Formation et devenir de l’aérosol organique secondaire : étude expérimentale de formation d’organosulfates à l’interface gaz-particules

This work deals with the formation and aging processes of secondary organic aerosol (SOA). More precisely, the objective was to document organosulfate formation, recently identified in ambient aerosol. Volatile organic compounds (VOCs) such as monoterpenes have been recognized as potentially important precursors of organosulfates in the atmosphere. However, organosulfate formation is not yet well understood. Reliable chemical mechanisms can only be accessible when studying individual reactions at the molecular level. In this work, organosulfate formation was studied for the reactions of α-pinene and associated oxidized species (α-pinene oxide, myrtenal, isopinocampheol and pinanediol) with acidified ammonium sulfate particles. On-line quantification of VOCs was carried out using proton-transfer-reaction mass spectrometry. Identification of products in the particulate phase has been performed using liquid chromatography coupled with tandem mass spectrometry. Experiments from quasi-static reactor and atmospheric simulation chamber experiments are compared and discussed, allowing to propose chemical mechanisms explaining organosulfate formation for the heterogeneous reactions of interest.Ce travail a eu pour objectif d’améliorer notre compréhension des processus de formation et d’évolution des aérosols organiques secondaires (AOS) en étudiant les réactions susceptibles d’expliquer la présence d’espèces « mixtes » organosoufrées observées récemment dans l’aérosol atmosphérique. Les composés organiques volatils et en particulier les monoterpènes ont été identifiés comme étant des précurseurs potentiellement importants d’organosulfates dans l’atmosphère. Cependant, les mécanismes de formation de ces derniers ne sont pas encore bien compris. Seule une étude au niveau moléculaire et ciblée sur une réaction multiphasique unique, peut donner accès à des mécanismes réactionnels détaillés. Ainsi, les réactions entre l’α-pinène et quatre produits d’oxydation associés (α-pinène oxyde, myrténal, isopinocamphéol et pinanediol), avec des particules modèles de sulfate d’ammonium ont été étudiées individuellement dans le but de documenter la formation d’organosulfates. L’effet de l’humidité relative et celui de l’acidité des particules sur ces réactions ont été étudiés. La quantification en ligne des composés organiques volatils a été effectuée à l’aide d’un spectromètre de masse à transfert protonique. L’identification des structures moléculaires des organosulfates, formés en phase particulaire, a été effectuée par chromatographie liquide couplée à la spectrométrie de masse en tandem. Deux approches complémentaires, impliquant des expériences en réacteur quasi-statique et en chambre de simulation atmosphérique, ont permis de mettre en évidence la formation d’organosulfates mais également de proposer des mécanismes réactionnels pour l’ensemble des composés oxydés étudiés

Steroid hormones, inorganic ions and botrydial in drinking water : Determination with capillary electrophoresis and liquid chromatography-orbitrap high resolution mass spectrometry

Steroid hormones, botrydial, and inorganic ions were studied from cold and hot tap water samples with capillary electrophoresis techniques using UV detection. Identification of the steroids and botrydial was made with ultra-high -performance liquid chromatography (UHPLC) coupled to electrospray ionization orbitrap high-resolution mass spectrometry. Solid phase extraction with nonpolar and ion-exchange sorbents was needed to enrich the compounds for CE and UHPLC studies. The steroids identified from the drinking water samples were estradiol glucoside, androstenedione, testosterone, and progesterone. However, only progesterone could be quantified in both cold and hot tap water samples from Helsinki households. Its concentration varied from 0.031 ng/L to 0.135 ng/L and from 0.054 ng/L to 0.191 ng/L, respectively. Chloride and nitrate amounts were 25 mg/L. Calcium, potassium, magnesium, and sodium were 20, 1, 1, and 17 mg/L at the highest, respectively. Copper, iron, sulphate, and ammonium were below the methods concentration limits. Botrydial from Botrytis cinerea mould was identified in all drinking waters. In both cold and hot tap waters its concentration was 861-3900% higher than in a drilled well water that was also used as the household tap water. The mould was also confirmed by identification of its metabolite abscisic acid. (C) 2017 Elsevier B.V. All rights reserved.Peer reviewe

Field measurements of biogenic volatile organic compounds in the atmosphere using solid-phase microextraction Arrow

Biogenic volatile organic compounds (BVOCs) emitted by terrestrial vegetation participate in a diversity of natural processes. These compounds impact both on short-range processes, such as on plant protection and communication, and on high-range processes, by e.g. participation on aerosol particle formation and growth. The biodiversity of plant species around the Earth, the vast assortment of emitted BVOCs, and their trace atmospheric concentrations contribute to the high remaining uncertainties about the effects of these compounds on atmospheric chemistry and physics, and call for the development of novel collection devices that can offer portability with improved selectivity and capacity. In this study, a novel solid-phase microextraction (SPME) Arrow sampling system was used for the static and dynamic collection of BVOCs from the boreal forest, and samples were subsequently analysed on-site by gas chromatography-mass spectrometry (GC-MS). This system offers higher sampling capacity and improved robustness than the traditional equilibrium-based SPME techniques, such as SPME fibers. Field measurements were performed in summer 2017 at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR II) in Hyytiälä, Finland. Complementary laboratory tests were also performed to compare the SPME-based techniques under controlled experimental conditions and to evaluate the effect of temperature and relative humidity on their extraction performance. The most abundant monoterpenes and aldehydes were successfully collected. A significant improvement on sampling capacity was observed with the new SPME Arrow system when compared to SPME fibers, with collected amounts being approximately 2 times higher for monoterpenes and 7-8 times higher for aldehydes. BVOC species exhibited different affinities for the type of sorbent materials used (PDMS/Carbon WR vs. PDMS/DVB). Higher extraction efficiencies were obtained with dynamic collection prior to equilibrium regime, but this benefit during the field measurements was small probably due to the natural agitation provided by the wind. An increase in temperature and relative humidity caused a decrease in the amounts of analytes extracted under controlled experimental conditions, even though the effect was more significant for PDMS/Carbon WR than for PDMS/DVB. Overall, results demonstrated the benefits and challenges of using SPME Arrow for the sampling of BVOCs in the atmosphere.Peer reviewe

Chemical Characterization of Gas- and Particle-Phase Products from the Ozonolysis of alpha-Pinene in the Presence of Dimethylamine

Amines are recognized as key compounds in new particle formation (NPF) and secondary organic aerosol (SOA) formation. In addition, ozonolysis of a-pinene contributes substantially to the formation of biogenic SOAs in the atmosphere. In the present study, ozonolysis of a-pinene in the presence of dimethylamine (DMA) was investigated in a flow tube reactor. Effects of amines on SOA formation and chemical composition were examined. Enhancement of NPF and SOA formation was observed in the presence of DMA. Chemical characterization of gas and particle-phase products by high-resolution mass spectrometric techniques revealed the formation of nitrogen containing compounds. Reactions between ozonolysis reaction products of a-pinene, such as pinonaldehyde or pinonic acid, and DMA were observed. Possible reaction pathways are suggested for the formation of the reaction products. Some of the compounds identified in the laboratory study were also observed in aerosol samples (PM1) collected at the SMEAR II station (Hyytiala, Finland) suggesting that DMA might affect the ozonolysis of a-pinene in ambient conditions.Peer reviewe

Potential of needle trap microextraction-portable gas chromatography-mass spectrometry for measurement of atmospheric volatile compounds

Volatile organic compounds (VOCs) play a key role in atmospheric chemistry and physics. They participate in photochemical reactions in the atmosphere, which have direct implications on climate through, e.g. aerosol particle formation. Forests are important sources of VOCs, and the limited resources and infrastructures often found in many remote environments call for the development of portable devices. In this research, the potential of needle trap microextraction and portable gas chromatography-mass spectrometry for the study of VOCs at forest site was evaluated. Measurements were performed in summer and autumn 2014 at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR II) in Hyytiala, Finland. During the first part of the campaign (summer) the applicability of the developed method was tested for the determination of monoterpenes, pinonaldehyde, aldehydes, amines and anthropogenic compounds. The temporal variation of aerosol precursors was determined, and evaluated against temperature and aerosol number concentration data. The most abundant monoterpenes, pinonaldehyde and aldehydes were successfully measured, their relative amounts being lower during days when particle number concentration was higher. Ethylbenzene, p- and m-xylene were also found when wind direction was from cities with substantial anthropogenic activity. An accumulation of VOCs in the snow cover was observed in the autumn campaign. Results demonstrated the successful applicability of needle trap microextraction and portable gas chromatography-mass spectrometry for the rapid in situ determination of organic gaseous compounds in the atmosphere.Peer reviewe

Passive Sampling as a Tool to Assess Atmospheric Pesticide Contamination Related to Vineyard Land Use

The massive use of pesticides in agriculture has led to widespread contamination of the environment, particularly the atmospheric compartment. Thirty-six pesticides, most used in viticul-ture, were monitored in ambient air using polyurethane foams as passive air samplers (PUF-PAS). Spatiotemporal data were collected from the samplers for 10 months (February–December 2013), using two different sampling times (1 and 2 months) at two different sites in a chateau vineyard in Gironde (France). A high-volume active air sampler was also deployed in June. Samples were extracted with dichloromethane using accelerated solvent extraction (ASE) (PUFs from both passive and active) or microwave-assisted extraction (MAE) (filters from active sampling). Extracts were analyzed by both gas and liquid chromatography coupled with tandem mass spectrometry. A total of 23 airborne pesticides were detected at least once. Concentrations in PUF exposed one month ranged from below the limits of quantification (LOQs) to 23,481 ng PUF−1. The highest concentrations were for folpet, boscalid, chlorpyrifos-methyl, and metalaxyl-m—23,481, 17,615, 3931, and 3324 ng PUF−1. Clear seasonal trends were observed for most of the pesticides detected, the highest levels (in the ng m−3 range or the µg PUF−1 range) being measured during their application period. Impregnation levels at both sites were heterogeneous, but the same pesticides were involved. Sampling rates (Rs) were also estimated using a high-volume active air sampler and varied significantly from one pesticide to another. These results provide preliminary information on the seasonality of pesticide concentrations in vineyard areas and evidence for the effectiveness of PUF-PAS to monitor pesticides in ambient air. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.COntinental To coastal Ecosystems: evolution, adaptability and governanc

Formation and aging of secondary organic aerosols : experimental study of organosulfate formation at the gas-particle interface

Ce travail a eu pour objectif d’améliorer notre compréhension des processus de formation et d’évolution des aérosols organiques secondaires (AOS) en étudiant les réactions susceptibles d’expliquer la présence d’espèces « mixtes » organosoufrées observées récemment dans l’aérosol atmosphérique. Les composés organiques volatils et en particulier les monoterpènes ont été identifiés comme étant des précurseurs potentiellement importants d’organosulfates dans l’atmosphère. Cependant, les mécanismes de formation de ces derniers ne sont pas encore bien compris. Seule une étude au niveau moléculaire et ciblée sur une réaction multiphasique unique, peut donner accès à des mécanismes réactionnels détaillés. Ainsi, les réactions entre l’α-pinène et quatre produits d’oxydation associés (α-pinène oxyde, myrténal, isopinocamphéol et pinanediol), avec des particules modèles de sulfate d’ammonium ont été étudiées individuellement dans le but de documenter la formation d’organosulfates. L’effet de l’humidité relative et celui de l’acidité des particules sur ces réactions ont été étudiés. La quantification en ligne des composés organiques volatils a été effectuée à l’aide d’un spectromètre de masse à transfert protonique. L’identification des structures moléculaires des organosulfates, formés en phase particulaire, a été effectuée par chromatographie liquide couplée à la spectrométrie de masse en tandem. Deux approches complémentaires, impliquant des expériences en réacteur quasi-statique et en chambre de simulation atmosphérique, ont permis de mettre en évidence la formation d’organosulfates mais également de proposer des mécanismes réactionnels pour l’ensemble des composés oxydés étudiés.This work deals with the formation and aging processes of secondary organic aerosol (SOA). More precisely, the objective was to document organosulfate formation, recently identified in ambient aerosol. Volatile organic compounds (VOCs) such as monoterpenes have been recognized as potentially important precursors of organosulfates in the atmosphere. However, organosulfate formation is not yet well understood. Reliable chemical mechanisms can only be accessible when studying individual reactions at the molecular level. In this work, organosulfate formation was studied for the reactions of α-pinene and associated oxidized species (α-pinene oxide, myrtenal, isopinocampheol and pinanediol) with acidified ammonium sulfate particles. On-line quantification of VOCs was carried out using proton-transfer-reaction mass spectrometry. Identification of products in the particulate phase has been performed using liquid chromatography coupled with tandem mass spectrometry. Experiments from quasi-static reactor and atmospheric simulation chamber experiments are compared and discussed, allowing to propose chemical mechanisms explaining organosulfate formation for the heterogeneous reactions of interest

Formation and aging of secondary organic aerosols : experimental study of organosulfate formation at the gas-particle interface

Ce travail a eu pour objectif d’améliorer notre compréhension des processus de formation et d’évolution des aérosols organiques secondaires (AOS) en étudiant les réactions susceptibles d’expliquer la présence d’espèces « mixtes » organosoufrées observées récemment dans l’aérosol atmosphérique. Les composés organiques volatils et en particulier les monoterpènes ont été identifiés comme étant des précurseurs potentiellement importants d’organosulfates dans l’atmosphère. Cependant, les mécanismes de formation de ces derniers ne sont pas encore bien compris. Seule une étude au niveau moléculaire et ciblée sur une réaction multiphasique unique, peut donner accès à des mécanismes réactionnels détaillés. Ainsi, les réactions entre l’α-pinène et quatre produits d’oxydation associés (α-pinène oxyde, myrténal, isopinocamphéol et pinanediol), avec des particules modèles de sulfate d’ammonium ont été étudiées individuellement dans le but de documenter la formation d’organosulfates. L’effet de l’humidité relative et celui de l’acidité des particules sur ces réactions ont été étudiés. La quantification en ligne des composés organiques volatils a été effectuée à l’aide d’un spectromètre de masse à transfert protonique. L’identification des structures moléculaires des organosulfates, formés en phase particulaire, a été effectuée par chromatographie liquide couplée à la spectrométrie de masse en tandem. Deux approches complémentaires, impliquant des expériences en réacteur quasi-statique et en chambre de simulation atmosphérique, ont permis de mettre en évidence la formation d’organosulfates mais également de proposer des mécanismes réactionnels pour l’ensemble des composés oxydés étudiés.This work deals with the formation and aging processes of secondary organic aerosol (SOA). More precisely, the objective was to document organosulfate formation, recently identified in ambient aerosol. Volatile organic compounds (VOCs) such as monoterpenes have been recognized as potentially important precursors of organosulfates in the atmosphere. However, organosulfate formation is not yet well understood. Reliable chemical mechanisms can only be accessible when studying individual reactions at the molecular level. In this work, organosulfate formation was studied for the reactions of α-pinene and associated oxidized species (α-pinene oxide, myrtenal, isopinocampheol and pinanediol) with acidified ammonium sulfate particles. On-line quantification of VOCs was carried out using proton-transfer-reaction mass spectrometry. Identification of products in the particulate phase has been performed using liquid chromatography coupled with tandem mass spectrometry. Experiments from quasi-static reactor and atmospheric simulation chamber experiments are compared and discussed, allowing to propose chemical mechanisms explaining organosulfate formation for the heterogeneous reactions of interest

Evaluation of sorption of sustainable materials for Nature-based solution in water reuse

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Non-targeted approaches to assess environmental pollution

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