Esther Borrás

Esther Borrás
Centro de Estudios Ambientales del Mediterráneo | CEAM · Atmospheric Chemistry

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61
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Publications

Publications (61)
Article
Full-text available
In early 2020, the COVID-19 pandemic spread globally, and severe measures to control it were implemented. This study investigates the impact of the lockdown on the air quality of three provinces in the Valencia region, eastern Spain, in the years 2015-2020, focusing on particulate matter (PM). A thorough statistical analysis using different approac...
Article
Full-text available
Multi-oxygenated volatile organic compounds are important markers of air pollution and precursors of ozone and secondary aerosols in both polluted and remote environments. Herein, their accurate determination was enhanced. The approach was based on an automated system for active sampling and on-fibre derivatization coupled with the gas chromatograp...
Article
Full-text available
This paper provides scientific results from a European LIFE project carried out in the Valencian region of Spain during the 2017 to 2018 time frame. In 2018, more than 60,000 tons of pesticides were commercialized in Spain, with approximately 15% destined for Valencian crops. In order to improve the air quality in the agricultural areas of this reg...
Article
Full-text available
Photolysis is one the main drivers in atmospheric chemistry. Volatile organic compounds that bear one or more carbonyl functions can absorb UV light between 295 nm and 450 nm, enabling them to possibly photolyze in the atmosphere. Yet, very few data are available regarding the impact of such photolysis processes on the fate of multifunctional carbo...
Preprint
Full-text available
Multi-oxygenated volatile organic compounds are important markers of air pollution and precursors of ozone and secondary aerosols in both polluted and remote environments. Herein, their accurate determination was enhanced. The approach was based on an automated system for active sampling and on-fiber derivatization coupled with GC-MS technique. The...
Article
Full-text available
The chemical characterization of aerosols, especially fine organic fraction, is a relevant atmospheric challenge because their composition highly depends on localization. Herein, we studied the concentration of multi-oxygenated organic compounds in the western Mediterranean area, focusing on sources and the effect of air patterns. The organic aeros...
Article
Full-text available
A large part of the European population is still exposed to ambient nitrogen dioxide (NO2) levels exceeding the European Union (EU) air quality standards, being a key challenge to reduce NO2 concentrations across many European urban areas, particularly close to roads. In this work, a trend analysis of pollutants involved in NO2 processes was done f...
Article
Full-text available
The gas-phase atmospheric degradation of prosulfocarb (a widely used thiocarbamate herbicide in winter cereals) at different NOx concentrations was investigated at the large outdoor European Photoreactor (EUPHORE) in Valencia, Spain. Photolysis under sunlight conditions and reaction with ozone were shown as unimportant. The rate constant for the re...
Article
The gas phase atmospheric degradation of pirimiphos-methyl (a widely used organophosphate insecticide and acaricide in many European regions) has been investigated at the large outdoor European Photoreactor (EUPHORE) in Valencia, Spain. Its photolysis has been studied under sunlight conditions and its reaction rate constant with OH radicals was mea...
Article
Full-text available
Several experiments were performed in the European Photo-reactor - EUPHORE - for studying aerosol formation from organophosphorus pesticides such as diazinon, chlorpyrifos, chlorpyrifos-methyl and pirimiphos-methyl. The mass concentration yields obtained (Y) were in the range 5 - 44% for the photo-oxidation reactions in the presence and the absence...
Article
Full-text available
The atmospheric particulate matter has a large impact on climate, biosphere behaviour and human health. Its study is complex because of large number of species are present at low concentrations and the continuous time evolution, being not easily separable from meteorology, and transport processes. Closed systems have been proposed by isolating spec...
Article
A reliable method for determining malodorous reduced sulfur compounds (RSC) in atmospheric samples has been developed. The method uses an activated coconut solid-phase sorbent for active sampling, hexane as desorption solvent, and gas chromatography-mass spectrometry (GC-MS) technique for specific and sensitive separation-detection. The compounds a...
Article
Secondary organic aerosol (SOA) is well known to have adverse effects on air quality and human health. However, the dynamic mechanisms occurring during SOA formation and evolution are poorly understood. The time resolved SOA composition formed during the photo-oxidation of three aromatic compounds, methyl chavicol, toluene and 4-methyl catechol, we...
Article
The phosphorothioate structure is highly present in several pesticides. However, there is a lack of information about its degradation process in air and the secondary pollutants formed. Herein, the atmospheric reactions of chlorpyrifos, one of the most world-used insecticide, and its main degradation product - chlorpyrifos-oxon - are described. The...
Article
Full-text available
The α-dicarbonyl compounds glyoxal (CHOCHO) and methyl glyoxal (CH3C(O)CHO) are produced in the atmosphere by the oxidation of hydrocarbons and emitted directly from pyrogenic sources. Measurements of ambient concentrations inform about the rate of hydrocarbon oxidation, oxidative capacity, and secondary organic aerosol (SOA) formation. We present...
Article
The phosphorothioate structure is highly present in several organophosphorus pesticides. However, there is insufficient information about its degradation process after the release to the atmosphere and the secondary pollutants formed. Herein, the atmospheric reaction of chlorpyrifos-methyl (o,o-dimethyl o-(3,5,6-trichloropyridin-2-yl) phosphorothio...
Article
The OH initiated oxidation of chlorpyrifos (a widely used insecticide) and its photooxidation product chlorpyrifos- oxon were investigated at the large outdoor European Photoreactor (EUPHORE). The rate constants for reaction of chlorpyrifos and chlorpyrifos oxonwith OH radicals weremeasured using a conventional relative rate method. The value of th...
Article
Full-text available
The α-dicarbonyl compounds glyoxal (CHOCHO) and methyl glyoxal (CH3C(O)CHO) are produced in the atmosphere by the oxidation of hydrocarbons, and emitted directly from pyrogenic sources. Measurements of ambient concentrations inform about the rate of hydrocarbon oxidation, oxidative capacity, and secondary organic aerosol (SOA) formation. We present...
Article
Full-text available
The increasing demand for palm oil for uses in biofuel and food products is leading to rapid expansion of oil palm agriculture. Methyl chavicol (also known as estragole and 1-allyl-4-methoxybenzene) is an oxygenated biogenic volatile organic compound (VOC) that was recently identified as the main floral emission from an oil palm plantation in Malay...
Conference Paper
Full-text available
With the aim of characterizing the main air pollutants (anthropogenic, biogenic and secondary reaction products) present in the Mediterranean coast of the Iberian Peninsula under different meteorological conditions (summer and winter) two field campaigns (February and June 2011) were performed in the context of the MODELISMOS project (Modelling and...
Conference Paper
Full-text available
Within the MODELISMOS project (Modelling and analysis of mesometeorological processes on transport and accumulation of pollutants in the Western Mediterranean and their influence on chemical degradation mechanisms) two different campaigns, the first one in winter-(February 2012) and the second one in summer (September 2012), were carried out at the...
Article
Full-text available
The increasing demand for palm oil for uses in biofuel and food products is leading to rapid expansion of oil palm agriculture. Methyl chavicol (also known as estragole and 1-allyl-4-methoxybenzene) is an oxygenated biogenic volatile organic compound that was recently identified as the main floral emission from an oil palm plantation in Malaysian B...
Article
Recent laboratory and modelling studies have shown that reactive uptake of low molecular weight alpha-dicarbonyls such as glyoxal (GLY) by aerosols is a potentially significant source of secondary organic aerosol (SOA). However, previous studies disagree in the magnitude of the uptake of GLY, the mechanism involved and the physicochemical factors a...
Article
The gas-phase degradation of ethalfluralin, N-ethyl-α,α,α-trifluoro-N-(2-methylallyl)-2,6-dinitro-p-toluidine, a widely used herbicide, was investigated under atmospheric conditions at the large outdoor European simulation chamber (EUPHORE) in Valencia, Spain. The photolysis of ethalfluralin was investigated under solar radiation and the mean photo...
Article
The isoxazole structure is present in several pesticides. However, there is a lack of information about its degradation products after the release to the atmosphere. The main atmospheric reactions of hymexazol (5-methylisoxazol-3-ol), selected as representative model, were investigated at a large outdoor simulation chamber. The predominant products...
Conference Paper
Full-text available
Pollutants are emitted into the troposphere as a result of human activity and natural sources. Once emitted, these compounds undergo physical and chemical changes that result in the formation of other secondary pollutants that may be even more harmful than their predecessors. These transformations are strongly affected by the meteorological conditi...
Conference Paper
Full-text available
Field measurements give on-site information about the state of the atmosphere under certain meteorological conditions on a specific time and location. But the atmosphere is a highly complicated reactive system on which many processes (transport, accumulation of pollutants, deposition, chemical reaction, etc) affected by weather conditions happen at...
Article
Full-text available
Los aerosoles orgánicos secundarios (AOS) constituyen una fracción de las partículas atmosféricas. Este tipo de partículas se forman como consecuencia de la reacción de oxidación de ciertos gases orgánicos, lo que conduce a la formación de compuestos de baja volatilidad. Del mismo modo que para otros contaminantes atmosféricos, los modelos de calid...
Article
Full-text available
The α-dicarbonyl compounds glyoxal (GLY, CH(O)CHO) and methylglyoxal (MGLY, CH3C(O)CHO)) are ubiquitous intermediates formed in the photooxidation of a wide range of anthropogenic and biogenic volatile organic compounds (VOCs). Recent measurements demonstrate that large uncertainties exist in the amount of glyoxal formed from isoprene photooxidatio...
Article
The gas-phase degradation of propachlor (2-chloro-N-isopropylacetanilide), a widely used herbicide, was investigated under atmospheric conditions at the large outdoor European simulation chamber (EUPHORE) in Valencia, Spain. The rate coefficient for the reaction of hydroxyl radicals with propachlor was measured using a conventional relative rate te...
Article
Carbon disulfide (CS2), a relevant reduced sulfur compound in air, is well-known for its malodor and its significant effect on global atmospheric chemistry. Therefore, a reliable method for determining CS2 in atmospheric samples has been developed based on solid-phase sampling and gas chromatography-mass spectrometry (GC-MS). Two types of solid-pha...
Article
The production of condensate compounds from the degradation of benzene by OH radical chemistry was studied. Secondary organic aerosol (SOA) formation was investigated in the EUPHORE (European Photoreactor) simulation chambers. Experiments were performed under different OH-production conditions – addition of H2O2, NO or HONO –, in a high-volume reac...
Article
The determination of multifunctional oxygenated compounds in secondary organic aerosols (SOA) usually requires a derivatisation protocol prior to gas chromatography-mass spectrometry analysis (GC-MS). Our proposed protocol, a combination of O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBHA) plus diluted N-methyl-N-trimethyl-silyltrifluoroacetami...
Article
The photolysis of o-tolualdehyde by natural sunlight has been investigated at the large outdoor European Photoreactor (EUPHORE) in Valencia, Spain. The photolysis rate coefficient was measured directly under different solar flux levels, with values in the range j(o-tolualdehyde) = (1.62-2.15) × 10(-4) s(-1) observed, yielding an average value of j(...
Article
A reliable multi-residue method for determining gaseous and particulate phase pesticides in atmospheric samples has been developed. This method, based on full scan gas chromatography-mass spectrometry (GC-MS), allowed the proper determination of sixteen relevant pesticides, in a wide range of concentrations and without the influence of interference...
Article
The gas phase atmospheric degradation of diazinon has been investigated at the large outdoor European Photoreactor (EUPHORE) in Valencia, Spain. The rate constant for reaction of diazinon with OH radicals was measured using a conventional relative rate method with di-n-buthylether as reference compound being k = (3.5 ± 1.2) × 10⁻¹¹ cm³ molecule⁻¹ s...
Article
The gas-phase degradation of hymexazol (5-methylisoxazol-3-ol), a widely used fungicide, was investigated under atmospheric conditions at the European Photoreactor (EUPHORE) in Valencia, Spain, a large outdoor simulation chamber. The rate coefficient for the reaction of hydroxyl radicals with hymexazol was measured using a conventional relative rat...
Article
The gas-phase atmospheric degradation of chlorpyrifos-methyl (a widely used organophosphate insecticide in Southern European regions) has been investigated at the large outdoor European Photoreactor (EUPHORE) in Valencia, Spain. Photolysis under sunlight conditions and reaction with ozone were shown to be unimportant. The rate constant for reaction...
Article
The study of diesel engine exhaust emissions is important due to their impact on atmospheric chemistry and air pollution. Although information on the general nature of diesel emissions is widely available, the gas and particulate phase characterization is still limited. Is known that hundreds of compounds are emitted from combustion and that they d...
Article
Full-text available
The tapered element oscillating microbalance (TEOM) system is widely used to measure continuous particle mass concentrations in air quality networks. However, the semi-volatile aerosol material is lost under normal operation conditions (50 °C). This study has evaluated the error in the organic fraction of the TEOM-measured secondary organic aerosol...
Article
Smog chambers have been extensively used to investigate the chemical routes of oxidation reactions for several organic gases. In this study we present the results of a set of experiments performed in the EUPHORE photoreactor to analyze SOA formation from a mixture of four organic gases related to anthropogenic emissions (1,3,5-trimethylbenzene, o-x...
Article
Full-text available
The degradation of 2-aminoethanol (MEA) by the hydroxyl radical (OH) was studied in the European Photoreactor (EUPHORE), a large outdoor environmental chamber. High-Temperature Proton-Transfer-Reaction Mass Spectrometry (HT-PTR-MS) and Fast Fourier Transform Infrared (FT-IR) were used to follow concentrations of reactants in the gas phase. Aerosol...
Article
Sulfur dioxide (SO2) is an important urban atmospheric pollutant, mainly produced by the combustion of fossil fuels containing sulfur. In the atmosphere, SO2 can react with OH radicals to form sulfuric acid, which can condense to form acidic aerosol. Sulfuric acid particles act as an acid catalyst for some heterogeneous carbonyl reactions like hydr...
Article
The study of light-duty diesel engine exhaust emissions is important due to their impact on atmospheric chemistry and air pollution. In this study, both the gas and the particulate phase of fuel exhaust were analyzed to investigate the effects of diesel reformulation and engine operating parameters. The research was focused on polycyclic aromatic h...
Article
Full-text available
Green leaf volatiles (GLVs) are an important group of chemicals released by vegetation which have emission fluxes that can be significantly increased when plants are damaged or stressed. A series of simulation chamber experiments has been conducted at the European Photoreactor in Valencia, Spain, to investigate secondary organic aerosol (SOA) forma...
Article
This study presents the application of O-(2,3,4,5,6)-pentafluorobenzyl-hydroxylamine hydrochloride (PFBHA) on-fibre derivatisation Solid Phase Microextraction (SPME) to the sampling and quantification of the unsaturated 1,4-dicarbonyl products obtained in the photo-oxidation of furan, 2-methylfuran and 3-methylfuran with HONO: butenedial, 4-oxo-2-p...
Article
Green leaf volatiles (GLVs) are an important group of chemicals released by vegetation which have emission fluxes that can be significantly increased when plants are damaged or stressed. A series of simulation chamber experiments has been conducted at the European Photoreactor in Valencia, Spain, to investigate secondary organic aerosol (SOA) forma...
Article
An accurate and reliable method for determining polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosols is described. This optimised gas chromatography-mass spectrometry (GC-MS) method permits a wide range of concentrations to be analysed without the influence of interferences. Pre-treatment comparison of four kinds of aerosol collector fil...
Article
The gas phase atmospheric degradation of trifluralin (a widely used herbicide) has been investigated at the EUPHORE facility. Its photolysis has been studied under sunlight conditions and its reaction rate constant with HO() radicals was measured using the relative rate method. Using 1,3,5-trimethylbenzene as reference compound, the rate constant o...
Article
The present work is an experimental study on the formation of secondary organic aerosol during the photochemical oxidation of aromatic hydrocarbons in an environmental smog chamber under realistic conditions, i.e., low precursor concentrations and natural solar irradiation. A series of newly designed smog chamber irradiations were performed in the...

Projects

Projects (4)
Archived project
Project
The general objective of the project is to demonstrate the reduction of the environmental contamination of pesticides and their metabolites in the air using Optimal Volume Rate Adjustment tools (OVRA) and drift reducing tools (SDRT) which will lead to a decrease of the pesticide risk for fauna, flora and humans. Besides a new ultra-fast, sensitive and time resolved technology for the analysis of pesticides will be developed to assess the application of pesticides from a health standpoint, in real agricultural conditions.
Project
The aim of the LIFE PHOTOCITYTEX project is to assess the effectiveness of using TiO2-based photocatalytic nanomaterials in building textiles as a way of improving air quality in urban areas. Moreover, information on secondary products formed during the tests will be obtained, yielding a better overall understanding of the whole process and its implications