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PubMed2006

Identifying the European fossil fuel plumes in the atmosphere over the Northeast Atlantic Region through isotopic observations and numerical modelling.

As part of the Danish NEAREX project the origin and variability of anthropogenic atmospheric CO(2) over the Northeast Atlantic Region (NEAR) has been studied. The project consisted of a combination of experimental and modelling activities. Local volunteers operated CO(2) sampling stations, built at University of Copenhagen, for (14)C analysis at four locations (East Denmark, Shetland Isles, Faroe Isles and Iceland). The samples were only collected during winter periods of south-easterly winds in an attempt to trace air enriched in fossil-fuel derived CO(2) due to combustion of fossil fuels within European countries. In order to study the transport and concentration fields over the region in detail, a three-dimensional Eulerian hemispheric air pollution model has been extended to include the main anthropogenic sources for atmospheric CO(2). During the project period (1998-2001) only a few episodes of transport from Central Europe towards NEAR arose, which makes the data set for the evaluation of the method sparse. The analysed samples indicate that the signal for fossil CO(2), as expected, is largest (up to 3.7+/-0.4% fossil CO(2)) at the Danish location closest to the European emissions areas and much weaker (up to approximately 1.5+/-0.6% fossil CO(2)) at the most remote location. As the anthropogenic signal is weak in the clean atmosphere over NEAR these numbers will, however, be very sensitive to the assumed background (14)CO(2) activity and the precision of the measurements. The model simulations include the interplay between the driving processes from the emission into the boundary layer and the following horizontal/vertical mixing and atmospheric transport and are used to analyse the meteorological conditions leading to the observed events of high fossil CO(2) over NEAR. This information about the history of the air masses is essential if an observed signal is to be utilised for identifying and quantifying sources for fossil CO(2).

Air Pollutants↗
PubMed2006

Atmospheric monitoring at abandoned mercury mine sites in Asturias (NW Spain).

Mercury concentrations are usually significant in historic Hg mining districts all over the world, so the atmospheric environment is potentially affected. In Asturias, northern Spain, past mining operations have left a legacy of ruins and Hg-rich wastes, soils and sediments in abandoned sites. Total Hg concentrations in the ambient air of these abandoned mine sites have been investigated to evaluate the impact of the Hg emissions. This paper presents the synthesis of current knowledge about atmospheric Hg contents in the area of the abandoned Hg mining and smelting works at 'La Peña-El Terronal' and La Soterraña, located in Mieres and Pola de Lena districts, respectively, both within the Caudal River basin. It was found that average atmospheric Hg concentrations are higher than the background level in the area (0.1 microg Nm(-3)), reaching up to 203.7 microg Nm(-3) at 0.2 m above the ground level, close to the old smelting chimney at El Terronal mine site. Data suggest that past Hg mining activities have big influences on the increased Hg concentrations around abandoned sites and that atmospheric transfer is a major pathway for Hg cycling in these environments.

Air Pollutants↗
PubMed1990

High oxygen atmosphere for neuronal cell culture with nerve growth factor. I. Primary culture of basal forebrain cholinergic neurons from fetal and postnatal rats.

Cholinergic neurons cultured from postnatal days 11-13 (P11-P13) rat basal forebrain showed better survival in the culture condition using a 50% O2 atmosphere with and without nerve growth factor (NGF) than in a low (10 or 20%) O2 atmosphere. Except for the culture at a low cell density, the beneficial effect of the highly oxidized culture condition was found in the culture from P3 neurons, but not from embryonic day 18 neurons. The survival of microtubule-associated protein 2 (MAP2)-positive neurons in culture from P3 basal forebrain regions was more enhanced in a 50% O2 atmosphere than in 20% and also 10% O2 atmosphere. The viable number of the MAP2-positive neurons in a 10% O2 condition was about half of that in a 20% condition. These results suggest that the response of the cultured neurons to an incubator O2 concentration changes during the neuronal development in CNS from fetal to postnatal stages.

Acetylcholine↗
PubMed1996

Occurrence of organochlorines (PCBs, pesticides) and herbicides (triazines, phenylureas) in the atmosphere and in the fallout from urban and rural stations of the Paris area.

The concentrations of organochlorines (PCBs, pesticides) and herbicides (triazines, phenylureas) were determined in the atmosphere. The total fallout in the Paris area in 1992 and in 1993 was measured. Fallout was investigated at two stations, urban and rural and the gaseous phase was studied at the rural one. PCB concentrations (0.3-4.9 ng/m3) and compositions in the atmosphere and in the fallout (20-520 ng/l) varied, according to the local emission, with the temperature and the direction of wind. Compared to our first results in 1986, there were no changes of pollution levels by organochlorines in that area. Pesticide concentrations in the atmosphere and in the fallout reached maximal values after the local agricultural treatments in spring. No phenylurea was detected in any of the gaseous or liquid samples. Lindane, atrazine and simazine were the main pesticides found. Their levels in the vapour phase, expressed as ng/m3, were: lindane 0.3-6.3, atrazine < 0.03-2, simazine < 0.03-3; in the fallout, expressed as ng/l they were: lindane 5-350, atrazine 5-380, simazine 5-650. In relative terms, the Parisian area is very small. No difference in the diversity and in the abundance of the micropollutants introduced by the atmosphere was observed between the rural and the urban stations. The pollution level of atrazine was close to that found in Europe and in North America, while the organochlorine and the simazine levels were higher.

Air Pollutants↗
PubMed1985

Occupational allergy to the common house fly. (Musca domestica): use of immunologic response to identify atmospheric allergen.

A 48-year-old scientific worker developed rhinitis that occurred when she entered the housefly (Musca domestica) rearing room where she worked. She was found to have specific IgE antibody to M. domestica in her serum by RAST. She was relocated at work and avoided further occupational exposure to M. domestica. The level of specific IgE decreased in serial samples but subsequently increased after her inadvertent reexposure at work. Extracts of fly-cage dust and of high volume atmospheric samples from the fly-rearing room inhibited the M. domestica RAST in a dose-dependent fashion. After logit transformation the lines of inhibition of the fly cage dust and of the atmospheric samples were parallel and steeper than the self-inhibition by M. domestica, implying the cage dust and atmospheric samples shared antigens not present in the M. domestica extract. This method of monitoring atmospheric antigen has considerable potential for evaluating the effectiveness of environmental change in the workplace.

Air↗
PubMed1993

The effects of modified atmospheres on the growth of psychrotrophic pseudomonads on a surface in a model system.

Atmospheres containing concentrations of CO2 as low as 20% (balance nitrogen) inhibited the growth of Pseudomonas fluorescens and Pseudomonas putida on the surface of buffered Brain Heart Infusion agar plates, pH 6.8, incubated at 5 or 15 degrees C in flexible packages. The modified atmospheres decreased the growth rates and reduced the populations attained at the end of the exponential phase of growth, but had no substantial effect on the lag phase. P. fluorescens was less tolerant of CO2 than P. putida. The inhibitory effect of CO2 increased with its concentration and inhibition was greater at 5 than at 15 degrees C. Growth occurred in packages flushed with 20, 40 and 100% CO2 and 100% N2 at 15 degrees C and 20 and 40% CO2 and 100% N2 at 5 degrees C. The residual O2 concentration in the packages after flushing was 0.2-0.5%. Storage of pseudomonads in CO2 under conditions that prevented growth (e.g., 100% CO2, 5 degrees C) did not cause substantial loss of viability. There was no detectable residual effect of CO2. If cultures were incubated in air after storage for up to 70 days in CO2-containing atmospheres which prevented growth, the subsequent growth curve did not differ noticeably from that observed when plates were incubated in air immediately after inoculation. When cultures in the exponential or stationary phases of growth in modified atmospheres were transferred to air, growth rates increased quickly to rates similar to those observed in air and the final populations observed in air were attained. A reduction in the pH of the medium to 5.5 substantially increased the inhibitory effect of CO2. At 5 degrees C and pH 5.5, substantial growth of P. fluorescens was not observed in any of the CO2 concentrations tested, nor in 40 or 100% CO2 for P. putida.

Air↗
PubMed1996

Survival and growth of Aeromonas hydrophila on modified atmosphere packaged normal and high pH lamb.

The growth of A. hydrophila on normal pH (5.5-5.8) and high pH ( > 6.0) lamb stored under modified atmospheres was examined. Lamb pieces and mince, inoculated with A. hydrophila were packaged in air, vacuum pack, 80% O2/20% CO2, 50% CO2/50% N2, or 100% CO2 and stored at 5 or 0 degrees C for up to 42 days. Samples were examined for the survival and/or growth of A. hydrophila by enrichment in alkaline peptone water and/or direct plating on starch ampicillin agar. The pH of each sample was estimated. On lamb pieces and mince of normal pH, A. hydrophila numbers decreased during storage at 5 and 0 degrees C under all the packaging conditions. The organism was not detected after 21 days storage. In contrast, A. hydrophila numbers were maintained or increased on high pH lamb under most storage regimes. Storage at 5 degrees C allowed significant increases in A. hydrophila numbers on high pH lamb under all the atmospheres, except 100% CO2. In lamb held at 5 degrees C under 100% CO2 for up to 42 days, A. hydrophila was recovered from most samples, although cell numbers decreased during storage. After storage at 0 degrees C, A. hydrophila was recovered from high pH packs stored under all atmospheres. Significant increases in cell numbers were only observed in minced lamb of high pH stored under air or vacuum. The pH values of lamb pieces and mince held at 5 or 0 degrees C under any of the packaging atmospheres did not change in a uniform manner during storage.

Aeromonas hydrophila↗
PubMed1996

Influence of modified atmosphere and preservatives on the growth of Zygosaccharomyces rouxii isolated from dried fruits.

The influence of water activity (alpha w), preservatives, modified atmosphere and their combinations on the growth of Z. rouxii was determined by cultivating two strains isolated from raisins and prunes in culture media under different conditions and by counting the colony forming units. Yeast extract glucose broths or agars were adjusted to the desired alpha w by means of glucose. Preservatives added to the media (0-600 ppm) were either K-sorbate, Na-benzoate or their mixture. Modified atmospheres were carried out by packing culture plates or flasks in plastic bags under different CO2-N2 gas mixture. Response surface design was carried out to optimize the growth inhibition of Z. rouxii by the mentioned factors. Although Z. rouxii is osmotolerant, the strains studied could not grow at alpha w 0.79. They also showed a high tolerance to CO2; even 80% CO2 seems to not inhibit growth. However, CO2 atmosphere at high pHs and low preservative concentrations stimulated yeast growth. At pH 4.0 and under modified atmosphere (80% CO2-20% N2), no growth was observed at any alpha w in the range of 0.80-0.90 when using a preservative concentration of 220 ppm Ksorbate or 280 ppm Na-benzoate.

Benzoates↗
PubMed1994

Regional and historical variation in the nitrogen content of Racomitrium lanuginosum in Britain in relation to atmospheric nitrogen deposition.

The moss Racomitrium lanuginosum (Hedw.) Brid. is an important component of the drier parts of ombrotrophic mires and montane heaths in north-western Britain. The extent and quality of the montane heaths dominated by R. lanuginosum has declined in recent decades, perhaps in part due to the effects of acidic deposition at high elevations. This paper examines the effect of atmospheric nitrogen deposition, which has increased during this century, on the nitrogen content of R. lanuginosum in Britain. The nitrogen content of the moss reflects the magnitude of the atmospheric supply being least in north-western Scotland and greatest (as much as six-fold greater) near to urban centres in northern England. This regional difference was less marked (only approx. two-fold) during the 19th century (as revealed from the analysis of herbarium specimens) when nitrogen concentrations were appreciably lower. Transplant studies both between regions and between sites within a mountain system demonstrated the importance of atmospheric deposition in determining the tissue nitrogen concentration of the moss. The results are discussed in relation to the potential importance of the enhanced atmospheric nitrogen supply to the normally nitrogen-impoverished montane heaths, and to the growth and persistence of the moss.

Journal Article↗
PubMed1994

Remote sensing of atmospheric aerosol in the nocturnal boundary layer using lidar.

This paper presents the results of the lidar experiments that have been performed during January 1989 through August 1990 to study the aerosol vertical distributions in the nocturnal atmosphere and their comparison with near-simultaneous aerological soundings for environmental monitoring. During the study period, the aerosol distributions showed significant stratified aerosol layer structures in the lower atmosphere throughout the south-west monsoon season (June-September), while these structures appear to be either erratic or absent during remaining months of the year. In addition, the aerosols present in the lowest air layers up to 200 m are found to contribute significantly (about 40%) to the aerosol loading in the nocturnal boundary layer at the lidar site. The pre-monsoon to winter ratio of mixing depth and ventilation coefficient were found to be 1.11 and 1.62, respectively. Thus the height of the mixed layer (around 350 m) and the associated ventilation coefficients suggest that early winter evenings tend to have higher pollution potential at the experimental site. The results indicate that the lidar technique has the potential to yield good information on the structure of the nocturnal atmosphere which is found to be influenced by the atmospheric stability conditions as revealed by aerological observations.

Journal Article↗
PubMed1992

Thymine photoproduct formation and inactivation of intact spores of Bacillus subtilis irradiated with short wavelength UV (200-300nm) at atmospheric pressure and in vacuo.

Vacuum exposure renders the survival of spores of Bacillus subtilis approximately five times more sensitive to ultraviolet light irradiation than exposure under atmospheric conditions. The photoproduct formation in spores irradiated under ultrahigh vacuum (UHV) conditions is compared to the photoproduct formation in spores irradiated at atmospheric pressure. Compared to irradiation at atmospheric pressure, where only the "spore photoproduct" 5-thyminyl-5,6-dihydrothymine (TDHT) can be detected, two additional photoproducts, known as the c,s and t,s isomers of thymine dimer (T<>T) are produced in vacuo. The spectral efficiencies for photoproduct formation in spores under atmospheric and vacuum conditions are compared. Since there is no increased formation of TDHT after irradiation in vacuum, TDHT cannot be made responsible for the observed vacuum effect. "Vacuum specific" photoproducts may cause a synergistic response of spores to the simultaneous action of ultraviolet light (UV) and UHV. Three different mechanisms are discussed for the enhanced sensitivity of B. subtilis spores to UV radiation in vacuum. The experiments described contribute valuable research information on the chance for survival of microorganisms in outer space.

Bacillus subtilis↗
PubMed1993

Nursing staff and patient perceptions of the ward atmosphere in a maximum security forensic hospital.

The purpose of this study is to describe the factors influencing nursing staff and patients' perceptions of the ward atmosphere in a maximum security forensic hospital. The study used the Ward Atmosphere Scale to identify specific factors. Findings indicate that structure and compliance with ward routine and behavioral standards are the most important factors in perceptions of the ward atmosphere. Also, despite the emphasis on security and the ever-present potential for violence, nursing staff were able to maintain a therapeutic ward atmosphere.

Adult↗
PubMed1991

Action spectra for survival and spore photoproduct formation of Bacillus subtilis irradiated with short-wavelength (200-300 nm) UV at atmospheric pressure and in vacuo.

Spores of Bacillus subtilis are approximately ten times less likely to survive UV light irradiation in a vacuum than under atmospheric conditions. Photoproduct formation was studied in spores irradiated under ultrahigh vacuum (UHV) conditions and in spores irradiated at atmospheric pressure. In addition to the "spore photoproduct" 5-thyminyl-5,6-dihydrothymine (TDHT), which is produced in response to irradiation at atmospheric pressure, two additional photoproducts, known as the cis-syn and trans-syn isomers of thymine dimer, are produced on irradiation in vacuo. The spectral efficiencies for photoproduct formation in spores are reduced under vacuum conditions compared with atmospheric conditions by a factor of 2-6, depending on the wavelength. Because formation of TDHT does not increase after irradiation in vacuo, TDHT cannot be responsible for the observed vacuum effect. Vacuum specific photoproducts may cause a synergistic response of spores to the simultaneous action of UV light and UHV. An increased quantum efficiency, destruction of repair systems and formation of irreparable lesions are postulated for the enhanced sensitivity of B. subtilis spores to UV radiation in vacuo.

Bacillus subtilis↗
PubMed2005

MEAD: an interdisciplinary study of the marine effects of atmospheric deposition in the Kattegat.

This paper summarises the results of the EU funded MEAD project, an interdisciplinary study of the effects of atmospheric nitrogen deposition on the Kattegat Sea between Denmark and Sweden. The study considers emissions of reactive nitrogen gases, their transport, transformations, deposition and effects on algal growth together with management options to reduce these effects. We conclude that atmospheric deposition is an important source of fixed nitrogen to the region particularly in summer, when nitrogen is the limiting nutrient for phytoplankton growth, and contributes to the overall eutrophication pressures in this region. However, we also conclude that it is unlikely that atmospheric deposition can, on its own, induce algal blooms in this region. A reduction of atmospheric nitrogen loads to this region will require strategies to reduce emissions of ammonia from local agriculture and Europe wide reductions in nitrous oxide emissions.

Agriculture↗
PubMed2004

Modeling the atmospheric transport and deposition of mercury to the Great Lakes.

A special version of the NOAA HYSPLIT_4 model has been developed and used to estimate the atmospheric fate and transport of mercury in a North American modeling domain. Spatial and chemical interpolation procedures were used to expand the modeling results and provide estimates of the contribution of each source in a 1996 anthropogenic US/Canadian emissions inventory to atmospheric mercury deposition to the Great Lakes. While there are uncertainties in the emissions inventories and ambient data suitable for model evaluation are scarce, model results were found to be reasonably consistent with wet deposition measurements in the Great Lakes region and with independent measurement-based estimates of deposition to Lake Michigan. Sources up to 2000 km from the Great Lakes contributed significant amounts of mercury through atmospheric transport and deposition. While there were significant contributions from incineration and metallurgical sources, coal combustion was generally found to be the largest contributor to atmospheric mercury deposition to the Great Lakes.

Air Movements↗
PubMed2005

Cd and Zn in atmospheric deposit, soil, wheat, and milk.

Continuous air quality monitoring in the Vojvodina district of Serbia and Montenegro has shown high levels of Cd, especially in the outskirts of large towns such as Kikinda. The construction and metal processing industries located in Kikinda have been emitting significant amounts of heavy metals into the environment. The levels of Cd and Zn were monitored in the region of Kikinda and compared to their concentrations detected in Novi Sad, the capital of Vojovodina, where emission of heavy metals originated mostly from vehicle traffic. The study was performed during the economic sanctions when industrial production decreased drastically. The consequence of that was a significant decrease of the concentration of Cd and Zn in atmospheric deposits. Data collected during 3 years indicated a direct influence of atmospheric deposits on heavy metal distribution in the chain soil-cattle feed-milk. Decreased Cd concentrations of 93% in atmospheric deposits in the Kikinda region resulted in decreased Cd concentrations of 17% in cattle feeds and 13% in milk. Decreased Zn concentrations of 58% in atmospheric deposits caused reduced Zn concentrations of 30% in soil, 17% in cattle feeds, and 17% in milk.

Air Pollutants↗
PubMed2005

Direct exposure methods for testing native atmospheres.

In vitro studies of adverse cellular effects induced by inhalable substances face a number of problems due to the difficulties in exposing cultured cells of the respiratory tract directly to test atmospheres composed of complex gases and particulate compounds. This paper discusses the characteristics of in vitro work and summarizes the use of different in vitro technologies to determine the adverse effects of inhaled pollutants. The exposure of cells to test atmospheres requires accurate control of the pollutant levels, as well as the close contact of cells and gas without interfering with the medium. Systems which rely on the solution of the gas in the medium overlay do not resemble the exposure conditions in vivo, and may not be suitable for studying, for example, the effects of poorly soluble gases. Exposure to gases or complex mixtures can be performed with roller bottles or flasks on rotating and rocking platforms and, using these techniques, the cells are periodically exposed to the test atmosphere. However, the most promising approach is based on a biphasic cell culture technique, where cells are grown on microporous membranes at an air-liquid interface. Here the cells are nutrified from the basal side of the membrane whilst the apical part with the cultivated cells is in direct contact with the test atmosphere. Based on this culture technique, different exposure systems have been developed and these are described and discussed. Exposure of cells from the respiratory tract to gases or particles is responsible for cell injury or cell activation associated with an overexpression of mRNA and the release of bioactive mediators. Therefore, in vitro studies using such a strategy, in combination with relevant and efficient exposure devices, open up new ways to test native complex gases and aerosols. Furthermore, such an experimental approach is not only suitable for cultivated cells, but it can also be used for exposing bacteria to inhalable test compounds. It is possible to analyze the mutagenic potency of in- and outdoor pollutants and several attempts have been made to determine the induction of revertants in a modified Ames assay after exposure to single gases or complex mixtures.

Air Pollutants↗
PubMed2004

Comparative study of carbon dioxide and nitrogen atmospheric effects on the chemical structure changes during pyrolysis of phenol-formaldehyde spheres.

The effect of CO(2) atmosphere on the chemical structure changes of resol-type phenol-formaldehyde spheres during pyrolysis was investigated, in comparison with that of N(2) atmosphere, using FT-IR, TGA, and elemental analysis techniques. It was found that, in contrast to the expectation that CO(2) may act as an oxidizing agent at high temperature, it behaves very similar to N(2) during pyrolysis of PF spheres up to 700 degree C, but results in a somewhat different extent of some specific reactions. That is, although the reactions occurring up to 700 degree C were dominated by crosslinking and/or polyaromatization under both CO(2) and N(2) atmospheres, fewer alkyl-phenolic ether bonds were formed under CO(2) than under N(2). As a consequence, the samples carbonized under CO(2) at 700 degree C were found to have more pendant groups on the edge carbon atoms of carbon in the carbonized samples than those prepared under N(2) atmosphere.

Journal Article↗