1992–2008 by 37% for ammonium, 28% for nitrate and 59% for sulfate. A comparison between the measurements and emissions are made in order to check whether the emissions show similar downward trends. Subsequently a comparison is made between measured and calculated wet deposition fluxes. These calculation results were performed with the Operational Priority Substances (OPS-model). The trends in both the emissions and the calculated wet deposition fluxes show good agreement for all three measured components. It is therefore concluded that the downward trends of the wet deposition fluxes are a direct effect of the decrease of emissions. Finally, it is shown that the relative downward trend of the wet deposition fluxes of sulfate in the Netherlands shows a large-scale structure with a gradient running from east to west. A similar pattern is seen in the simulations performed with the OPS-model.► Wet deposition levels of sulfur and nitrogen in the Netherlands are presented. ► Both components have a downward trend over the period 1992–2008. ► These downward trends are statistically significant. ► The downward trends are the result of emission reduction of the precursors.
Keywords: Wet deposition; Monitoring network; Ammonium; Sulfate; Nitrate; Modeling
Wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992–2008 by Eric van der Swaluw; Willem A.H. Asman; Hans van Jaarsveld; Ronald Hoogerbrugge (pp. 3819-3826).
We present measurements of wet deposition of ammonium, nitrate and sulfate in the Netherlands over the period 1992–2008. These data series are obtained from the Dutch National Precipitation Chemistry Monitoring Network which consists of 11 monitoring stations which are homogeneously spread over the Netherlands. These long-term measurements allow for a trend analysis over this period, which are to a large extent not influenced by the year to year variations in meteorological circumstances. It is shown that the downward trend of ammonium, nitrate and sulfate wet deposition over the period 1992–2008 are statistically significant: the wet deposition in the Netherlands decreased in the period 1992–2008 by 37% for ammonium, 28% for nitrate and 59% for sulfate. A comparison between the measurements and emissions are made in order to check whether the emissions show similar downward trends. Subsequently a comparison is made between measured and calculated wet deposition fluxes. These calculation results were performed with the Operational Priority Substances (OPS-model). The trends in both the emissions and the calculated wet deposition fluxes show good agreement for all three measured components. It is therefore concluded that the downward trends of the wet deposition fluxes are a direct effect of the decrease of emissions. Finally, it is shown that the relative downward trend of the wet deposition fluxes of sulfate in the Netherlands shows a large-scale structure with a gradient running from east to west. A similar pattern is seen in the simulations performed with the OPS-model.► Wet deposition levels of sulfur and nitrogen in the Netherlands are presented. ► Both components have a downward trend over the period 1992–2008. ► These downward trends are statistically significant. ► The downward trends are the result of emission reduction of the precursors.
Keywords: Wet deposition; Monitoring network; Ammonium; Sulfate; Nitrate; Modeling
Carbon dioxide emission from surface water in cascade reservoirs–river system on the Maotiao River, southwest of China by Fushun Wang; Baoli Wang; Cong-Qiang Liu; Yuchun Wang; Jin Guan; Xiaolong Liu; Yuanxiu Yu (pp. 3827-3834).
Recently, controversies about whether hydropower is still a clean energy have been arisen up with the studies about high CO2 emission flux from hydroelectric reservoirs in boreal and tropical regions. In this study, four subtropical reservoirs and their related reaches, draining on karstic area in southwest of China, were investigated to understand their CO2 emission, with monthly sampling strategy from July 2007 to June 2008. pCO2 values in the surface water of these reservoirs ranged from 38 to 3300 μ atm, indicating that reservoir surface could be not only source but also sink to atmosphere CO2 in different seasons. In Hongfeng reservoir, the flux of CO2 from surface water varied from −9 to 70 mmol m−2 d−2 with an average of 15 mmol m−2 d−2, and in Baihua reservoir, it had a range from −8 to 77 mmol m−2 d−2 with an average of 24 mmol m−2 d−2. Hongyan reservoir had similar average flux of CO2 to Baihua reservoir. Xiuwen had the highest average flux of CO2 with a value of 47 mmol m−2 d−2 among the studied reservoirs. Downstream the dams discharged by hydropower generation from these reservoirs generally had quite high flux of CO2, with an average of 489 ± 297 mmol m−2 d−2, which is close to those from tropical rivers. This means that water releasing from these reservoirs would be an important way for CO2 emission into atmosphere. The results showed that dam construction has significant impacts on the river water chemistry, with abrupt changes in pCO2, DO, T, pH and SIc in surface water and their outlets. In addition, with the development of thermal gradient in warm seasons, water chemistry along the water column of reservoirs also showed seasonal variations, except in Xiuwen reservoir which only has daily storage capacity.► We report the carbon dioxide emission from cascade reservoirs in subtropical region. ► We examine the impact on CO2 emission by deep water discharge for power generation. ► Reservoir surface can become the sink to atmospheric CO2.
Keywords: Maotiao River; CO; 2; diffusion flux; Cascade reservoirs; Karstic area; Subtropical region
Carbon dioxide emission from surface water in cascade reservoirs–river system on the Maotiao River, southwest of China by Fushun Wang; Baoli Wang; Cong-Qiang Liu; Yuchun Wang; Jin Guan; Xiaolong Liu; Yuanxiu Yu (pp. 3827-3834).
Recently, controversies about whether hydropower is still a clean energy have been arisen up with the studies about high CO2 emission flux from hydroelectric reservoirs in boreal and tropical regions. In this study, four subtropical reservoirs and their related reaches, draining on karstic area in southwest of China, were investigated to understand their CO2 emission, with monthly sampling strategy from July 2007 to June 2008. pCO2 values in the surface water of these reservoirs ranged from 38 to 3300 μ atm, indicating that reservoir surface could be not only source but also sink to atmosphere CO2 in different seasons. In Hongfeng reservoir, the flux of CO2 from surface water varied from −9 to 70 mmol m−2 d−2 with an average of 15 mmol m−2 d−2, and in Baihua reservoir, it had a range from −8 to 77 mmol m−2 d−2 with an average of 24 mmol m−2 d−2. Hongyan reservoir had similar average flux of CO2 to Baihua reservoir. Xiuwen had the highest average flux of CO2 with a value of 47 mmol m−2 d−2 among the studied reservoirs. Downstream the dams discharged by hydropower generation from these reservoirs generally had quite high flux of CO2, with an average of 489 ± 297 mmol m−2 d−2, which is close to those from tropical rivers. This means that water releasing from these reservoirs would be an important way for CO2 emission into atmosphere. The results showed that dam construction has significant impacts on the river water chemistry, with abrupt changes in pCO2, DO, T, pH and SIc in surface water and their outlets. In addition, with the development of thermal gradient in warm seasons, water chemistry along the water column of reservoirs also showed seasonal variations, except in Xiuwen reservoir which only has daily storage capacity.► We report the carbon dioxide emission from cascade reservoirs in subtropical region. ► We examine the impact on CO2 emission by deep water discharge for power generation. ► Reservoir surface can become the sink to atmospheric CO2.
Keywords: Maotiao River; CO; 2; diffusion flux; Cascade reservoirs; Karstic area; Subtropical region
Carbon dioxide emission from surface water in cascade reservoirs–river system on the Maotiao River, southwest of China by Fushun Wang; Baoli Wang; Cong-Qiang Liu; Yuchun Wang; Jin Guan; Xiaolong Liu; Yuanxiu Yu (pp. 3827-3834).
Recently, controversies about whether hydropower is still a clean energy have been arisen up with the studies about high CO2 emission flux from hydroelectric reservoirs in boreal and tropical regions. In this study, four subtropical reservoirs and their related reaches, draining on karstic area in southwest of China, were investigated to understand their CO2 emission, with monthly sampling strategy from July 2007 to June 2008. pCO2 values in the surface water of these reservoirs ranged from 38 to 3300 μ atm, indicating that reservoir surface could be not only source but also sink to atmosphere CO2 in different seasons. In Hongfeng reservoir, the flux of CO2 from surface water varied from −9 to 70 mmol m−2 d−2 with an average of 15 mmol m−2 d−2, and in Baihua reservoir, it had a range from −8 to 77 mmol m−2 d−2 with an average of 24 mmol m−2 d−2. Hongyan reservoir had similar average flux of CO2 to Baihua reservoir. Xiuwen had the highest average flux of CO2 with a value of 47 mmol m−2 d−2 among the studied reservoirs. Downstream the dams discharged by hydropower generation from these reservoirs generally had quite high flux of CO2, with an average of 489 ± 297 mmol m−2 d−2, which is close to those from tropical rivers. This means that water releasing from these reservoirs would be an important way for CO2 emission into atmosphere. The results showed that dam construction has significant impacts on the river water chemistry, with abrupt changes in pCO2, DO, T, pH and SIc in surface water and their outlets. In addition, with the development of thermal gradient in warm seasons, water chemistry along the water column of reservoirs also showed seasonal variations, except in Xiuwen reservoir which only has daily storage capacity.► We report the carbon dioxide emission from cascade reservoirs in subtropical region. ► We examine the impact on CO2 emission by deep water discharge for power generation. ► Reservoir surface can become the sink to atmospheric CO2.
Keywords: Maotiao River; CO; 2; diffusion flux; Cascade reservoirs; Karstic area; Subtropical region
Application of a tagged-species method to source apportionment of primary PM2.5 components in a regional air quality model by Mehrez Samaali; Véronique S. Bouchet; Michael D. Moran; Mourad Sassi (pp. 3835-3847).
A tagged-species method for source apportionment was implemented in a regional air quality model (AURAMS) in order to track the contribution of four anthropogenic emissions source categories to the primary-organic-matter (POM) and elemental carbon (EC) components of PM2.5. The four tagged source categories encompassed all anthropogenic source types and consisted of two area source (on-road, “off road and other” [ORAO]) and two point source (minor, major) categories. Natural POM2.5 and EC2.5 sources were not included in the inventory and thus were not tagged. A 14-week simulation starting on May 25, 2002 was performed for a North American domain. A check on the tagging results showed that the sum of the tagged-species at specific locations in the domain as well as the sum of the domain-averaged tagged-species concentration values were within 0.001 μg m−3 (3%) of the predicted reference total POM2.5 and EC2.5 concentrations. The linear dependence between primary emissions and concentration contributions for each tagged-species was also well reproduced.An analysis of the tagging results at the continental scale showed that the contributions of emissions from the on-road and ORAO source categories to total POM2.5 and EC2.5 concentrations dominated in both the U.S. and Canada, whereas contributions from the minor- and major-point source categories were small (less than 12%). Overall, at this scale close agreement was obtained between the relative contributions to emissions and to concentration for each source category. Local-level analysis for five Canadian cities showed that relative contributions from the on-road source category to POM2.5 and EC2.5 mean concentrations were highest in Montreal (27% and 89%, respectively). Relative contributions from the ORAO source category to POM2.5 and EC2.5 mean concentrations were highest in Calgary (91% and 28%, respectively). The minor- and major-point source categories again made only small contributions (up to 6%) in all five cities. At this smaller scale, it was found that the tagged sources’ relative contributions to emissions may not scale proportionally with the tagged sources’ relative contributions to concentrations due to transport from neighboring areas. With this new source-apportionment capability, AURAMS can be used to accurately and efficiently track the contribution of selected emissions sources of carbonaceous aerosols for longer simulations at regional or continental scales. This capability will also provide the foundation for the development of tagging for secondary PM species to allow the apportionment of PM component concentrations across all sources.► We implement a new tagging capacity in the AURAMS regional AQ modeling system. ► The accuracy of the tagging method has been checked for EC and POM species. ► Emission trends from the tagged source categories explain well concentration trends. ► Local and long-range contributions to EC and POM are shown for five Canadian cities. ► Contributions from various source categories can be tracked with this method.
Keywords: Source apportionment; Tagged-species; Tagging; Regional air quality; Primary PM; AURAMS
Application of a tagged-species method to source apportionment of primary PM2.5 components in a regional air quality model by Mehrez Samaali; Véronique S. Bouchet; Michael D. Moran; Mourad Sassi (pp. 3835-3847).
A tagged-species method for source apportionment was implemented in a regional air quality model (AURAMS) in order to track the contribution of four anthropogenic emissions source categories to the primary-organic-matter (POM) and elemental carbon (EC) components of PM2.5. The four tagged source categories encompassed all anthropogenic source types and consisted of two area source (on-road, “off road and other” [ORAO]) and two point source (minor, major) categories. Natural POM2.5 and EC2.5 sources were not included in the inventory and thus were not tagged. A 14-week simulation starting on May 25, 2002 was performed for a North American domain. A check on the tagging results showed that the sum of the tagged-species at specific locations in the domain as well as the sum of the domain-averaged tagged-species concentration values were within 0.001 μg m−3 (3%) of the predicted reference total POM2.5 and EC2.5 concentrations. The linear dependence between primary emissions and concentration contributions for each tagged-species was also well reproduced.An analysis of the tagging results at the continental scale showed that the contributions of emissions from the on-road and ORAO source categories to total POM2.5 and EC2.5 concentrations dominated in both the U.S. and Canada, whereas contributions from the minor- and major-point source categories were small (less than 12%). Overall, at this scale close agreement was obtained between the relative contributions to emissions and to concentration for each source category. Local-level analysis for five Canadian cities showed that relative contributions from the on-road source category to POM2.5 and EC2.5 mean concentrations were highest in Montreal (27% and 89%, respectively). Relative contributions from the ORAO source category to POM2.5 and EC2.5 mean concentrations were highest in Calgary (91% and 28%, respectively). The minor- and major-point source categories again made only small contributions (up to 6%) in all five cities. At this smaller scale, it was found that the tagged sources’ relative contributions to emissions may not scale proportionally with the tagged sources’ relative contributions to concentrations due to transport from neighboring areas. With this new source-apportionment capability, AURAMS can be used to accurately and efficiently track the contribution of selected emissions sources of carbonaceous aerosols for longer simulations at regional or continental scales. This capability will also provide the foundation for the development of tagging for secondary PM species to allow the apportionment of PM component concentrations across all sources.► We implement a new tagging capacity in the AURAMS regional AQ modeling system. ► The accuracy of the tagging method has been checked for EC and POM species. ► Emission trends from the tagged source categories explain well concentration trends. ► Local and long-range contributions to EC and POM are shown for five Canadian cities. ► Contributions from various source categories can be tracked with this method.
Keywords: Source apportionment; Tagged-species; Tagging; Regional air quality; Primary PM; AURAMS
Application of a tagged-species method to source apportionment of primary PM2.5 components in a regional air quality model by Mehrez Samaali; Véronique S. Bouchet; Michael D. Moran; Mourad Sassi (pp. 3835-3847).
A tagged-species method for source apportionment was implemented in a regional air quality model (AURAMS) in order to track the contribution of four anthropogenic emissions source categories to the primary-organic-matter (POM) and elemental carbon (EC) components of PM2.5. The four tagged source categories encompassed all anthropogenic source types and consisted of two area source (on-road, “off road and other” [ORAO]) and two point source (minor, major) categories. Natural POM2.5 and EC2.5 sources were not included in the inventory and thus were not tagged. A 14-week simulation starting on May 25, 2002 was performed for a North American domain. A check on the tagging results showed that the sum of the tagged-species at specific locations in the domain as well as the sum of the domain-averaged tagged-species concentration values were within 0.001 μg m−3 (3%) of the predicted reference total POM2.5 and EC2.5 concentrations. The linear dependence between primary emissions and concentration contributions for each tagged-species was also well reproduced.An analysis of the tagging results at the continental scale showed that the contributions of emissions from the on-road and ORAO source categories to total POM2.5 and EC2.5 concentrations dominated in both the U.S. and Canada, whereas contributions from the minor- and major-point source categories were small (less than 12%). Overall, at this scale close agreement was obtained between the relative contributions to emissions and to concentration for each source category. Local-level analysis for five Canadian cities showed that relative contributions from the on-road source category to POM2.5 and EC2.5 mean concentrations were highest in Montreal (27% and 89%, respectively). Relative contributions from the ORAO source category to POM2.5 and EC2.5 mean concentrations were highest in Calgary (91% and 28%, respectively). The minor- and major-point source categories again made only small contributions (up to 6%) in all five cities. At this smaller scale, it was found that the tagged sources’ relative contributions to emissions may not scale proportionally with the tagged sources’ relative contributions to concentrations due to transport from neighboring areas. With this new source-apportionment capability, AURAMS can be used to accurately and efficiently track the contribution of selected emissions sources of carbonaceous aerosols for longer simulations at regional or continental scales. This capability will also provide the foundation for the development of tagging for secondary PM species to allow the apportionment of PM component concentrations across all sources.► We implement a new tagging capacity in the AURAMS regional AQ modeling system. ► The accuracy of the tagging method has been checked for EC and POM species. ► Emission trends from the tagged source categories explain well concentration trends. ► Local and long-range contributions to EC and POM are shown for five Canadian cities. ► Contributions from various source categories can be tracked with this method.
Keywords: Source apportionment; Tagged-species; Tagging; Regional air quality; Primary PM; AURAMS
The reactive oxidant potential of different types of aged atmospheric particles: An outdoor chamber study by Weruka Rattanavaraha; Eli Rosen; Haofei Zhang; Qianfeng Li; Karun Pantong; Richard M. Kamens (pp. 3848-3855).
The reactive oxygen species (ROS) potential of aged diesel exhaust particulate matter (PM) and other aged aerosol systems in the presence and absence of an urban hydrocarbon environment was assessed. Experiments were performed in a 274 m3 dual outdoor Teflon film chamber. Filter samples were taken to assess the oxidant generation associated with PM by an optimized dithiothreitol (DTT) method. Diesel exhaust PM had a higher ROS response when it was in the presence of an urban hydrocarbon mixture and was associated with significant O3 production. For all the aged dilute diesel systems, ROS expression increased by a factor of 2–4 over fresh diesel particles. Other particle systems were also investigated. A low ROS was observed in most of the nighttime experiments, including the nighttime aerosols from SO2 with O3 and SO2 aged by itself. However, when all the systems were compared, aged diesel exhaust tended to express very high ROS potentials, with secondary organic aerosols from an α-pinene + toluene + an urban HC mixture giving the highest ROS response.► ROS from diesel particles increased by a factor of 2–4 as they aged in sunlight. ► Increases in Diesel ROS were associated with PAH decay and increases in SOA. ► ROS from toluene and α-pinene SOA formation were among the highest observed.
Keywords: Diesel particle; Sunlight; Dithiothreitol (DTT); ROS; Quinones; SOA
The reactive oxidant potential of different types of aged atmospheric particles: An outdoor chamber study by Weruka Rattanavaraha; Eli Rosen; Haofei Zhang; Qianfeng Li; Karun Pantong; Richard M. Kamens (pp. 3848-3855).
The reactive oxygen species (ROS) potential of aged diesel exhaust particulate matter (PM) and other aged aerosol systems in the presence and absence of an urban hydrocarbon environment was assessed. Experiments were performed in a 274 m3 dual outdoor Teflon film chamber. Filter samples were taken to assess the oxidant generation associated with PM by an optimized dithiothreitol (DTT) method. Diesel exhaust PM had a higher ROS response when it was in the presence of an urban hydrocarbon mixture and was associated with significant O3 production. For all the aged dilute diesel systems, ROS expression increased by a factor of 2–4 over fresh diesel particles. Other particle systems were also investigated. A low ROS was observed in most of the nighttime experiments, including the nighttime aerosols from SO2 with O3 and SO2 aged by itself. However, when all the systems were compared, aged diesel exhaust tended to express very high ROS potentials, with secondary organic aerosols from an α-pinene + toluene + an urban HC mixture giving the highest ROS response.► ROS from diesel particles increased by a factor of 2–4 as they aged in sunlight. ► Increases in Diesel ROS were associated with PAH decay and increases in SOA. ► ROS from toluene and α-pinene SOA formation were among the highest observed.
Keywords: Diesel particle; Sunlight; Dithiothreitol (DTT); ROS; Quinones; SOA
The reactive oxidant potential of different types of aged atmospheric particles: An outdoor chamber study by Weruka Rattanavaraha; Eli Rosen; Haofei Zhang; Qianfeng Li; Karun Pantong; Richard M. Kamens (pp. 3848-3855).
The reactive oxygen species (ROS) potential of aged diesel exhaust particulate matter (PM) and other aged aerosol systems in the presence and absence of an urban hydrocarbon environment was assessed. Experiments were performed in a 274 m3 dual outdoor Teflon film chamber. Filter samples were taken to assess the oxidant generation associated with PM by an optimized dithiothreitol (DTT) method. Diesel exhaust PM had a higher ROS response when it was in the presence of an urban hydrocarbon mixture and was associated with significant O3 production. For all the aged dilute diesel systems, ROS expression increased by a factor of 2–4 over fresh diesel particles. Other particle systems were also investigated. A low ROS was observed in most of the nighttime experiments, including the nighttime aerosols from SO2 with O3 and SO2 aged by itself. However, when all the systems were compared, aged diesel exhaust tended to express very high ROS potentials, with secondary organic aerosols from an α-pinene + toluene + an urban HC mixture giving the highest ROS response.► ROS from diesel particles increased by a factor of 2–4 as they aged in sunlight. ► Increases in Diesel ROS were associated with PAH decay and increases in SOA. ► ROS from toluene and α-pinene SOA formation were among the highest observed.
Keywords: Diesel particle; Sunlight; Dithiothreitol (DTT); ROS; Quinones; SOA
On bromine, nitrogen oxides and ozone depletion in the tropospheric plume of Erebus volcano (Antarctica) by Marie Boichu; Clive Oppenheimer; Tjarda J. Roberts; Vitchko Tsanev; Philip R. Kyle (pp. 3856-3866).
Since the discovery of bromine oxide (BrO) in volcanic emissions, there has been speculation concerning its role in chemical evolution and notably ozone depletion in volcanic plumes. We report the first measurements using Differential Optical Absorption Spectroscopy (DOAS) of BrO in the tropospheric plume of the persistently degassing Erebus volcano (Antarctica). These are the first observations pertaining to emissions from an alkaline phonolitic magma. The observed BrO/SO2 ratio of 2.5 × 10−4 is similar to that measured at andesitic arc volcanoes. The high abundance of BrO is consistent with high abundances of F and Cl relative to sulfur in the Erebus plume.Our estimations of HBr flux and BrO production rate suggest that reactive bromine chemistry can explain a 35% loss of tropospheric O3 observed in the Erebus plume at approximately 30 km from source ().Erebus also has a permanent lava lake, which could result in generation of NO x by thermal fixation of atmospheric N2 at the hot lava surface. Any NO x emission could play a potent role in reactive bromine chemistry. However, the presence of NO2 could not be detected in the plume, about 400 m above the lake, in our DOAS observations of 2005. Nor could we reproduce spectroscopic retrievals that reportedly identified NO2 in DOAS observations from 2003 made of the Erebus plume (). Based on the NO2 detection limit of our analysis, we can state an upper limit of the NO2/SO2 ratio of ≤0.012, an order of magnitude lower than previously reported. Our new result supports a rapid oxidation of NO x in the young plume and is more consistent with measurements of NO y species measured using an instrumented aircraft flying in the plume. Model simulations, tuned for Erebus, were performed to reproduce the BrO/SO2 observed in the young plume and to investigate the impact of NO x emissions at source on the subsequent formation of BrO in the plume. They support our hypothesis of rapid conversion of NO x to NO y in the vicinity of the lava lake. This study thus places new constraints on the interaction between reactive nitrogen and bromine species in volcanic plumes, and its effects on ozone.► 1st observation of BrO simultaneously to O3 depletion in a volcanic plume. ► 1st detection of BrO in the plume of Erebus which impacts the Antarctic troposphere. ► 1st detection of BrO for a phonolitic volcano. ► Reactive Br chemistry can cause the ozone depletion observed in the plume of Erebus. ► Observations and model simulations support a rapid conversion of NO x to NO y species.
Keywords: Volcanic plume; Antarctic troposphere; Reactive bromine chemistry; Reactive nitrogen chemistry; Ozone depletion; Phonolitic magma
On bromine, nitrogen oxides and ozone depletion in the tropospheric plume of Erebus volcano (Antarctica) by Marie Boichu; Clive Oppenheimer; Tjarda J. Roberts; Vitchko Tsanev; Philip R. Kyle (pp. 3856-3866).
Since the discovery of bromine oxide (BrO) in volcanic emissions, there has been speculation concerning its role in chemical evolution and notably ozone depletion in volcanic plumes. We report the first measurements using Differential Optical Absorption Spectroscopy (DOAS) of BrO in the tropospheric plume of the persistently degassing Erebus volcano (Antarctica). These are the first observations pertaining to emissions from an alkaline phonolitic magma. The observed BrO/SO2 ratio of 2.5 × 10−4 is similar to that measured at andesitic arc volcanoes. The high abundance of BrO is consistent with high abundances of F and Cl relative to sulfur in the Erebus plume.Our estimations of HBr flux and BrO production rate suggest that reactive bromine chemistry can explain a 35% loss of tropospheric O3 observed in the Erebus plume at approximately 30 km from source ().Erebus also has a permanent lava lake, which could result in generation of NO x by thermal fixation of atmospheric N2 at the hot lava surface. Any NO x emission could play a potent role in reactive bromine chemistry. However, the presence of NO2 could not be detected in the plume, about 400 m above the lake, in our DOAS observations of 2005. Nor could we reproduce spectroscopic retrievals that reportedly identified NO2 in DOAS observations from 2003 made of the Erebus plume (). Based on the NO2 detection limit of our analysis, we can state an upper limit of the NO2/SO2 ratio of ≤0.012, an order of magnitude lower than previously reported. Our new result supports a rapid oxidation of NO x in the young plume and is more consistent with measurements of NO y species measured using an instrumented aircraft flying in the plume. Model simulations, tuned for Erebus, were performed to reproduce the BrO/SO2 observed in the young plume and to investigate the impact of NO x emissions at source on the subsequent formation of BrO in the plume. They support our hypothesis of rapid conversion of NO x to NO y in the vicinity of the lava lake. This study thus places new constraints on the interaction between reactive nitrogen and bromine species in volcanic plumes, and its effects on ozone.► 1st observation of BrO simultaneously to O3 depletion in a volcanic plume. ► 1st detection of BrO in the plume of Erebus which impacts the Antarctic troposphere. ► 1st detection of BrO for a phonolitic volcano. ► Reactive Br chemistry can cause the ozone depletion observed in the plume of Erebus. ► Observations and model simulations support a rapid conversion of NO x to NO y species.
Keywords: Volcanic plume; Antarctic troposphere; Reactive bromine chemistry; Reactive nitrogen chemistry; Ozone depletion; Phonolitic magma
On bromine, nitrogen oxides and ozone depletion in the tropospheric plume of Erebus volcano (Antarctica) by Marie Boichu; Clive Oppenheimer; Tjarda J. Roberts; Vitchko Tsanev; Philip R. Kyle (pp. 3856-3866).
Since the discovery of bromine oxide (BrO) in volcanic emissions, there has been speculation concerning its role in chemical evolution and notably ozone depletion in volcanic plumes. We report the first measurements using Differential Optical Absorption Spectroscopy (DOAS) of BrO in the tropospheric plume of the persistently degassing Erebus volcano (Antarctica). These are the first observations pertaining to emissions from an alkaline phonolitic magma. The observed BrO/SO2 ratio of 2.5 × 10−4 is similar to that measured at andesitic arc volcanoes. The high abundance of BrO is consistent with high abundances of F and Cl relative to sulfur in the Erebus plume.Our estimations of HBr flux and BrO production rate suggest that reactive bromine chemistry can explain a 35% loss of tropospheric O3 observed in the Erebus plume at approximately 30 km from source ().Erebus also has a permanent lava lake, which could result in generation of NO x by thermal fixation of atmospheric N2 at the hot lava surface. Any NO x emission could play a potent role in reactive bromine chemistry. However, the presence of NO2 could not be detected in the plume, about 400 m above the lake, in our DOAS observations of 2005. Nor could we reproduce spectroscopic retrievals that reportedly identified NO2 in DOAS observations from 2003 made of the Erebus plume (). Based on the NO2 detection limit of our analysis, we can state an upper limit of the NO2/SO2 ratio of ≤0.012, an order of magnitude lower than previously reported. Our new result supports a rapid oxidation of NO x in the young plume and is more consistent with measurements of NO y species measured using an instrumented aircraft flying in the plume. Model simulations, tuned for Erebus, were performed to reproduce the BrO/SO2 observed in the young plume and to investigate the impact of NO x emissions at source on the subsequent formation of BrO in the plume. They support our hypothesis of rapid conversion of NO x to NO y in the vicinity of the lava lake. This study thus places new constraints on the interaction between reactive nitrogen and bromine species in volcanic plumes, and its effects on ozone.► 1st observation of BrO simultaneously to O3 depletion in a volcanic plume. ► 1st detection of BrO in the plume of Erebus which impacts the Antarctic troposphere. ► 1st detection of BrO for a phonolitic volcano. ► Reactive Br chemistry can cause the ozone depletion observed in the plume of Erebus. ► Observations and model simulations support a rapid conversion of NO x to NO y species.
Keywords: Volcanic plume; Antarctic troposphere; Reactive bromine chemistry; Reactive nitrogen chemistry; Ozone depletion; Phonolitic magma
Vertical gradients of HONO, NOx and O3 in Santiago de Chile by Guillermo Villena; Jörg Kleffmann; Ralf Kurtenbach; Peter Wiesen; Eduardo Lissi; Maria A. Rubio; Giovanna Croxatto; Bernhard Rappenglück (pp. 3867-3873).
Gradients of HONO, NOx (NO + NO2) and O3 were measured during an early summer campaign on a high-rise building in downtown Santiago de Chile. Distinct gradients of decreasing concentrations with altitude were observed for HONO and NOx, while O3 concentrations were found to increase with altitude. From the observed daytime maximum of the HONO/NOx ratio the existence of a strong daytime source of HONO is proposed, thus confirming recent results from another measurement site in downtown Santiago, where a high contribution of HONO to the OH radical initiation sources of >50% was observed. Since the HONO/NOx ratio and its daytime maximum were found to be independent of the altitude, it is concluded that HONO is an important OH radical source in Santiago not only close to the ground surface, but also at higher altitudes of the boundary layer.► HONO/NOx daytime maximum indicates daytime source of HONO in Santiago de Chile. ► No HONO/NOx gradients observed during daytime in Santiago de Chile. ► HONO important OH source in the whole boundary layer. ► HONO/NOx and NO2/NOx ratios from direct emissions of 0.6% and 13% were determined in Santiago de Chile.
Keywords: Oxidation capacity; OH radical; Nitrous acid; Nitrogen oxides; Gradient study
Vertical gradients of HONO, NOx and O3 in Santiago de Chile by Guillermo Villena; Jörg Kleffmann; Ralf Kurtenbach; Peter Wiesen; Eduardo Lissi; Maria A. Rubio; Giovanna Croxatto; Bernhard Rappenglück (pp. 3867-3873).
Gradients of HONO, NOx (NO + NO2) and O3 were measured during an early summer campaign on a high-rise building in downtown Santiago de Chile. Distinct gradients of decreasing concentrations with altitude were observed for HONO and NOx, while O3 concentrations were found to increase with altitude. From the observed daytime maximum of the HONO/NOx ratio the existence of a strong daytime source of HONO is proposed, thus confirming recent results from another measurement site in downtown Santiago, where a high contribution of HONO to the OH radical initiation sources of >50% was observed. Since the HONO/NOx ratio and its daytime maximum were found to be independent of the altitude, it is concluded that HONO is an important OH radical source in Santiago not only close to the ground surface, but also at higher altitudes of the boundary layer.► HONO/NOx daytime maximum indicates daytime source of HONO in Santiago de Chile. ► No HONO/NOx gradients observed during daytime in Santiago de Chile. ► HONO important OH source in the whole boundary layer. ► HONO/NOx and NO2/NOx ratios from direct emissions of 0.6% and 13% were determined in Santiago de Chile.
Keywords: Oxidation capacity; OH radical; Nitrous acid; Nitrogen oxides; Gradient study
Vertical gradients of HONO, NOx and O3 in Santiago de Chile by Guillermo Villena; Jörg Kleffmann; Ralf Kurtenbach; Peter Wiesen; Eduardo Lissi; Maria A. Rubio; Giovanna Croxatto; Bernhard Rappenglück (pp. 3867-3873).
Gradients of HONO, NOx (NO + NO2) and O3 were measured during an early summer campaign on a high-rise building in downtown Santiago de Chile. Distinct gradients of decreasing concentrations with altitude were observed for HONO and NOx, while O3 concentrations were found to increase with altitude. From the observed daytime maximum of the HONO/NOx ratio the existence of a strong daytime source of HONO is proposed, thus confirming recent results from another measurement site in downtown Santiago, where a high contribution of HONO to the OH radical initiation sources of >50% was observed. Since the HONO/NOx ratio and its daytime maximum were found to be independent of the altitude, it is concluded that HONO is an important OH radical source in Santiago not only close to the ground surface, but also at higher altitudes of the boundary layer.► HONO/NOx daytime maximum indicates daytime source of HONO in Santiago de Chile. ► No HONO/NOx gradients observed during daytime in Santiago de Chile. ► HONO important OH source in the whole boundary layer. ► HONO/NOx and NO2/NOx ratios from direct emissions of 0.6% and 13% were determined in Santiago de Chile.
Keywords: Oxidation capacity; OH radical; Nitrous acid; Nitrogen oxides; Gradient study
Source characterization of organic aerosols using Monte Carlo source apportionment of PAHs at two South Asian receptor sites by Rebecca J. Sheesley; August Andersson; Örjan Gustafsson (pp. 3874-3881).
The quantification of source contributions is of key importance for proposing environmental mitigation strategies for particulate organic matter. Organic molecular tracer analysis of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes was conducted on a set of winter samples from two regional receptor sites in South Asia: the Island of Hanimaadhoo (the Republic of Maldives) and a mountain top near Sinhagad (W. India). Monte Carlo source apportionment (MCSA) techniques were applied to the observed PAH ratios using profiles of a representative range of regional combustion sources from the literature to estimate the relative source contributions from petroleum combustion, coal combustion and biomass burning. One advantage of this methodology is the combined use of the mean and standard deviation of the diagnostic ratios to calculate probability distribution functions for the fractional contributions from petroleum, coal and biomass combustion. The results of this strategy indicate a higher input from coal combustion at the Hanimaadhoo site (32–43 ± 21%) than the Sinhagad site (24–25 ± 18%). The estimated biomass contribution for Sinhagad (53 ± 22%) parallels previous radiocarbon-based source apportionment of elemental carbon at this location (54 ± 3%). In Hanimaadhoo, the MCSA results indicate 34 ± 20% biomass burning contribution compared to 41 ± 5% by radiocarbon apportionment of EC. While the MCSA based on PAH ratio diagnostic distributions are less precise than the radiocarbon-based apportionment, it provides additional information of the relative contribution of two subgroups, coal and petroleum combustion, within the overall contribution from fossil fuel combustion.► Novel Monte Carlo (MC) source apportionment using diagnostic PAH ratios. ► 27% petroleum, 42% coal and 31% biomass combustion by MC for Maldives TSP. ► 22% petroleum, 24% coal and 54% biomass combustion by MC for Sinhagad TSP.
Keywords: PAH; Alkane; Monte Carlo; India; Particulate matter
Source characterization of organic aerosols using Monte Carlo source apportionment of PAHs at two South Asian receptor sites by Rebecca J. Sheesley; August Andersson; Örjan Gustafsson (pp. 3874-3881).
The quantification of source contributions is of key importance for proposing environmental mitigation strategies for particulate organic matter. Organic molecular tracer analysis of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes was conducted on a set of winter samples from two regional receptor sites in South Asia: the Island of Hanimaadhoo (the Republic of Maldives) and a mountain top near Sinhagad (W. India). Monte Carlo source apportionment (MCSA) techniques were applied to the observed PAH ratios using profiles of a representative range of regional combustion sources from the literature to estimate the relative source contributions from petroleum combustion, coal combustion and biomass burning. One advantage of this methodology is the combined use of the mean and standard deviation of the diagnostic ratios to calculate probability distribution functions for the fractional contributions from petroleum, coal and biomass combustion. The results of this strategy indicate a higher input from coal combustion at the Hanimaadhoo site (32–43 ± 21%) than the Sinhagad site (24–25 ± 18%). The estimated biomass contribution for Sinhagad (53 ± 22%) parallels previous radiocarbon-based source apportionment of elemental carbon at this location (54 ± 3%). In Hanimaadhoo, the MCSA results indicate 34 ± 20% biomass burning contribution compared to 41 ± 5% by radiocarbon apportionment of EC. While the MCSA based on PAH ratio diagnostic distributions are less precise than the radiocarbon-based apportionment, it provides additional information of the relative contribution of two subgroups, coal and petroleum combustion, within the overall contribution from fossil fuel combustion.► Novel Monte Carlo (MC) source apportionment using diagnostic PAH ratios. ► 27% petroleum, 42% coal and 31% biomass combustion by MC for Maldives TSP. ► 22% petroleum, 24% coal and 54% biomass combustion by MC for Sinhagad TSP.
Keywords: PAH; Alkane; Monte Carlo; India; Particulate matter
Source characterization of organic aerosols using Monte Carlo source apportionment of PAHs at two South Asian receptor sites by Rebecca J. Sheesley; August Andersson; Örjan Gustafsson (pp. 3874-3881).
The quantification of source contributions is of key importance for proposing environmental mitigation strategies for particulate organic matter. Organic molecular tracer analysis of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes was conducted on a set of winter samples from two regional receptor sites in South Asia: the Island of Hanimaadhoo (the Republic of Maldives) and a mountain top near Sinhagad (W. India). Monte Carlo source apportionment (MCSA) techniques were applied to the observed PAH ratios using profiles of a representative range of regional combustion sources from the literature to estimate the relative source contributions from petroleum combustion, coal combustion and biomass burning. One advantage of this methodology is the combined use of the mean and standard deviation of the diagnostic ratios to calculate probability distribution functions for the fractional contributions from petroleum, coal and biomass combustion. The results of this strategy indicate a higher input from coal combustion at the Hanimaadhoo site (32–43 ± 21%) than the Sinhagad site (24–25 ± 18%). The estimated biomass contribution for Sinhagad (53 ± 22%) parallels previous radiocarbon-based source apportionment of elemental carbon at this location (54 ± 3%). In Hanimaadhoo, the MCSA results indicate 34 ± 20% biomass burning contribution compared to 41 ± 5% by radiocarbon apportionment of EC. While the MCSA based on PAH ratio diagnostic distributions are less precise than the radiocarbon-based apportionment, it provides additional information of the relative contribution of two subgroups, coal and petroleum combustion, within the overall contribution from fossil fuel combustion.► Novel Monte Carlo (MC) source apportionment using diagnostic PAH ratios. ► 27% petroleum, 42% coal and 31% biomass combustion by MC for Maldives TSP. ► 22% petroleum, 24% coal and 54% biomass combustion by MC for Sinhagad TSP.
Keywords: PAH; Alkane; Monte Carlo; India; Particulate matter
Secondary organic aerosol formation from xylenes and mixtures of toluene and xylenes in an atmospheric urban hydrocarbon mixture: Water and particle seed effects (II) by Yang Zhou; Haofei Zhang; Harshal M. Parikh; Eric H. Chen; Weruka Rattanavaraha; Elias P. Rosen; Wenxing Wang; Richard M. Kamens (pp. 3882-3890).
Secondary organic aerosol (SOA) formation from the photooxidation of o-, p-xylene, and toluene with xylene mixtures was investigated in the UNC dual outdoor smog chambers. Experiments were performed with different initial background aerosol concentrations and levels of relative humidity (RH) in the environment of an eleven component mixture of non-SOA-forming dilute urban hydrocarbon mixture, oxides of nitrogen and sunlight. Post-nucleation was observed in most of the experiments in the 14–20nm range except under the conditions with high background aerosol (>5μgm−3) and with low o-xylene concentrations (<0.092ppmv). The SOA yields of o-xylene varied from 0.8% to 6.5% depending on the RH and initial seed concentrations. p-Xylene had a lower SOA yield compared with o-xylene and the yields in experiments with toluene and xylene mixtures ranged from 1.1% to 10.3%. SOA yield was found to be positively correlated with the particle water (H2Op) content. A new condensed aromatic kinetic mechanism employing uptake of organics in H2Op as a key parameter was applied to all the experiments and the simulations showed reasonable fits to the observed data.► First paper to show that SOA from xylenes is strongly influenced by relative humidity and corresponding particle phase water. ► The SOA from xylenes can be two to three times higher under very humid vs. dry atmospheres. ► Simulations with an new condensed kinetics mechanism of outdoor chamber experiments with xylenes in a dilute non-forming SOA HC mixture showed reasonable predictions of O3, NOx, xylenes, and SOA behavior.
Keywords: Xylene SOA; Secondary organic aerosol modeling; SOA yields; Glyoxal; Aqueous phase; Particle water
Secondary organic aerosol formation from xylenes and mixtures of toluene and xylenes in an atmospheric urban hydrocarbon mixture: Water and particle seed effects (II) by Yang Zhou; Haofei Zhang; Harshal M. Parikh; Eric H. Chen; Weruka Rattanavaraha; Elias P. Rosen; Wenxing Wang; Richard M. Kamens (pp. 3882-3890).
Secondary organic aerosol (SOA) formation from the photooxidation of o-, p-xylene, and toluene with xylene mixtures was investigated in the UNC dual outdoor smog chambers. Experiments were performed with different initial background aerosol concentrations and levels of relative humidity (RH) in the environment of an eleven component mixture of non-SOA-forming dilute urban hydrocarbon mixture, oxides of nitrogen and sunlight. Post-nucleation was observed in most of the experiments in the 14–20nm range except under the conditions with high background aerosol (>5μgm−3) and with low o-xylene concentrations (<0.092ppmv). The SOA yields of o-xylene varied from 0.8% to 6.5% depending on the RH and initial seed concentrations. p-Xylene had a lower SOA yield compared with o-xylene and the yields in experiments with toluene and xylene mixtures ranged from 1.1% to 10.3%. SOA yield was found to be positively correlated with the particle water (H2Op) content. A new condensed aromatic kinetic mechanism employing uptake of organics in H2Op as a key parameter was applied to all the experiments and the simulations showed reasonable fits to the observed data.► First paper to show that SOA from xylenes is strongly influenced by relative humidity and corresponding particle phase water. ► The SOA from xylenes can be two to three times higher under very humid vs. dry atmospheres. ► Simulations with an new condensed kinetics mechanism of outdoor chamber experiments with xylenes in a dilute non-forming SOA HC mixture showed reasonable predictions of O3, NOx, xylenes, and SOA behavior.
Keywords: Xylene SOA; Secondary organic aerosol modeling; SOA yields; Glyoxal; Aqueous phase; Particle water
Secondary organic aerosol formation from xylenes and mixtures of toluene and xylenes in an atmospheric urban hydrocarbon mixture: Water and particle seed effects (II) by Yang Zhou; Haofei Zhang; Harshal M. Parikh; Eric H. Chen; Weruka Rattanavaraha; Elias P. Rosen; Wenxing Wang; Richard M. Kamens (pp. 3882-3890).
Secondary organic aerosol (SOA) formation from the photooxidation of o-, p-xylene, and toluene with xylene mixtures was investigated in the UNC dual outdoor smog chambers. Experiments were performed with different initial background aerosol concentrations and levels of relative humidity (RH) in the environment of an eleven component mixture of non-SOA-forming dilute urban hydrocarbon mixture, oxides of nitrogen and sunlight. Post-nucleation was observed in most of the experiments in the 14–20nm range except under the conditions with high background aerosol (>5μgm−3) and with low o-xylene concentrations (<0.092ppmv). The SOA yields of o-xylene varied from 0.8% to 6.5% depending on the RH and initial seed concentrations. p-Xylene had a lower SOA yield compared with o-xylene and the yields in experiments with toluene and xylene mixtures ranged from 1.1% to 10.3%. SOA yield was found to be positively correlated with the particle water (H2Op) content. A new condensed aromatic kinetic mechanism employing uptake of organics in H2Op as a key parameter was applied to all the experiments and the simulations showed reasonable fits to the observed data.► First paper to show that SOA from xylenes is strongly influenced by relative humidity and corresponding particle phase water. ► The SOA from xylenes can be two to three times higher under very humid vs. dry atmospheres. ► Simulations with an new condensed kinetics mechanism of outdoor chamber experiments with xylenes in a dilute non-forming SOA HC mixture showed reasonable predictions of O3, NOx, xylenes, and SOA behavior.
Keywords: Xylene SOA; Secondary organic aerosol modeling; SOA yields; Glyoxal; Aqueous phase; Particle water
Exploratory study for estimating atmospheric low level particle pollution based on vertical integrated optical measurements by Houda Yahi; Richard Santer; Alain Weill; Michel Crepon; Sylvie Thiria (pp. 3891-3902).
We present a method for retrieving atmospheric particulate matter (PM10) from sun-sky photometer measurements (AOT). As PM10 is a “surface parameter” and AOT is an “integrated parameters”, we first determined whether a “functional relationship” linking these two quantities exists. Since these two parameters strongly depend on atmospheric structures and meteorological variables, we classified the meteorological situations in terms of weather types by using a neuronal classifier (Self organizing Map). For each weather type, we found that a relationship between AOT and PM10 can be established.We applied this approach to the Lille region (France) for the summer 2007 and then extended to a five summer period (summers of the years 2003–2007) in order to increase the statistical confidence of the PM10 retrieval from AOT measurements. The good performances of the method led us to envisage the possibility of deriving the PM10 from satellite observations.
Keywords: Weather types; Unsupervised classification; Aerosols; Atmospheric particulate matter (PM10); Aerosol Optical Thickness (AOT)
Exploratory study for estimating atmospheric low level particle pollution based on vertical integrated optical measurements by Houda Yahi; Richard Santer; Alain Weill; Michel Crepon; Sylvie Thiria (pp. 3891-3902).
We present a method for retrieving atmospheric particulate matter (PM10) from sun-sky photometer measurements (AOT). As PM10 is a “surface parameter” and AOT is an “integrated parameters”, we first determined whether a “functional relationship” linking these two quantities exists. Since these two parameters strongly depend on atmospheric structures and meteorological variables, we classified the meteorological situations in terms of weather types by using a neuronal classifier (Self organizing Map). For each weather type, we found that a relationship between AOT and PM10 can be established.We applied this approach to the Lille region (France) for the summer 2007 and then extended to a five summer period (summers of the years 2003–2007) in order to increase the statistical confidence of the PM10 retrieval from AOT measurements. The good performances of the method led us to envisage the possibility of deriving the PM10 from satellite observations.
Keywords: Weather types; Unsupervised classification; Aerosols; Atmospheric particulate matter (PM10); Aerosol Optical Thickness (AOT)
Exploratory study for estimating atmospheric low level particle pollution based on vertical integrated optical measurements by Houda Yahi; Richard Santer; Alain Weill; Michel Crepon; Sylvie Thiria (pp. 3891-3902).
We present a method for retrieving atmospheric particulate matter (PM10) from sun-sky photometer measurements (AOT). As PM10 is a “surface parameter” and AOT is an “integrated parameters”, we first determined whether a “functional relationship” linking these two quantities exists. Since these two parameters strongly depend on atmospheric structures and meteorological variables, we classified the meteorological situations in terms of weather types by using a neuronal classifier (Self organizing Map). For each weather type, we found that a relationship between AOT and PM10 can be established.We applied this approach to the Lille region (France) for the summer 2007 and then extended to a five summer period (summers of the years 2003–2007) in order to increase the statistical confidence of the PM10 retrieval from AOT measurements. The good performances of the method led us to envisage the possibility of deriving the PM10 from satellite observations.
Keywords: Weather types; Unsupervised classification; Aerosols; Atmospheric particulate matter (PM10); Aerosol Optical Thickness (AOT)
Coupled micrometeorological and biological processes on atmospheric CO2 concentrations at the land–ocean boundary, NE coast of India by D. Ganguly; M. Dey; C. Chowdhury; A.A. Pattnaik; B.K. Sahu; T.K. Jana (pp. 3903-3910).
This study reveals that land–sea breezes, atmospheric stability and influence of net ecosystem metabolism for the conversion of organic carbon to atmospheric CO2 are the major driving forces behind the variation of atmospheric CO2 at the land–ocean boundary, northeast coast of India. The seasonal variation of partial pressure of CO2 (pCO2) and its efflux from the coastal water were several fold higher in the pre-monsoon (1807.9 ± 757.03 μ atm; 579.03 ± 172.9 μM m−2 h−1) than in the monsoon (1070.5 ± 328.5 μ atm; 258.96 ± 185.65 μM m−2 h−1) and the post-monsoon (615.7 ± 121.6 μ atm; 53.27 ± 19.24 μM m−2 h−1). The mean photic zone productivity to column respiration ratio was 0.12 ± 0.08, revealing predominance of heterotrophic processes. Community respiration was at minimum during monsoon (38.82 ± 8.63 mM C m−2 d−1) but was at maximum (173.8 ± 111.8 mM C m−2 d−1) during pre-monsoon and intermittent (125.07 ± 11.97 mM C m−2 d−1) during post-monsoon. Diurnal variations of atmospheric CO2 concentration were determined by local air circulations and atmospheric stability. Seasonal variations of atmospheric CO2 bear a significant signature of biological processes occurring in the coastal water by means of air–sea exchange, markedly affected by the net ecosystem metabolism. Important predictors of coastal atmospheric CO2 in decreasing order of explained variability are wind direction, stability, CO2 efflux and wind velocity.
Keywords: Atmospheric CO; 2; Micrometeorological forcing; Heterotrophy; Coastal water
Coupled micrometeorological and biological processes on atmospheric CO2 concentrations at the land–ocean boundary, NE coast of India by D. Ganguly; M. Dey; C. Chowdhury; A.A. Pattnaik; B.K. Sahu; T.K. Jana (pp. 3903-3910).
This study reveals that land–sea breezes, atmospheric stability and influence of net ecosystem metabolism for the conversion of organic carbon to atmospheric CO2 are the major driving forces behind the variation of atmospheric CO2 at the land–ocean boundary, northeast coast of India. The seasonal variation of partial pressure of CO2 (pCO2) and its efflux from the coastal water were several fold higher in the pre-monsoon (1807.9 ± 757.03 μ atm; 579.03 ± 172.9 μM m−2 h−1) than in the monsoon (1070.5 ± 328.5 μ atm; 258.96 ± 185.65 μM m−2 h−1) and the post-monsoon (615.7 ± 121.6 μ atm; 53.27 ± 19.24 μM m−2 h−1). The mean photic zone productivity to column respiration ratio was 0.12 ± 0.08, revealing predominance of heterotrophic processes. Community respiration was at minimum during monsoon (38.82 ± 8.63 mM C m−2 d−1) but was at maximum (173.8 ± 111.8 mM C m−2 d−1) during pre-monsoon and intermittent (125.07 ± 11.97 mM C m−2 d−1) during post-monsoon. Diurnal variations of atmospheric CO2 concentration were determined by local air circulations and atmospheric stability. Seasonal variations of atmospheric CO2 bear a significant signature of biological processes occurring in the coastal water by means of air–sea exchange, markedly affected by the net ecosystem metabolism. Important predictors of coastal atmospheric CO2 in decreasing order of explained variability are wind direction, stability, CO2 efflux and wind velocity.
Keywords: Atmospheric CO; 2; Micrometeorological forcing; Heterotrophy; Coastal water
Coupled micrometeorological and biological processes on atmospheric CO2 concentrations at the land–ocean boundary, NE coast of India by D. Ganguly; M. Dey; C. Chowdhury; A.A. Pattnaik; B.K. Sahu; T.K. Jana (pp. 3903-3910).
This study reveals that land–sea breezes, atmospheric stability and influence of net ecosystem metabolism for the conversion of organic carbon to atmospheric CO2 are the major driving forces behind the variation of atmospheric CO2 at the land–ocean boundary, northeast coast of India. The seasonal variation of partial pressure of CO2 (pCO2) and its efflux from the coastal water were several fold higher in the pre-monsoon (1807.9 ± 757.03 μ atm; 579.03 ± 172.9 μM m−2 h−1) than in the monsoon (1070.5 ± 328.5 μ atm; 258.96 ± 185.65 μM m−2 h−1) and the post-monsoon (615.7 ± 121.6 μ atm; 53.27 ± 19.24 μM m−2 h−1). The mean photic zone productivity to column respiration ratio was 0.12 ± 0.08, revealing predominance of heterotrophic processes. Community respiration was at minimum during monsoon (38.82 ± 8.63 mM C m−2 d−1) but was at maximum (173.8 ± 111.8 mM C m−2 d−1) during pre-monsoon and intermittent (125.07 ± 11.97 mM C m−2 d−1) during post-monsoon. Diurnal variations of atmospheric CO2 concentration were determined by local air circulations and atmospheric stability. Seasonal variations of atmospheric CO2 bear a significant signature of biological processes occurring in the coastal water by means of air–sea exchange, markedly affected by the net ecosystem metabolism. Important predictors of coastal atmospheric CO2 in decreasing order of explained variability are wind direction, stability, CO2 efflux and wind velocity.
Keywords: Atmospheric CO; 2; Micrometeorological forcing; Heterotrophy; Coastal water
New Directions: Science and policy – Out of step on NOx and NO2?
by Martin L. Williams; David C. Carslaw (pp. 3911-3912).
New Directions: Science and policy – Out of step on NOx and NO2?
by Martin L. Williams; David C. Carslaw (pp. 3911-3912).
New Directions: Science and policy – Out of step on NOx and NO2?
by Martin L. Williams; David C. Carslaw (pp. 3911-3912).