Oxidation capacity changes in the atmosphere of large urban areas in Europe: Modelling and experimental campaigns in atmospheric simulation chambers.

Air pollution is a major concern for human health and the environment. Consequently, environmental standards have become stricter to improve air quality. Thanks to this, the ambient levels of O precursors such as VOCs and NO have decreased.

Atmospheric Oxidation of a Thiocarbamate Herbicide Used in Winter Cereals.

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 reaction of prosulfocarb with OH radicals was determined as k = (2.

Atmospheric degradation of the organothiophosphate insecticide - Pirimiphos-methyl.

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 measured by the relative rate method. The reaction with ozone was also investigated.

Risk assessment of airborne pesticides in a Mediterranean region of Spain.

A risk assessment strategy based on the quantitative target analysis and semi-quantitative retrospective screening determination of pesticides in PM10 has been developed. The proposed methodology was applied to 345 real samples from nine stations of a Mediterranean area in Spain, and the risk was assessed for adult, children and infants. Forty pesticides were detected with average concentrations ranging from 8 to 30,000pgm.

Determination of reduced sulfur compounds in air samples for the monitoring of malodor caused by landfills.

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 analyzed were hydrogen sulfide, ethyl mercaptan, dimethyl sulfide, carbon disulfide, butyl mercaptan and dimethyl disulfide.

Insights into the Formation and Evolution of Individual Compounds in the Particulate Phase during Aromatic Photo-Oxidation.

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, were investigated at the European Photoreactor.

Atmospheric degradation of lindane and 1,3-dichloroacetone in the gas phase. Studies at the EUPHORE simulation chamber.

The gas-phase degradation of lindane (γ-isomer of hexachlorocyclohexane) towards OH radical 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 lindane was measured using a conventional relative rate technique leading to a value of kOH(lindane)=(6.4±1.

Gas-phase and particulate products from the atmospheric degradation of the organothiophosphorus insecticide chlorpyrifos-methyl.

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) phosphorothioate), is described for semi-urban or rural locations.

The gas-phase degradation of chlorpyrifos and chlorpyrifos-oxon towards OH radical under atmospheric conditions.

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 oxon with OH radicals were measured using a conventional relative rate method. The value of the OH reaction rate constants with chlorpyrifos and chlorpyrifos-oxon were determined to be k=(9.

Gas-phase degradation of the herbicide ethalfluralin under atmospheric conditions.

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 photolysis rate coefficient was determined: J(ethalfluralin)=(1.3±0.

Gas-phase and particulate products from the atmospheric degradation of an isoxazole fungicide.

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.

Online and offline mass spectrometric study of the impact of oxidation and ageing on glyoxal chemistry and uptake onto ammonium sulfate aerosols.

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 affecting particle formation. In this study, the chemistry of GLY with ammonium sulfate (AS) in both bulk laboratory solutions and in aerosol particles is investigated.

The atmospheric photolysis of o-tolualdehyde.

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.

Studies on atmospheric degradation of diazinon in the EUPHORE simulation chamber.

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.

Temperature effect of tapered element oscillating microbalance (TEOM) system measuring semi-volatile organic particulate matter.

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 aerosols formed from the degradation of biogenic pollutants.

Studies on the atmospheric degradation of chlorpyrifos-methyl.

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 of chlorpyrifos-methyl with OH radicals was measured using a conventional relative rate method with cyclohexane and n-octane employed as reference compounds with k = (4.