scholarly journals Increase of secondary organic aerosol over four years in an urban environment

2020 ◽  
Author(s):  
Marta Via ◽  
María Cruz Minguillón ◽  
Cristina Reche ◽  
Xavier Querol ◽  
Andrés Alastuey
Keyword(s):  
Inorganic Compounds ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Urban Background ◽  
Secondary Sources ◽  
Relative Contribution ◽  
Western Mediterranean Basin ◽  
Fine Aerosol ◽  
One Year ◽  
Radiation Conditions

Abstract. The evolution of fine aerosol (PM1) species as well as the contribution of potential sources to the total organic aerosol (OA) at an urban background site (Palau Reial, PR, 80 m a.s.l) in the western Mediterranean basin (WMB) was investigated. For this purpose, an aerosol chemical speciation monitor (ACSM) was deployed to acquire real-time measurements for two one-year periods: May 2014–May 2015 (period A) and Sep 2017–Oct 2018 (period B). Total PM1 concentrations showed a slight decrease (from 10.1 to 9.6 µg · m−3 from A to B), although the relative contribution of both inorganic and organic compounds varied significantly. Regarding inorganic compounds, SO42−, black carbon and NH4+ showed a significant decrease from period A to B, whilst NO3− concentration was found higher in B. Source apportionment revealed OA was 46 % and 70 % of secondary origin (SOA) in periods A and B, respectively. Two oxygenated secondary sources (OOA) were differentiated by their oxidation status (i.e. aging): less-oxidized (LO-OOA) and more-oxidized (MO-OOA). Disregarding winter periods, where LO-OOA production is not favoured, LO-OOA transformation into MO-OOA was found more effective in period B. The highest MO-OOA-to-LO-OOA ratio (1.5) was found in September–October 2018, implying an accumulation effect after the high temperature and solar radiation conditions in the summer season. In addition, SOA was found sensitive to a NOx-polluted ambient and to other pollutants, especially to ozone, which could be enhancing its production specially during afternoon hours. The anthropogenic primary OA sources identified, cooking-like OA (COA), hydrocarbon-like OA (HOA), and biomass burning OA (BBOA), decreased from period A to B in both absolute concentrations and relative contribution (as a whole, 44 % and 40 %, respectively). However, their concentrations and proportion to OA grow rapidly during highly-polluted episodes. The influence of certain atmospheric episodes on OA sources was also assessed. Both SOA factors seem linked with long and medium-range circulations, especially those coming from inland Europe and the Mediterranean (triggering mainly MO-OOA) and summer breeze-driven regional circulation (triggering mainly LO-OOA). In contrast, POA pollution is enhanced either during air-cleaning episodes or stagnation anticyclonic events.

scholarly journals Increase in secondary organic aerosol in an urban environment

2021 ◽  
Vol 21 (10) ◽  
pp. 8323-8339
Author(s):  
Marta Via ◽  
María Cruz Minguillón ◽  
Cristina Reche ◽  
Xavier Querol ◽  
Andrés Alastuey
Keyword(s):  
Inorganic Compounds ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Urban Background ◽  
Relative Contribution ◽  
Western Mediterranean Basin ◽  
Fine Aerosol ◽  
Oxidation Status ◽  
Radiation Conditions ◽  
Urban Background Site

Abstract. The evolution of fine aerosol (PM1) species as well as the contribution of potential sources to the total organic aerosol (OA) at an urban background site in Barcelona, in the western Mediterranean basin (WMB) was investigated. For this purpose, a quadrupole aerosol chemical speciation monitor (Q-ACSM) was deployed to acquire real-time measurements for two 1-year periods: May 2014–May 2015 (period A) and September 2017–October 2018 (period B). Total PM1 concentrations showed a slight decrease (from 10.1 to 9.6 µg m−3 from A to B), although the relative contribution of inorganic and organic compounds varied significantly. Regarding inorganic compounds, SO42-, black carbon (BC) and NH4+ showed a significant decrease from period A to B (−21 %, −18 % and −9 %, respectively), whilst NO3- concentrations were higher in B (+8 %). Source apportionment revealed OA contained 46 % and 70 % secondary OA (SOA) in periods A and B, respectively. Two secondary oxygenated OA sources (OOA) were differentiated by their oxidation status (i.e. ageing): less oxidized (LO-OOA) and more oxidized (MO-OOA). Disregarding winter periods, when LO-OOA production was not favoured, LO-OOA transformation into MO-OOA was found to be more effective in period B. The lowest LO-OOA-to-MO-OOA ratio, excluding winter, was in September–October 2018 (0.65), implying an accumulation of aged OA after the high temperature and solar radiation conditions in the summer season. In addition to temperature, SOA (sum of OOA factors) was enhanced by exposure to NOx-polluted ambient and other pollutants, especially to O3 and during afternoon hours. The anthropogenic primary OA sources identified, cooking-related OA (COA), hydrocarbon-like OA (HOA), and biomass burning OA (BBOA), decreased from period A to B in both absolute concentrations and relative contribution (as a whole, 44 % and 30 %, respectively). However, their concentrations and proportion to OA grew rapidly during highly polluted episodes. The influence of certain atmospheric episodes on OA sources was also assessed. Both SOA factors were boosted with long- and medium-range circulations, especially those coming from inland Europe and the Mediterranean (triggering mainly MO-OOA) and summer breeze-driven regional circulation (mainly LO-OOA). In contrast, POA was enhanced either during air-renewal episodes or stagnation anticyclonic events.

scholarly journals Molecular characterization of gaseous and particulate oxygenated compounds at a remote site in Cape Corsica in the western Mediterranean Basin

2021 ◽  
Vol 21 (10) ◽  
pp. 8067-8088
Author(s):  
Vincent Michoud ◽  
Elise Hallemans ◽  
Laura Chiappini ◽  
Eva Leoz-Garziandia ◽  
Aurélie Colomb ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carboxylic Acids ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Water Soluble ◽  
Molecular Composition ◽  
Particle Phase ◽  
Western Mediterranean Basin ◽  
Partitioning Coefficients

Abstract. The characterization of the molecular composition of organic carbon in both gaseous and aerosol is key to understanding the processes involved in the formation and aging of secondary organic aerosol. Therefore a technique using active sampling on cartridges and filters and derivatization followed by analysis using a thermal desorption–gas chromatography–mass spectrometer (TD–GC–MS) has been used. It is aimed at studying the molecular composition of organic carbon in both gaseous and aerosol phases (PM2.5) during an intensive field campaign which took place in Corsica (France) during the summer of 2013: the ChArMEx (Chemistry and Aerosol Mediterranean Experiment) SOP1b (Special Observation Period 1B) campaign. These measurements led to the identification of 51 oxygenated (carbonyl and or hydroxyl) compounds in the gaseous phase with concentrations between 21 and 3900 ng m−3 and of 85 compounds in the particulate phase with concentrations between 0.3 and 277 ng m−3. Comparisons of these measurements with collocated data using other techniques have been conducted, showing fair agreement in general for most species except for glyoxal in the gas phase and malonic, tartaric, malic and succinic acids in the particle phase, with disagreements that can reach up to a factor of 8 and 20 on average, respectively, for the latter two acids. Comparison between the sum of all compounds identified by TD–GC–MS in the particle phase and the total organic matter (OM) mass reveals that on average 18 % of the total OM mass can be explained by the compounds measured by TD–GC–MS. This number increases to 24 % of the total water-soluble OM (WSOM) measured by coupling the Particle Into Liquid Sampler (PILS)-TOC (total organic carbon) if we consider only the sum of the soluble compounds measured by TD–GC–MS. This highlights the important fraction of the OM mass identified by these measurements but also the relative important fraction of OM mass remaining unidentified during the campaign and therefore the complexity of characterizing exhaustively the organic aerosol (OA) molecular chemical composition. The fraction of OM measured by TD–GC–MS is largely dominated by di-carboxylic acids, which represent 49 % of the PM2.5 content detected and quantified by this technique. Other contributions to PM2.5 composition measured by TD–GC–MS are then represented by tri-carboxylic acids (15 %), alcohols (13 %), aldehydes (10 %), di-hydroxy-carboxylic acids (5 %), monocarboxylic acids and ketones (3 % each), and hydroxyl-carboxylic acids (2 %). These results highlight the importance of polyfunctionalized carboxylic acids for OM, while the chemical processes responsible for their formation in both phases remain uncertain. While not measured by the TD–GC–MS technique, humic-like substances (HULISs) represent the most abundant identified species in the aerosol, contributing for 59 % of the total OM mass on average during the campaign. A total of 14 compounds were detected and quantified in both phases, allowing the calculation of experimental partitioning coefficients for these species. The comparison of these experimental partitioning coefficients with theoretical ones, estimated by three different models, reveals large discrepancies varying from 2 to 7 orders of magnitude. These results suggest that the supposed instantaneous equilibrium being established between gaseous and particulate phases assuming a homogeneous non-viscous particle phase is questionable.

scholarly journals Molecular characterization of gaseous and particulate oxygenated compounds at a remote site in Cape Corsica in the western Mediterranean basin

2020 ◽  
Author(s):  
Vincent Michoud ◽  
Elise Hallemans ◽  
Laura Chiappini ◽  
Eva Leoz-Garziandia ◽  
Aurélie Colomb ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carboxylic Acids ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Water Soluble ◽  
Molecular Composition ◽  
Particle Phase ◽  
Western Mediterranean Basin ◽  
Hydroxyl Compounds

Abstract. The characterization of the molecular composition of organic carbon in both gaseous and aerosol is key to understand the processes involved in the formation and aging of secondary organic aerosol. Therefore a technique using active sampling on cartridges and filters and derivatization followed by analysis using a Thermal Desorption-Gas Chromatography/mass spectrometer (TD-GC/MS) has been used to study the molecular composition of organic carbon in both gaseous and aerosol phases during an intensive field campaign which took place in Corsica during the summer 2013: the ChArMEx (Chemistry and Aerosol Mediterranean Experiment) SOP1b (Special Observation Period 1B) campaign. These measurements led to the identification of 51 oxygenated (carbonyl and or hydroxyl) compounds in the gaseous phase with concentrations comprised between 21 ng m−3 and 3900 ng m−3 and of 85 compounds in the particulate phase with concentrations comprised between 0.3 and 277 ng m−3. Comparisons of these measurements with collocated data using other techniques have been conducted showing fair agreement in general for most species except for glyoxal in the gas phase and malonic, tartaric, malic and succinic acids in the particle phase with disagreements that can reach up to a factor of 8 and 20 on average, respectively for the latter two acids. Comparison between the sum of all compounds identified by TD-GC/MS in particle phase with the total Organic Matter (OM) mass reveal that 18 % of the total OM mass can be explained by the compounds measured by TD-GC/MS for the whole campaign. This number increase to 24 % of the total Water Soluble OM (WSOM) measured by PILS-TOC if we consider only the sum of the soluble compounds measured by TD-GC/MS. This highlights the non-negligible fraction of the OM mass identified by these measurements but also the relative important fraction of OM mass remaining unidentified during the campaign and therefore the complexity of characterizing exhaustively the Organic Aerosol (OA) molecular chemical composition. The fraction of OM measured by TD-GC/MS is largely dominated by di-carboxylic acids which represents 49 % of the PM2.5 content detected and quantified by this technique. Other contributions to PM2.5 composition measured by TD-GC/MS are then represented by tri-carboxylic acids (15 %), alcohols (13 %), aldehydes (10 %), di-hydroxy-carboxylic acids (5 %), monocarboxylic acids and ketones (3 % each) and hydroxyl-carboxylic acids (2 %). These results highlight the importance of poly functionalized carboxylic acids for OM while the chemical processes responsible for their formation in both phases remain uncertain. While not measured by TD-GC/MS technique, HUmic-LIke Substances (HULIS) represent the most abundant identified species in the aerosol, contributing for 59 % of the total identified OM mass on average during the campaign. 14 compounds were detected and quantified in both phases allowing the calculation of experimental partitioning coefficient for these species. The comparison of these experimental partitioning coefficients with theoretical ones, estimated by three different models, reveals large discrepancies varying from 2 to 7 orders of magnitude. These results suggest that the supposed instantaneous equilibrium being established between gaseous and particulate phases assuming a homogeneous non-viscous particle phase is questionable.

scholarly journals Assessing the ammonium nitrate formation regime in the Paris megacity and its representation in the CHIMERE model

2015 ◽  
Vol 15 (17) ◽  
pp. 23731-23794 ◽  
Author(s):  
H. Petetin ◽  
J. Sciare ◽  
M. Bressi ◽  
A. Rosso ◽  
O. Sanchez ◽  
...  
Keyword(s):  
Ammonium Nitrate ◽  
Transport Model ◽  
Inorganic Compounds ◽  
Urban Environments ◽  
Local Formation ◽  
Urban Background ◽  
Uncertainty Sources ◽  
Direct Measurements ◽  
Fine Aerosol ◽  
The City

Abstract. Secondary inorganic compounds represent a major fraction of fine aerosol in the Paris megacity. The thermodynamics behind their formation is now relatively well constrained, but due to sparse direct measurements of their precursors (in particular NH3 and HNO3), uncertainties remain on their concentrations and variability as well as the formation regime of ammonium nitrate (in terms of limited species, among NH3 and HNO3) in urban environments such as Paris. This study presents the first urban background measurements of both inorganic aerosol compounds and their gaseous precursors during several months within the city of Paris. Intense agriculture-related NH3 episodes are observed in spring/summer while HNO3 concentrations remain relatively low, even during summer, which leads to a NH3-rich regime in Paris. The local formation of ammonium nitrate within the city appears low, despite high NOx emissions. The dataset is also used to evaluate the CHIMERE chemistry-transport model (CTM). Interestingly, the rather good results obtained on ammonium nitrates hide significant errors on gaseous precursors (e.g. mean bias of −75 and +195 % for NH3 and HNO3, respectively). It thus leads to a mis-representation of the nitrate formation regime through a highly underestimated Gas Ratio metric (introduced by Ansari and Pandis, 1998) and a much higher sensitivity of nitrate concentrations to ammonia changes. Several uncertainty sources are investigated, pointing out the importance of better assessing both NH3 emissions and OH concentrations in the future. These results finally remind the caution required in the use of CTMs for emission scenario analysis, highlighting the importance of prior diagnostic and dynamic evaluations.

scholarly journals Presenting SAPUSS: solving aerosol problem by using synergistic strategies at Barcelona, Spain

2012 ◽  
Vol 12 (7) ◽  
pp. 18741-18815 ◽  
Author(s):  
M. Dall'Osto ◽  
X. Querol ◽  
A. Alastuey ◽  
M. C. Minguillon ◽  
M. Alier ◽  
...  
Keyword(s):  
Road Traffic ◽  
Ground Level ◽  
Quality Parameters ◽  
Western Mediterranean ◽  
Night Time ◽  
Urban Background ◽  
Western Mediterranean Basin ◽  
Unique Approach ◽  
The City ◽  
Aerosol Source

Abstract. This paper presents the summary of the key objectives, instrumentation and logistic details, goals, and initial scientific findings of the Marie Curie Action FP7-EU SAPUSS project carried out in the Western Mediterranean Basin (WMB) from 20 September–20 October 2010. The experiment involved concurrent measurements of aerosols with multiple techniques occurring simultaneously. The key objective is to deduce point aerosol source characteristics and to understand the atmospheric processes responsible for their generations and transformations. The unique approach is the large variety of instrumentation deployed simultaneously in six monitoring sites in Barcelona (NE Spain) and around the city, including: a main road traffic site, two urban background sites, a regional background site and two tower sites (150 m and 545 m a.s.l., 150 m and 80 m above ground, respectively). The SAPUSS experiment allows us to interpret the variability of aerosols levels and composition in an Urban Mediterranean, an environment not well characterized so far. During SAPUSS different air mass scenarios were encountered, including warm Saharan, cold Atlantic, wet European and stagnant Regional ones and presenting different local meteorology and boundary layer conditions. Analysis of part of the data collected allows us to compare the monitoring sites as well as to draw scientific conclusions about relevant air quality parameters. High levels of traffic-related gaseous pollutants were measured at the urban ground level monitoring sites, whereas layers of tropospheric ozone were recorded at tower levels. Particularly, tower level night time average ozone concentrations (80 ± 25 μg m−3) were up to double than ground level ones. Particle number concentrations (N>5: 9980 ± 6500 cm−1, average of all measurements) were generally traffic dependent, although a contribution from two different types of nucleation events was also found. Analysis of the particulate matter (PM) mass concentrations shows an enhancement of coarse particles (PM2.5-10) at the urban ground level (+64%, average 11.7 μg m−3) but of fine ones (PM1) at urban tower level (+28%, average 14.4 μg m−3). Preliminary modeling findings reveal an underestimation of the fine accumulation aerosols. In summary, this paper lays the foundation of SAPUSS, an integrated study of relevance to many other similar urban Mediterranean coastal environment sites.

Arcobleu, an integrated surveillance system for chronic and accidental pollution

1995 ◽  
Vol 32 (9-10) ◽  
pp. 25-31
Author(s):  
D. Sauzade ◽  
Y. Hénocque ◽  
A. H. Carof
Keyword(s):  
Surveillance System ◽  
Marine Pollution ◽  
Western Mediterranean ◽  
Private Companies ◽  
Information Tools ◽  
Western Mediterranean Basin ◽  
System Requirement ◽  
Future Extension ◽  
Tools And Techniques ◽  
Preliminary Phase

An integrated surveillance system for chronic and accidental marine pollution is proposed to improve decision making. This project, called ARCOBLEU, is based on organizing advanced communication and information tools and techniques in a multi-source / multi-user architecture. A Franco-Italian consortium associating private companies and public research institutes has already received the support of the EEC MAST program to carry out the preliminary phase of the system requirement, by using the high Tyrrhenean sea as a pilot zone. Future extension to the Western Mediterranean basin is already planned under the name of MED-ARCOBLEU.

scholarly journals Gm and Km alleles in two Spanish Pyrenean populations (Andorra and Pallars Sobira): a review of Gm variation in the Western Mediterranean basin

2001 ◽  
Vol 65 (6) ◽  
pp. 537-548 ◽  
Author(s):  
M. P. GIRALDO ◽  
E. ESTEBAN ◽  
M. P. ALUJA ◽  
R. M. NOGUES ◽  
CH. BACKES-DURO ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Western Mediterranean Basin

scholarly journals Algerian Olive Germplasm and Its Relationships with the Central-Western Mediterranean Varieties Contributes to Clarify Cultivated Olive Diversification

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 678
Author(s):  
Kamel Atrouz ◽  
Ratiba Bousba ◽  
Francesco Paolo Marra ◽  
Annalisa Marchese ◽  
Francesca Luisa Conforti ◽  
...  
Keyword(s):  
Mediterranean Basin ◽  
Genetic Relationships ◽  
Olive Tree ◽  
Mediterranean Area ◽  
Western Mediterranean ◽  
Central Mediterranean ◽  
Western Mediterranean Basin ◽  
New Information ◽  
Mediterranean History ◽  
New Synonymy

Olive tree with its main final product, olive oil, is an important element of Mediterranean history, considered the emblematic fruit of a civilization. Despite its wide diffusion and economic and cultural importance, its evolutionary and phylogenetic history is still difficult to clarify. As part of the Mediterranean basin, Algeria was indicated as a secondary diversification center. However, genetic characterization studies from Maghreb area, are currently underrepresented. In this context, we characterized 119 endemic Algerian accessions by using 12 microsatellite markers with the main goal to evaluate the genetic diversity and population structure. In order to provide new insights about the history of olive diversification events in the Central-Western Mediterranean basin, we included and analyzed a sample of 103 Italian accessions from Sicily and, a set of molecular profiles of cultivars from the Central-Western Mediterranean area. The phylogenetic investigation let us to evaluate genetic relationships among Central-Mediterranean basin olive germplasm, highlight new synonymy cases to support the importance of vegetative propagation in the cultivated olive diffusion and consolidate the hypothesis of more recent admixture events occurrence. This work provided new information about Algerian germplasm biodiversity and contributed to clarify olive diversification process.

scholarly journals Potential deployment of offshore bottom pressure gauges and adoption of data assimilation for tsunami warning system in the western Mediterranean Sea

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohammad Heidarzadeh ◽  
Yuchen Wang ◽  
Kenji Satake ◽  
Iyan E. Mulia
Keyword(s):  
Data Assimilation ◽  
Warning System ◽  
Western Mediterranean ◽  
Tsunami Warning ◽  
Sensitivity Analyses ◽  
Bottom Pressure ◽  
Tsunami Warning System ◽  
Earthquake Scenarios ◽  
The North ◽  
Western Mediterranean Basin

AbstractWestern Mediterranean Basin (WMB) is among tsunamigenic zones with numerous historical records of tsunami damage and deaths. Most recently, a moderate tsunami on 21 May 2003 offshore Algeria, North Africa, was a fresh call for strengthening tsunami warning capabilities in this enclosed water basin. Here, we propose to deploy offshore bottom pressure gauges (OBPGs) and to adopt the framework of a tsunami data assimilation (TDA) approach for providing timely tsunami forecasts. We demonstrate the potential enhancement of the tsunami warning system through the case study of the 2003 Algeria tsunami. Four scenarios of OBPG arrangements involving 10, 5, 3 and 2 gauges are considered. The offshore gauges are located at distances of 120–300 km from the North African coast. The warning lead times are 20, 30, 48 and 55 min for four points of interest considered in this study: Ibiza, Palma, Sant Antoni and Barcelona, respectively. The forecast accuracies are in the range of 69–85% for the four OBPG scenarios revealing acceptable accuracies for tsunami warnings. We conclude that installation of OBPGs in the WMB can be helpful for providing successful and timely tsunami forecasts. We note that the OBPG scenarios proposed in this study are applicable only for the case of the 2003 Algeria tsunami. Further studies including sensitivity analyses (e.g., number of OBPG stations; earthquake magnitude, strike, epicenter) are required in order to determine OBPG arrangements that could be useful for various earthquake scenarios in the WMB.

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