Search

Improving knowledge of current and future spatio-temporal variability of surface solar radiation is essential in the context of climate change and associated environmental and societal issues. Such an evolution will be influenced by changes in both meteorological parameters and atmospheric composition, notably by anthropogenic emissions. We investigate both all-sky and clear-sky surface solar radiation (SSR) variability, along with cloud cover, aerosols and water vapor content, over Northern France and Benelux. This region of Europe is largely influenced by cloudy conditions and anthropogenic aerosols, especially nitrate species. Our analysis relies on the CNRM-ALADIN64 regional climate model at 12.5 km x 12.5 km spatial resolution, which includes the TACTIC interactive aerosol scheme. First, hindcast reanalysis-driven simulations over 2010-2020 allow a regional evaluation of ALADIN outputs and to investigate recent spatial variability of SSR and associated atmospheric parameters. Secondly, their possible evolution at mid and end of the 21st century are investigated based on ALADIN climate simulations following two contrasted CMIP6 scenarios, namely the shared socioeconomic pathways (SSP), SSP1-1.9 and SSP3-7.0. Our regional evaluation of clear-sky and all-sky SSR, clear-sky frequency and aerosols over northern France and Benelux shows reasonable agreement between 2010-2020 ALADIN hindcast simulations and coincident multi-site groundbased measurements, despite some overestimation of nitrate aerosols in spring and an overall underestimation of organic particles by the model. Focusing on spring and summer seasons, hindcast simulations show maximum of solar radiation around the southern parts and over sea areas of the region. In addition to latitudinal effects, elevated aerosol loads over Benelux, and high cloud cover over the South West of England reduce the SSR. Compared to 2005-2014 atmospheric conditions, ALADIN mid and long-term simulations for SSP1-1.9 predict a significant reduction of aerosol loads, especially over the Benelux, associated with an increase in future clear-sky SSR but geographically limited all-sky SSR evolution. In contrast, SSP3-7.0 simulations projected pronounced and extended decreases of clear-sky and all-sky SSR over most of the Benelux/northern France region. These reductions are maximum in spring due to combined effects of cloud cover and nitrate aerosol increases over the Benelux starting in 2050, that are amplified by an additional water vapor increase in 2100. Thus, this regional climate model approach suggests that future SSR evolution over this part of western Europe will be drastically affected by combined effects of anthropogenic aerosol emissions trajectories, cloud cover and water vapor changes, which also induce strong spatial patterns. [ABSTRACT FROM AUTHOR]

Understanding the lifecycle of light-absorbing carbonaceous aerosols, from emission to deposition, is critical for assessing their climate impact. This study integrated multi-year aerosol observations from the ATOLL (ATmospheric Observations in liLLe, northern France) platform, with air mass back trajectories and emission inventory as a newly developed "INTERPLAY" (IN-siTu obsERvations, hysPLit, And emission inventorY) approach. Applied to black carbon (BC), the method apportioned source contributions (shipping, vehicular, residential heating, industrial) and studied aerosol aging effects, notably on the brown carbon (BrC) component. Results estimate that, throughout the year, vehicular traffic dominated BC (31 %), followed by shipping (25 %, of which one-third was from canals/rivers) and residential heating (21 %). Comparing INTERPLAY results with the aethalometer model highlights that the "residential sector" BC can be entirely apportioned to BC from wood burning (BCwb), notably in winter, while vehicular traffic corresponds to only about 41% of BC fossil fuel (BCff) at the ATOLL site, the rest being apportioned to shipping (33 %) and industrial (23 %) emissions. Thus, vehicular traffic and BCff should not be used interchangeably, particularly in regions near intense maritime traffic. Concerning BrC, our analysis confirms a dominant role of residential heating. Focusing on winter, results suggest a considerable decrease in the BrC component only 24 h after emission, with fresh residential emissions being responsible for 72% of BrC absorption at ATOLL. The results from this study allow for an improved understanding of sources and atmospheric dynamics of light-absorbing carbonaceous aerosols in northern France, being crucial for both source abatement strategies as well as a better assessment of their climate impact. [ABSTRACT FROM AUTHOR]

A growing portion of scientists realises the need to not only alert about climate change, but also change their professional practices. A range of tools have emerged to promote more sustainable activities, yet many scientists struggle to go beyond simple awareness-raising to create concrete transition actions. Here we propose a game-based transition support system MaTerre180', which has been designed to build scenarios of greenhouse gas (GHG) emission reductions in the academic community. After providing a common scientific background about the context (global warming issue, its causes and consequences) and setting up a challenge (50% reduction of carbon budget by 2030), the participants belonging to the academic community and its governance bodies immerse themselves into fictional characters, to simulate the behaviour of real research groups. The game has been deployed during the year 2021, with six hundred participants from nine countries and 50 cities. Results explore clear pathways for GHG reductions between 25 and 60%, and a median reduction of 46%. The alternatives allowing the greatest reduction are video communication tools (36%), followed by mutualization of professional activities and voluntary cancellation or reduction, that represent 22 and 14% of reduction, respectively. The remaining 28% of reduction consists of transport alternative, relocation of professional activities, extended duration of some travels, etc. In addition, the analyses pointed out the importance of the guided negotiation phase to bring out some alternatives such as relocation, local partners and computing optimization. An added value of this transition support system is that the information it collects (anonymously) will be used to answer pressing research questions in climate change science and environmental psychology regarding the use of serious games for promoting changes in attitudes and behaviours towards sustainability, and including broader questions on how network structures influence "climate behaviour", knowledge and the governance of the commons. Modestly, MaTerre180' offers an innovative game-based transition support system to build scenarios of greenhouse gas (GHG) emission reductions in the academic community. It is not simply a question of moving tokens on a virtual gameboard and a playful adjustment of practices, but rather a question of brainstorming about possible and desirable ways of remodelling research and teaching communities and embracing a new paradigm. After tens of workshops, our results show clear pathways for reaching up to 50% GHG reductions and stress the importance of guided negotiations to bring out alternatives to carbonized activities. This first attempt reinforces our belief that scientific engagement is at the heart of the international development agenda and a key approach to tear down the institutional barriers that inhibit the transformation needed to achieve a more sustainable society. [ABSTRACT FROM AUTHOR]

Formation of ultrafine particles (UFPs) in the urban atmosphere is expected to be less favored than in the rural atmosphere due to the high existing particle surface area acting as a sink for newly formed particles. Despite large condensation sink (CS) values, previous comparative studies between rural and urban sites reported higher frequency of new particle formation (NPF) events over urban sites in comparison to background sites as well as higher particle formation and growth rates attributed to the higher concentration of condensable species. The present study aims at a better understanding the environmental factors favoring, or disfavoring, atmospheric NPF over Lille, a large city in the north of France, and to analyze their impact on particle number concentration using a 4-year long-term dataset. The results highlight a strong seasonal variation of NPF occurrences with a maximum frequency observed during spring (27 events) and summer (53 events). It was found that high temperature (T>295 K), low relative humidity (RH <45 %), and high solar radiation are ideal to observe NPF events over Lille. Relatively high CS values (i.e., ∼2×10-2 s -1) are reported during event days suggesting that high CS does not inhibit the occurrence of NPF over the ATmospheric Observations in LiLLE (ATOLL) station. Moreover, the particle growth rate was positively correlated with temperatures most probably due to higher emission of precursors. Finally, the nucleation strength factor (NSF) was calculated to highlight the impact of those NPF events on particle number concentrations. NSF reached a maximum of four in summer, evidencing a huge contribution of NPF events to particle number concentration at this time of the year. [ABSTRACT FROM AUTHOR]

Particulate matter (PM) has become a major concern in terms of human health and climate impact. In particular, the source apportionment (SA) of organic aerosols (OA) present in submicron particles (PM 1) has gained relevance as an atmospheric research field due to the diversity and complexity of its primary sources and secondary formation processes. Moreover, relatively simple but robust instruments such as the Aerosol Chemical Speciation Monitor (ACSM) are now widely available for the near-real-time online determination of the composition of the non-refractory PM 1. One of the most used tools for SA purposes is the source-receptor positive matrix factorisation (PMF) model. Even though the recently developed rolling PMF technique has already been used for OA SA on ACSM datasets, no study has assessed its added value compared to the more common seasonal PMF method using a practical approach yet. In this paper, both techniques were applied to a synthetic dataset and to nine European ACSM datasets in order to spot the main output discrepancies between methods. The main advantage of the synthetic dataset approach was that the methods' outputs could be compared to the expected "true" values, i.e. the original synthetic dataset values. This approach revealed similar apportionment results amongst methods, although the rolling PMF profile's adaptability feature proved to be advantageous, as it generated output profiles that moved nearer to the truth points. Nevertheless, these results highlighted the impact of the profile anchor on the solution, as the use of a different anchor with respect to the truth led to significantly different results in both methods. In the multi-site study, while differences were generally not significant when considering year-long periods, their importance grew towards shorter time spans, as in intra-month or intra-day cycles. As far as correlation with external measurements is concerned, rolling PMF performed better than seasonal PMF globally for the ambient datasets investigated here, especially in periods between seasons. The results of this multi-site comparison coincide with the synthetic dataset in terms of rolling–seasonal similarity and rolling PMF reporting moderate improvements. Altogether, the results of this study provide solid evidence of the robustness of both methods and of the overall efficiency of the recently proposed rolling PMF approach. [ABSTRACT FROM AUTHOR]

Formation of Ultrafine particles (UFPs) in the urban atmosphere is expected to be less favored than in the rural atmosphere due to the high existing particle surface area acting as a sink for newly-formed particles Despite the large condensation sink (CS) values, previous comparative studies between rural and urban site reported higher frequency of new particle formation (NPF) events over urban sites in comparison to background sites as well as higher particle formation and growth rates attributed to the higher concentration of condensable species. The present study aims to better understand the environmental factors favoring, or disfavoring, atmospheric NPF over Lille, a large city North of France and to analyze their impact on particle number concentration using a long-term dataset (4 years : 1st July 2017 to 31st December 2020). The results highlight a strong seasonal variation of the NPF occurrences with a maximum observed during spring (27 events) and summer (53 events). It was found that high temperature (T > 295 K), low RH (RH < 45 %) and high solar radiation are ideal to observe NPF events over Lille. Relatively high values of condensation sink (CS ~ 2.10-2 s-1) are reported during event days suggesting that high CS does not inhibit the occurrence of NPFt over our site. Moreover, the particle Growth Rate (GR15.7-30 nm) was positively correlated with the temperature most probably linked to the higher emissions of precursors. Finally, the nucleation strength factor (NSF) was calculated to highlight the impact of those NPF events on particle number concentrations. NSF15.7-100 reaches a maximum of 4 in summer, indicating an enormous contribution of NPF events to particle number concentration at this time of the year. [ABSTRACT FROM AUTHOR]

Seasonal variability of non-refractory PM 1 (NR-PM 1) was studied at a rural background site (National Atmospheric Observatory Košetice – NAOK) in the Czech Republic to investigate the effect of regional and long-range atmospheric transport in central Europe. NR-PM 1 measurements were performed by compact time-of-flight aerosol mass spectrometry (C-ToF-AMS), and the chemically speciated mass size distributions, density, shape, and origin were discussed. Average PM 1 concentrations, calculated as the sum of the NR-PM 1 and the equivalent black carbon (eBC) concentrations measured by an aethalometer (AE), were 8.58 ± 3.70 µ g m -3 in summer and 10.08 ± 8.04 µ g m -3 in winter. Organics were dominant during both campaigns (summer/winter: 4.97 ± 2.92 / 4.55 ± 4.40 µ g m -3), followed by SO 42- in summer (1.68 ± 0.81/1.36 ± 1.38 µ g m -3) and NO 3- in winter (0.67 ± 0.38/2.03 ± 1.71 µ g m -3). The accumulation mode dominated the average mass size distribution during both seasons, with larger particles of all species measured in winter (mode diameters: Org: 334 / 413 nm, NO 3- : 377/501 nm, SO 42- : 400 / 547 nm, and NH 4+ : 489 / 515 nm) indicating regional and long-range transport. However, since the winter aerosols were less oxidized than the summer aerosols (comparing fragments f44 and f43), the importance of local sources in the cold part of the year was still enough to be considered. Although aged continental air masses from the south-east (SE) were rare in summer (7 %), they were related to the highest concentrations of PM 1 , eBC, and all NR-PM 1 species, especially SO 42- and NH 4+. In winter, slow continental air masses from the south-west (SW) (44 %) were linked to inversion conditions over central Europe and were associated with the highest concentrations among all NR-PM 1 species as well as PM 1 and eBC. Average PM 1 material density (ρm) corresponded to higher inorganic contents in both seasons (summer: ∼ 1.30 g cm -3 and winter: ∼ 1.40 g cm -3). During episodes of higher mass concentrations ρm ranged from 1.30–1.40 g cm -3 in summer and from 1.30–1.50 g cm -3 in winter. The dynamic shape factors (χ) decreased slightly with particle mobility diameter (Dm) in both seasons. This study provides insights into the seasonal effects and air mass variability on aerosol particles, focusing on episodes of high mass and number concentrations measured at a central European rural background site. [ABSTRACT FROM AUTHOR]

The indoor environment is usually more polluted than outdoors due to emissions of gas and particle-phase pollutants from multiple sources, leading to their accumulation on top of the infiltration of outdoor pollution. While it is widely recognized that negative health effects arise from the exposure to outdoor air pollution, exposure to indoor pollutants also needs to be well assessed since we spend most of our time (~90%) breathing indoors. Indoor concentrations of pollutants are driven by physicochemical processes and chemical transformations taking place indoors, acting as sources and/or sinks. While these basic concepts are understood, assessing the contribution of each process is still challenging. In this study, we deployed online instrumentation in an unoccupied room to test a methodology for the apportionment of indoor and outdoor pollutant sources. This method was successfully applied to the apportionment of PM1 and VOCs, however, there are limitations for reactive gases such as O3. The results showed that this unoccupied indoor environment acts as a source of VOCs and contributes 87% on OVOCs and 6% on CxHy, while it acts as a sink for particles, likely due to losses through volatilization up to 60%. [ABSTRACT FROM AUTHOR]

The seasonal variability of non-refractory PM1 (NR-PM1) was studied at a rural background site (National Atmospheric Observatory KoŠetice - NAOK) in the Czech Republic to examine the impact of atmospheric regional and long-range transport in Central Europe. NR-PM1 measurements were performed by compact time-of-flight aerosol mass spectrometry (C-ToF-AMS), and the chemically speciated mass size distributions, effective density, and origin were discussed. The average PM1 concentrations, calculated as the sum of the NR-PM1 (after collection efficiency corrections - CE corrections of 0.4 and 0.33 in summer and winter, respectively) and the equivalent black carbon (eBC) concentrations measured by an aethalometer (AE), were 8.58 ± 3.70 µg m-3 in summer and 10.08±8.04 µg m-3 in winter. Organics dominated during both campaigns (summer/winter: 4.97 ± 2.92/4.55± 4.40 µg m-3), followed by SO42--in summer (1.68 ± 0.81/1.36± 1.38 µg m-3) and NO3- - in winter (0.67 ± 0.38/2.03 ± 1.71 µg m-3). The accumulation mode dominated the average mass size distribution during both seasons, with larger particles of all species measured in winter (mode diameters: Org: 334/413 nm, NO3-: 377/501 nm, SO42-: 400/547 nm, and NH4+: 489/515 nm) pointing to regional and long-range transport. However, since the winter aerosols were less oxidized than the summer aerosols (comparing fragments f44 and f43), the importance of local sources in the cold part of the year was not negligible. The average PM1 particle effective density, defined as the ratio of the mass to the volume of a particle, corresponded to higher inorganic contents during both seasons (summer: ~1.30 g cm-3 and winter: ~1.40 g cm-3). However, the effective densities during episodes of higher mass concentrations calculated based on the particle number (mobility diameter) and mass size distribution (vacuum aerodynamic diameter) were even higher, ranging from 1.40 - 1.60 g cm-3 in summer and from 1.40 - 1.75 g cm-3 in winter. Although aged continental air masses from the SE were rare in summer (7%), they were connected with the highest concentrations of all NR-PM1 species, especially SO42- and NH4+. In winter, slow continental air masses from the SW (44%) were linked to inversion conditions over Central Europe and were associated with the highest concentrations among all NR-PM1 measurements. [ABSTRACT FROM AUTHOR]

Here we report results of a detailed analysis of the urban and non-urban contributions to particulate matter (PM) concentrations and source contributions in five European cities, namely Schiedam (the Netherlands, NL), Lens (France, FR), Leipzig (Germany, DE), Zurich (Switzerland, CH) and Barcelona (Spain, ES). PM chemically speciated data from 12 European paired monitoring sites (one traffic, five urban, five regional and one continental background) were analysed by positive matrix factorisation (PMF) and Lenschow's approach to assign measured PM and source contributions to the different spatial levels. Five common sources were obtained at the 12 sites: sulfate-rich (SSA) and nitrate-rich (NSA) aerosols, road traffic (RT), mineral matter (MM), and aged sea salt (SS). These sources explained from 55 % to 88 % of PM mass at urban low-traffic-impact sites (UB) depending on the country. Three additional common sources were identified at a subset of sites/countries, namely biomass burning (BB) (FR, CH and DE), explaining an additional 9 %–13 % of PM mass, and residual oil combustion (V–Ni) and primary industrial (IND) (NL and ES), together explaining an additional 11 %–15 % of PM mass. In all countries, the majority of PM measured at UB sites was of a regional + continental (R + C) nature (64 %–74 %). The R + C PM increments due to anthropogenic emissions in DE, NL, CH, ES and FR represented around 66 %, 62 %, 52 %, 32 % and 23 %, respectively, of UB PM mass. Overall, the R + C PM increments due to natural and anthropogenic sources showed opposite seasonal profiles with the former increasing in summer and the latter increasing in winter, even if exceptions were observed. In ES, the anthropogenic R + C PM increment was higher in summer due to high contributions from regional SSA and V–Ni sources, both being mostly related to maritime shipping emissions at the Spanish sites. Conversely, in the other countries, higher anthropogenic R + C PM increments in winter were mostly due to high contributions from NSA and BB regional sources during the cold season. On annual average, the sources showing higher R + C increments were SSA (77 %–91 % of SSA source contribution at the urban level), NSA (51 %–94 %), MM (58 %–80 %), BB (42 %–78 %) and IND (91 % in NL). Other sources showing high R + C increments were photochemistry and coal combustion (97 %–99 %; identified only in DE). The highest regional SSA increment was observed in ES, especially in summer, and was related to ship emissions, enhanced photochemistry and peculiar meteorological patterns of the Western Mediterranean. The highest R + C and urban NSA increments were observed in NL and associated with high availability of precursors such as NOx and NH3. Conversely, on average, the sources showing higher local increments were RT (62 %–90 % at all sites) and V–Ni (65 %–80 % in ES and NL). The relationship between SSA and V–Ni indicated that the contribution of ship emissions to the local sulfate concentrations in NL has strongly decreased since 2007 thanks to the shift from high-sulfur- to low-sulfur-content fuel used by ships. An improvement of air quality in the five cities included here could be achieved by further reducing local (urban) emissions of PM, NOx and NH3 (from both traffic and non-traffic sources) but also SO2 and PM (from maritime ships and ports) and giving high relevance to non-urban contributions by further reducing emissions of SO2 (maritime shipping) and NH3 (agriculture) and those from industry, regional BB sources and coal combustion. [ABSTRACT FROM AUTHOR]

Volcanic sulfate aerosols play a key role in air quality and climate. However, the rate of oxidation of sulfur dioxide (SO2) precursor gas to sulfate aerosols (SO42-) in volcanic plumes is poorly known, especially in the troposphere. Here we determine the chemical speciation as well as the intensity and temporal persistence of the impact on air quality of sulfate aerosols from the 2014–2015 Holuhraun flood lava eruption of Icelandic volcano Bárðarbunga. To do so, we jointly analyse a set of SO2 observations from satellite (OMPS and IASI) and ground-level measurements from air quality monitoring stations together with high temporal resolution mass spectrometry measurements of an Aerosol Chemical Speciation Monitor (ACSM) performed far from the volcanic source. We explore month/year long ACSM data in France from stations in contrasting environments, close and far from industrial sulfur-rich activities. We demonstrate that volcanic sulfate aerosols exhibit a distinct chemical signature in urban/rural conditions, with NO3:SO4 mass concentration ratios lower than for non-volcanic background aerosols. These results are supported by thermodynamic simulations of aerosol composition, using the ISORROPIA II model, which show that ammonium sulfate aerosols are preferentially formed at a high concentration of sulfate, leading to a decrease in the production of particulate ammonium nitrate. Such a chemical signature is however more difficult to identify at heavily polluted industrial sites due to a high level of background noise in sulfur. Nevertheless, aged volcanic sulfates can be distinguished from freshly emitted industrial sulfates according to their contrasting degree of anion neutralization. Combining AERONET (AErosol RObotic NETwork) sunphotometric data with ACSM observations, we also show a long persistence over weeks of pollution in volcanic sulfate aerosols, while SO2 pollution disappears in a few days at most. Finally, gathering 6-month long datasets from 27 sulfur monitoring stations of the EMEP (European Monitoring and Evaluation Programme) network allows us to demonstrate a much broader large-scale European pollution, in both SO2 and SO4 , associated with the Holuhraun eruption, from Scandinavia to France. While widespread SO2 anomalies, with ground-level mass concentrations far exceeding background values, almost entirely result from the volcanic source, the origin of sulfate aerosols is more complex. Using a multi-site concentration-weighted trajectory analysis, emissions from the Holuhraun eruption are shown to be one of the main sources of SO4 at all EMEP sites across Europe and can be distinguished from anthropogenic emissions from eastern Europe but also from Great Britain. A wide variability in SO2:SO4 mass concentration ratios, ranging from 0.8 to 8.0, is shown at several stations geographically dispersed at thousands of kilometres from the eruption site. Despite this apparent spatial complexity, we demonstrate that these mass oxidation ratios can be explained by a simple linear dependency on the age of the plume, with a SO2 -to- SO4 oxidation rate of 0.23 h -1. Most current studies generally focus on SO2 , an unambiguous and more readily measured marker of the volcanic plume. However, the long persistence of the chemical fingerprint of volcanic sulfate aerosols at continental scale, as shown for the Holuhraun eruption here, casts light on the impact of tropospheric eruptions and passive degassing activities on air quality, health, atmospheric chemistry and climate. [ABSTRACT FROM AUTHOR]

The primary sugar compounds (SCs, defined as glucose, arabitol, and mannitol) are widely recognized as suitable molecular markers to characterize and apportion primary biogenic organic aerosol emission sources. This work improves our understanding of the spatial behavior and distribution of these chemical species and evidences their major effective environmental drivers. We conducted a large study focusing on the daily (24 h) PM 10 SC concentrations for 16 increasing space scale sites (local to nationwide), over at least 1 complete year. These sites are distributed in several French geographic areas of different environmental conditions. Our analyses, mainly based on the examination of the short-term evolutions of SC concentrations, clearly show distance-dependent correlations. SC concentration evolutions are highly synchronous at an urban city scale and remain well correlated throughout the same geographic regions, even if the sites are situated in different cities. However, sampling sites located in two distinct geographic areas are poorly correlated. Such a pattern indicates that the processes responsible for the evolution of the atmospheric SC concentrations present a spatial homogeneity over typical areas of at least tens of kilometers. Local phenomena, such as the resuspension of topsoil and associated microbiota, do no account for the major emissions processes of SC in urban areas not directly influenced by agricultural activities. The concentrations of SC and cellulose display remarkably synchronous temporal evolution cycles at an urban site in Grenoble, indicating a common source ascribed to vegetation. Additionally, higher concentrations of SC at another site located in a crop field region occur during each harvest periods, indicating resuspension processes of plant materials (crop detritus, leaf debris) and associated microbiota for agricultural and nearby urbanized areas. Finally, ambient air temperature, relative humidity, and vegetation density constitute the main effective drivers of SC atmospheric concentrations. [ABSTRACT FROM AUTHOR]

We report here results of a detailed analysis of the urban and non-urban contributions to PM concentrations and source contributions in 5 European cities, namely: Shiedam (The Netherlands; NL), Lens (France; FR), Leipzig (Germany; DE), Zurich (Switzerland; CH) and Barcelona (Spain; ES). PM chemically speciated data from 12 European paired monitoring sites (1 traffic, 5 urban, 5 regional and 1 continental background) were analyzed by Positive Matrix Factorization (PMF) and Lenschow's approach to assign measured PM and source contributions to the different spatial levels. Five common sources were obtained at the 12 sites: sulfate-rich (SSA) and nitrate-rich (NSA) aerosols, road traffic (RT), mineral matter (MM), and sea salt (SS). These sources explained from 55 % to 88 % of PM mass at urban low-traffic impact sites (UB) depending on the country. Three additional common sources were detected at a subset of sites/countries, namely: biomass burning (BB) (FR, CH, and DE), explaining an additional 9–13 % of PM mass, residual oil combustion (V-Ni), and primary industrial (IND) (NL and ES), together explaining an additional 11–15 % of PM mass. In all countries, the majority of PM measured at UB sites was of regional + continental (R + C) nature (64–74 %). The R + C PM increments due to anthropogenic emissions were in the range 10–11 μg/m3 in CH, NL and DE (52 %, 62 % and 66 %, respectively, of UB PM mass), followed by ES (8 g/m3; 32 %) and FR (5 g/m3; 23 %). Overall, the R + C PM increments due to natural and anthropogenic sources showed opposite seasonal profiles with the former increasing in summer and the latter increasing in winter, even if exceptions were observed. In ES, the anthropogenic R + C PM increment was higher in summer due to high contributions from regional SSA and V-Ni sources, both being mostly related to maritime shipping emissions at the Spanish sites. Conversely, in the other countries, higher anthropogenic R + C PM increments in winter were mostly due to high contributions from NSA and BB regional sources during the cold season. On annual average, the sources showing higher R + C increments were SSA (77–91 % of SSA source contribution at urban level), NSA (51–94 %), MM (58–80 %), BB (42–78 %), IND (91 % in the Netherlands). Other sources showing high R + C increments were photochemistry (PHO) and coal combustion (CC) (97–99 %; detected only in DE). The highest regional SSA increment was observed in ES, especially in summer, and was related to ship emissions, enhanced photochemistry and peculiar meteorological patterns of the Western Mediterranean. The highest R + C and urban NSA increments were observed in NL and associated with high availability of precursors such as NOx and NH3. Conversely, on average, the sources showing higher local increments were RT (62–90 % at all sites) and V-Ni (65–80 % in ES and NL). The relationship between SSA and V-Ni indicated that the contribution of ship emissions to the local sulfate concentrations in NL strongly decreased from 2007 thanks to the shift from high-sulfur to low-sulfur content fuel used by ships. Based on the present analysis, an improvement of air quality in the 5 cities included here could be achieved by further reducing local (urban) emissions of PM, NOx and NH3 (from both traffic and non-traffic sources) but also SO2 and PM (from maritime ships and ports) and giving high relevance to non-urban contributions by further reducing emissions of SO2 (maritime shipping) and NH3 (agriculture) and those from industry, regional BB sources and coal combustion. [ABSTRACT FROM AUTHOR]

The primary sugar compounds (SC, defined as glucose, arabitol and mannitol) are widely recognized as suitable molecular markers to characterize and apportion primary biogenic organic aerosol emission sources. This work improves our understanding of the spatial behavior and distribution of these chemical species and evidences their major effective environmental drivers. We conducted a large study focusing on the daily (24h) PM10 SC concentrations for 16 increasing space scale sites (local to nation-wide), over at least one complete year. These sites are distributed in several French geographic areas of different environmental conditions. Our analyses, mainly based on the examination of the short-term evolutions of SC concentrations, clearly show distance-dependent correlations. SC concentration evolutions are highly synchronous at an urban city-scale and remain well correlated throughout the same geographic regions, even if the sites are situated in different cities. However, sampling sites located in two distinct geographic areas are poorly correlated. Such pattern indicates that the processes responsible for the evolution of the atmospheric SC concentrations present a spatial homogeneity over typical areas of at least tens of kilometers. Local phenomena, such as resuspension of topsoil and associated microbiota, do no account for the major emissions processes of SC in urban areas not directly influenced by agricultural activities. The concentrations of SC and cellulose display remarkably synchronous temporal evolution cycles at an urban site in Grenoble, indicating a common source ascribed to vegetation. Additionally, higher concentrations of SC at another site located in a crop field region occur during each harvest periods, pointing out resuspension processes of plant materials (crop detritus, leaf debris) and associated microbiota for agricultural and nearby urbanized areas. Finally, ambient air temperature, relative humidity and vegetation density constitute the main effective drivers of SC atmospheric concentrations. [ABSTRACT FROM AUTHOR]

A growing number of studies are using specific primary sugar species, such as sugar alcohols or primary saccharides, as marker compounds to characterize and apportion primary biogenic organic aerosols (PBOAs) in the atmosphere. To better understand their annual cycles, as well as their spatiotemporal abundance in terms of concentrations and sources, we conducted a large study focusing on three major atmospheric primary sugar compounds (i.e., arabitol, mannitol, and glucose) measured in various environmental conditions for about 5300 filter samples collected at 28 sites in France. Our results show significant atmospheric concentrations of polyols (defined here as the sum of arabitol and mannitol) and glucose at each sampling location, highlighting their ubiquity. Results also confirm that polyols and glucose are mainly associated with the coarse rather than the fine aerosol mode. At nearly all sites, atmospheric concentrations of polyols and glucose display a well-marked seasonal pattern, with maximum concentrations from late spring to early autumn, followed by an abrupt decrease in late autumn, and a minimum concentration during wintertime. Such seasonal patterns support biogenic emissions associated with higher biological metabolic activities (sporulation, growth, etc.) during warmer periods. Results from a previous comprehensive study using positive matrix factorization (PMF) based on an extended aerosol chemical composition dataset of up to 130 species for 16 of the same sample series have also been used in the present work. The polyols-to-PM PBOA ratio is 0.024±0.010 on average for all sites, with no clear distinction between traffic, urban, or rural typology. Overall, even if the exact origin of the PBOA source is still under investigation, it appears to be an important source of particulate matter (PM), especially during summertime. Results also show that PBOAs are significant sources of total organic matter (OM) in PM 10 (13±4 % on a yearly average, and up to 40 % in some environments in summer) at most of the investigated sites. The mean PBOA chemical profile is clearly dominated by contribution from OM (78±9 % of the mass of the PBOA PMF on average), and only a minor contribution from the dust class (3±4 %), suggesting that ambient polyols are most likely associated with biological particle emissions (e.g., active spore discharge) rather than soil dust resuspension. [ABSTRACT FROM AUTHOR]

Volcanic sulfate aerosols play a key role on air quality and climate. However, the oxidation of sulfur dioxide (SO2) precursor gas to sulfate aerosols (SO42−) in volcanic clouds is poorly known, especially in the troposphere. Here we determine the chemical speciation, lifetime and impact on air quality of sulfate aerosols from the 2014–15 Holuhraun flood lava eruption of Bárðarbunga icelandic volcano. To do so, we jointly analyze a set of SO2 observations from satellite (OMPS and IASI) and ground-level measurements from air quality monitoring stations together with, for the first time, high temporal resolution mass spectrometry measurements of Aerosol Chemical Speciation Monitor (ACSM) performed far from the source. We explore month/year-long ACSM data in France from stations in contrasted environments, close and far from industrial sulfur-rich activities. We demonstrate that aged volcanic sulfate aerosols exhibit a distinct chemical fingerprint, with NO3 : SO4 and Organic : SO4 concentration ratios higher than freshly-emitted industrial sulfate but lower than background aerosols in urban/rural conditions. Combining AERONET (AErosol RObotic NETwork) sunphotometric data with ACSM observations, we also show a long persistence over weeks of volcanic sulfate aerosols while SO2 disappears in a few days at most. Finally, gathering 6 month-long datasets from 19 sulfur monitoring stations of the EMEP (European Monitoring and Evaluation Programme) network allows us to demonstrate a much broader large-scale European particulate pollution in SO4 associated to the Holuhraun eruption, from Scandinavia to France. Exploiting these in-situ data, we also show the various rates of SO2 oxidation observed in the volcanic cloud, with SO2 : SO4 concentration ratios ranging in 0.6–7, distinct from background conditions of about 50. Most current studies generally focus on SO2, an unambiguous and more readily measured marker of the volcanic cloud. However, our results here on sulfate aerosols raise fundamental questions about the cumulative impact of tropospheric eruptions on air quality, health, atmospheric composition and climate, which may be significantly underestimated. [ABSTRACT FROM AUTHOR]

A growing number of studies are using specific primary sugar species, such as sugar alcohols or primary saccharides, as marker compounds to characterize and apportion primary biogenic organic aerosols (PBOA) in the atmosphere. To better understand their annual cycles, as well as their spatio-temporal abundance in terms of concentrations and sources, we conducted a large study focusing on three major atmospheric primary sugar compounds (i.e. arabitol, mannitol and glucose) measured in various environmental conditions on about 5,300 filter samples collected at 28 sites in France. Our results show significant atmospheric concentrations of polyols (defined here as the sum of arabitol and mannitol) and glucose at each sampling location, highlighting their ubiquity. Results also confirm that polyols and glucose are mainly associated with the coarse rather than the fine aerosol mode. At nearly all sites, atmospheric concentrations of polyols and glucose display a well-marked seasonal pattern, with maximum concentrations from late spring to early autumn, followed by an abrupt decrease in late autumn, and a minimum concentration during wintertime. Such seasonal patterns support biogenic emissions associated with higher biological metabolic activities (e.g. sporulation, growth, etc.) during warmer periods. Results from a previous comprehensive study using Positive Matrix Factorization (PMF) based on an extended aerosol chemical composition dataset of up to 130 species for 16 of the same sample series has also been used in the present work. Results show that PBOA are significant sources of total OM in PM10 (13 ± 4 % on a yearly average, and up to 40 % in some environments in summer) at most of the investigated sites. The mean PBOA chemical profile is clearly dominated by OM (78 ± 9 % of the mass of the PBOA PMF factor on average), suggesting that ambient polyols are most likely associated with biological particle emissions (e.g. active spore discharge) rather than soil dust resuspension. [ABSTRACT FROM AUTHOR]

The present study offers the first chemical characterization of the submicron (PM1/ fraction in western Africa at a high time resolution, thanks to collocated measurements of nonrefractory (NR) species with an Aerosol Chemical Speciation Monitor (ACSM), black carbon and iron concentrations derived from absorption coefficient measurements with a 7-wavelength Aethalometer, and total PM1 determined by a TEOM-FDMS (tapered element oscillating microbalance-filtered dynamic measurement system) for mass closure. The field campaign was carried out over 3 months (March to June 2015) as part of the SHADOW (SaHAran Dust Over West Africa) project at a coastal site located in the outskirts of the city of Mbour, Senegal. With an averaged mass concentration of 5.4 μgm-3, levels of NR PM1 in Mbour were 3 to 10 times lower than those generally measured in urban and suburban polluted environments. Nonetheless the first half of the observation period was marked by intense but short pollution events (NR PM1 concentrations higher than 15 μgm-3/, sea breeze phenomena and Saharan desert dust outbreaks (PM10 up to 900 μgm-3/. During the second half of the campaign, the sampling site was mainly under the influence of marine air masses. The air masses on days under continental and sea breeze influences were dominated by organics (36-40 %), whereas sulfate particles were predominant (40 %) for days under oceanic influence. Overall, measurements showed that about threequarters of the total PM1 were explained by NR PM1, BC (black carbon) and Fe (a proxy for dust) concentrations, leaving approximately one-quarter for other refractory species. A mean value of 4.6% for the Fe =PM1 ratio was obtained. Source apportionment of the organic fraction, using positive matrix factorization (PMF), highlighted the impact of local combustion sources, such as traffic and residential activities, which contribute on average to 52% of the total organic fraction. A new organic aerosol (OA) source, representing on average 3% of the total OA fraction, showed similar variation to nonrefractory particulate chloride. Its rose plot and daily pattern pointed to local combustion processes, i.e., two open waste-burning areas located about 6 and 11 km away from the receptor site and to a lesser extent a traditional fish-smoking location. The remaining fraction was identified as oxygenated organic aerosols (OOA), a factor that prevailed regardless of the day type (45 %) and was representative of regional (approximately three-quarters) but also local (approximately one-quarter) sources due to enhanced photochemical processes. [ABSTRACT FROM AUTHOR]

This review synthesizes the existing knowledge on the characteristics of PM2.5at sites under the direct influence of industrial emissions, with a specific focus on their morphology, size distributions and chemical composition. Results from online and off-line analytical techniques indicate a high temporal and spatial variability of mass size distribution and chemical composition depending on the type of industrial processes, the sampling distances and frequencies, and the meteorological conditions. Tracers of specific activities have been identified in a number of studies and may help to provide estimates of the relative contribution of pollutant sources from heavily industrialized areas. [ABSTRACT FROM AUTHOR]

The gas-phase ozonolysis of three methylated alkenes, i.e., trans-2,2-dimethyl-3-hexene (22dM3H), trans-2,5-dimethyl-3-hexene (25dM3H), and 4-methyl-1-pentene (4M1P), has been investigated in the presence of sufficient hydroxyl radical scavenger in a laminar flow reactor at ambient temperature (296 ± 2 K) and P = 1 atm of dry air (RH ≤ 5%). Ozone levels in the reactor were monitored by an automatic analyzer. Alkene and gas-phase product concentrations were determined via online sampling either on three-bed adsorbent cartridges followed by thermodesorption and GC/FID-MS analysis or on 2,4-dinitrophenylhydrazine (DNPH) cartridges for subsequent HPLC/UV analysis. Reaction rate coefficients of (3.38 ± 0.12) × 10-17 for 22dM3H and (2.71 ± 0.26) × 10-17 for 25dM3H, both in cm³ molecule-1 s-1 units, have been obtained under pseudo-first-order conditions. Primary carbonyl products have been identified for the three investigated alkenes, and branching ratios are reported. In the case of 4M1P ozonolysis, the yield of a Criegee intermediate was indirectly determined. Kinetics and product study results are compared to those of literature when available. This work represents the first investigation of reaction products in the ozonolysis of 22dM3H, 25dM3H, and 4M1P in a flow reactor. [ABSTRACT FROM AUTHOR]

Two measurement campaigns of volatile organic compounds (VOC) were carried out in the industrial city of Dunkerque, using Radiello passive samplers during winter (16–23 January) and summer (6–13 June) 2007. 174 compounds were identified belonging to six chemical families. Classifying sampling sites with similar chemical profiles by hierarchical ascending classification resulted in 4 groups that reflected the influence of the main industrial and urban sources of pollution. Also, the BTEX (Benzene, Toluene, Ethylbenzene and Xylenes) quantification allowed us to map their levels of concentration. Benzene and toluene (BT) showed high concentrations in Northern Dunkerque reflecting the influence of two industrial plants. Differences among spatial distributions of the BT concentrations over contrasted meteorological conditions were also observed. An atypical ratio of T/B in the summer samples led us to investigate the BTEX origins shedding light on the contribution of pollutants transported across various zones of VOC emissions situated in Europe. [Copyright &y& Elsevier]

Abstract: An ultra-high-performance liquid chromatography/time-of-flight mass spectrometry (with negative ion electrospray ionization) methodology was developed for the simultaneous quantification of benzoic acid and 15 long-chain monocarboxylic acids (MCAs) in ambient aerosols. A fast and quantitative pressurized fluid extraction procedure was optimized using experimental design and the extracts were analyzed without any further clean-up step. Chromatographic separation was achieved on a BEH-C18 column with a mobile phase consisting of 5mM formic acid in water/acetonitrile (90:10, v/v) and methanol. Excellent precision and accuracies in the MS mass measurements were observed. The method was validated using actual samples spiked with a solution containing either standards or 13C-surrogates. Matrix effects were observed for the C14 MCA only. It was then applied to air particulate reference materials and atmospheric samples collected by a low-volume sampler. [Copyright &y& Elsevier]

Industrial metalworking facilities emit a variety of air toxics including volatile organic compounds, polycyclic aromatic hydrocarbons (PAHs) and heavy metals. In order to investigate these emissions, a 1-month multi-instrument field campaign was undertaken at an industrial site in Grande-Synthe, Dunkirk (France), in May and June 2012. One of the main objectives of the study was to provide new information on the chemical composition of particulate matter with aerodynamic diameters smaller than 2.5 μm (PM 2.5) in the vicinity of metalworking facilities. An aerosol time-of-flight mass spectrometer (ATOFMS) was deployed to provide size-resolved chemical mixing state measurements of ambient single particles at high temporal resolution. This mixing state information was then used to apportion PM 2.5 to local metalworking facilities influencing the receptor site. Periods when the site was influenced by metalworking sources were characterised by a pronounced increase in particles containing toxic metals (manganese, iron, lead) and polycyclic aromatic hydrocarbons (PAHs) with a variety of chemical mixing states. The association of specific particle classes with a nearby ferromanganese alloy manufacturing plant was confirmed through comparison with previous analysis of raw materials (ores) and chimney filter particle samples collected at the facility. Particles associated with emissions from a nearby steelworks were also identified. The contribution of local metalworking activities to PM 2.5 at the receptor site for the period when the ATOFMS was deployed ranged from 1 to 65% with an average contribution of 17%, while the remaining mass was attributed to other local and regional sources. These findings demonstrate the impact of metalworking facilities on air quality downwind and provide useful single particle signatures for future source apportionment studies in communities impacted by metalworking emissions. Image 1 • Particles assigned to a ferromanganese facility and a steelworks based on composition. • Metalworking particle composition and mixing state is complex and diverse. • Metalworking emissions contributed 17% to PM 2.5 on average at the receptor site. • Metalworking is the dominant source of metals and polycyclic aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

The CARA program has been running since 2008 by the French reference laboratory for air quality monitoring (LCSQA) and the regional monitoring networks, to gain better knowledge—at a national level—on particulate matter (PM) chemistry and its diverse origins in urban environments. It results in strong collaborations with international-level academic partners for state-of-the-art, straightforward, and robust results and methodologies within operational air quality stakeholders (and subsequently, decision makers). Here, we illustrate some of the main outputs obtained over the last decade, thanks to this program, regarding methodological aspects (both in terms of measurement techniques and data treatment procedures) as well as acquired knowledge on the predominant PM sources. Offline and online methods are used following well-suited quality assurance and quality control procedures, notably including inter-laboratory comparison exercises. Source apportionment studies are conducted using various receptor modeling approaches. Overall, the results presented herewith underline the major influences of residential wood burning (during the cold period) and road transport emissions (exhaust and non-exhaust ones, all throughout the year), as well as substantial contributions of mineral dust and primary biogenic particles (mostly during the warm period). Long-range transport phenomena, e.g., advection of secondary inorganic aerosols from the European continental sector and of Saharan dust into the French West Indies, are also discussed in this paper. Finally, we briefly address the use of stable isotope measurements (δ15N) and of various organic molecular markers for a better understanding of the origins of ammonium and of the different organic aerosol fractions, respectively. [ABSTRACT FROM AUTHOR]