Quantification of levoglucosan and its isomers by High Performance Liquid Chromatography - Electrospray Ionization tandem Mass Spectrometry and its application to atmospheric and soil samples

http://www.atmos-meas-tech-discuss.net/4/4539/2011/amtd-4-4539-2011.htmlInternational audienceThe determination of atmospheric concentrations of levoglucosan and its two isomers, unambiguous tracers of biomass burning emissions, became even more important with the development of wood as renewable energy for domestic heating. Many researches demonstrated the increase during recent years of atmospheric particulate matter load due to domestic biomass combustion in developed countries. Analysis of biomass burning tracers is traditionally performed with Gas Chromatography-Mass Spectrometry (GC-MS) technique after derivatization and requires an organic solvent extraction. A simpler and faster technique using Liquid Chromatography - Electrospray Ionisation - tandem Mass Spectrometry (LC-ESI-MS/MS) was optimized for the analysis of levoglucosan, mannosan and galactosan isomers after an aqueous extraction. This technique allows a good separation between the three compounds in a very reduced time (runtime ~5 min). LOD and LOQ of this method are 30 μg l−1 and 100 μg l−1 respectively, allowing the use of filters from low-volume sampler (as commonly used in routine campaigns). A comparison of simultaneous levoglucosan measurements by GC-MS and LC-ESI-MS/MS for about 50 samples coming from different types of sampling sites and seasons was realized and shows very good agreement between the two methods. Therefore LC-ESI-MS/MS method can be used as an alternative to GC-MS particularly for measurement campaigns in routine where analysis time is important and detection limit is reduced. This paper shows that this method is also applicable to other environmental sample types like soil

Nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons in the ambient air of two French alpine valleys: Part 1: Concentrations, sources and gas/particle partitioning

International audienceAmbient measurements (gas+particle phases) of 16 polycyclic aromatic hydrocarbons, 17 nitrated PAHs (NPAHs) and eight oxygenated PAHs (OPAHs) were carried out during the winter 2002-2003 and the summer 2003 in two French alpine valleys on various types of sites (traffic, sub-urban, altitude and rural). Atmospheric concentrations of these classes of compounds are of interest because they include potential mutagens and carcinogens. During both summer and winter campaigns, OPAH concentration levels were of the same order of magnitude as PAH ones while NPAH concentrations were one to two orders of magnitude lower. Total particulate PAH, OPAH and NPAH concentrations were higher in the Chamonix valley than in the Maurienne valley. A heavier pollutant accumulation process in the Chamonix valley and geomorphology promoting their dispersion seem to explain such differences. Despite reaching lower atmospheric concentrations, NPAHs seemed to account up to 20% of carcinogenic potency of particulates collected at the sites away from pollution sources. The formation of secondary compounds such as NPAHs increases significantly the carcinogenic risk at the sites away from pollution sources. Study with 2-nitrofluoranthene/1-nitropyrene ratio showed that NPAH gas phase formation was hindered in winter, and when relative contribution from primary sources was higher. Nevertheless, in winter under specific conditions, evidence of secondary NPAH formations was observed at sub-urban and traffic sites (snowfalls) and rural site (accumulation of pollutants and snowfalls). For all sampling sites, the daytime OH initiated reaction seemed to be the dominant gas phase formation pathway over the NO3 initiated reaction. The fraction of PAHs, OPAHs and NPAHs associated with the particle phase was strongly depending on their vapour pressure and the ambient conditions

Oxidative potential in rural, suburban and city centre atmospheric environments in central Europe

Oxidative potential (OP) is an emerging health-related metric which integrates several physicochemical properties of particulate matter (PM) that are involved in the pathogenesis of the diseases resulting from exposure to PM. Daily PM2.5-fraction aerosol samples collected in the rural background of the Carpathian Basin and in the suburban area and centre of its largest city of Budapest in each season over 1 year were utilised to study the OP at the related locations for the first time. The samples were analysed for particulate matter mass, main carbonaceous species, levoglucosan and 20 chemical elements. The resulting data sets were subjected to positive matrix factorisation to derive the main aerosol sources. Biomass burning (BB), suspended dust, road traffic, oil combustion mixed with coal combustion and long-range transport, vehicle metal wear, and mixed industrial sources were identified. The OP of the sample extracts in simulated lung fluid was determined by ascorbic acid (AA) and dithiothreitol (DTT) assays. The comparison of the OP data sets revealed some differences in the sensitivities of the assays. In the heating period, both the OP and PM mass levels were higher than in spring and summer, but there was a clear misalignment between them. In addition, the heating period : non-heating period OP ratios in the urban locations were larger than for the rural background by factors of 2–4. The OP data sets were attributed to the main aerosol sources using multiple linear regression with the weighted least squares approach. The OP was unambiguously dominated by BB at all sampling locations in winter and autumn. The joint effects of motor vehicles involving the road traffic and vehicle metal wear played the most important role in summer and spring, with considerable contributions from oil combustion and resuspended dust. In winter, there is temporal coincidence between the most severe daily PM health limit exceedances in the whole Carpathian Basin and the chemical PM composition causing larger OP. Similarly, in spring and summer, there is a spatial coincidence in Budapest between the urban hotspots of OP-active aerosol constituents from traffic and the high population density in central quarters. These features offer possibilities for more efficient season-specific air quality regulations focusing on well-selected aerosol sources or experimentally determined OP, rather than on PM mass in general.</p

Estimation de la contribution des émissions Îhiculaires à l'échappement et hors-échappement aux teneurs atmosphériques en PM10 par Positive Matrix Factorization (PMF)

The goal of this work is the development of a methodology allowing the assessment of road traffic exhaust and non-exhaust contributions (resuspension of road dusts, from brakes, tyres and road-surface-wear, from the corrosion of vehicle components...) to PM10 in an urban site. The approach used source apportionment modelling by PMF (Positive Matrix Factorization) with a chemical data set including chemical tracers. These data are obtained thanks to filter samples collected during short-time periods (4h temporal resolution). This study also includes the simultaneous sampling of chemical species on an urban background site (Grenoble-Les Frênes, France) and on a roadside site (Grenoble-Echirolles, France). This combination leads to accurate determination of traffic indicators sources. Finally, the source apportionment using PMF applied to this database gives possible contribution of sources to PM10. Results show that the road traffic source contribution to PM10 (exhaust + non-exhaust sources) was on average 34% and ranged from about 57% during the rush hours to 14% during less busy periods. Non-exhaust contribution is on average equivalent to the exhaust one.L'objectif de cette étude est de tester une méthodologie permettant de déterminer les contributions respectives aux teneurs atmosphériques en PM10 des émissions Îhiculaires à l'échappement et hors échappement (abrasion des freins, des pneus et de la route, remise en suspension des poussières de la chaussée...) dans un milieu urbain. La stratégie adoptée est d'appliquer une méthode de déconvolution des sources par un modèle statistique d'analyses multivariées (PMF, Positive Matrix Factorization) sur un jeu de données chimiques obtenues avec des filtres collectés sur des durées réduites (4h) et comprenant des traceurs spécifiques. Les prélèvements ont été réalisés simultanément sur un site de fond urbain (Grenoble-Les Frênes, France) et sur un site de proximité automobile (Grenoble-Échirolles, France). La discrimination des sources et la quantification de leur contribution par PMF sont ensuite obtenues sur la base de données établie. Les résultats montrent que les émissions Îhiculaires à l'échappement et hors échappement contribuent en moyenne à 34 % des PM10 et jusqu'à 57 % durant les heures de pointe, contre seulement 14 % durant les heures creuses. Sur la période de mesure, les émissions hors échappement sont en moyenne équivalentes aux émissions à l'échappement pour le site d'étude de proximité trafic

Measurement report : Long-range transport and the fate of dimethyl sulfide oxidation products in the free troposphere derived from observations at the high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes

Dimethyl sulfide (DMS) is the primary natural contributor to the atmospheric sulfur burden. Observations concerning the fate of DMS oxidation products after long-range transport in the remote free troposphere are, however, sparse. Here we present quantitative chemical ionization mass spectrometric measurements of DMS and its oxidation products sulfuric acid (H2SO4), methanesulfonic acid (MSA), dimethylsulfoxide (DMSO), dimethylsulfone (DMSO2), methanesulfinic acid (MSIA), methyl thioformate (MTF), methanesulfenic acid (MSEA, CH3SOH), and a compound of the likely structure CH3S(O)(2)OOH in the gas phase, as well as measurements of the sulfate and methanesulfonate aerosol mass fractions. The measurements were performed at the Global Atmosphere Watch (GAW) station Chacaltaya in the Bolivian Andes located at 5240 m above sea level (a.s.l.). DMS and DMS oxidation products are brought to the Andean high-altitude station by Pacific air masses during the dry season after convective lifting over the remote Pacific ocean to 6000-8000 m a.s.l. and subsequent longrange transport in the free troposphere (FT). Most of the DMS reaching the station is already converted to the rather unreactive sulfur reservoirs DMSO2 in the gas phase and methanesulfonate (MS-) in the particle phase, which carried nearly equal amounts of sulfur to the station. The particulate sulfate at Chacaltaya is however dominated by regional volcanic emissions during the time of the measurement and not significantly affected by the marine air masses. In one of the FT events, even some DMS was observed next to reactive intermediates such as methyl thioformate, dimethylsulfoxide, and methanesulfinic acid. Also for this event, back trajectory calculations show that the air masses came from above the ocean (distance > 330 km) with no local surface contacts. This study demonstrates the potential impact of marine DMS emissions on the availability of sulfur containing vapors in the remote free troposphere far away from the ocean.Peer reviewe

Collection of substantial amount of fine and ultrafine particles during the combustion of miscanthus and forest residues in small and medium scale boilers for morphological and chemical characterizations

Renewable energies are destined to play a very important role in the future world energy balance. Among these energies, biomass production and utilization is growing considerably since it offers the possibility to provide partial substitution of fossil fuels. If health impacts of fine particles (PM2.5) from diesel combustion are well documented (Gangwar et al., 2012), those from biomass combustion need substantial information and improvements. Size fractionations of PM2.5 have to be performed in order to both determine morphological and chemical characteristics, these properties being essential for biological effects. Particulate matter was sampled during combustion of miscanthus and forest residues in medium and small scale biomass boilers (400 kW from Köb Pyrot and 40 kW from REKA). Fly ashes from medium scale boiler were sampled with a cyclone device and their granulometry was studied with both optical microscope and Malvern laser granulometer. PM2.5 (sized in the range of 0.4 μm to 2.07 μm) from low scale boiler were sampled using a DEKATI DGI impactor modified for substantial PM collection. A quick overview of setup modifications for manual impactor will be developed. Particles were observed using fluorescence microscopy. A semi-quantitative method to compare fly ashes fluorescence was developped using ImageJ (Schneider et al., 2012). Speciation of organic compounds Polycyclic Aromatic Hydrocarbon (PAH) and Humic Like Substances (HULIS) was determined on PM2.5 and fly ashes. A correlation between observed fluorescence and concentration was attempted

Geochemistry and oxidative potential of the respirable fraction of powdered mined Chinese coals

This study evaluates geochemical and oxidative potential (OP) properties of the respirable (finer than 4 μm) fractions of 22 powdered coal samples from channel profiles (CP4) in Chinese mined coals. The CP4 fractions extracted from milled samples of 22 different coals were mineralogically and geochemically analysed and the relationships with the OP evaluated. The evaluation between CP4/CP demonstrated that CP4 increased concentrations of anatase, Cs, W, Zn and Zr, whereas sulphates, Fe, S, Mo, Mn, Hf and Ge decreased their CP4 concentrations. OP results from ascorbic acid (AA), glutathione (GSH) and dithiothreitol (DTT) tests evidenced a clear link between specific inorganic components of CP4 with OPAA and the organic fraction of OPGSH and OPDTT. Correlation analyses were performed for OP indicators and the geochemical patterns of CP4. These were compared with respirable dust samples from prior studies. They indicate that Fe (r = 0.83), pyrite (r = 0.66) and sulphate minerals (r = 0.42) (tracing acidic species from pyrite oxidation), followed by S (r = 0.50) and ash yield (r = 0.46), and, to a much lesser extent, Ti, anatase, U, Mo, V and Pb, are clearly linked with OPAA. Moreover, OPGSH correlation was identified by organic matter, as moisture (r = 0.73), Na (r = 0.56) and B (r = 0.51), and to a lesser extent by the coarse particle size, Ca and carbonate minerals. In addition, Mg (r = 0.70), B (r = 0.47), Na (r = 0.59), Mn, Ba, quartz, particle size and Sr regulate OPDTT correlations. These became more noticeable when the analysis was done for samples of the same type of coal rank, in this case, bituminous.This study was supported by Generalitat de Catalunya (AGAUR 2017 SGR41), Spain; by the National Science Foundation of China (grant 41972180); the Program of Introducing Talents of Discipline to Universities (grant B14031) and Overseas Top Scholars Program for the Recruitment of Global Experts, China; and by the Spanish Ministry of Science and Innovation (Excelencia Severo Ochoa, Project CEX2018-000794-S). Malvern Mastersizer Scirocco 2000 extension measurements were performed at the ICTS NANBIOSIS by the Nanostructured Liquids Unit (U12) of the CIBER in Bioengineering, Biomaterials & Nanomedicine (CIBER-BBN), located at the IQAC-CSIC (Barcelona, Spain). Pedro Trechera is contracted by the ROCD (Reducing risks from Occupational exposure to Coal Dust) project supported by the European Commission Research Fund for Coal and Steel; Grant Agreement Number 754205.Peer reviewe

Elucidating the present-day chemical composition, seasonality and source regions of climate-relevant aerosols across the Arctic land surface

The Arctic is warming two to three times faster than the global average, and the role of aerosols is not well constrained. Aerosol number concentrations can be very low in remote environments, rendering local cloud radiative properties highly sensitive to available aerosol. The composition and sources of the climate-relevant aerosols, affecting Arctic cloud formation and altering their microphysics, remain largely elusive due to a lack of harmonized concurrent multi-component, multi-site, and multi-season observations. Here, we present a dataset on the overall chemical composition and seasonal variability of the Arctic total particulate matter (with a size cut at 10 mu m, PM10, or without any size cut) at eight observatories representing all Arctic sectors. Our holistic observational approach includes the Russian Arctic, a significant emission source area with less dedicated aerosol monitoring, and extends beyond the more traditionally studied summer period and black carbon/sulfate or fine-mode pollutants. The major airborne Arctic PM components in terms of dry mass are sea salt, secondary (non-sea-salt, nss) sulfate, and organic aerosol (OA), with minor contributions from elemental carbon (EC) and ammonium. We observe substantial spatiotemporal variability in component ratios, such as EC/OA, ammonium/nss-sulfate and OA/nss-sulfate, and fractional contributions to PM. When combined with component-specific back-trajectory analysis to identify marine or terrestrial origins, as well as the companion study by Moschos et al 2022 Nat. Geosci. focusing on OA, the composition analysis provides policy-guiding observational insights into sector-based differences in natural and anthropogenic Arctic aerosol sources. In this regard, we first reveal major source regions of inner-Arctic sea salt, biogenic sulfate, and natural organics, and highlight an underappreciated wintertime source of primary carbonaceous aerosols (EC and OA) in West Siberia, potentially associated with the oil and gas sector. The presented dataset can assist in reducing uncertainties in modelling pan-Arctic aerosol-climate interactions, as the major contributors to yearly aerosol mass can be constrained. These models can then be used to predict the future evolution of individual inner-Arctic atmospheric PM components in light of current and emerging pollution mitigation measures and improved region-specific emission inventories.Peer reviewe