In-cloud processes of methacrolein under simulated conditions – Part 2: Formation of secondary organic aerosol

The fate of methacrolein in cloud evapo-condensation cycles was experimentally investigated. To this end, aqueous-phase reactions of methacrolein with OH radicals were performed (as described in Liu et al., 2009), and the obtained solutions were then nebulized and dried into a mixing chamber. ESI-MS and ESI-MS/MS analyses of the aqueous phase composition denoted the formation of high molecular weight multifunctional products containing hydroxyl, carbonyl and carboxylic acid moieties. The time profiles of these products suggest that their formation can imply radical pathways. These high molecular weight organic products are certainly responsible for the formation of secondary organic aerosol (SOA) observed during the nebulization experiments. The size, number and mass concentration of these particles increased significantly with the reaction time: after 22 h of reaction, the aerosol mass concentration was about three orders of magnitude higher than the initial aerosol quantity. The evaluated SOA yield ranged from 2 to 12%. These yields were confirmed by another estimation method based on the hygroscopic and volatility properties of the obtained SOA measured and reported by Michaud et al. (2009). These results provide, for the first time to our knowledge, strong experimental evidence that cloud processes can act, through photooxidation reactions, as important contributors to secondary organic aerosol formation in the troposphere

Widespread pesticide distribution in the European atmosphere questions their degradability in air

Risk assessment of pesticide impacts on remote ecosystems makes use of model-estimated degradation in air. Recent studies suggest these degradation rates to be overestimated, questioning current pesticide regulation. Here, we investigated the concentrations of 76 pesticides in Europe at 29 rural, coastal, mountain, and polar sites during the agricultural application season. Overall, 58 pesticides were observed in the European atmosphere. Low spatial variation of 7 pesticides suggests continental-scale atmospheric dispersal. Based on concentrations in free tropospheric air and at Arctic sites, 22 pesticides were identified to be prone to long-range atmospheric transport, which included 15 substances approved for agricultural use in Europe and 7 banned ones. Comparison between concentrations at remote sites and those found at pesticide source areas suggests long atmospheric lifetimes of atrazine, cyprodinil, spiroxamine, tebuconazole, terbuthylazine, and thiacloprid. In general, our findings suggest that atmospheric transport and persistence of pesticides have been underestimated and that their risk assessment needs to be improved

Widespread pesticide distribution in the European atmosphere questions their degradability in air

Risk assessment of pesticide impacts on remote ecosystems makes use of model-estimated degradation in air. Recent studies suggest these degradation rates to be overestimated, questioning current pesticide regulation. Here, we investigated the concentrations of 76 pesticides in Europe at 29 rural, coastal, mountain, and polar sites during the agricultural application season. Overall, 58 pesticides were observed in the European atmosphere. Low spatial variation of 7 pesticides suggests continental-scale atmospheric dispersal. Based on concentrations in free tropospheric air and at Arctic sites, 22 pesticides were identified to be prone to long-range atmospheric transport, which included 15 substances approved for agricultural use in Europe and 7 banned ones. Comparison between concentrations at remote sites and those found at pesticide source areas suggests long atmospheric lifetimes of atrazine, cyprodinil, spiroxamine, tebuconazole, terbuthylazine, and thiacloprid. In general, our findings suggest that atmospheric transport and persistence of pesticides have been underestimated and that their risk assessment needs to be improved

Hydrolytic and photolytic behaviour of imidazolinone pesticides. Case of imazamox and imazapyr

International audiencePhotolysis of imazamox and imazapyr, two broad-spectrum herbicides of the imidazolinone family, leads to photoproducts. Appearance and disappearance kinetics of photoproducts are followed by LC-UV. After a pre-concentration step, the characterization of photoproducts is carried out by LC-MS and by high resolution mass spectrometry, leading to suggest pesticide degradation schemes

Adsorption isotherms of an imidazolinone herbicide on activated carbon

229th National Meeting of the American-Chemical-Society, San Diego, CA, MAR 13-17, 2005International audienceno abstrac

Hydrolytic and photolytic behaviour of imidazolinone pesticides. Case of imazamox and imazapyr

International audiencePhotolysis of imazamox and imazapyr, two broad-spectrum herbicides of the imidazolinone family, leads to photoproducts. Appearance and disappearance kinetics of photoproducts are followed by LC-UV. After a pre-concentration step, the characterization of photoproducts is carried out by LC-MS and by high resolution mass spectrometry, leading to suggest pesticide degradation schemes

Adsorption isotherms of an imidazolinone herbicide on activated carbon

229th National Meeting of the American-Chemical-Society, San Diego, CA, MAR 13-17, 2005International audienceno abstrac

Measurements of VOC/SVOC emission factors from burning incenses in an environmental test chamber: influence of temperature, relative humidity, and air exchange rate

International audienceThis study investigates the influence of three environmental indoor parameters (i.e., temperature, relative humidity, and air exchange rate) on the emission of 13 volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) during incense burning. Experiments have been carried out using an environmental test chamber. Statistical results from a classical two-level full factorial design highlight the predominant effect of ventilation on emission factors. The higher the ventilation, the higher the emission factor. Moreover, thanks to these results, an estimation of the concentration range for the compounds under study can be calculated and allows a quick look of indoor pollution induced by incense combustion. Carcinogenic substances (i.e., benzene, benzo(a)pyrene, and formaldehyde) produced from the incense combustion would be predicted in typical living indoors conditions to reach instantaneous concentration levels close to or higher than air quality exposure threshold values