L'Anses publie les resultats de travaux d'expertise collective visant a proposer les moda... more L'Anses publie les resultats de travaux d'expertise collective visant a proposer les modalites de mise en œuvre d’une surveillance nationale des pesticides dans l'air ambiant en France metropolitaine et dans les departements et regions d'outre-mer (DROM). Fondee sur une liste de 90 substances prioritaires, cette surveillance nationale doit permettre d'evaluer l'exposition chronique de la population generale et les risques sanitaires associes. L’Agence recommande en complement de mettre en place des campagnes de mesures ponctuelles visant a evaluer l'exposition de populations vivant a proximite des sources d'emissions de pesticides, notamment les riverains de zones agricoles.
Burning incenses and candles have been identified as source of Volatile and Semi Volatile Organic... more Burning incenses and candles have been identified as source of Volatile and Semi Volatile Organic Compounds (VOC/SVOC) and particles in indoor environments. In this study, the repeatability and reproducibility of test methods using emission chambers to investigate emissions of volatile and particulate compounds from scented candles and incense products as well as the impact of experimental volume of the emission test chamber has been studied. Finally, the best-adapted emission test chamber and test protocol for the evaluation of incense and candles emissions will be proposed.
As part of the EBENE research project, a health risk assessment was performed for two types of wi... more As part of the EBENE research project, a health risk assessment was performed for two types of widely used combustible air fresheners: scented candles and incenses. The assessment was based on physiochemical characterization of the particulate and gaseous emissions of 9 scented candles and 10 incenses, tested under real conditions in an experimental house MARIA (CSTB), combined with a national phone survey about household uses. Results obtained showed that chronic exposures could exceed usual health reference values for a reasonable-worst-case type scenario. Substances of concern included PM (particulate matter), benzene, acrolein and, to a lesser extent, formaldehyde, for incenses, and formaldehyde, acrolein and, to a lesser extent, PM, for scented candles. For all of these substances, exceedances were also identified for short term exposures (1 hour). These results suggest that good practice – use reasonably, ventilate the room after use, avoid direct inhalation of any smoke, etc....
IOP Conference Series: Materials Science and Engineering, 2019
Isothiazolinones, a family of biocides, are used as preservatives in a wide range of consumer and... more Isothiazolinones, a family of biocides, are used as preservatives in a wide range of consumer and building products, such as cleaning agents, paints, or cosmetics for their fungicide, bactericide, and algaecide properties. Moreover, some isothiazolinones are classified as skin sensitizer (MIT, CMI, BIT and OIT) since they can cause eczema, oedema, or allergic contact dermatitis by dermal contact or inhalation. In this study, sensitive and robust analytical methods using GC-MS and UPLC-MS/MS as well as sampling and extraction protocols were developed to identify the emissions of seven isothiazolinones from building and consumer products. Two sampling supports (C18 Cartridge and PUF) were tested; Elution by acetonitrile for C18 Cartridge and ASE extraction using acetone and dichloromethane for PUF are chosen as extraction procedures. The first application of these developed methods on paints showed promising results.
HIGHLIGHTS: Laboratory experiments at an atmospheric relevant concentration of NO 3 radicals ... more HIGHLIGHTS: Laboratory experiments at an atmospheric relevant concentration of NO 3 radicals Current-use pesticide studied were degraded by NO 3 radicals in the particle phase Heterogeneous half-lives of pesticides toward NO 3 radicals range from 2 to 16 days NO 3 radicals must be considered for the heterogeneous degradation of pesticides
A fraction of the atmospheric pesticides can be adsorbed on particles surface according to their ... more A fraction of the atmospheric pesticides can be adsorbed on particles surface according to their physicochemical properties. After adsorption, pesticides can undergo heterogeneous reactivity with atmospheric oxidants such as ozone, but the influence of the pesticide surface coating (i.e., the percentage of the particle surface covered by pesticide molecules) on the degradation kinetics is not well-understood. To estimate the importance of this phenomenon, the influence of the surface coating level in pesticides on the heterogeneous ozonolysis of cyprodinil, deltamethrin, permethrin, and pendimethalin adsorbed on hydrophobic and hydrophilic silicas was investigated. Surface coating level varied from 0.3% to 15% of a monolayer. Generally, the increase of the surface coating level induced a slower degradation of the pesticides above 1% to 3% of a monolayer. This decrease was attributed to a shielding
Pesticides can be adsorbed on the surface of atmospheric aerosol, depending on their physicochemi... more Pesticides can be adsorbed on the surface of atmospheric aerosol, depending on their physicochemical properties. They can be degraded by atmospheric oxidants such as OH radicals but the influence of some environmental parameters on the degradation kinetics, especially relative humidity and particle surface type, is not well understood. Heterogeneous degradation by OH radicals of eight commonly used pesticides (i.e., difenoconazole, tetraconazole, cyprodinil, fipronil, oxadiazon, pendimethalin, deltamethrin, and permethrin) adsorbed on hydrophobic and hydrophilic silicas at a relative humidity ranging from 0% to 70% was studied. Under experimental conditions, only cyprodinil, deltamethrin, permethrin, and pendimethalin were degraded by OH radical in atmospheric relevant concentration. Second-order kinetic constants calculated for the pesticides degraded by OH radicals ranged from (1.93 ± 0.61) x 10-13 cm 3 molecule-1 s-1 (permethrin, hydrophobic silica, 30% RH) to (4.08 ± 0.27) x 10-12 cm 3 molecule-1 s-1 (pendimethalin, hydrophilic silica, 0% RH). Results obtained can contribute to improve the understanding of the atmospheric fate of pesticides and other semi-volatile organic compounds in the particulate phase and they highlight the importance of taking humidity and particle type into account for the determination of pesticides atmospheric half-lives.
In the atmosphere pesticides can be adsorbed on the surface of particles, depending on their phys... more In the atmosphere pesticides can be adsorbed on the surface of particles, depending on their physico-chemical properties. They can react with atmospheric oxidants such as ozone but parameters influencing the degradation kinetics are not clear enough. In this study the heterogeneous ozonolysis of eight commonly used pesticides (i.e., difenoconazole, tetraconazole, cyprodinil, fipronil, oxadiazon, pendimethalin, deltamethrin, and permethrin) adsorbed on hydrophobic and hydrophilic silicas, and Arizona dust at relative humidity ranging from 0% to 80% was investigated. Under experimental conditions, only cyprodinil, deltamethrin, permethrin and pendimethalin were degraded by ozone. Secondorder kinetic constants calculated for the pesticides degraded by ozone ranged from (4.7 ± 0.4) × 10-20 cm 3 molecule-1 s-1 (pendimethalin, hydrophobic silica, 55% RH) to (2.3 ± 0.4) × 10-17 cm 3 molecule-1 s-1 (cyprodinil, Arizona dust, 0% RH). Results obtained can contribute to a better understanding of the atmospheric fate of pesticides in the particulate phase and show the importance of taking humidity and particle type into account for the determination of pesticides atmospheric half-lives.
The persistent organic pollutants (POPs) due to their physicochemical properties can be widely sp... more The persistent organic pollutants (POPs) due to their physicochemical properties can be widely spread all over the globe; as such they represent a serious threat to both humans and wildlife. According to Stockholm convention out of 24 officially recognized POPs, 16 are pesticides. The atmospheric life times of pesticides, up to now were estimated based on their gas-phase reactivity. It has been only speculated that sorption to aerosol particles may increase significantly the half-lives of pesticides in the atmosphere. The results presented here challenge the current view of the half-lives of pesticides in the lower boundary layer of the atmosphere and their impact on air quality and human health. We demonstrate that semivolatile pesticides which are mostly adsorbed on atmospheric aerosol particles are very persistent with respect to the highly reactive hydroxyl radicals (OH) that is the self-cleaning agent of the atmosphere. The half-lives in particulate phase of difenoconazole, tet...
One of the current essential issues to unravel our ability to forecast future climate change and ... more One of the current essential issues to unravel our ability to forecast future climate change and air quality, implies a better understanding of natural processes leading of secondary organic aerosol (SOA) formation, and in particular the formation and fate of oligomers. The difficulty in characterizing macromolecules is to discern between large oxygenated molecules from series of oligomers containing repeated small monomers of diverse structures. In the present study, taking advantage from previously established radical vinyl oligomerization of methyl vinylketone (MVK) in the aqueous phase, where relatively simple oligomers containing up to 14 monomers were observed, we have investigated the same reactivity on several other unsaturated water soluble organic compounds (UWSOCs) and on a few mixtures of these precursor compounds. The technique used to characterize the formed oligomers was a traveling wave ion mobility spectrometry coupled to a hybrid quadrupoletime of flight mass spectrometer (IMS-MS) fitted with an electrospray source and ultra-high performance liquid chromatography (UPLC). The technique allows for an additional separation, especially for large ions, containing long carbon chains. We have shown the efficiency of the IMS-mass spectrometry technique to detect oligomers derived from MVK photooxidation in the aqueous phase. The results were then compared to other oligomers, derived from ten other individual biogenic UWSOCs. The technique allowed distinguishing 2 between different oligomers arising from different precursors. It also clearly showed that compounds bearing a non-conjugated unsaturation did not provide oligomerization. Finally, it was shown that the IMS-mass spectrometry technique, applied to mixtures of unsaturated conjugated precursors, exhibited the ability of these precursors to co-oligomerize, i.e. forming only one complex oligomer system bearing monomers of different structures. The results are discussed in terms of atmospheric implications for the detection of oligomers in complex chamber and/or field samples.
The fate of imazapyr (2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid), a broad-s... more The fate of imazapyr (2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid), a broad-spectrum herbicide in the imidazolinone family, has been studied upon UV irradiation. Most of the photoproducts occurring during the photodegradation have been ...
The imidazolinone herbicide imazapyr, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2yl)nicotinic ac... more The imidazolinone herbicide imazapyr, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2yl)nicotinic acid (H 2 imz) interacts with Cu(II) leading to [Cu(Himz) 2 (H 2 O) 2 ] which crystallizes in the space group Pbca, with a = 12.5370(3)Å, b = 19.8500(5)Å, c = 22.7720(9)Å, and Z = 8. The Cu(II) atom is octahedrally surrounded by four nitrogen atoms of two Himz − anions and two water molecules. Each Himz − acts as a chelating ligand by means of N pyridine and N lactam atoms leading to five-membered chelate rings. The Cu-N distances vary from 1.948(4) to 2.299(5)Å while the Cu-O are 2.114(5) and 2.256(6)Å. The imidazol N-H are involved in short intramolecular hydrogen bonds with the carboxylate groups. The structure is stabilized by an intermolecular hydrogen-bonded network involving the water molecules and the carboxylate groups.
Environmental Science and Pollution Research, 2014
Gaseous nitrogen dioxide (NO2) represents an oxidant that is present in relatively high concentra... more Gaseous nitrogen dioxide (NO2) represents an oxidant that is present in relatively high concentrations in various indoor settings. Remarkably increased NO2 levels up to 1.5 ppm are associated with homes using gas stoves. The heterogeneous reactions of NO2 with adsorbed water on surfaces lead to the generation of nitrous acid (HONO). Here, we present a HONO source induced by heterogeneous reactions of NO2 with selected indoor paint surfaces in the presence of light (300 nm<λ<400 nm). We demonstrate that the formation of HONO is much more pronounced at elevated relative humidity. In the presence of light (5.5 W m(-2)), an increase of HONO production rate of up to 8.6·10(9) molecules cm(-2) s(-1) was observed at [NO2]=60 ppb and 50% relative humidity (RH). At higher light intensity of 10.6 (W m(-2)), the HONO production rate increased to 2.1·10(10) molecules cm(-2) s(-1). A high NO2 to HONO conversion yield of up to 84% was observed. This result strongly suggests that a light-driven process of indoor HONO production is operational. This work highlights the potential of paint surfaces to generate HONO within indoor environments by light-induced NO2 heterogeneous reactions.
Environmental Science and Pollution Research, 2013
Volatile organic compounds (VOCs) and particles emitted by incense sticks and candles combustion ... more Volatile organic compounds (VOCs) and particles emitted by incense sticks and candles combustion in an experimental room have been monitored on-line and continuously with a high time resolution using a state-of-the-art high sensitivity-proton transfer reaction-mass spectrometer (HS-PTR-MS) and a condensation particle counter (CPC), respectively. The VOC concentration-time profiles, i.e., an increase up to a maximum concentration immediately after the burning period followed by a decrease which returns to the initial concentration levels, were strongly influenced by the ventilation and surface interactions. The obtained kinetic data set allows establishing a qualitative correlation between the elimination rate constants of VOCs and their physicochemical properties such as vapor pressure and molecular weight. The emission of particles increased dramatically during the combustion, up to 9.1(±0.2)×10 4 and 22.0(±0.2)×10 4 part cm −3 for incenses and candles, respectively. The performed kinetic measurements highlight the temporal evolution of the exposure level and reveal the importance of ventilation and deposition to remove the particles in a few hours in indoor environments.
For the first time we investigated the effect of solar irradiation upon the heterogeneous ozonati... more For the first time we investigated the effect of solar irradiation upon the heterogeneous ozonation of adsorbed 3,4,5-trimethoxybenzaldehyde on solid surface. Light-induced heterogeneous reactions between gas-phase ozone and 3,4,5-trimethoxybenzaldehyde adsorbed on silica particles were performed and the consecutive reaction products were identified. At an ozone mixing ratio of 250 ppb, the loss of 3,4,5-trimethoxybenzaldehyde ranged from 1.0 $ 10 À6 s À1 in the dark to 2.9 $ 10 À5 s À1 under light irradiation. Such large enhancement of 29 times clearly shows the importance of light (l > 300 nm) during the heterogeneous ozonolysis on organic coated particles. The reaction products identified in this study (3,4,5-trimethoxybenzoic acid, syringic acid, methyl 3,4,5-trimethoxybenzoate) absorb light in the spectral window (l > 300 nm) which implies that lightinduced heterogeneous ozone processing can have an influence on the aerosol surfaces by changing their physico-chemical properties. The main identified product of the heterogeneous reactions between gas-phase ozone and 3,4,5-trimethoxybenzaldehyde under dark conditions and in presence of light was 3,4,5-trimethoxybenzoic acid. For this reason we estimated the carbon yield of 3,4,5-trimethoxybenzoic acid. Carbon yields of 3,4,5trimethoxybenzoic acid decreased with increasing ozone mixing ratio; from 40% at 250 ppb to 15% at !2.5 ppm under dark conditions. At ozone mixing ratio (250 ppbe1 ppm), carbon yields of 3,4,5-trimethoxybenzaldehyde are relatively higher in the experiment under dark condition than under simulated solar light.
You may download, copy and otherwise use the AAM for non-commercial purposes provided that your l... more You may download, copy and otherwise use the AAM for non-commercial purposes provided that your license is limited by the following restrictions: (1) You may use this AAM for non-commercial purposes only under the terms of the CC-BY-NC-ND license. (2) The integrity of the work and identification of the author, copyright owner, and publisher must be preserved in any copy.
L'Anses publie les resultats de travaux d'expertise collective visant a proposer les moda... more L'Anses publie les resultats de travaux d'expertise collective visant a proposer les modalites de mise en œuvre d’une surveillance nationale des pesticides dans l'air ambiant en France metropolitaine et dans les departements et regions d'outre-mer (DROM). Fondee sur une liste de 90 substances prioritaires, cette surveillance nationale doit permettre d'evaluer l'exposition chronique de la population generale et les risques sanitaires associes. L’Agence recommande en complement de mettre en place des campagnes de mesures ponctuelles visant a evaluer l'exposition de populations vivant a proximite des sources d'emissions de pesticides, notamment les riverains de zones agricoles.
Burning incenses and candles have been identified as source of Volatile and Semi Volatile Organic... more Burning incenses and candles have been identified as source of Volatile and Semi Volatile Organic Compounds (VOC/SVOC) and particles in indoor environments. In this study, the repeatability and reproducibility of test methods using emission chambers to investigate emissions of volatile and particulate compounds from scented candles and incense products as well as the impact of experimental volume of the emission test chamber has been studied. Finally, the best-adapted emission test chamber and test protocol for the evaluation of incense and candles emissions will be proposed.
As part of the EBENE research project, a health risk assessment was performed for two types of wi... more As part of the EBENE research project, a health risk assessment was performed for two types of widely used combustible air fresheners: scented candles and incenses. The assessment was based on physiochemical characterization of the particulate and gaseous emissions of 9 scented candles and 10 incenses, tested under real conditions in an experimental house MARIA (CSTB), combined with a national phone survey about household uses. Results obtained showed that chronic exposures could exceed usual health reference values for a reasonable-worst-case type scenario. Substances of concern included PM (particulate matter), benzene, acrolein and, to a lesser extent, formaldehyde, for incenses, and formaldehyde, acrolein and, to a lesser extent, PM, for scented candles. For all of these substances, exceedances were also identified for short term exposures (1 hour). These results suggest that good practice – use reasonably, ventilate the room after use, avoid direct inhalation of any smoke, etc....
IOP Conference Series: Materials Science and Engineering, 2019
Isothiazolinones, a family of biocides, are used as preservatives in a wide range of consumer and... more Isothiazolinones, a family of biocides, are used as preservatives in a wide range of consumer and building products, such as cleaning agents, paints, or cosmetics for their fungicide, bactericide, and algaecide properties. Moreover, some isothiazolinones are classified as skin sensitizer (MIT, CMI, BIT and OIT) since they can cause eczema, oedema, or allergic contact dermatitis by dermal contact or inhalation. In this study, sensitive and robust analytical methods using GC-MS and UPLC-MS/MS as well as sampling and extraction protocols were developed to identify the emissions of seven isothiazolinones from building and consumer products. Two sampling supports (C18 Cartridge and PUF) were tested; Elution by acetonitrile for C18 Cartridge and ASE extraction using acetone and dichloromethane for PUF are chosen as extraction procedures. The first application of these developed methods on paints showed promising results.
HIGHLIGHTS: Laboratory experiments at an atmospheric relevant concentration of NO 3 radicals ... more HIGHLIGHTS: Laboratory experiments at an atmospheric relevant concentration of NO 3 radicals Current-use pesticide studied were degraded by NO 3 radicals in the particle phase Heterogeneous half-lives of pesticides toward NO 3 radicals range from 2 to 16 days NO 3 radicals must be considered for the heterogeneous degradation of pesticides
A fraction of the atmospheric pesticides can be adsorbed on particles surface according to their ... more A fraction of the atmospheric pesticides can be adsorbed on particles surface according to their physicochemical properties. After adsorption, pesticides can undergo heterogeneous reactivity with atmospheric oxidants such as ozone, but the influence of the pesticide surface coating (i.e., the percentage of the particle surface covered by pesticide molecules) on the degradation kinetics is not well-understood. To estimate the importance of this phenomenon, the influence of the surface coating level in pesticides on the heterogeneous ozonolysis of cyprodinil, deltamethrin, permethrin, and pendimethalin adsorbed on hydrophobic and hydrophilic silicas was investigated. Surface coating level varied from 0.3% to 15% of a monolayer. Generally, the increase of the surface coating level induced a slower degradation of the pesticides above 1% to 3% of a monolayer. This decrease was attributed to a shielding
Pesticides can be adsorbed on the surface of atmospheric aerosol, depending on their physicochemi... more Pesticides can be adsorbed on the surface of atmospheric aerosol, depending on their physicochemical properties. They can be degraded by atmospheric oxidants such as OH radicals but the influence of some environmental parameters on the degradation kinetics, especially relative humidity and particle surface type, is not well understood. Heterogeneous degradation by OH radicals of eight commonly used pesticides (i.e., difenoconazole, tetraconazole, cyprodinil, fipronil, oxadiazon, pendimethalin, deltamethrin, and permethrin) adsorbed on hydrophobic and hydrophilic silicas at a relative humidity ranging from 0% to 70% was studied. Under experimental conditions, only cyprodinil, deltamethrin, permethrin, and pendimethalin were degraded by OH radical in atmospheric relevant concentration. Second-order kinetic constants calculated for the pesticides degraded by OH radicals ranged from (1.93 ± 0.61) x 10-13 cm 3 molecule-1 s-1 (permethrin, hydrophobic silica, 30% RH) to (4.08 ± 0.27) x 10-12 cm 3 molecule-1 s-1 (pendimethalin, hydrophilic silica, 0% RH). Results obtained can contribute to improve the understanding of the atmospheric fate of pesticides and other semi-volatile organic compounds in the particulate phase and they highlight the importance of taking humidity and particle type into account for the determination of pesticides atmospheric half-lives.
In the atmosphere pesticides can be adsorbed on the surface of particles, depending on their phys... more In the atmosphere pesticides can be adsorbed on the surface of particles, depending on their physico-chemical properties. They can react with atmospheric oxidants such as ozone but parameters influencing the degradation kinetics are not clear enough. In this study the heterogeneous ozonolysis of eight commonly used pesticides (i.e., difenoconazole, tetraconazole, cyprodinil, fipronil, oxadiazon, pendimethalin, deltamethrin, and permethrin) adsorbed on hydrophobic and hydrophilic silicas, and Arizona dust at relative humidity ranging from 0% to 80% was investigated. Under experimental conditions, only cyprodinil, deltamethrin, permethrin and pendimethalin were degraded by ozone. Secondorder kinetic constants calculated for the pesticides degraded by ozone ranged from (4.7 ± 0.4) × 10-20 cm 3 molecule-1 s-1 (pendimethalin, hydrophobic silica, 55% RH) to (2.3 ± 0.4) × 10-17 cm 3 molecule-1 s-1 (cyprodinil, Arizona dust, 0% RH). Results obtained can contribute to a better understanding of the atmospheric fate of pesticides in the particulate phase and show the importance of taking humidity and particle type into account for the determination of pesticides atmospheric half-lives.
The persistent organic pollutants (POPs) due to their physicochemical properties can be widely sp... more The persistent organic pollutants (POPs) due to their physicochemical properties can be widely spread all over the globe; as such they represent a serious threat to both humans and wildlife. According to Stockholm convention out of 24 officially recognized POPs, 16 are pesticides. The atmospheric life times of pesticides, up to now were estimated based on their gas-phase reactivity. It has been only speculated that sorption to aerosol particles may increase significantly the half-lives of pesticides in the atmosphere. The results presented here challenge the current view of the half-lives of pesticides in the lower boundary layer of the atmosphere and their impact on air quality and human health. We demonstrate that semivolatile pesticides which are mostly adsorbed on atmospheric aerosol particles are very persistent with respect to the highly reactive hydroxyl radicals (OH) that is the self-cleaning agent of the atmosphere. The half-lives in particulate phase of difenoconazole, tet...
One of the current essential issues to unravel our ability to forecast future climate change and ... more One of the current essential issues to unravel our ability to forecast future climate change and air quality, implies a better understanding of natural processes leading of secondary organic aerosol (SOA) formation, and in particular the formation and fate of oligomers. The difficulty in characterizing macromolecules is to discern between large oxygenated molecules from series of oligomers containing repeated small monomers of diverse structures. In the present study, taking advantage from previously established radical vinyl oligomerization of methyl vinylketone (MVK) in the aqueous phase, where relatively simple oligomers containing up to 14 monomers were observed, we have investigated the same reactivity on several other unsaturated water soluble organic compounds (UWSOCs) and on a few mixtures of these precursor compounds. The technique used to characterize the formed oligomers was a traveling wave ion mobility spectrometry coupled to a hybrid quadrupoletime of flight mass spectrometer (IMS-MS) fitted with an electrospray source and ultra-high performance liquid chromatography (UPLC). The technique allows for an additional separation, especially for large ions, containing long carbon chains. We have shown the efficiency of the IMS-mass spectrometry technique to detect oligomers derived from MVK photooxidation in the aqueous phase. The results were then compared to other oligomers, derived from ten other individual biogenic UWSOCs. The technique allowed distinguishing 2 between different oligomers arising from different precursors. It also clearly showed that compounds bearing a non-conjugated unsaturation did not provide oligomerization. Finally, it was shown that the IMS-mass spectrometry technique, applied to mixtures of unsaturated conjugated precursors, exhibited the ability of these precursors to co-oligomerize, i.e. forming only one complex oligomer system bearing monomers of different structures. The results are discussed in terms of atmospheric implications for the detection of oligomers in complex chamber and/or field samples.
The fate of imazapyr (2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid), a broad-s... more The fate of imazapyr (2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid), a broad-spectrum herbicide in the imidazolinone family, has been studied upon UV irradiation. Most of the photoproducts occurring during the photodegradation have been ...
The imidazolinone herbicide imazapyr, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2yl)nicotinic ac... more The imidazolinone herbicide imazapyr, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2yl)nicotinic acid (H 2 imz) interacts with Cu(II) leading to [Cu(Himz) 2 (H 2 O) 2 ] which crystallizes in the space group Pbca, with a = 12.5370(3)Å, b = 19.8500(5)Å, c = 22.7720(9)Å, and Z = 8. The Cu(II) atom is octahedrally surrounded by four nitrogen atoms of two Himz − anions and two water molecules. Each Himz − acts as a chelating ligand by means of N pyridine and N lactam atoms leading to five-membered chelate rings. The Cu-N distances vary from 1.948(4) to 2.299(5)Å while the Cu-O are 2.114(5) and 2.256(6)Å. The imidazol N-H are involved in short intramolecular hydrogen bonds with the carboxylate groups. The structure is stabilized by an intermolecular hydrogen-bonded network involving the water molecules and the carboxylate groups.
Environmental Science and Pollution Research, 2014
Gaseous nitrogen dioxide (NO2) represents an oxidant that is present in relatively high concentra... more Gaseous nitrogen dioxide (NO2) represents an oxidant that is present in relatively high concentrations in various indoor settings. Remarkably increased NO2 levels up to 1.5 ppm are associated with homes using gas stoves. The heterogeneous reactions of NO2 with adsorbed water on surfaces lead to the generation of nitrous acid (HONO). Here, we present a HONO source induced by heterogeneous reactions of NO2 with selected indoor paint surfaces in the presence of light (300 nm<λ<400 nm). We demonstrate that the formation of HONO is much more pronounced at elevated relative humidity. In the presence of light (5.5 W m(-2)), an increase of HONO production rate of up to 8.6·10(9) molecules cm(-2) s(-1) was observed at [NO2]=60 ppb and 50% relative humidity (RH). At higher light intensity of 10.6 (W m(-2)), the HONO production rate increased to 2.1·10(10) molecules cm(-2) s(-1). A high NO2 to HONO conversion yield of up to 84% was observed. This result strongly suggests that a light-driven process of indoor HONO production is operational. This work highlights the potential of paint surfaces to generate HONO within indoor environments by light-induced NO2 heterogeneous reactions.
Environmental Science and Pollution Research, 2013
Volatile organic compounds (VOCs) and particles emitted by incense sticks and candles combustion ... more Volatile organic compounds (VOCs) and particles emitted by incense sticks and candles combustion in an experimental room have been monitored on-line and continuously with a high time resolution using a state-of-the-art high sensitivity-proton transfer reaction-mass spectrometer (HS-PTR-MS) and a condensation particle counter (CPC), respectively. The VOC concentration-time profiles, i.e., an increase up to a maximum concentration immediately after the burning period followed by a decrease which returns to the initial concentration levels, were strongly influenced by the ventilation and surface interactions. The obtained kinetic data set allows establishing a qualitative correlation between the elimination rate constants of VOCs and their physicochemical properties such as vapor pressure and molecular weight. The emission of particles increased dramatically during the combustion, up to 9.1(±0.2)×10 4 and 22.0(±0.2)×10 4 part cm −3 for incenses and candles, respectively. The performed kinetic measurements highlight the temporal evolution of the exposure level and reveal the importance of ventilation and deposition to remove the particles in a few hours in indoor environments.
For the first time we investigated the effect of solar irradiation upon the heterogeneous ozonati... more For the first time we investigated the effect of solar irradiation upon the heterogeneous ozonation of adsorbed 3,4,5-trimethoxybenzaldehyde on solid surface. Light-induced heterogeneous reactions between gas-phase ozone and 3,4,5-trimethoxybenzaldehyde adsorbed on silica particles were performed and the consecutive reaction products were identified. At an ozone mixing ratio of 250 ppb, the loss of 3,4,5-trimethoxybenzaldehyde ranged from 1.0 $ 10 À6 s À1 in the dark to 2.9 $ 10 À5 s À1 under light irradiation. Such large enhancement of 29 times clearly shows the importance of light (l > 300 nm) during the heterogeneous ozonolysis on organic coated particles. The reaction products identified in this study (3,4,5-trimethoxybenzoic acid, syringic acid, methyl 3,4,5-trimethoxybenzoate) absorb light in the spectral window (l > 300 nm) which implies that lightinduced heterogeneous ozone processing can have an influence on the aerosol surfaces by changing their physico-chemical properties. The main identified product of the heterogeneous reactions between gas-phase ozone and 3,4,5-trimethoxybenzaldehyde under dark conditions and in presence of light was 3,4,5-trimethoxybenzoic acid. For this reason we estimated the carbon yield of 3,4,5-trimethoxybenzoic acid. Carbon yields of 3,4,5trimethoxybenzoic acid decreased with increasing ozone mixing ratio; from 40% at 250 ppb to 15% at !2.5 ppm under dark conditions. At ozone mixing ratio (250 ppbe1 ppm), carbon yields of 3,4,5-trimethoxybenzaldehyde are relatively higher in the experiment under dark condition than under simulated solar light.
You may download, copy and otherwise use the AAM for non-commercial purposes provided that your l... more You may download, copy and otherwise use the AAM for non-commercial purposes provided that your license is limited by the following restrictions: (1) You may use this AAM for non-commercial purposes only under the terms of the CC-BY-NC-ND license. (2) The integrity of the work and identification of the author, copyright owner, and publisher must be preserved in any copy.
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Papers by Etienne Quivet