Gerhard Lammel - Academia.edu (original) (raw)

Papers by Gerhard Lammel

Fresenius Journal of Analytical Chemistry, 1996

Suppressed ion chromatography has been applied to the determination of S(IV) species in cloud and... more Suppressed ion chromatography has been applied to the determination of S(IV) species in cloud and fog water in the range 0.012-2.4 mg S(IV)-S/L. The samples have been preserved prior to storage and S(IV) species have been determined as hydroxy methanesulfonate (HMS) together with the low molecular weight carboxylic acid anions, formate and acetate. Samples have been divided and treated differently such that total S(IV) as well as the non-oxidizable fraction of S(IV) (as given by the reactivity with H(2)O(2), added in surplus) could be determined. The difference between the two corresponds to the S(IV) fraction subjected to oxididation, which is of paramount interest in cloud and fogwater chemistry.

Global Biogeochemical Cycles in the Climate System, 2001

... 1 Risk types, Criteria and Examples Type 1 Sword of Damocles Type 2 Cyclops Type 3 Pythia Typ... more ... 1 Risk types, Criteria and Examples Type 1 Sword of Damocles Type 2 Cyclops Type 3 Pythia Type 4 Pandora's Box Type ... of mobilization high Nuclear energy, chemical plants, dams, meteorite impacts Floods, earthquakes, volcanic eruptions, AIDS, El Nino, mass developments ...

Chemie in unserer Zeit, 2007

ABSTRACT POPs, persistent organic pollutants, sind in der Umwelt schwer abbaubare, gleichzeitig b... more ABSTRACT POPs, persistent organic pollutants, sind in der Umwelt schwer abbaubare, gleichzeitig bioakkumulative und toxische Stoffe. Die meisten sind mittelflüchtig und lipophil. Sie werden in der Atmosphäre zu einem erheblichen Teil an Aerosolpartikel sorbiert und nach Ablagerung am Boden oder Deposition in den Ozean in die Atmosphäre zurück verflüchtigt und können so mehrere Emissions-Transport-Depositions-Zyklen durchlaufen. Die Transport- und Verteilungsmuster und das Ferntransport-Potenzial sind damit ganz anders als bei herkömmlichen Luftschadstoffen, deren Transport nach Ablagerung aus der Atmosphäre endet. Dass weite Strecken durch mehrere, jeweils kürzere Wege überwunden werden können, wird als Grashüpfer-Effekt bezeichnet. Eine wichtige Hypothese der Umweltchemie besagt, dass die beobachtete Anreicherung von vielen persistenten und bioakkumulativen Schadstoffen in den Polargebieten, fernab der Anwendungsgebiete eine Konsequenz des Grashüpfer-Effekts sei in Verbindung mit stärkerer Kondensation in kalten Gebieten. Die Lipophilie ist die Voraussetzung für die Bioakkumulation und beeinflusst die Verteilung der Stoffe über mehrere Umweltmedien. Weil es sich bei den POPs im Allgemeinen um teilhalogenierte Stoffe handelt, ist der atmosphärische Abbau zumeist langsamer als für andere Luftschadstoffe, aber schneller als in den anderen Umweltkompartimenten, in denen erst bei Verweildauern von Monaten von Persistenz gesprochen wird. Ferntransport-Potenzial und Persistenz eines Stoffes sind wichtig für die Einschätzung der Gefährdung, die von ihm ausgeht. Sie sind das Ergebnis des Zusammenwirkens physikalisch-chemischer Stoffeigenschaften mit den in Raum und Zeit variablen Umweltbedingungen. Sie variieren deswegen in Raum und Zeit.POPs, persistent organic pollutants, are slowly degradable, bio-accumulative and toxic substances. Most of them are semivolatile and lipophilic. In the atmosphere they sorb to aerosol particles, and upon deposition to soil or water surfaces they may return through volatilisation, enabling them to undergo sequential cycles of emission, atmospheric transport and deposition. These patterns of transport and distribution as well as the long-range transport potential differ significantly from those of conventional air pollutants, which undergo only one such cycle. The capability to travel long distances by several hops is called the grasshopper effect. According to a key hypothesis of environmental chemistry the accumulation of persistent and bio-accumulative pollutants in polar regions, far from the areas of usage, is due to the combination of the grasshopper effect and enhanced condensation in cold areas. Lipophilicity is a prerequisite for bio-accumulation and influences the partitioning among environmental media (multicompartment compounds). As POPs are typically halogenated compounds, chemical degradation in the atmosphere is in most cases slower than of other air pollutants, but faster than in the other environmental compartments, where persistence coincides with residence times of months. The long-range transport potential and persistence are crucial for chemical hazard assessment. These characteristics result from the combined action of physico-chemical properties and environmental conditions variable in time and space. Hence, they vary in time and space.

Nachrichten aus der Chemie, 2008

In der Atmosph äre, in Oberfläch enund Meerwass er, in Regionen fernab der Zivilisatio n finden U... more In der Atmosph äre, in Oberfläch enund Meerwass er, in Regionen fernab der Zivilisatio n finden Umweltfo rscher immer wieder bisher nachgew iesene Chemikal ien, aktuell unter anderem Flammsc hutzmitte l, Textilhilf smittel und Pestizide. Gegensta nd bodem:he mischer Forschun gsaktiviti: iten sind vermehrt bioaktive Substanz en, insbeson dere Veteriniir pharmaka " Kohlenwas serstoffe und Oxidations kapazität Unimoleku larer Zerfall Produkte Nachrichten aus der Chemie 1 56 I März 2008 I www.gdch.de

Geophysical Research Letters, 2009

The global distribution and fate of the insecticide DDT was modeled for the first time using a sp... more The global distribution and fate of the insecticide DDT was modeled for the first time using a spatially resolved global multicompartment chemistry-transport model comprising a 3D coupled atmosphere and ocean GCM, coupled to 2D vegetation surfaces and top soils. DDT enters the model environment as a pesticide in agriculture only. Final sinks of DDT in the total environment are degradation in air (hydroxyl radical reaction), on vegetation surfaces, in ocean sediments and soils. The process resolution of the ocean compartment, i.e., either a fixed or variable size and sinking velocity of suspended particles, has almost no effect on the large-scale cycling and fate of DDT. The residence times in various ocean basins were declining but varied regionally. The global ocean absorbed until 1977 and since then has been losing DDT, while large sea areas are still accumulating the pollutant. The main sink is volatilization to the atmosphere. In 1990, the year when emissions ceased, 292 kt of DDT were deposited to the global ocean, 301 kt were volatilized, and 41 kt were exported from the surface layer to the deeper levels. The sea region that has been representing the most significant (secondary) DDT source is the western N Atlantic (Gulf stream and N Atlantic Drift regions). It has been a source since approximately 1970. Also large parts of the tropical ocean and the southern midlatitude ocean have turned net volatilizational (i.e., volatilization flux > deposition flux) during the 1980s. Despite the emissions migrating southward as a consequence of substance ban in mid latitudes, the geographic distribution of the contaminant (and, hence, environmental exposure) has been migrating steadily northward since the 1960s.

Environmental Science and Pollution Research, 2014

Environmental Science and Pollution Research, 2001

Environmental Pollution, 2004

With the aim to investigate the justification of time-averaging of climate parameters in multicom... more With the aim to investigate the justification of time-averaging of climate parameters in multicompartment modelling the effects of various climate parameters and different modes of entry on the predicted substances' total environmental burdens and the compartmental fractions were studied. A simple, non-steady state zero-dimensional (box) mass-balance model of intercompartmental mass exchange which comprises four compartments was used for this purpose. Each two runs were performed, one temporally unresolved (time-averaged conditions) and a time-resolved (hourly or higher) control run. In many cases significant discrepancies are predicted, depending on the substance and on the parameter. We find discrepancies exceeding 10% relative to the control run and up to an order of magnitude for prediction of the total environmental burden from neglecting seasonalities of the soil and ocean temperatures and the hydroxyl radical concentration in the atmosphere and diurnalities of atmospheric mixing depth and the hydroxyl radical concentration in the atmosphere. Under some conditions it was indicated that substance sensitivity could be explained by the magnitude of the sink terms in the compartment(s) with parameters varying. In general, however, any key for understanding substance sensitivity seems not be linked in an easy manner to the properties of the substance, to the fractions of its burden or to the sink terms in either of the compartments with parameters varying. Averaging of diurnal variability was found to cause errors of total environmental residence time of different sign for different substances. The effects of time-averaging of several parameters are in general not additive but synergistic as well as compensatory effects occur. An implication of these findings is that the ranking of substances according to persistence is sensitive to time resolution on the scale of hours to months. As a conclusion it is recommended to use high temporal resolution in multi-media modelling.

Environmental Pollution, 2010

Urban emission source strengths were estimated for seven polychlorinated biphenyl (PCB) congeners... more Urban emission source strengths were estimated for seven polychlorinated biphenyl (PCB) congeners for Banja Luka, Zurich and Chicago.

Environmental Pollution, 2009

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Chemosphere, 2009

The global atmospheric distribution and long-range transport (LRT) potential of three polycyclic ... more The global atmospheric distribution and long-range transport (LRT) potential of three polycyclic aromatic hydrocarbons (PAH)-anthracene, fluoranthene and benzo[a]pyrene-are studied. The model used is a global aerosol-chemistry-transport-model, which is based on an atmospheric general circulation model. The model includes an in-built dynamic aerosol model coupled to two-dimensional surface compartments. Several parameterisations of gas/particle partitioning and different assumptions of degradation in the aerosol particulate phase were tested. PAHs are mostly distributed in the source regions but reach the Arctic and the Antarctic. The Canadian Arctic is predicted to be significantly less affected by mid-latitude PAH emissions than the European Arctic. Re-volatilisation is significant for semivolatile PAHs. Accumulation of semivolatile PAHs in polar regions, however, is not indicated. The model study suggests that gas/particle partitioning in air drastically influences the atmospheric cycling, the total environmental fate (e.g. compartmental distributions) and the LRT potential of the substances studied. A parameterisation which calculates the gas/particle partitioning assuming absorption into organic matter and adsorption to black carbon (soot) agrees best with the observations at remote sites. The study provides evidence that the degradation in the particulate phase must be slower than that in the gas-phase. The predicted concentrations of the semivolatile PAHs anthracene and fluoranthene in near-ground air at remote sites in mid and high northern latitudes are in line with measured concentrations, if adsorption of the substances to soot combined with absorption in particulate organic matter is assumed to determine gas/particle partitioning, but cannot be explained by adsorption alone (Junge-Pankow parameterisation of gas/particle partitioning). The results suggest that PAHs absorbed in the organic matrix of particulate matter is shielded from the gas-phase.

Chemosphere, 2002

An ion chromatographic method was developed which is able to separate five unsubstituted and hydr... more An ion chromatographic method was developed which is able to separate five unsubstituted and hydroxy C 4 dicarboxylic acids, succinic, malic, tartaric, maleic and fumaric acid, besides the other unsubstituted C 2-C 5 dicarboxylic acids, oxalic, malonic and glutaric acids, as well as inorganic ions in samples extracted from atmospheric particulate matter. By the application of this method it was found for both rural and urban sites and for various types of air masses that in the summertime malic acid is the most prominent C 4 diacid (64 ng m À3 by average), exceeding succinic acid concentration (28 ng m À3 by average) considerably. In winter-time considerably less, a factor of 4-15, C 4 acids occurred and succinic acid was more concentrated than malic acid. Tartaric, fumaric and maleic acids were less concentrated (5.1, 5.0 and 4:5 ng m À3 by average, respectively). Tartaric acid was observed for the first time in ambient air. The results indicate that in particular anthropogenic sources are important for the precursors of succinic, maleic and fumaric acids. Biogenic sources seem to influence the occurrence of malic acid significantly.

Chemical Society Reviews, 2013

Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their well-recognised ... more Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their well-recognised toxicity and especially due to the carcinogenic hazard which they present. PAHs are semi-volatile and therefore partition between vapour and condensed phases in the atmosphere and both the vapour and particulate forms undergo chemical reactions. This article briefly reviews the current understanding of vapour-particle partitioning of PAHs and the PAH deposition processes, and in greater detail, their chemical reactions. PAHs are reactive towards a number of atmospheric oxidants, most notably the hydroxyl radical, ozone, the nitrate radical (NO 3) and nitrogen dioxide. Rate coefficient data are reviewed for reactions of lower molecular weight PAH vapour with these species as well as for heterogeneous reactions of higher molecular weight compounds. Whereas the data for reactions of the 2-3-ring PAH vapour are quite extensive and generally consistent, such data are mostly lacking for the 4-ring PAHs and the heterogeneous rate data (5 and more rings), which are dependent on the substrate type and reaction conditions, are less comprehensive. The atmospheric reactions of PAH lead to the formation of oxy and nitro derivatives, reviewed here, too. Finally, the capacity of PAHs for long range transport and the results of numerical model studies are described. Research needs are identified.

Atmospheric Research, 1993

In order to determine trace substances in a multiphase atmospheric system, their distribution and... more In order to determine trace substances in a multiphase atmospheric system, their distribution and the extent of homogeneity of both the droplets and interstitial particles with respect to chemical composition, an approach was used analy~ing bulk samples as well as single particles of both phases of an orographic cloud. Besides standard techniques (ion chromatography, total-reflectance X-ray fluorescence spectroscopy, and others) laser microprobe mass spectrometry was used as an analytical tool. Panicles and droplets of different sizes exhibited different chemical composition. All trace substances analysed have been found to be more concentrated in those panicles (and droplets) exceeding 2/an of size (aerodynamic equivalent diameter) than in droplets exceeding 15/zm of size. Mineral panicles in particular were incorporated into large droplets. The ions ammonium, sulphate and nitrate have partially been found in internal mixture: Ammonium and sulphate ions dominated the nonactivated panicle mode (interstitial aerosol) in the size range from 1 to 5/zm and have been mixed with carbon internally in the fine particle mode, whereas nitrate was more localized in large droplets. It is suggested that the existence of a haze droplet mode with a chemical composition distinguishly different from the bulk cloud-water may explain strong discrepancies between solute mass size distribution and the mass size distributions of individual constituents. These are governed by the degree of supersaturation achieved and by chemical composition and the degree of mixing of the underlying aerosol. RI~SUMI~ Afin d'6tudier les substances ~ l'6tat de trace dans un syst~me atmosph6rique multiphase, leur distribution et l'~tendue de l'homog6n~it~ des gouttelettes et des particules interstitielles en fonction de la composition chimique, on a analys~ de l'eau ainsi que des particules individuelles ~chantillonn6es dans les deux phases d'un nuage orographique. En plus des techniques standards (chromatographie ionique, spectroscopie/~ fluorescence...), on a employ6 la spectrom& trie de masse/l microsonde.

Atmospheric Environment, 2011

A new high-resolution microphysicsechemistry-transport model (LES-AOP) was developed and applied ... more A new high-resolution microphysicsechemistry-transport model (LES-AOP) was developed and applied for the investigation of aerosol transformation and transport in the vicinity of a livestock facility in northern Germany (PLUS1 field campaign). The model is an extension of a Large-Eddy Simulation (LES) model. The PLUS1 field campaign included the first deployment of the new eye-safe scanning aerosol lidar system of the University of Hohenheim. In a combined approach, model and lidar results were used to characterise a faint aerosol source. The farm plume structure was investigated and the absolute value of its particle backscatter coefficient was determined. Aerosol optical properties were predicted on spatial and temporal resolutions below 100 m and 1 min, upon initialisation by measured meteorological and size-resolved particulate matter mass concentration and composition data. Faint aerosol plumes corresponding to a particle backscatter coefficient down to 10 À6 sr À1 m À1 were measured and realistically simulated. Budget-related quantities such as the emission flux and change of the particulate matter mass, were estimated from model results and ground measurements.

Atmospheric Environment, 2011

The physical and chemical properties of aerosols emitted from a livestock farm were determined by... more The physical and chemical properties of aerosols emitted from a livestock farm were determined by a novel approach which combines high-resolution lidar measurements (0.33 s, 30 m) with simulations of a microphysicsechemistryetransport model. This first of two companion papers describes the scanning lidar measurements of optical particle properties. The lidar system employed laser radiation at a wavelength of 355 nm with a power of 9 W and a pulse repetition rate of 30 Hz. The laser beam was expanded before transmission to the atmosphere so that it became eye-safe at distances >270 m to the lidar. The elastic backscatter signal was detected with a resolution of 0.033 s and 3 m. A receiving telescope with a primary-mirror diameter of 40 cm was used. For this system, we developed a novel method for twodimensional retrievals of the particle backscatter coefficient. With this set up and approach, the lidar was able to identify the aerosol plume up to a range of w2.5 km from the source, a farm in northern Germany, in daytime. The measurements confirm that the optical particle properties of the emission plume vary largely with distance from the source and that the maximum particle backscatter coefficient is found away from the source. Within a close-to-horizontal scan (elevation angle of 2.3), we found a mean particle backscatter coefficient of 1.5$10 À5 m À1 sr À1 inside the plume between 1.5 and 2.0 km distance from the source. Subtraction of the mean particle backscatter coefficient of the background aerosol present in this case (4.1$10 À6 m À1 sr À1) yields a particle backscatter coefficient of the livestock aerosols of 1.1$10 À5 m À1 sr À1. The limited extend of the plume is revealed with the scanning lidar: Scans with a slightly higher elevation angle of 4.8 did not pick up the plume.

Atmospheric Environment, 1997

Dry and wet deposition of ionic trace substances and total carbon to the walls of a historical mo... more Dry and wet deposition of ionic trace substances and total carbon to the walls of a historical monument (Salem Abbey, Germany) was determined based on periodical collection of rain water samples and washing solutions from cumulative collectors (surrogate surfaces). It is estimated that only a small fraction, ca. 1.5–3% of the precipitation and ⩽10% of the pollutants deposition (to a horizontal receptor area) reached the (vertical) collectors (at 3 m above ground). With only one quarter of the pollutants wet deposited, dry deposition to the building was more important. Hereby, the building was a source of particulate material itself (sodium salts, CaCO3). While the fluxes of dry deposited pollutants to the individual façades differed only little from each other (with a preference to East), the wet deposited fractions differed widely due to a pronounced preference of precipitation from West. Large fluxes of total carbon (CS = 9) were obviously not primarily related to carbonate stone weathering but to airborne carbonaceous material. It is concluded that the building is susceptible to stone decay in the forms of granular disintegration, dark encrustation and other as resulting from a combination of both physical factors (humid environment, the buildings orientation towards the sun and prevailing weather) and chemical factors (dry and wet depositional fluxes of pollutants, albeit at moderate concentrations).

Atmospheric Environment, 1995

In laboratory experiments we studied the hygroscopic properties of carbon black and diesel soot a... more In laboratory experiments we studied the hygroscopic properties of carbon black and diesel soot aerosols with and without chemical modification. The fraction of particles activated to droplets was determined by simultaneous measurement of condensation nuclei (CN) and cloud condensation nuclei (CCN) for a range of supersaturations (0.2-1.3%) and particle sizes (r = 0.02-0.2/~m). The chemical modification enhanced the soluble mass fraction of the particles produced. At fixed supersaturation the CCN/CN ratio was a function of particle size (large CCN/CN ratios at large sizes) and the particle soluble mass fraction. This ratio was also influenced by the method of aerosol generation. The nucleation ability of chemically modified carbonaceous particles increased with increasing soluble mass fraction and was comparable te that of(NH,)2SO4 when the soluble mass fraction exceeded about 10%. The hygroscopicity of particles ge:aerated by combustion of diesel fuel in a diffusion flame increased when a sulfur-containing compound was added to the fuel. The CCN characteristics of diesel soot appears to be comparable to that of wood smoke aerosol.

Atmospheric Environment, 2011

Ratios of levels of 9 polycyclic aromatic hydrocarbons (PAHs) in air at central European sites du... more Ratios of levels of 9 polycyclic aromatic hydrocarbons (PAHs) in air at central European sites during 1996e 2008 were used to assess the suitability of 5 commonly used diagnostic ratios (DRs) for PAH source apportionment. DRs derived from a detailed literature study on emission factors were reflected in ambient air samples only at sites located near major sources. A significant seasonality was observed in a long-term time series of ambient DRs at a background site indicating possible capability of this method to reflect changes in source characteristics. The results of a mass balance study suggest that current knowledge of PAH reactivities is insufficient for a source apportionment based on DRs at receptor sites, even when limited to major types of PAH sources. However, DRs could be used to narrow down ozone and hydroxyl radical reaction rate coefficients' uncertainties: k O 3 (2) of pyrene and benzo(ghi)perylene in the particulate phase seem to be 10% of the highest rate coefficient measured using model aerosols in the laboratory and k O 3 (2) of indeno(1,2,3cd)pyrene in the gas phase could be higher than previously estimated by three orders of magnitude. The suitability of DRs for source apportionment at (especially background) receptor sites cannot be expected in the general case. However, measurements carried out close to sources are in accordance with literature data suggesting that the ratios of benzo(a)anthracene/(benzo(a)anthracene þ chrysene) and indeno(123cd)pyrene/(indeno(123cd)pyrene þ benzo(ghi)perylene) are capable of distinguishing between traffic and residential heating, while the ratio of anthracene/(anthracene þ phenanthrene) was the least useful DR due to its low variability.

Atmospheric Environment, 2010

Polycyclic aromatic hydrocarbons (PAHs) were measured together with inorganic air pollutants at t... more Polycyclic aromatic hydrocarbons (PAHs) were measured together with inorganic air pollutants at two urban sites and one rural background site in the Banja Luka area, Bosnia and Hercegovina, during 72 h in July 2008 using a high time resolution (5 samples per day) with the aim to study the spatial and temporal variabilities and to explore the significance of averaging effects inherent to 24 h-sampling. Measurement uncertainty was quantified on basis of three independent side-by-side samplers, deployed at one of the sites. PAH abundances in the urban and rural environments differed largely. Levels at the urban sites exceeded the levels at the rural site by >100%. The discrepancy was largely dominated by emission of 3e4 ring PAHs in the city, while 5e6 ring PAHs were more evenly distributed between city sites and the hill site. During the night a higher fraction of the semivolatile PAHs might have been stored in the soil or sorbed to surfaces. PAH patterns were undistinguishable across the three sites. However, concentrations of more particle-associated substances differed significantly between the urban sites than between one of the urban sites and the rural site (3s uncertainty). Time-averaging (on a 24 h-basis) would have masked the significant inter-site differences of half of the substances which were found at different levels (on a 4 h-basis).

Fresenius Journal of Analytical Chemistry, 1996

Suppressed ion chromatography has been applied to the determination of S(IV) species in cloud and... more Suppressed ion chromatography has been applied to the determination of S(IV) species in cloud and fog water in the range 0.012-2.4 mg S(IV)-S/L. The samples have been preserved prior to storage and S(IV) species have been determined as hydroxy methanesulfonate (HMS) together with the low molecular weight carboxylic acid anions, formate and acetate. Samples have been divided and treated differently such that total S(IV) as well as the non-oxidizable fraction of S(IV) (as given by the reactivity with H(2)O(2), added in surplus) could be determined. The difference between the two corresponds to the S(IV) fraction subjected to oxididation, which is of paramount interest in cloud and fogwater chemistry.

Global Biogeochemical Cycles in the Climate System, 2001

... 1 Risk types, Criteria and Examples Type 1 Sword of Damocles Type 2 Cyclops Type 3 Pythia Typ... more ... 1 Risk types, Criteria and Examples Type 1 Sword of Damocles Type 2 Cyclops Type 3 Pythia Type 4 Pandora's Box Type ... of mobilization high Nuclear energy, chemical plants, dams, meteorite impacts Floods, earthquakes, volcanic eruptions, AIDS, El Nino, mass developments ...

Chemie in unserer Zeit, 2007

ABSTRACT POPs, persistent organic pollutants, sind in der Umwelt schwer abbaubare, gleichzeitig b... more ABSTRACT POPs, persistent organic pollutants, sind in der Umwelt schwer abbaubare, gleichzeitig bioakkumulative und toxische Stoffe. Die meisten sind mittelflüchtig und lipophil. Sie werden in der Atmosphäre zu einem erheblichen Teil an Aerosolpartikel sorbiert und nach Ablagerung am Boden oder Deposition in den Ozean in die Atmosphäre zurück verflüchtigt und können so mehrere Emissions-Transport-Depositions-Zyklen durchlaufen. Die Transport- und Verteilungsmuster und das Ferntransport-Potenzial sind damit ganz anders als bei herkömmlichen Luftschadstoffen, deren Transport nach Ablagerung aus der Atmosphäre endet. Dass weite Strecken durch mehrere, jeweils kürzere Wege überwunden werden können, wird als Grashüpfer-Effekt bezeichnet. Eine wichtige Hypothese der Umweltchemie besagt, dass die beobachtete Anreicherung von vielen persistenten und bioakkumulativen Schadstoffen in den Polargebieten, fernab der Anwendungsgebiete eine Konsequenz des Grashüpfer-Effekts sei in Verbindung mit stärkerer Kondensation in kalten Gebieten. Die Lipophilie ist die Voraussetzung für die Bioakkumulation und beeinflusst die Verteilung der Stoffe über mehrere Umweltmedien. Weil es sich bei den POPs im Allgemeinen um teilhalogenierte Stoffe handelt, ist der atmosphärische Abbau zumeist langsamer als für andere Luftschadstoffe, aber schneller als in den anderen Umweltkompartimenten, in denen erst bei Verweildauern von Monaten von Persistenz gesprochen wird. Ferntransport-Potenzial und Persistenz eines Stoffes sind wichtig für die Einschätzung der Gefährdung, die von ihm ausgeht. Sie sind das Ergebnis des Zusammenwirkens physikalisch-chemischer Stoffeigenschaften mit den in Raum und Zeit variablen Umweltbedingungen. Sie variieren deswegen in Raum und Zeit.POPs, persistent organic pollutants, are slowly degradable, bio-accumulative and toxic substances. Most of them are semivolatile and lipophilic. In the atmosphere they sorb to aerosol particles, and upon deposition to soil or water surfaces they may return through volatilisation, enabling them to undergo sequential cycles of emission, atmospheric transport and deposition. These patterns of transport and distribution as well as the long-range transport potential differ significantly from those of conventional air pollutants, which undergo only one such cycle. The capability to travel long distances by several hops is called the grasshopper effect. According to a key hypothesis of environmental chemistry the accumulation of persistent and bio-accumulative pollutants in polar regions, far from the areas of usage, is due to the combination of the grasshopper effect and enhanced condensation in cold areas. Lipophilicity is a prerequisite for bio-accumulation and influences the partitioning among environmental media (multicompartment compounds). As POPs are typically halogenated compounds, chemical degradation in the atmosphere is in most cases slower than of other air pollutants, but faster than in the other environmental compartments, where persistence coincides with residence times of months. The long-range transport potential and persistence are crucial for chemical hazard assessment. These characteristics result from the combined action of physico-chemical properties and environmental conditions variable in time and space. Hence, they vary in time and space.

Nachrichten aus der Chemie, 2008

In der Atmosph äre, in Oberfläch enund Meerwass er, in Regionen fernab der Zivilisatio n finden U... more In der Atmosph äre, in Oberfläch enund Meerwass er, in Regionen fernab der Zivilisatio n finden Umweltfo rscher immer wieder bisher nachgew iesene Chemikal ien, aktuell unter anderem Flammsc hutzmitte l, Textilhilf smittel und Pestizide. Gegensta nd bodem:he mischer Forschun gsaktiviti: iten sind vermehrt bioaktive Substanz en, insbeson dere Veteriniir pharmaka " Kohlenwas serstoffe und Oxidations kapazität Unimoleku larer Zerfall Produkte Nachrichten aus der Chemie 1 56 I März 2008 I www.gdch.de

Geophysical Research Letters, 2009

The global distribution and fate of the insecticide DDT was modeled for the first time using a sp... more The global distribution and fate of the insecticide DDT was modeled for the first time using a spatially resolved global multicompartment chemistry-transport model comprising a 3D coupled atmosphere and ocean GCM, coupled to 2D vegetation surfaces and top soils. DDT enters the model environment as a pesticide in agriculture only. Final sinks of DDT in the total environment are degradation in air (hydroxyl radical reaction), on vegetation surfaces, in ocean sediments and soils. The process resolution of the ocean compartment, i.e., either a fixed or variable size and sinking velocity of suspended particles, has almost no effect on the large-scale cycling and fate of DDT. The residence times in various ocean basins were declining but varied regionally. The global ocean absorbed until 1977 and since then has been losing DDT, while large sea areas are still accumulating the pollutant. The main sink is volatilization to the atmosphere. In 1990, the year when emissions ceased, 292 kt of DDT were deposited to the global ocean, 301 kt were volatilized, and 41 kt were exported from the surface layer to the deeper levels. The sea region that has been representing the most significant (secondary) DDT source is the western N Atlantic (Gulf stream and N Atlantic Drift regions). It has been a source since approximately 1970. Also large parts of the tropical ocean and the southern midlatitude ocean have turned net volatilizational (i.e., volatilization flux > deposition flux) during the 1980s. Despite the emissions migrating southward as a consequence of substance ban in mid latitudes, the geographic distribution of the contaminant (and, hence, environmental exposure) has been migrating steadily northward since the 1960s.

Environmental Science and Pollution Research, 2014

Environmental Science and Pollution Research, 2001

Environmental Pollution, 2004

With the aim to investigate the justification of time-averaging of climate parameters in multicom... more With the aim to investigate the justification of time-averaging of climate parameters in multicompartment modelling the effects of various climate parameters and different modes of entry on the predicted substances' total environmental burdens and the compartmental fractions were studied. A simple, non-steady state zero-dimensional (box) mass-balance model of intercompartmental mass exchange which comprises four compartments was used for this purpose. Each two runs were performed, one temporally unresolved (time-averaged conditions) and a time-resolved (hourly or higher) control run. In many cases significant discrepancies are predicted, depending on the substance and on the parameter. We find discrepancies exceeding 10% relative to the control run and up to an order of magnitude for prediction of the total environmental burden from neglecting seasonalities of the soil and ocean temperatures and the hydroxyl radical concentration in the atmosphere and diurnalities of atmospheric mixing depth and the hydroxyl radical concentration in the atmosphere. Under some conditions it was indicated that substance sensitivity could be explained by the magnitude of the sink terms in the compartment(s) with parameters varying. In general, however, any key for understanding substance sensitivity seems not be linked in an easy manner to the properties of the substance, to the fractions of its burden or to the sink terms in either of the compartments with parameters varying. Averaging of diurnal variability was found to cause errors of total environmental residence time of different sign for different substances. The effects of time-averaging of several parameters are in general not additive but synergistic as well as compensatory effects occur. An implication of these findings is that the ranking of substances according to persistence is sensitive to time resolution on the scale of hours to months. As a conclusion it is recommended to use high temporal resolution in multi-media modelling.

Environmental Pollution, 2010

Urban emission source strengths were estimated for seven polychlorinated biphenyl (PCB) congeners... more Urban emission source strengths were estimated for seven polychlorinated biphenyl (PCB) congeners for Banja Luka, Zurich and Chicago.

Environmental Pollution, 2009

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Chemosphere, 2009

The global atmospheric distribution and long-range transport (LRT) potential of three polycyclic ... more The global atmospheric distribution and long-range transport (LRT) potential of three polycyclic aromatic hydrocarbons (PAH)-anthracene, fluoranthene and benzo[a]pyrene-are studied. The model used is a global aerosol-chemistry-transport-model, which is based on an atmospheric general circulation model. The model includes an in-built dynamic aerosol model coupled to two-dimensional surface compartments. Several parameterisations of gas/particle partitioning and different assumptions of degradation in the aerosol particulate phase were tested. PAHs are mostly distributed in the source regions but reach the Arctic and the Antarctic. The Canadian Arctic is predicted to be significantly less affected by mid-latitude PAH emissions than the European Arctic. Re-volatilisation is significant for semivolatile PAHs. Accumulation of semivolatile PAHs in polar regions, however, is not indicated. The model study suggests that gas/particle partitioning in air drastically influences the atmospheric cycling, the total environmental fate (e.g. compartmental distributions) and the LRT potential of the substances studied. A parameterisation which calculates the gas/particle partitioning assuming absorption into organic matter and adsorption to black carbon (soot) agrees best with the observations at remote sites. The study provides evidence that the degradation in the particulate phase must be slower than that in the gas-phase. The predicted concentrations of the semivolatile PAHs anthracene and fluoranthene in near-ground air at remote sites in mid and high northern latitudes are in line with measured concentrations, if adsorption of the substances to soot combined with absorption in particulate organic matter is assumed to determine gas/particle partitioning, but cannot be explained by adsorption alone (Junge-Pankow parameterisation of gas/particle partitioning). The results suggest that PAHs absorbed in the organic matrix of particulate matter is shielded from the gas-phase.

Chemosphere, 2002

An ion chromatographic method was developed which is able to separate five unsubstituted and hydr... more An ion chromatographic method was developed which is able to separate five unsubstituted and hydroxy C 4 dicarboxylic acids, succinic, malic, tartaric, maleic and fumaric acid, besides the other unsubstituted C 2-C 5 dicarboxylic acids, oxalic, malonic and glutaric acids, as well as inorganic ions in samples extracted from atmospheric particulate matter. By the application of this method it was found for both rural and urban sites and for various types of air masses that in the summertime malic acid is the most prominent C 4 diacid (64 ng m À3 by average), exceeding succinic acid concentration (28 ng m À3 by average) considerably. In winter-time considerably less, a factor of 4-15, C 4 acids occurred and succinic acid was more concentrated than malic acid. Tartaric, fumaric and maleic acids were less concentrated (5.1, 5.0 and 4:5 ng m À3 by average, respectively). Tartaric acid was observed for the first time in ambient air. The results indicate that in particular anthropogenic sources are important for the precursors of succinic, maleic and fumaric acids. Biogenic sources seem to influence the occurrence of malic acid significantly.

Chemical Society Reviews, 2013

Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their well-recognised ... more Polycyclic aromatic hydrocarbons (PAHs) are of considerable concern due to their well-recognised toxicity and especially due to the carcinogenic hazard which they present. PAHs are semi-volatile and therefore partition between vapour and condensed phases in the atmosphere and both the vapour and particulate forms undergo chemical reactions. This article briefly reviews the current understanding of vapour-particle partitioning of PAHs and the PAH deposition processes, and in greater detail, their chemical reactions. PAHs are reactive towards a number of atmospheric oxidants, most notably the hydroxyl radical, ozone, the nitrate radical (NO 3) and nitrogen dioxide. Rate coefficient data are reviewed for reactions of lower molecular weight PAH vapour with these species as well as for heterogeneous reactions of higher molecular weight compounds. Whereas the data for reactions of the 2-3-ring PAH vapour are quite extensive and generally consistent, such data are mostly lacking for the 4-ring PAHs and the heterogeneous rate data (5 and more rings), which are dependent on the substrate type and reaction conditions, are less comprehensive. The atmospheric reactions of PAH lead to the formation of oxy and nitro derivatives, reviewed here, too. Finally, the capacity of PAHs for long range transport and the results of numerical model studies are described. Research needs are identified.

Atmospheric Research, 1993

In order to determine trace substances in a multiphase atmospheric system, their distribution and... more In order to determine trace substances in a multiphase atmospheric system, their distribution and the extent of homogeneity of both the droplets and interstitial particles with respect to chemical composition, an approach was used analy~ing bulk samples as well as single particles of both phases of an orographic cloud. Besides standard techniques (ion chromatography, total-reflectance X-ray fluorescence spectroscopy, and others) laser microprobe mass spectrometry was used as an analytical tool. Panicles and droplets of different sizes exhibited different chemical composition. All trace substances analysed have been found to be more concentrated in those panicles (and droplets) exceeding 2/an of size (aerodynamic equivalent diameter) than in droplets exceeding 15/zm of size. Mineral panicles in particular were incorporated into large droplets. The ions ammonium, sulphate and nitrate have partially been found in internal mixture: Ammonium and sulphate ions dominated the nonactivated panicle mode (interstitial aerosol) in the size range from 1 to 5/zm and have been mixed with carbon internally in the fine particle mode, whereas nitrate was more localized in large droplets. It is suggested that the existence of a haze droplet mode with a chemical composition distinguishly different from the bulk cloud-water may explain strong discrepancies between solute mass size distribution and the mass size distributions of individual constituents. These are governed by the degree of supersaturation achieved and by chemical composition and the degree of mixing of the underlying aerosol. RI~SUMI~ Afin d'6tudier les substances ~ l'6tat de trace dans un syst~me atmosph6rique multiphase, leur distribution et l'~tendue de l'homog6n~it~ des gouttelettes et des particules interstitielles en fonction de la composition chimique, on a analys~ de l'eau ainsi que des particules individuelles ~chantillonn6es dans les deux phases d'un nuage orographique. En plus des techniques standards (chromatographie ionique, spectroscopie/~ fluorescence...), on a employ6 la spectrom& trie de masse/l microsonde.

Atmospheric Environment, 2011

A new high-resolution microphysicsechemistry-transport model (LES-AOP) was developed and applied ... more A new high-resolution microphysicsechemistry-transport model (LES-AOP) was developed and applied for the investigation of aerosol transformation and transport in the vicinity of a livestock facility in northern Germany (PLUS1 field campaign). The model is an extension of a Large-Eddy Simulation (LES) model. The PLUS1 field campaign included the first deployment of the new eye-safe scanning aerosol lidar system of the University of Hohenheim. In a combined approach, model and lidar results were used to characterise a faint aerosol source. The farm plume structure was investigated and the absolute value of its particle backscatter coefficient was determined. Aerosol optical properties were predicted on spatial and temporal resolutions below 100 m and 1 min, upon initialisation by measured meteorological and size-resolved particulate matter mass concentration and composition data. Faint aerosol plumes corresponding to a particle backscatter coefficient down to 10 À6 sr À1 m À1 were measured and realistically simulated. Budget-related quantities such as the emission flux and change of the particulate matter mass, were estimated from model results and ground measurements.

Atmospheric Environment, 2011

The physical and chemical properties of aerosols emitted from a livestock farm were determined by... more The physical and chemical properties of aerosols emitted from a livestock farm were determined by a novel approach which combines high-resolution lidar measurements (0.33 s, 30 m) with simulations of a microphysicsechemistryetransport model. This first of two companion papers describes the scanning lidar measurements of optical particle properties. The lidar system employed laser radiation at a wavelength of 355 nm with a power of 9 W and a pulse repetition rate of 30 Hz. The laser beam was expanded before transmission to the atmosphere so that it became eye-safe at distances >270 m to the lidar. The elastic backscatter signal was detected with a resolution of 0.033 s and 3 m. A receiving telescope with a primary-mirror diameter of 40 cm was used. For this system, we developed a novel method for twodimensional retrievals of the particle backscatter coefficient. With this set up and approach, the lidar was able to identify the aerosol plume up to a range of w2.5 km from the source, a farm in northern Germany, in daytime. The measurements confirm that the optical particle properties of the emission plume vary largely with distance from the source and that the maximum particle backscatter coefficient is found away from the source. Within a close-to-horizontal scan (elevation angle of 2.3), we found a mean particle backscatter coefficient of 1.5$10 À5 m À1 sr À1 inside the plume between 1.5 and 2.0 km distance from the source. Subtraction of the mean particle backscatter coefficient of the background aerosol present in this case (4.1$10 À6 m À1 sr À1) yields a particle backscatter coefficient of the livestock aerosols of 1.1$10 À5 m À1 sr À1. The limited extend of the plume is revealed with the scanning lidar: Scans with a slightly higher elevation angle of 4.8 did not pick up the plume.

Atmospheric Environment, 1997

Dry and wet deposition of ionic trace substances and total carbon to the walls of a historical mo... more Dry and wet deposition of ionic trace substances and total carbon to the walls of a historical monument (Salem Abbey, Germany) was determined based on periodical collection of rain water samples and washing solutions from cumulative collectors (surrogate surfaces). It is estimated that only a small fraction, ca. 1.5–3% of the precipitation and ⩽10% of the pollutants deposition (to a horizontal receptor area) reached the (vertical) collectors (at 3 m above ground). With only one quarter of the pollutants wet deposited, dry deposition to the building was more important. Hereby, the building was a source of particulate material itself (sodium salts, CaCO3). While the fluxes of dry deposited pollutants to the individual façades differed only little from each other (with a preference to East), the wet deposited fractions differed widely due to a pronounced preference of precipitation from West. Large fluxes of total carbon (CS = 9) were obviously not primarily related to carbonate stone weathering but to airborne carbonaceous material. It is concluded that the building is susceptible to stone decay in the forms of granular disintegration, dark encrustation and other as resulting from a combination of both physical factors (humid environment, the buildings orientation towards the sun and prevailing weather) and chemical factors (dry and wet depositional fluxes of pollutants, albeit at moderate concentrations).

Atmospheric Environment, 1995

In laboratory experiments we studied the hygroscopic properties of carbon black and diesel soot a... more In laboratory experiments we studied the hygroscopic properties of carbon black and diesel soot aerosols with and without chemical modification. The fraction of particles activated to droplets was determined by simultaneous measurement of condensation nuclei (CN) and cloud condensation nuclei (CCN) for a range of supersaturations (0.2-1.3%) and particle sizes (r = 0.02-0.2/~m). The chemical modification enhanced the soluble mass fraction of the particles produced. At fixed supersaturation the CCN/CN ratio was a function of particle size (large CCN/CN ratios at large sizes) and the particle soluble mass fraction. This ratio was also influenced by the method of aerosol generation. The nucleation ability of chemically modified carbonaceous particles increased with increasing soluble mass fraction and was comparable te that of(NH,)2SO4 when the soluble mass fraction exceeded about 10%. The hygroscopicity of particles ge:aerated by combustion of diesel fuel in a diffusion flame increased when a sulfur-containing compound was added to the fuel. The CCN characteristics of diesel soot appears to be comparable to that of wood smoke aerosol.

Atmospheric Environment, 2011

Ratios of levels of 9 polycyclic aromatic hydrocarbons (PAHs) in air at central European sites du... more Ratios of levels of 9 polycyclic aromatic hydrocarbons (PAHs) in air at central European sites during 1996e 2008 were used to assess the suitability of 5 commonly used diagnostic ratios (DRs) for PAH source apportionment. DRs derived from a detailed literature study on emission factors were reflected in ambient air samples only at sites located near major sources. A significant seasonality was observed in a long-term time series of ambient DRs at a background site indicating possible capability of this method to reflect changes in source characteristics. The results of a mass balance study suggest that current knowledge of PAH reactivities is insufficient for a source apportionment based on DRs at receptor sites, even when limited to major types of PAH sources. However, DRs could be used to narrow down ozone and hydroxyl radical reaction rate coefficients' uncertainties: k O 3 (2) of pyrene and benzo(ghi)perylene in the particulate phase seem to be 10% of the highest rate coefficient measured using model aerosols in the laboratory and k O 3 (2) of indeno(1,2,3cd)pyrene in the gas phase could be higher than previously estimated by three orders of magnitude. The suitability of DRs for source apportionment at (especially background) receptor sites cannot be expected in the general case. However, measurements carried out close to sources are in accordance with literature data suggesting that the ratios of benzo(a)anthracene/(benzo(a)anthracene þ chrysene) and indeno(123cd)pyrene/(indeno(123cd)pyrene þ benzo(ghi)perylene) are capable of distinguishing between traffic and residential heating, while the ratio of anthracene/(anthracene þ phenanthrene) was the least useful DR due to its low variability.

Atmospheric Environment, 2010

Polycyclic aromatic hydrocarbons (PAHs) were measured together with inorganic air pollutants at t... more Polycyclic aromatic hydrocarbons (PAHs) were measured together with inorganic air pollutants at two urban sites and one rural background site in the Banja Luka area, Bosnia and Hercegovina, during 72 h in July 2008 using a high time resolution (5 samples per day) with the aim to study the spatial and temporal variabilities and to explore the significance of averaging effects inherent to 24 h-sampling. Measurement uncertainty was quantified on basis of three independent side-by-side samplers, deployed at one of the sites. PAH abundances in the urban and rural environments differed largely. Levels at the urban sites exceeded the levels at the rural site by >100%. The discrepancy was largely dominated by emission of 3e4 ring PAHs in the city, while 5e6 ring PAHs were more evenly distributed between city sites and the hill site. During the night a higher fraction of the semivolatile PAHs might have been stored in the soil or sorbed to surfaces. PAH patterns were undistinguishable across the three sites. However, concentrations of more particle-associated substances differed significantly between the urban sites than between one of the urban sites and the rural site (3s uncertainty). Time-averaging (on a 24 h-basis) would have masked the significant inter-site differences of half of the substances which were found at different levels (on a 4 h-basis).