0000000000073708
AUTHOR
T. Hoffmann
Determination of alkyl amines in atmospheric aerosol particles: a comparison of gas chromatography-mass spectrometry and ion chromatography approaches
Abstract. In recent years low molecular weight alkyl amines have been recognized to play an important role in particle formation and growth in the lower atmosphere. However, major uncertainties are associated with their atmospheric processes, sources and sinks, mostly due to the lack of ambient measurements and the difficulties in accurate quantification of alkyl amines at trace level. In this study, we present the evaluation and optimization of two analytical approaches, i.e., gas chromatography-mass spectrometry (GC-MS) and ion chromatography (IC), for the determination of alkyl amines in aerosol particles. Alkyl amines were converted to carbamates through derivatization with isobutyl chl…
Nanoimprint lithography for organic electronics
Thin films made of organic semiconductors (α-sexithiophene, PDAS and PBAS) have been printed and the impact on morphology studied by optical, atomic force and electron microscopy. Surfaces in contact with the stamp during printing undergo a change towards smoother and more ordered material at the macromolecular scale. Interdigitated nanoelectrodes to be used as source and drain in TFTs have been made and printed down to 100 nm. PDAS and PBAS can be printed at room temperature and preserve their printed feature provided they are cross-linked afterwards.
Abstracts of the 6th FECS Conference 1998 Lectures.
International audience
A comparison of HONO budgets for two measurement heights at a field station within the boreal forest in Finland
Atmospheric concentrations of nitrous acid (HONO), one of the major precursors of the hydroxyl radical (OH) in the troposphere, significantly exceed the values predicted by the assumption of a photostationary state (PSS) during daytime. Therefore, additional sources of HONO were intensively investigated in the last decades. This study presents budget calculations of HONO based on simultaneous measurements of all relevant species, including HONO and OH at two different measurement heights, i.e. 1 m above the ground and about 2 to 3 m above the canopy (24 m above the ground), conducted in a boreal forest environment. We observed mean HONO concentrations of about 6.5 × 108 molecules cm−3 (26 p…
Determination of n-alkanes, polycyclic aromatic hydrocarbons and hopanes in atmospheric aerosol: evaluation and comparison of thermal desorption GC-MS and solvent extraction GC-MS approaches
Organic aerosol (OA) constitutes a large fraction of fine particulate matter (PM) in the urban air. However, the chemical nature and sources of OA are not well constrained. Quantitative analysis of OA is essential for understanding the sources and atmospheric evolution of fine PM, which requires accurate quantification of some organic compounds (e.g., markers). In this study, two analytical approaches, i.e., thermal desorption (TD) gas chromatography mass spectrometry (GC-MS) and solvent extract (SE) GC-MS, were evaluated for the determination of n-alkanes, polycyclic aromatic hydrocarbons (PAHs) and hopanes in ambient aerosol. For the SE approach, the recovery obtained is 89.3 %–101…
The summertime Boreal forest field measurement intensive (HUMPPA-COPEC-2010): an overview of meteorological and chemical influences
This paper describes the background, instrumentation, goals, and the regional influences on the HUMPPACOPEC intensive field measurement campaign, conducted at the Boreal forest research station SMEAR II (Station for Measuring Ecosystem-Atmosphere Relation) in Hyyti¨al¨a, Finland from 12 July–12 August 2010. The prevailing meteorological conditions during the campaign are examined and contrasted with those of the past six years. Back trajectory analyses show that meteorological conditions at the site in 2010 were characterized by a higher proportion of southerly flow than in the other years studied. As a result the summer of 2010 was anomalously warm and high in ozone making the campaign rel…
Historic records of organic compounds from a high Alpine glacier: influences of biomass burning, anthropogenic emissions, and dust transport
Historic records of α-dicarbonyls (glyoxal, methylglyoxal), carboxylic acids (C6–C12 dicarboxylic acids, pinic acid, p-hydroxybenzoic acid, phthalic acid, 4-methylphthalic acid), and ions (oxalate, formate, calcium) were determined with annual resolution in an ice core from Grenzgletscher in the southern Swiss Alps, covering the time period from 1942 to 1993. Chemical analysis of the organic compounds was conducted using ultra-high-performance liquid chromatography (UHPLC) coupled to electrospray ionization high-resolution mass spectrometry (ESI-HRMS) for dicarbonyls and long-chain carboxylic acids and ion chromatography for short-chain carboxylates. Long-term records of the carboxylic acid…
Characterization of the light-absorbing properties, chromophore composition and sources of brown carbon aerosol in Xi'an, northwestern China
The impact of brown carbon aerosol (BrC) on the Earth's radiative forcing balance has been widely recognized but remains uncertain, mainly because the relationships among BrC sources, chromophores and optical properties of aerosol are poorly understood. In this work, the light absorption properties and chromophore composition of BrC were investigated for samples collected in Xi'an, northwestern China, from 2015 to 2016. Both absorption Ångström exponent (AAE) and mass absorption efficiency (MAE) show distinct seasonal differences, which could be attributed to the differences in sources and chromophore composition of BrC. Three groups of light-absorbing organics were found to be important Br…
Bromine speciation in volcanic plumes: new in situ derivatization LC-MS method for the determination of gaseous hydrogen bromide by gas diffusion denuder sampling
The chemical characterization of volcanic gas emissions gives insights into the interior of volcanoes. Monitoring of BrO/SO2-ratios has recently been correlated with changes in the activity of a volcano. BrO and SO2 can both be measured autonomously and simultaneously with the same instruments from a safe distance, making their ratio potentially a strong monitoring tool. However, BrO is not a primary emitted volcanic volatile and there exist still uncertainties about the formation of BrO in volcanic plumes, mostly due to the lack of analytical approaches for the accurate speciation of certain key compounds. This study describes a new method for the determination of the BrO precursor, the ga…
Online atmospheric pressure chemical ionization ion trap mass spectrometry (APCI-IT-MSn) for measuring organic acids in concentrated bulk aerosol – a laboratory and field study
The field application of an aerosol concentrator in conjunction with an atmospheric pressure chemical ionization ion trap mass spectrometer (APCI-IT-MS) at the boreal forest station SMEAR II at Hyytiälä, Finland, is demonstrated in this study. APCI is a soft-ionization technique allowing online measurements of organic acids in the gas and particle phase. The detection limit for the acid species in the particle phase was improved by a factor of 7.5 to 11 (e.g. ∼40 ng m3 for pinonic acid) by using the miniature versatile aerosol concentration enrichment system (mVACES) upstream of the mass spectrometer. The APCI-IT-MS was calibrated in the negative ion mode with two biogenic organic acid …
Emission of nitrous acid from soil and biological soil crusts represents an important source of HONO in the remote atmosphere in Cyprus
Abstract. Soil and biological soil crusts can emit nitrous acid (HONO) and nitric oxide (NO). The terrestrial ground surface in arid and semiarid regions is anticipated to play an important role in the local atmospheric HONO budget, deemed to represent one of the unaccounted-for HONO sources frequently observed in field studies. In this study HONO and NO emissions from a representative variety of soil and biological soil crust samples from the Mediterranean island Cyprus were investigated under controlled laboratory conditions. A wide range of fluxes was observed, ranging from 0.6 to 264 ng m−2 s−1 HONO-N at optimal soil water content (20–30 % of water holding capacity, WHC). Maximum NO-N f…
A multi-purpose, multi-rotor drone system for long-range and high-altitude volcanic gas plume measurements
A multi-rotor drone has been adapted for studies of volcanic gas plumes. This adaptation includes improved capacity for high-altitude and long-range, real-time SO2 concentration monitoring, long-range manual control, remotely activated bag sampling and plume speed measurement capability. The drone is capable of acting as a stable platform for various instrument configurations, including multi-component gas analysis system (MultiGAS) instruments for in situ measurements of SO2, H2S, and CO2 concentrations in the gas plume and portable differential optical absorption spectrometer (MobileDOAS) instruments for spectroscopic measurement of total SO2 emission rate, remotely controlled gas samplin…
Summertime and wintertime atmospheric processes of secondary aerosol in Beijing
Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable study in recent years. To elucidate the seasonal variations in fine-particle composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM), combined with other online instruments, was used to characterize the sub-micrometer particulate matter (diameter < 1 µm, PM1) in Beijing during summer and winter 2015. Our results suggest that photochemical oxidation was the major pathway for sulfate formation during summer, whereas aqueou…
Historic records of organic aerosols from a high Alpine glacier: implications of biomass burning, anthropogenic emissions, and dust transport
Abstract. Historic records of α-dicarbonyls (glyoxal, methylglyoxal), carboxylic acids (C6–C12 dicarboxylic acids, pinic acid, p-hydroxybenzoic acid, phthalic acid, 4-methylphthalic acid), and major ions (oxalate, formate, calcium) were determined with annual resolution in an ice core from Grenzgletscher in the southern Swiss Alps, covering the time period from 1942 to 1993. Measurements were conducted using ultra-high performance liquid chromatography (UHPLC) coupled to electrospray ionization high resolution mass spectrometry (ESI-HRMS). For the first time, long-term records of the carboxylic acids and dicarbonyls as well as their source apportionment are reported for Western Europe. Sour…
Organosulfates in atmospheric aerosol: synthesis and quantitative analysis of PM2.5 from Xi'an, northwestern China
The sources, formation mechanism and amount of organosulfates (OS) in atmospheric aerosol are not yet well understood, partly due to the lack of authentic standards for quantification. In this study, we report an improved robust procedure for the synthesis of organosulfates with different functional groups. Nine authentic organosulfate standards were synthesized and four standards (benzyl sulfate, phenyl sulfate, glycolic acid sulfate, and hydroxyacetone sulfate) were used to quantify their ambient concentrations. The authentic standards and ambient aerosol samples were analyzed using an optimized ultra performance liquid chromatography–electrospray ionization-tandem mass spectrometric meth…
Nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) for investigating hygroscopic properties of sub-10 nm aerosol nanoparticles
Interactions between water and nanoparticles are relevant for atmospheric multiphase processes, physical chemistry, and materials science. Current knowledge of the hygroscopic and related physicochemical properties of nanoparticles, however, is restricted by the limitations of the available measurement techniques. Here, we present the design and performance of a nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) apparatus that enables high accuracy and precision in hygroscopic growth measurements of aerosol nanoparticles with diameters less than 10 nm. Detailed methods of calibration and validation are provided. Besides maintaining accurate and stable sheath and a…
Summertime total OH reactivity measurements from boreal forest during HUMPPA-COPEC 2010
Ambient total OH reactivity was measured at the Finnish boreal forest station SMEAR II in Hyytiälä (Latitude 61&deg;51' N; Longitude 24&deg;17' E) in July and August 2010 using the Comparative Reactivity Method (CRM). The CRM – total OH reactivity method – is a direct, in-situ determination of the total loss rate of hydroxyl radicals (OH) caused by all reactive species in air. During the intensive field campaign HUMPPA-COPEC 2010 (<b>H</b>yytiälä <b>U</b>nited <b>M</b>easurements of <b>P</b>hotochemistry and <b>P</b>articles in <b>A</b>ir – <b>C</b>omprehensive <b>O</b>rganic <b>P&l…
Uptake of gaseous formaldehyde by soil surfaces: a combination of adsorption/desorption equilibrium and chemical reactions
Gaseous formaldehyde (HCHO) is an important precursor of OH radicals and a key intermediate molecule in the oxidation of atmospheric volatile organic compounds (VOCs). Budget analyses reveal large discrepancies between modeled and observed HCHO concentrations in the atmosphere. Here, we investigate the interactions of gaseous HCHO with soil surfaces through coated-wall flow tube experiments applying atmospherically relevant HCHO concentrations of ∼ 10 to 40 ppbv. For the determination of uptake coefficients (γ), we provide a Matlab code to account for the diffusion correction under laminar flow conditions. Under dry conditions (relative humidity = 0 %), an initial γ of (1.1 ± 0.05) × …
Urban organic aerosol composition in eastern China differs from north to south:Molecular insight from a liquid chromatography-mass spectrometry (Orbitrap) study
Air pollution by particulate matter in China affects human health, the ecosystem and the climate. However, the chemical composition of particulate aerosol, especially of the organic fraction, is still not well understood. In this study, particulate aerosol samples with a diameter of ≤2.5 µm (PM2.5) were collected in January 2014 in three cities located in northeast, east and southeast China, namely Changchun, Shanghai and Guangzhou. Organic aerosol (OA) in the PM2.5 samples was analyzed by an ultrahigh-performance liquid chromatograph (UHPLC) coupled to a high-resolution Orbitrap mass spectrometer in both negative mode (ESI-) and positive mode electrospray ionization (ESI+). After non-targe…
Black and brown carbon over central Amazonia: long-term aerosol measurements at the ATTO site
The Amazon rainforest is a sensitive ecosystem experiencing the combined pressures of progressing deforestation and climate change. Its atmospheric conditions oscillate between biogenic and biomass burning (BB) dominated states. The Amazon further represents one of the few remaining continental places where the atmosphere approaches pristine conditions during occasional wet season episodes. The Amazon Tall Tower Observatory (ATTO) has been established in central Amazonia to investigate the complex interactions between the rainforest ecosystem and the atmosphere. Physical and chemical aerosol properties have been analyzed continuously since 2012. This paper provides an in-depth analysis of t…
The seaweeds Fucus vesiculosus and Ascophyllum nodosum are significant contributors to coastal iodine emissions
Based on the results of a pilot study in 2007, which found high mixing ratios of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds at Mweenish Bay (Ireland), we extended the study to nine different locations in the vicinity of Mace Head Atmospheric Research Station on the west coast of Ireland during a field campaign in 2009. The mean values of I2 mixing ratio found above the macroalgae beds at nine different locations ranged from 104 to 393 ppt, implying a high source strength of I2. Such mixing ratios are sufficient to result in photochemically driven coastal new-particle formation events. Mixing ratios above the Ascophyllum nodosum and Fucus vesiculosus beds increased …
Aqueous-phase reactive species formed by fine particulate matter from remote forests and polluted urban air
In the aqueous phase, fine particulate matter can form reactive species (RS) that influence the aging, properties, and health effects of atmospheric aerosols. In this study, we explore the RS yields of aerosol samples from a remote forest (Hyytiälä, Finland) and polluted urban locations (Mainz, Germany; Beijing, China), and we relate the RS yields to different chemical constituents and reaction mechanisms. Ultra-high-resolution mass spectrometry was used to characterize organic aerosol composition, electron paramagnetic resonance (EPR) spectroscopy with a spin-trapping technique was applied to determine the concentrations of ⚫OH, O2⚫-, and carbon- or oxygen-centered organic radicals, and a …
Abiotic versus biotic iron mineral transformation studied by a miniaturized backscattering Mössbauer spectrometer (MIMOS II), X-ray diffraction and Raman spectroscopy
Abstract Searching for biomarkers or signatures of microbial transformations of minerals is a critical aspect for determining how life evolved on Earth, and whether or not life may have existed in other planets, including Mars. In order to solve such questions, several missions to Mars have sought to determine the geochemistry and mineralogy on the Martian surface. This research includes the two miniaturized Mossbauer spectrometers (MIMOS II) on board the Mars Exploration Rovers Spirit and Opportunity, which have detected a variety of iron minerals on Mars, including magnetite (Fe2+Fe3+2O4) and goethite (α-FeO(OH)). On Earth, both minerals can derive from microbiological activity (e.g. thro…
Contrasting sources and processes of particulate species in haze days with low and high relative humidity in wintertime Beijing
Although there are many studies of particulate matter (PM) pollution in Beijing, the sources and processes of secondary PM species during haze periods remain unclear. Limited studies have investigated the PM formation in highly polluted environments under low- and high-relative-humidity (RH) conditions. Herein, we present a systematic comparison of species in submicron particles (PM1) in wintertime Beijing (29 December 2014 to 28 February 2015) for clean periods and pollution periods under low- and high-RH conditions. PM1 species were measured with an aerosol chemical species monitor (ACSM) and an Aethalometer. Sources and processes for organic aerosol (OA) were resolved by positive matrix …
Daytime formation of nitrous acid at a coastal remote site in Cyprus indicating a common ground source of atmospheric HONO and NO
Characterization of daytime sources of nitrous acid (HONO) is crucial to understand atmospheric oxidation and radical cycling in the planetary boundary layer. HONO and numerous other atmospheric trace constituents were measured on the Mediterranean island of Cyprus during the CYPHEX (CYprus PHotochemical EXperiment) campaign in summer 2014. Average volume mixing ratios of HONO were 35 pptv (±25 pptv) with a HONO ∕ NOx ratio of 0.33, which was considerably higher than reported for most other rural and urban regions. Diel profiles of HONO showed peak values in the late morning (60 ± 28 pptv around 09:00 local time) and persistently high mixing ratios during daytime (45 ± 18 pptv), indicating …
Light-induced protein nitration and degradation with HONO emission
Proteins can be nitrated by air pollutants (NO2), enhancing their allergenic potential. This work provides insight into protein nitration and subsequent decomposition in the presence of solar radiation. We also investigated light-induced formation of nitrous acid (HONO) from protein surfaces that were nitrated either online with instantaneous gas-phase exposure to NO2 or offline by an efficient nitration agent (tetranitromethane, TNM). Bovine serum albumin (BSA) and ovalbumin (OVA) were used as model substances for proteins. Nitration degrees of about 1 % were derived applying NO2 concentrations of 100 ppb under VIS∕UV illuminated conditions, while simultaneous decomposition of (nitrated) p…
Suppression of new particle formation from monoterpene oxidation by NOx
The impact of nitrogen oxides (NOx = NO + NO2) on new particle formation (NPF) and on photochemical ozone production from real plant volatile organic compound (BVOC) emissions was studied in a laboratory setup. At high NOx conditions ([BVOC] / [NOx] x] > 23 ppb) new particle formation was suppressed. Instead, photochemical ozone formation was observed resulting in higher hydroxyl radical (OH) and lower nitrogen monoxide (NO) concentrations. When [NO] was reduced back to levels below 1 ppb by OH reactions, NPF was observed. Adding high amounts of NOx caused NPF to be slowed by orders of magnitude compared to analogous experiments at low NOx conditions ([NOx] ~300 ppt), although OH concentrat…