Long-range transport and multimedia partitioning of semivolatile organic compounds: A case study on two modern agrochemicals

The global environmental fate of two modern pesticides was studied using a multimedia model based on a three- dimensional atmosphere general circulation model. The emissions are predicted dynamically based on agricultural application inventories. The insecticide methyl parathion, when assuming properties at the high mobility end of the respective data uncertainties, was found to be distributed on continental and even global scales. This finding implies that based on present knowledge one cannot exclude that methyl parathion reaches regions as far from the sources as e.g. the Arctic. Two scenarios of the environmental cycling of the herbicide atrazine were studied which reflect a lower and an upper estimate of the substance’ mobility. Atrazine largely remains in the source (application) regions and the neighbouring seas. But also atrazine seems to have an albeit limited potential for long-range transport. The findings on substance mobilities are quantified by indicators which address spatial range in the zonal direction in individual media. The seasonal variability of the total environmental burden of both pesticides is governed by the degradation in soil and vegetation which together host 73 % of methyl parathion and 90-99 % of atrazine. Also, the cycling between compartments was studied. Methyl parathion undergoes more deposition and re-emission cycles than atrazine, a characteristics of the environmental fate of semivolatile substances. Persistence is addressed by determination of global total environmental decay times during periods without introduction of new substance into the environment. These are in the range 4-7 months. It is found that the seasonal variability of persistence is pronounced

Diagnose und Graduierung zervikaler intraepithelialer Neoplasien

Zusammenfassung: Diagnose und Graduierung von zervikalen intraepithelialen Neoplasien (CIN) gehören zu den häufigen Fragestellungen in der histopathologischen Diagnostik. Trotzdem kann die Unterscheidung zwischen reaktiven Veränderungen und CIN1 bzw. die Graduierung einer CIN Schwierigkeiten bereiten. In dieser Studie wurde untersucht, ob die Bestimmung der Proliferationsmarker Ki-67 und Mcm2 sowie von p16 zur Beantwortung dieser Fragestellungen beitragen. Untersucht wurden die immunhistochemischen Expressionsprofile dieser Marker an 297Proben aus dysplasiefreiem Portioepithel, CIN1, CIN2 und CIN3 mittels Gewebemikroarrays. Die mittels Ki-67 bzw. Mcm2 ermittelte Proliferationsrate zeigte eine Zunahme von dysplasiefreiem Epithel über CIN1, CIN2 zu CIN3 (p<0.001 bei beiden Markern). Mittels Ki-67 ließ sich am besten zwischen dysplasiefreiem Epithel und CIN1 unterscheiden. Zur Abgrenzung von CIN1 zu CIN2 bot sich eine Kombination von Ki-67 und p16 an. Bei einer Ki-67-Expression von<25% handelte es sich um eine CIN1 mit einer Sensitivität von 91,7% und einer Spezifität von 54,3%. Die zusätzliche Untersuchung der Expression von p16 konnte einen weiteren Teil der Fälle mit einer Ki-67-Expression von<25% stratifizieren. Die Anzahl p16-positiver Fälle betrug bei normalen Epithelien 0%, bei CIN1 7%, bei CIN2 46% und bei CIN3 86%. Somit war mittels p16 eine Abgrenzung der CIN2 zur CIN3 nur zum Teil möglich. Die histopathologische Evaluation am HE-Schnitt bleibt Grundlage der Beurteilung von zervikalen intraepithelialen Neoplasien, jedoch kann die Analyse von Ki-67 und p16 zur Diagnose und Graduierung beitrage

Oil Return Measurements In A Unitary Split System Air Conditioner Using Different Refrigerant Mixtures

The aim of the study presented in this paper is an experimental investigation of the oil return characteristics of alternative refrigerants for residential air conditioning systems using R22. Due to the phase-out of HCFC refrigerants, the production of R22 will be stopped by the year 2020. In some cases of vapor compression systems installed in the field, it will be necessary to replace the R22 with alternative drop-in refrigerants as a part of maintenance procedures. Since R22 system typically use mineral oils and HFC replacement refrigerants use POE or PAG oils. It may be necessary to change the type of oil used inside the system when retrofitting an existing R22 system with an alternative drop-in refrigerant. Changing the oil in a vapor compression system is an expensive proposition due to the required flushing and cleaning of the system before the new oil can be installed. Therefore, refrigerant manufacturers are searching for alternative refrigerants, which are compatible with mineral oils and have similar working performance and conditions as R22. The measurement of the oil return in the suction line helps to draw conclusions about the ability of the oil circulating back to the compressor. In this study, a unitary spilt-system air conditioner with a cooling capacity of 7 kW was equipped with an oil separator and oil measuring cylinder in the suction line. The experimental test setup was designed and built to measure the mass of oil returned to the compressor. Â The weight of the oil collected in the suction line using three different compositions of the alternative drop-in refrigerant R438 are compared to the mass of oil returned when using R22

How present aerosol pollution from North America impacts North Atlantic climate

This paper describes the potential effects of present-day aerosol pollution from North America (USA, Canada) on the climate of the North Atlantic region. The study has been performed by applying the comprehensive atmospheric general circulation model ECHAM5-HAM, which is coupled to a mixed-layer ocean with an embedded thermodynamic sea ice module. The model includes a microphysical aerosol model (HAM), which allows for the assessment of aerosol impacts on climate. Sulphate, black and organic carbon, sea salt and mineral dust are considered as aerosol species. Two equilibrium simulations with two different aerosol pollutant scenarios are compared for each season. We investigate the effect on radiation, temperature, hydrological quantities and dynamics, when human-induced aerosol emissions from North America were omitted. The decrease of both direct and indirect aerosol effects induces a positive change in top of the atmosphere (TOA) radiative fluxes resulting in an overall warming in the whole region. Our results demonstrate the vulnerability especially of the Arctic to the reduction in aerosol load. For fall we find an increase in precipitation over the North Atlantic, associated with a tendency to a larger number of cyclones with high-pressure gradients and a higher frequency in storm days

Gas/particle partitioning and global distribution of polycyclic aromatic hydrocarbons – A modelling approach

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. (C) 2009 Elsevier Ltd. All rights reserved. [References: 42

The aerosol-climate model ECHAM5-HAM

The aerosol-climate modelling system ECHAM5-HAM is introduced. It is based on a flexible microphysical approach and, as the number of externally imposed parameters is minimised, allows the application in a wide range of climate regimes. ECHAM5-HAM predicts the evolution of an ensemble of microphysically interacting internally- and externally-mixed aerosol populations as well as their size-distribution and composition. The size-distribution is represented by a superposition of log-normal modes. In the current setup, the major global aerosol compounds sulfate (SU), black carbon (BC), particulate organic matter (POM), sea salt (SS), and mineral dust (DU) are included. The simulated global annual mean aerosol burdens (lifetimes) for the year 2000 are for SU: 0.80 Tg(S) (3.9 days), for BC: 0.11 Tg (5.4 days), for POM: 0.99 Tg (5.4 days), for SS: 10.5 Tg (0.8 days), and for DU: 8.28 Tg (4.6 days). An extensive evaluation with in-situ and remote sensing measurements underscores that the model results are generally in good agreement with observations of the global aerosol system. The simulated global annual mean aerosol optical depth (AOD) is with 0.14 in excellent agreement with an estimate derived from AERONET measurements (0.14) and a composite derived from MODIS-MISR satellite retrievals (0.16). Regionally, the deviations are not negligible. However, the main patterns of AOD attributable to anthropogenic activity are reproduced

Brightening of the global cloud field by nitric acid and the associated radiative forcing

Clouds cool Earth's climate by reflecting 20% of the incoming solar energy, while also trapping part of the outgoing radiation. The effect of human activities on clouds is poorly understood, but the present-day anthropogenic cooling via changes of cloud albedo and lifetime could be of the same order as warming from anthropogenic addition in CO&lt;sub&gt;2&lt;/sub&gt;. Soluble trace gases can increase water condensation to particles, possibly leading to activation of smaller aerosols and more numerous cloud droplets. We have studied the effect of nitric acid on the aerosol indirect effect with the global aerosol-climate model ECHAM5.5-HAM2. Including the nitric acid effect in the model increases cloud droplet number concentrations globally by 7%. The nitric acid contribution to the present-day cloud albedo effect was found to be −0.32 W m&lt;sup&gt;−2&lt;/sup&gt; and to the total indirect effect −0.46 W m&lt;sup&gt;−2&lt;/sup&gt;. The contribution to the cloud albedo effect is shown to increase to −0.37 W m&lt;sup&gt;−2&lt;/sup&gt; by the year 2100, if considering only the reductions in available cloud condensation nuclei. Overall, the effect of nitric acid can play a large part in aerosol cooling during the following decades with decreasing SO&lt;sub&gt;2&lt;/sub&gt; emissions and increasing NO&lt;sub&gt;x&lt;/sub&gt; and greenhouse gases

Ferntransport von persistenten Chemikalien und Verteilung über verschiedene Umweltmedien - Modelluntersuchungen

Viele Schadstoffe zeichnen sich durch eine Kombination aus schwerer Abbaubarkeit (Persistenz) und hoher Mobilität aus. Sie sind mittelflüchtig, d. h. sie verteilen sich über die Umweltmedien Boden, Wasser, Luft und werden über weite Strecken transportiert. Klima und Stoffeigenschaften wirken in komplexer Weise zusammen und bestimmen globale Transportwege und Verteilung dieser Stoffe, zu denen die so genannten persistenten organischen Schadstoffe (persistent organic pollutants, POPs) und weitere Pestizide und Industriechemikalien zählen. Um Informationen über ihr Umweltverhalten, d. h. Transporte und Umwandlungen, zu gewinnen, muss man Böden, Vegetation, Luft, Ozeane und Eis mit in die Untersuchungen einbeziehen. Von der Gruppe Aerosolchemie des Max-Planck-Instituts für Meteorologie wurde Verteilung, Persistenz und Ferntransport-Potenzial (Reichweite) von einigen POPs mithilfe eines globalen Multikompartiment-Modells, das auf einem allgemeinen Zirkulationsmodell der Atmosphäre aufbaut, studiert

Influences of in-cloud aerosol scavenging parameterizations on aerosol concentrations and wet deposition in ECHAM5-HAM

A diagnostic cloud nucleation scavenging scheme, which determines stratiform cloud scavenging ratios for both aerosol mass and number distributions, based on cloud droplet, and ice crystal number concentrations, is introduced into the ECHAM5-HAM global climate model. This scheme is coupled with a size-dependent in-cloud impaction scavenging parameterization for both cloud droplet-aerosol, and ice crystal-aerosol collisions. The aerosol mass scavenged in stratiform clouds is found to be primarily (&amp;gt;90%) scavenged by cloud nucleation processes for all aerosol species, except for dust (50%). The aerosol number scavenged is primarily (&amp;gt;90%) attributed to impaction. 99% of this impaction scavenging occurs in clouds with temperatures less than 273 K. Sensitivity studies are presented, which compare aerosol concentrations, burdens, and deposition for a variety of in-cloud scavenging approaches: prescribed fractions, a more computationally expensive prognostic aerosol cloud processing treatment, and the new diagnostic scheme, also with modified assumptions about in-cloud impaction and nucleation scavenging. Our results show that while uncertainties in the representation of in-cloud scavenging processes can lead to differences in the range of 20–30% for the predicted annual, global mean aerosol mass burdens, and near to 50% for accumulation mode aerosol number burden, the differences in predicted aerosol mass concentrations can be up to one order of magnitude, particularly for regions of the middle troposphere with temperatures below 273 K where mixed and ice phase clouds exist. Different parameterizations for impaction scavenging changed the predicted global, annual mean number removal attributed to ice clouds by seven-fold, and the global, annual dust mass removal attributed to impaction by two orders of magnitude. Closer agreement with observations of black carbon profiles from aircraft (increases near to one order of magnitude for mixed phase clouds), mid-troposphere &lt;sup&gt;210&lt;/sup&gt;Pb vertical profiles, and the geographic distribution of aerosol optical depth is found for the new diagnostic scavenging scheme compared to the prescribed scavenging fraction scheme of the standard ECHAM5-HAM. The diagnostic and prognostic schemes represent the variability of scavenged fractions particularly for submicron size aerosols, and for mixed and ice phase clouds, and are recommended in preference to the prescribed scavenging fractions method

Urban eddy covariance measurements reveal significant missing NOx emissions in Central Europe

Nitrogen oxide (NOx) pollution is emerging as a primary environmental concern across Europe. While some large European metropolitan areas are already in breach of EU safety limits for NO2, this phenomenon does not seem to be only restricted to large industrialized areas anymore. Many smaller scale populated agglomerations including their surrounding rural areas are seeing frequent NO2 concentration violations. The question of a quantitative understanding of different NOx emission sources is therefore of immanent relevance for climate and air chemistry models as well as air pollution management and health. Here we report simultaneous eddy covariance flux measurements of NOx, CO2, CO and non methane volatile organic compound tracers in a city that might be considered representative for Central Europe and the greater Alpine region. Our data show that NOx fluxes are largely at variance with modelled emission projections, suggesting an appreciable underestimation of the traffic related atmospheric NOx input in Europe, comparable to the weekend-weekday effect, which locally changes ozone production rates by 40%