Molecular speciation of atmospheric organic matter was investigated during a short summer field campaign performed in a citrus fruit field in northern Corsica(June 2011).Aimedat assessing the performance on the field ...Molecular speciation of atmospheric organic matter was investigated during a short summer field campaign performed in a citrus fruit field in northern Corsica(June 2011).Aimedat assessing the performance on the field of newly developed analytical protocols,this work focuses on the molecular composition of both gas and particulate phases and provides an insight into partitioning behavior of the semi-volatile oxygenated fraction.Limonene ozonolysis tracers were specifically searched for,according to gas chromatography–mass spectrometry(GC–MS)data previously recorded for smog chamber experiments.A screening of other oxygenated species present in the field atmosphere was also performed.About sixty polar molecules were positively or tentatively identified in gas and/or particle phases.These molecules comprise a wide range of branched and linear,mono and di-carbonyls(C_3–C7),mono and di-carboxylic acids(C_3–C_18),and compounds bearing up to three functionalities.Among these compounds,some can be specifically attributed to limonene oxidation and others can be related toα-orβ-pinene oxidation.This provides an original snapshot of the organic matter composition at a Mediterranean site in summer.Furthermore,for compounds identified and quantified in both gaseous and particulate phases,an experimental gas/particle partitioning coefficient was determined.Several volatile products,which are not expected in the particulate phase assuming thermodynamic equilibrium,were nonetheless present in significant concentrations.Hypotheses are proposed to explain these observations,such as the possible aerosol viscosity that could hinder the theoretical equilibrium to be rapidly reached.展开更多
PM10 was monitored during 2008-2011 period at LUT and BON, two urban tropical stations close to each other at Saint-Pierre city, in Reunion Island (south-western Indian Ocean). During the study period, notable PM10 co...PM10 was monitored during 2008-2011 period at LUT and BON, two urban tropical stations close to each other at Saint-Pierre city, in Reunion Island (south-western Indian Ocean). During the study period, notable PM10 concentrations are observed at BON close to the coasts. At LUT, a more inland site, the daily PM10 concentration range between 13 and 70 μg/m3. Importantly, the limit value for the protection of the human health is systematically exceeded at BON while it is never exceeded at LUT. Also, the quality objective (QO: 30 μg/m3, on annual average) and the limit value for the human health protection (LV: 40 μg/m3, on annual average) are exceeded at BON each year during 2008-2011, while at LUT no regulatory values are exceeded. Nitrogen dioxide, an atmospheric tracer of anthropogenic activities was also monitored at LUT and BON. The mean diurnal NO2 variation is of the same level and order of magnitude and exhibits a similar pattern at both stations suggesting that distinct sources influence the PM10 at LUT and at BON. Chemical analysis was performed on daily filters sampled in September-November 2011 at the two stations to determine the sea salt contribution on PM10 across Saint-Pierre city. It showed that the sea salt contribution to the PM10 is 55% at BON in September 2011. The sea salt particles are therefore the main cause for the exceedances of the regulatory values of PM10 recorded at BON. The results importantly suggest that the notable PM10 concentrations measured at this urban marine site might have some but minor impact on human health.展开更多
文摘Molecular speciation of atmospheric organic matter was investigated during a short summer field campaign performed in a citrus fruit field in northern Corsica(June 2011).Aimedat assessing the performance on the field of newly developed analytical protocols,this work focuses on the molecular composition of both gas and particulate phases and provides an insight into partitioning behavior of the semi-volatile oxygenated fraction.Limonene ozonolysis tracers were specifically searched for,according to gas chromatography–mass spectrometry(GC–MS)data previously recorded for smog chamber experiments.A screening of other oxygenated species present in the field atmosphere was also performed.About sixty polar molecules were positively or tentatively identified in gas and/or particle phases.These molecules comprise a wide range of branched and linear,mono and di-carbonyls(C_3–C7),mono and di-carboxylic acids(C_3–C_18),and compounds bearing up to three functionalities.Among these compounds,some can be specifically attributed to limonene oxidation and others can be related toα-orβ-pinene oxidation.This provides an original snapshot of the organic matter composition at a Mediterranean site in summer.Furthermore,for compounds identified and quantified in both gaseous and particulate phases,an experimental gas/particle partitioning coefficient was determined.Several volatile products,which are not expected in the particulate phase assuming thermodynamic equilibrium,were nonetheless present in significant concentrations.Hypotheses are proposed to explain these observations,such as the possible aerosol viscosity that could hinder the theoretical equilibrium to be rapidly reached.
文摘PM10 was monitored during 2008-2011 period at LUT and BON, two urban tropical stations close to each other at Saint-Pierre city, in Reunion Island (south-western Indian Ocean). During the study period, notable PM10 concentrations are observed at BON close to the coasts. At LUT, a more inland site, the daily PM10 concentration range between 13 and 70 μg/m3. Importantly, the limit value for the protection of the human health is systematically exceeded at BON while it is never exceeded at LUT. Also, the quality objective (QO: 30 μg/m3, on annual average) and the limit value for the human health protection (LV: 40 μg/m3, on annual average) are exceeded at BON each year during 2008-2011, while at LUT no regulatory values are exceeded. Nitrogen dioxide, an atmospheric tracer of anthropogenic activities was also monitored at LUT and BON. The mean diurnal NO2 variation is of the same level and order of magnitude and exhibits a similar pattern at both stations suggesting that distinct sources influence the PM10 at LUT and at BON. Chemical analysis was performed on daily filters sampled in September-November 2011 at the two stations to determine the sea salt contribution on PM10 across Saint-Pierre city. It showed that the sea salt contribution to the PM10 is 55% at BON in September 2011. The sea salt particles are therefore the main cause for the exceedances of the regulatory values of PM10 recorded at BON. The results importantly suggest that the notable PM10 concentrations measured at this urban marine site might have some but minor impact on human health.
