A5007772091- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Air Quality Monitoring and Forecasting
- Atmospheric and Environmental Gas Dynamics
- Air Quality and Health Impacts
- Atmospheric aerosols and clouds
- Spectroscopy and Laser Applications
- Catalytic Processes in Materials Science
- Water Quality Monitoring and Analysis
- Vehicle emissions and performance
- Meteorological Phenomena and Simulations
- Odor and Emission Control Technologies
- Marine and coastal ecosystems
- Advanced Chemical Physics Studies
- Plant responses to elevated CO2
- Industrial Gas Emission Control
- COVID-19 impact on air quality
- Ocean Acidification Effects and Responses
- Calibration and Measurement Techniques
- Catalysis and Oxidation Reactions
- Ionosphere and magnetosphere dynamics
- Photochemistry and Electron Transfer Studies
- Advanced Chemical Sensor Technologies
- Free Radicals and Antioxidants
- Environmental and Agricultural Sciences
Forschungszentrum Jülich
2015-2024
Institut für Kälte-, Klima- und Energietechnik
2014-2015
Stadtwerke Jülich (Germany)
2014-2015
Leibniz Institute for Tropospheric Research
2004-2005
Fraunhofer Institute for Toxicology and Experimental Medicine
1997-2002
Fraunhofer Society
1997-1998
Ruhr University Bochum
1992-1995
Going Faster The concentrations of most tropospheric pollutants and trace gases are kept in check by their reactions with hydroxyl radicals (OH). OH is a short-lived, highly reactive species that produced the atmosphere photochemical processes, regenerated chain chemical follows oxidative destruction those molecules. These regeneration mechanisms were thought to be fairly well understood, but now Hofzumahaus et al. (p. 1702 , published online 4 June) present evidence pathway not previously...
Abstract. A comprehensive field campaign was carried out in summer 2014 Wangdu, located the North China Plain. month of continuous OH, HO2 and RO2 measurements achieved. Observations radicals by laser-induced fluorescence (LIF) technique revealed daily maximum concentrations between (5–15) × 106 cm−3, (3–14) 108 cm−3 (3–15) for RO2, respectively. Measured OH reactivities (inverse lifetime) were 10 to 20 s−1 during daytime. The chemical box model RACM 2, including Leuven isoprene mechanism...
Abstract. Ambient OH and HO2 concentrations were measured by laser induced fluorescence (LIF) during the PRIDE-PRD2006 (Program of Regional Integrated Experiments Air Quality over Pearl River Delta, 2006) campaign at a rural site downwind megacity Guangzhou in Southern China. The observed reached daily peak values (15–26) × 106 cm−3 which are among highest so far reported for urban suburban areas. shows consistent high correlation with j(O1D) broad range NOx conditions. cannot be reproduced...
HONO formation has been proposed as an important OH radical source in simulation chambers for more than two decades. Besides the heterogeneous by dark reaction of NO2 and adsorbed water, a photolytic to explain elevated reactivity chamber experiments. However, mechanism process is not well understood so far. As expected, production NOx was also observed inside new atmospheric SAPHIR under solar irradiation. This studied with sensitive instrument reproducible controlled conditions at...
The Multiple Chamber Aerosol Chemical Aging Study (MUCHACHAS) tested the hypothesis that hydroxyl radical (OH) aging significantly increases concentration of first-generation biogenic secondary organic aerosol (SOA). OH is dominant atmospheric oxidant, and MUCHACHAS employed environmental chambers very different designs, using multiple sources to explore a range chemical conditions potential systematic error. We isolated effect aging, confirming our while observing corresponding changes in...
Abstract. Total atmospheric OH reactivities (kOH) have been measured as reciprocal lifetimes by a newly developed instrument at rural site in the densely populated Pearl River Delta (PRD) Southern China summer 2006. The deployed technique, LP-LIF, uses laser flash photolysis (LP) for artificial generation and laser-induced fluorescence (LIF) to measure time-dependent decay samples of ambient air. observed PRD covered range from 10 s−1 120 s−1, indicating large load chemical reactants. On...
Abstract. Measurements of ambient OH and HO2 radicals were performed by laser induced fluorescence (LIF) during CAREBeijing2006 (Campaigns Air Quality Research in Beijing Surrounding Region 2006) at the suburban site Yufa south summer 2006. On most days, local air chemistry was influenced aged pollution that advected a slow, almost stagnant wind from southern regions. Observed daily concentration maxima range (4–17) × 106 cm−3 for (2–24) 108 (including an estimated interference 25% RO2)....
Abstract. The first wintertime in situ measurements of hydroxyl (OH), hydroperoxy (HO2) and organic peroxy (RO2) radicals (ROx=OH+HO2+RO2) combination with observations total reactivity OH radicals, kOH Beijing are presented. field campaign “Beijing winter finE particle STudy – Oxidation, Nucleation light Extinctions” (BEST-ONE) was conducted at the suburban site Huairou near from January to March 2016. It aimed understand oxidative capacity during elucidate secondary pollutants' formation...
Abstract. We performed measurements of nitrous acid (HONO) during the PRIDE-PRD2006 campaign in Pearl River Delta region 60 km north Guangzhou, China, for 4 weeks June 2006. HONO was measured by a LOPAP in-situ instrument which setup one supersites along with variety instruments measuring hydroxyl radicals, trace gases, aerosols, and meteorological parameters. Maximum diurnal mixing ratios 1–5 ppb were observed nights. found that nighttime build-up can be attributed to heterogeneous NO2...
On a Zeppelin Nitrous acid (HONO) is an important atmospheric trace gas that acts as precursor of tropospheric hydroxyl-radicals (OH), which responsible for the self-cleansing capacity atmosphere and also controls concentrations greenhouse gases, such methane ozone. How HONO made mystery. Flying onboard over Po Valley in Northern Italy, Li et al. (p. 292 ) discovered undisturbed morning troposphere, indicating must be produced there, rather than mixed from surface. The high are likely to...
In contrast to summer smog, the contribution of photochemistry formation winter haze in northern mid-to-high latitude is generally assumed be minor due reduced solar UV and water vapor concentrations. Our comprehensive observations atmospheric radicals relevant parameters during several events 2016 Beijing, however, reveal surprisingly high hydroxyl radical oxidation rates up 15 ppbv/h, which comparable values reported photochemical smog two three times larger than those determined previous...
Abstract. HO2 concentration measurements are widely accomplished by chemical conversion of to OH including reaction with NO and subsequent detection laser-induced fluorescence. RO2 radicals can be converted via a similar radical sequence NO, so that they potential interferences for measurements. Here, the efficiency various species is investigated. Experiments were conducted source produces water photolysis at 185 nm, which frequently used calibration LIF instruments. The ratio sum...
Abstract. Nitryl chloride (ClNO2) is a dominant source of chlorine radical in polluted environment, and can significantly affect the atmospheric oxidative chemistry. However, abundance ClNO2 its exact role are not fully understood under different environmental conditions. During summer 2014, we deployed chemical ionization mass spectrometer to measure dinitrogen pentoxide (N2O5) at rural site North China Plain. Elevated mixing ratios (> 350 pptv) were observed most nights with low levels...
Abstract. Hydroxyl (OH) and peroxy radicals (HO2 RO2) were measured in the Pearl River Delta, which is one of most polluted areas China, autumn 2014. The radical observations complemented by measurements OH reactivity (inverse lifetime) a comprehensive set trace gases including carbon monoxide (CO), nitrogen oxides (NOx=NO, NO2) volatile organic compounds (VOCs). was range from 15 to 80 s−1, about 50 % unexplained reactants. In 3 weeks campaign, maximum median concentrations 4.5×106 cm−3 for...
Abstract During spring 2020, the COVID-19 pandemic caused massive reductions in emissions from industry and ground airborne transportation. To explore resulting atmospheric composition changes, we conducted BLUESKY campaign with two research aircraft measured trace gases, aerosols, cloud properties boundary layer to lower stratosphere. From 16 May 9 June performed 20 flights early lockdown phase over Europe Atlantic Ocean. We found up 50% nitrogen dioxide concentrations urban areas GOME-2B...
Formation of nitrous acid (HONO) in the gas phase has been observed for first time a flow tube photoreactor upon irradiation (λ = 300–500 nm) 2-nitrophenol and methyl substituted derivatives using selective sensitive instrument (LOPAP) detection HONO. HONO by heterogeneous NO2 photochemistry excluded, since production under experimental conditions is negligible. Variation surface to volume ratio nitrophenol concentration showed that photolysis occurred indicating formation initiated...
Abstract. The interactions of aerosols consisting humic acids with gaseous nitrogen dioxide (NO2) were investigated under different light conditions in aerosol flow tube experiments at ambient pressure and temperature. results show that NO2 is converted on the acid into nitrous (HONO), which released from can be detected gas phase reactor exit. formation HONO strongly activated by light: In dark, HONO-formation was below detection limit, but it increasing intensity irradiation visible light....
Nitrous acid and OH were measured concurrently with a number of other atmospheric components relevant photolysis frequencies during two campaigns at the Meteorological Observatory Hohenpeissenberg (980 m a.s.l.) in summer 2002 2004. On most 26 measurement days HNO 2 concentration surprisingly showed broad maximum around noon (on average 100 pptv) much lower concentrations night (∼30 pptv). The results indicate strong unknown daytime source production rate on order 2–4 × 10 6 cm −3 s −1 ....
Abstract. The present study investigates effects of wildfire emissions on air quality in Europe during an intense fire season that occurred summer 2003. A meso-scale chemistry transport model CHIMERE is used, together with ground based and satellite aerosol optical measurements, to assess the dispersion quantify associated radiative effects. has been improved take into account a MODIS-derived daily smoke emission inventory as well injection altitude particles. simulated properties are put...
We present the first measurements of nitryl chloride (ClNO 2 ) over continental Europe. Significant quantities ClNO , up to 800 pptv, were measured at a mountaintop field site in Hessen, southwest Germany. was detected during majority nights between 15th August and 16th September 2011, its largest mixing ratios being associated with air masses influenced by sea salt anthropogenic NO x emissions. persisted measurable until early afternoons on days low photolysis frequencies. As consequence,...
Recent studies have shown that measured OH under NO x ‐limited, high‐isoprene conditions are many times higher than modeled OH. In this study, a detailed analysis of the HO radical budgets low‐NO , rural was performed employing box model based on Master Chemical Mechanism (MCMv3.2). The results were compared with measurements during international HOxComp campaign carried out in Jülich, Germany, summer 2005. Two different air masses influenced measurement site denoted as high‐NO (NO, 1–3...
Abstract. Measurements of OH and HO2 radicals were conducted in a pine-dominated forest southern Finland during the HUMPPA-COPEC-2010 (Hyytiälä United Photochemistry Particles Air – Comprehensive Organic Precursor Emission Concentration study) field campaign summer 2010. Simultaneous side-by-side measurements hydroxyl with two instruments using chemical ionization mass spectrometry (CIMS) laser-induced fluorescence (LIF), indicating small systematic disagreement, OHLIF / OHCIMS = (1.31 ±...
Abstract. Characterization of daytime sources nitrous acid (HONO) is crucial to understand atmospheric oxidation and radical cycling in the planetary boundary layer. HONO numerous other trace constituents were measured on Mediterranean island Cyprus during CYPHEX (CYprus PHotochemical EXperiment) campaign summer 2014. Average volume mixing ratios 35 pptv (±25 pptv) with a ∕ NOx ratio 0.33, which was considerably higher than reported for most rural urban regions. Diel profiles showed peak...