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Publications (61)
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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(...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
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...
