Oxidation of biogenic and water-soluble compounds in aqueous and organic aerosol droplets by ozone: a kinetic and product analysis approach using laser Raman tweezers

The results of an experimental study into the oxidative degradation of proxies for atmospheric aerosol are presented. We demonstrate that the laser Raman tweezers method can be used successfully to obtain uptake coeffcients for gaseous oxidants on individual aqueous and organic droplets, whilst the size and composition of the droplets is simultaneously followed. A laser tweezers system was used to trap individual droplets containing an unsaturated organic compound in either an aqueous or organic ( alkane) solvent. The droplet was exposed to gas- phase ozone and the reaction kinetics and products followed using Raman spectroscopy. The reactions of three different organic compounds with ozone were studied: fumarate anions, benzoate anions and alpha pinene. The fumarate and benzoate anions in aqueous solution were used to represent components of humic- like substances, HULIS; a alpha- pinene in an alkane solvent was studied as a proxy for biogenic aerosol. The kinetic analysis shows that for these systems the diffusive transport and mass accommodation of ozone is relatively fast, and that liquid- phase di. ffusion and reaction are the rate determining steps. Uptake coe. ffcients, g, were found to be ( 1.1 +/- 0.7) x 10(-5), ( 1.5 +/- 0.7) x 10 (-5) and ( 3.0 - 7.5) x 10 (-3) for the reactions of ozone with the fumarate, benzoate and a- pinene containing droplets, respectively. Liquid- phase bimolecular rate coe. cients for reactions of dissolved ozone molecules with fumarate, benzoate and a- pinene were also obtained: k(fumarate) = ( 2.7 +/- 2) x 10 (5), k(benzoate) = ( 3.5 +/- 3) x 10 (5) and k(alpha-pinene) = ( 1-3) x 10(7) dm(3) mol (-1) s (- 1). The droplet size was found to remain stable over the course of the oxidation process for the HULIS- proxies and for the oxidation of a- pinene in pentadecane. The study of the alpha- pinene/ ozone system is the first using organic seed particles to show that the hygroscopicity of the particle does not increase dramatically over the course of the oxidation. No products were detected by Raman spectroscopy for the reaction of benzoate ions with ozone. One product peak, consistent with aqueous carbonate anions, was observed when following the oxidation of fumarate ions by ozone. Product peaks observed in the reaction of ozone with alpha- pinene suggest the formation of new species containing carbonyl groups

Seasonal Variation of Essential Oil Yield and Composition of Sage (Salvia officinalis L.) Grown in Castilla - La Mancha (Central Spain)

Links between phenology, yield and composition of the essential oil of common sage, Salvia officinalis L., grown in Guadalajara (Central Spain) were determined in the different phases of the biological cycle during one year. Data showed an average yield about 1.0%. The analysis of the oil components was carried out by GC-FID and GC/MS. The main oil constituent was alpha thujone (40.1 - 46.5%). Other identified compounds are beta pinene (2.6 - 4.5%), cineole (3.5 - 8.7%), beta thujone (4.1 - 5.6%), camphor (4.1 - 8.0%), borneol (1.3 - 3.7%), alpha humulene (3.8 - 7.3%), viridiflorol (3.4-12.6%) and manool (0.1-4.5%). The highest yield of oil was obtained in the period of full flowering and the highest concentration of alpha thujone in the period of initial flowering

Microbial community changes during different empty bed residence times and operational fluctuations in an air diffusion reactor for odor abatement

Producción CientíficaThe succession of bacterial and fungal populations was assessed in an activated sludge (AS) diffusion bioreactor treating a synthetic malodorous emission containing H2S, toluene, butanone and alpha-pinene. Microbial community characteristics (bacterial and fungal diversity, richness, evenness and composition) and bioreactor function relationships were evaluated at different empty bed residence times (EBRTs) and after process fluctuations and operational failures (robustness test). For H2S, butanone and toluene, the bioreactor showed a stable and efficient abatement performance regardless of the EBRT and fluctuations applied, while low alpha-pinene removals were observed. While no clear positive or negative relationship between community characteristics and bioreactor functions was observed, ecological parameters such as evenness and community dynamics seemed to be of importance for maintaining reactor stability. The optimal degree of evenness of the inoculum likely contributed to the high robustness of the system towards the fluctuations imposed. Actinobacteria, Proteobacteria and Fungi (Hypocreales, Chaeatothyriales) were the most abundant groups retrieved from the AS system with a putative key role in the degradation of butanone and toluene. Typical H2S and alpha-pinene degraders were not retrieved from the system. The inoculation of P. fluorescens, a known alpha-pinene degrader, to the system did not result in the enhancement of the degradation of this compound. This strain was likely outcompeted by the microorganisms already adapted to the AS environment.2019-03-08Ministerio de Economía, Industria y Competitividad (CTQ2007-64324, 18ISMW)Junta de Castilla y Leon (UIC 476 71

Influence of Humidity, Temperature and Radicals on the Formation and Thermal Properties of Secondary Organic Aerosol (SOA) from Ozonolysis of {\beta}-pinene

The influence of water and radicals on SOAs produced by {\beta}-pinene ozonolysis was investigated at 298 and 288 K using a laminar flow reactor. A volatility tandem differential mobility analyzer (VTDMA) was used to measure the evaporation of the SOA, enabling the parameterization of its volatility properties. The parameters extracted included the temperature at which 50% of the aerosol had evaporated (TVFR0.5) and the slope factor (SVFR). An increase in SVFR indicates a broader distribution of vapor pressures for the aerosol constituents. Reducing the reaction temperature increased SVFR and decreased TVFR0.5 under humid conditions but had less effect on TVFR0.5 under dry conditions. In general, higher water concentrations gave lower TVFR0.5 values, more negative SVFR values, and a reduction in total SOA production. The radical conditions were changed by introducing OH scavengers to generate systems with and without OH radicals and with different [HO2]/[RO2] ratios. Presence of a scavenger and lower [HO2]/[RO2] ratio reduced SOA production. Observed changes in SVFR values could be linked to the more complex chemistry that occurs in the absence of a scavenger, and indicated that additional HO2 chemistry gives products with a wider range of vapor pressures. Updates to existing ozonolysis mechanisms with routes that describe the observed responses to water and radical conditions for monoterpenes with endocyclic and exocyclic double bonds are discussed

α-pinene photooxidation under controlled chemical conditions – Part 2: SOA yield and composition in low- and high-NO_x environments

The gas-phase oxidation of α-pinene produces a large amount of secondary organic aerosol (SOA) in the atmosphere. A number of carboxylic acids, organosulfates and nitrooxy organosulfates associated with α-pinene have been found in field samples and some are used as tracers of α-pinene oxidation. α-pinene reacts readily with OH and O_3 in the atmosphere followed by reactions with both HO_2 and NO. Due to the large number of potential reaction pathways, it can be difficult to determine what conditions lead to SOA. To better understand the SOA yield and chemical composition from low- and high-NO_x OH oxidation of α-pinene, studies were conducted in the Caltech atmospheric chamber under controlled chemical conditions. Experiments used low O_3 concentrations to ensure that OH was the main oxidant and low α-pinene concentrations such that the peroxy radical (RO_2) reacted primarily with either HO_2 under low-NO_x conditions or NO under high-NO_x conditions. SOA yield was suppressed under conditions of high-NO_x. SOA yield under high-NO_x conditions was greater when ammonium sulfate/sulfuric acid seed particles (highly acidic) were present prior to the onset of growth than when ammonium sulfate seed particles (mildly acidic) were present; this dependence was not observed under low-NO_x conditions. When aerosol seed particles were introduced after OH oxidation, allowing for later generation species to be exposed to fresh inorganic seed particles, a number of low-NO_x products partitioned to the highly acidic aerosol. This indicates that the effect of seed acidity and SOA yield might be under-estimated in traditional experiments where aerosol seed particles are introduced prior to oxidation. We also identify the presence of a number of carboxylic acids that are used as tracer compounds of α-pinene oxidation in the field as well as the formation of organosulfates and nitrooxy organosulfates. A number of the carboxylic acids were observed under all conditions, however, pinic and pinonic acid were only observed under low-NO_x conditions. Evidence is provided for particle-phase sulfate esterification of multi-functional alcohols

Modeling of secondary organic aerosol yields from laboratory chamber data

Laboratory chamber data serve as the basis for constraining models of secondary organic aerosol (SOA) formation. Current models fall into three categories: empirical two-product (Odum), product-specific, and volatility basis set. The product-specific and volatility basis set models are applied here to represent laboratory data on the ozonolysis of α-pinene under dry, dark, and low-NOx conditions in the presence of ammonium sulfate seed aerosol. Using five major identified products, the model is fit to the chamber data. From the optimal fitting, SOA oxygen-to-carbon (O/C) and hydrogen-to-carbon (H/C) ratios are modeled. The discrepancy between measured H/C ratios and those based on the oxidation products used in the model fitting suggests the potential importance of particle-phase reactions. Data fitting is also carried out using the volatility basis set, wherein oxidation products are parsed into volatility bins. The product-specific model is most likely hindered by lack of explicit inclusion of particle-phase accretion compounds. While prospects for identification of the majority of SOA products for major volatile organic compounds (VOCs) classes remain promising, for the near future empirical product or volatility basis set models remain the approaches of choice

Analysis by gas chromatography-mass spectrometry of the volatile components of Teucrium lusitanicum and Teucrium algarbiensis

The essential oils from four samples of Teucrium lusitanicum and one sample of Teucrium algarbiensis, grown in Algarve (southern Portugal) were analyzed by gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS). Seventy-one volatile compounds were identified. Major compounds of T. algarbiensis oil were alpha-pinene (8.3%), sabinene (7.2%), beta-pinene (10.2%), limonene (11.8%) and germacrene D (7.6%). Concerning T. lusitanicum, some quantitative differences were found with regards to the major constituents of the oils from four populations: alpha-pinene (0.8-8.5%), sabinene (2.1-9.6%), beta-pinene (2.5-11.9%), limonene (1.2-11.5%) and elemol (2.6-12.0%). (C) 2004 Elsevier B.V. All rights reserved

New Records of Native and Non-Native Bark and Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae) in Illinois

From 2009–2012, we conducted surveys with Lindgren funnel traps for native and non-native bark and ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) in northeastern Illinois. During this study, we collected a total of 10,194 bark and ambrosia beetles representing 50 species in 28 genera. Ten scolytine species not previously reported to occur in Illinois were collected during this survey. Three of these new records are species not native to North America, including Cyclorhipidion bodoanum (Reitter), Cyclorhipidion pelliculosum (Eichhoff), and Hylastinus obscurus (Marsham). Native species reported from Illinois for the first time include: Anisandrus obesus (LeConte), Dryocoetes autographus (Ratzeburg), Hylocurus spadix Blackman, Pityophthorus cariniceps LeConte, Pityophthorus puberulus (LeConte), Pseudothysanoes lecontei Blackman, and Xyleborinus gracilis (Eichhoff). The results presented here will update and improve the somewhat limited information regarding the overall bark and ambrosia beetle community in northeastern Illinois