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PubMed2004

[Study on atmospheric photo-oxidation of methyl hydroperoxide initiated by Cl-atom].

Organic peroxides play an important role in chemistry of the atmosphere and in controlling urban air quality; however, accurate knowledge about their atmospheric reactions is lacking. In this paper, the experimental simulation was employed to study the atmospheric photo-oxidation of methyl hydroperoxide (CH3OOH, MHP), a key organic peroxide in the atmosphere. At the temperature of (292 +/- 2) K and pressure of 9.3 x 10(4) Pa (20% O2 + 80% N2), the MHP photo-oxidation was initiated by Cl-atom and the process of reaction was in-situ observed by long path Fourier transform infrared (Long Path FTIR) spectrometry. From FTIR spectra, the main products observed were formaldehyde (HCHO), formic acid (HCOOH), carbon monoxide (CO) and carbon dioxide (CO2), and minor methanol (CH3OH) was found as well. Within the reaction period of 60 min, yields were determined: 24% for HCOOH and 6% for CO; 50% for HCHO at its maximum concentration although its yield was varying with the reaction time. Finally, reaction mechanisms were discussed, which implied that MHP is a reservoir of odd-hydrogen radicals (HOx) and plays an important role in atmospheric photo-reactions.

Atmosphere↗
PubMed2006

Effects of atmospheric temperature and pressure on the occurrence of acute myocardial infarction in Hiroshima City, Japan.

In contrast to studies of the effects of atmospheric temperature and pressure on the occurrence of acute myocardial infarction (AMI), the interaction of these two factors has rarely been studied. We analyzed ambulance data (1993-2002) due to AMI in Hiroshima City using the poisson regression model to examine the main effects and the interaction of atmospheric temperature and pressure on AMI (n=3755). In the analysis, thermohydrological-index (THI), or humidity adjusted temperature, was calculated to involve the effect of relative humidity. The significant influence of atmospheric temperature on AMI was confirmed. Daily events of AMI decreased as temperature increased. Daily events in the low, moderate, and high temperature groups were 1.16, 1.07 and 0.90, respectively (average=1.03/day). Atmospheric pressure showed a weaker effect in the presence of temperature. A more profound interaction was found between temperature and pressure. The highest daily events 1.38 were observed in the low temperature and low pressure group, while this meteorological type was always accompanied by rain and/or snow. It was significant (p=0.047) and 37% higher than that of the high temperature and moderate pressure group. The lowest daily events 0.87 were observed in the high temperature and low pressure group. These associations were reinforced when temperature adjusted by relative humidity was used. Atmospheric temperature and the interaction of temperature and pressure had significant influences on the occurrence of AMI. The highest risk was found on days with low temperature and low pressure. Days with high risk were characterized by winter rain and/or snow.

Acute Disease↗
PubMed1982

Survey of atmospheric pollen allergens in Delhi: seasonal periodicity.

Atmospheric pollen surveys were conducted at four different zones within the metropolitan capital city of India, Delhi, for a period of three years (1973-1975). Durham's Gravity Sampling Device was employed for sampling airborne pollen. Altogether 86 pollen types were identified from the atmosphere of Delhi; 22 types are new records for the atmosphere of Delhi. Two major pollen seasons--February to April and August to October--are recognized for Delhi. The atmosphere pollen concentration of different types as well as of the total counts showed significant annual and seasonal variations and also revealed marked differences in the quality and quantity of the pollen from site to site. Habitat factors seem to be the causal agents for the wide range of variations in the pollen content of the atmosphere of Delhi. The results of the survey are discussed in the light of relevant published literature.

Atmosphere↗
PubMed1993

Microbiologic effects of atmospheric conditions used in operative laparoscopy.

We tested whether the atmospheric conditions used in operative laparoscopy were responsible for its low infection rate. A plexiglass chamber was used to recreate the atmospheric conditions in an operative laparoscopic procedure with CO2 pneumoperitoneum, including a CO2 atmosphere, gas flow and temperature control. Staphylococcus aureus and Escherichia coli were exposed to this atmosphere and their growth compared to that on control plates exposed to standard culture conditions. The ratio of colony growth on experimental versus control plates was 1.08 +/- 0.19 SD for Staphylococcus and 1.13 +/- 0.66 SD for E coli. We noted no direct inhibitory effect of the pelviscopic atmosphere upon microbiologic growth. The factors responsible for pelviscopy's low infection rate remain obscure.

Atmosphere Exposure Chambers↗
PubMed1997

Atmospheric degradation of HFCs and HCFCs: chemistry and noxiousness.

Hydrohaloalkanes are potential alternatives to the fully halogenated compounds (CFCs) that are believed to be responsible for depletion of the stratospheric ozone. In order to establish whether hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) are actually more environmentally acceptable, it is extremely important to know, in addition to ODP and HGWP, their atmospheric degradation mechanism, tropospheric lifetime, and toxicity and noxiousness of their atmospheric degradation products. The primary atmospheric sink for hydrohaloalkanes is the reaction with hydroxyl radicals (OH), so that laboratory measurements or a reliable estimation of the rate constants (kOH) of these reactions is essential in order to assess their atmospheric lifetimes. The previsional models for kOH developed in our laboratory allow the estimation of the atmospheric lifetimes of as many as 449 halocarbons (i.e., all the halocarbons containing F and/or Cl with one, two, and three carbon atoms). The harmful character of some degradation products halogenated and oxygenated is also discussed.

Air Pollutants↗
PubMed2003

Influence of modified atmosphere packaging on the shelf life of prebaked pizza dough with and without preservative added.

The possible effect of different modified atmospheres on the shelf life of prebaked pizza dough, with and without added calcium propionate, was investigated. Three packaging atmospheres were tested: 20% CO2: 80% N2, 50% CO2: 50% N2, 100% CO2, and air (control). Samples were examined daily for visible mold growth and analysed after 2, 8, 17 and 31 days throughout storage (15-20 degrees C and 54-65% relative humidity, RH) for changes in gaseous composition, pH and microbial populations (mesophilic aerobic and anaerobic bacteria, lactic acid bacteria (LAB), and yeasts and molds). Microbiological results showed that molds had a greater sensitivity to CO2 than bacteria and yeasts. Products containing calcium propionate did not show mold growth throughout storage (31 days) when packaged in air or in CO2-enriched atmospheres (20, 50 and 100%). However, in pizza dough without preservative (calcium propionate), mold growth was evident after 7 days, except under 100% CO2 atmosphere (13 days) regardless of the packaging atmosphere. From these results we conclude that the addition of calcium propionate had more and decisive influence on the shelf life extension of prebaked pizza dough.

Carbon Dioxide↗
PubMed2006

Improvement of 2,4-dinitrophenylhydrazine derivatization method for carbon isotope analysis of atmospheric acetone.

Through simulation experiments of atmospheric sampling, a method via 2,4-dinitrophenylhydrazine (DNPH) derivatization was developed to measure the carbon isotopic composition of atmospheric acetone. Using acetone and a DNPH reagent of known carbon isotopic compositions, the simulation experiments were performed to show that no carbon isotope fractionation occurred during the processes: the differences between the predicted and measured data of acetone-DNPH derivatives were all less than 0.5 per thousand. The results permitted the calculation of the carbon isotopic compositions of atmospheric acetone using a mass balance equation. In this method, the atmospheric acetone was collected by a DNPH-coated silica cartridge, washed out as acetone-DNPH derivatives, and then analyzed by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Using this method, the first available delta13C data of atmospheric acetone are presented.

Journal Article↗
PubMed1976

[The influence of atmospheric gases on growth and toxin production of sterigmatocystin-and patulin-producing molds (author's transl)].

The influence of one-and two-sided regulated atmospheres with lower 02-and increased CO2-concentrations in comparison with air was studied on the growth and toxin-production of 4 different mycotoxin-producing molds (A. versicolor, P. expansum, P. urticae, B. nivea). Low O2-values in the atmosphere (2-0.5%) had scarely an influence on the development and toxinproduction in different nutrient media after 14 d at 25 degrees C. Only higher CO2-and lower O2-concentrations than that of the air (e.g. 40% CO2, 6% O2) reduced the sterigmatocystin-and patulin-production in nearly all cultures, whereas growth was only retarded insignificantly. Atmospheres with 90% CO2 and 10% air as well nitrogen atmospheres with 10% CO2 inhibited remarkably the growth of molds and prevented the toxin-production of nearly all strains. In pure N2-atmospheres most of the A. versicolor strains exhibited growth with toxic mycelia whereas only minimum growth of the patulin-producing species without any patulin synthesis had been observed.

Aspergillus↗
PubMed2006

Influence of meteorological parameters on particulates and atmospheric pollutants at Taichung harbor sampling site.

Atmospheric aerosol particles and metallic concentrations, ionic species were monitored at the Experimental harbor of Taichung sampling site in this study. This work attempted to characterize metallic elements and ionic species associated with meteorological conditions variation on atmospheric particulate matter in TSP, PM2.5, PM2.5-10. The concentration distribution trend between TSP, PM2.5, PM2.5-10 particle concentration at the TH (Taichung harbor) sampling site were also displayed in this study. Besides, the meteorological conditions variation of metallic elements (Fe, Mg, Cr, Cu, Zn, Mn and Pb) and ions species (Cl(-), NO3 (-), SO4 (2-), NH4+, Mg2+, Ca2+ and Na+) concentrations attached with those particulate were also analyzed in this study. On non-parametric (Spearman) correlation analysis, the results indicated that the meteorological conditions have high correlation at largest particulate concentrations for TSP at TH sampling site in this study. In addition, the temperature and relative humidity of meteorological conditions that played a key role to affect particulate matter (PM) and have higher correlations then other meteorological conditions such as wind speed and atmospheric pressure. The parameter temperature and relative humidity also have high correlations with atmospheric pollutants compared with those of the other meteorological variables (wind speed, atmospheric pressure and prevalent wind direction). In addition, relative statistical equations between pollutants and meteorological variables were also characterized in this study.

Air Pollutants↗
PubMed1990

High oxygen atmosphere for neuronal cell culture with nerve growth factor. II. Survival and growth of clonal rat pheochromocytoma PC12h cells.

When clonal rat pheochromocytoma PC12h cells were cultured in a 50% O2 atmosphere, cells gradually died during the cultivation. On the other hand, the addition of NGF at the final concentration of 50 ng/ml could rescue the cells from death. The culture in a 40% O2 atmosphere had little effect on the growth of PC12h cells, as compared with the culture in a normal 20% O2 condition. A very high O2 concentration, as 60%, caused severe damage to PC12h cell growth, and the restoration of cell growth by NGF seemed to be insufficient. PC12h cells were fully differentiated and extended dense long neurites by NGF even in a 50% O2 atmosphere. However, the neurite extension in the culture in a 60% O2 atmosphere was suppressed. The cell-saving effect of NGF on cell death in culture under a 50% O2 atmosphere was dose-dependent, and the ED50 value of NGF was 5 ng/ml. Basic fibroblast growth factor and epidermal growth factor also had a potent effect to rescue the cell death in the high O2 culture, but insulin had no effect. Since the differentiation effects of NGF on PC12h cells are thought to offer a model system to investigate the effect of NGF on neurons, the present observations suggest that a protection machinery for high O2 toxicity to neurons may exist in the neuronal differentiated PC12h cells by NGF, but not in the undifferentiated cells.

Animals↗
PubMed1995

Deposition of fixed atmospheric nitrogen and foliar nitrogen content of bryophytes and Calluna vulgaris (L.) Hull.

Atmospheric deposition of fixed nitrogen as nitrate and ammonium in rain and by dry deposition of nitrogen dioxide, nitric acid and ammonia has increased throughout Europe during the last two decades, from 2-6 kg N ha(-1) year(-1) to 15-60 kg N ha(-1) year(-1). The nitrogen contents of bryophytes and the ericaceous shrub Calluna vulgaris have been measured at a range of sites, with the objective of showing the degree to which nitrogen deposition is reflected in foliar plant nitrogen. Tissue nitrogen concentrations of herbarium bryophyte samples and current samples of the same species collected from the same sites were compared. No significant change in tissue nitrogen was recorded at a remote site in north-west Scotland where nitrogen inputs are small (< 6 kg N ha(-1) year(-1)). Significant increases in tissue N occurred at four sites ranging from 38% in central Scotland to 63% in Cumbria where nitrogen inputs range from 15 to 30 kg N ha(-1) year(-1). The relationships found between the estimated input of atmospheric nitrogen and the tissue nitrogen content of the selected bryophytes and Calluna at the sites investigated were found to be generally linear and fitted the form N(tissue) = 0.62 + 0.022 N(dep) for bryophytes and N(tissue) = 0.83 + 0.045 N(dep) for Calluna. There was thus an increase in total tissue nitrogen of 0.02 mg g(-1) dry weight for bryophytes and 0.045 mg g(-1) dry weight for Calluna for an increase in atmospheric nitrogen deposition of 1 kg ha(-1) year(-1). The lowest concentrations were found in north-west Scotland and the highest in Cumbria and the Breckland heaths of East Anglia, both areas of high atmospheric nitrogen deposition (30-40 kg N ha(-1) year(-1)). The implications of increased tissue nitrogen content in terms of vegetation change are discussed. Changes in atmospheric nitrogen deposition with time were also examined using measured values and values inferred from tissue nitrogen content of mosses. The rate of increase in nitrogen deposition is not linear over the 90-year period, and the increases were negligible over the period 1880-1915. However, during the period 1950 to 1990 the data suggest an increase in nitrogen deposition of 2 kg N ha(-1) every 10 years.

Journal Article↗
PubMed2005

Seasonal patterns of ascorbate in the needles of Scots Pine (Pinus sylvestris L.) trees: correlation analyses with atmospheric O3 and NO2 gas mixing ratios and meteorological parameters.

In the present field study the role of ascorbate in scavenging the harmful atmospheric trace gases O3 and NO2 was examined. For this purpose ascorbate contents were determined in needles of adult Scots pine trees (Pinus sylvestris L.) during three consecutive years. Ascorbate contents were correlated with ambient tropospheric O3 and NO2 concentrations and with meteorological parameters. The results showed a strong correlation of atmospheric O3 but not of atmospheric NO2 concentrations with the apoplastic content of ascorbate during the seasonal course. Ascorbate contents in needle extracts did not correlate with ambient trace gas concentrations. In the apoplastic space, but not in needle extracts ascorbate contents correlate highly significantly with global radiation. From these results it is assumed that apoplastic ascorbate in Scots pine needles is adapted to the actual atmospheric O3 concentration to mediate immediate detoxification of O3, while the atmospheric O3 concentration itself is largely dependent on light intensity.

Air Pollutants↗
PubMed2004

Arctic atmospheric contaminants in NE Greenland: levels, variations, origins, transport, transformations and trends 1990-2001.

This review is based on the results obtained from the Danish AMAP programme for the Arctic atmosphere during the 1990s. The purpose of the programme is to quantify the pollution, apportion source contributions, follow the trends, and identify midlatitude source areas and transport pathways. The project has been carried out in North Greenland as integrated monitoring, which is an interacting combination of field measurements and model calculations of atmospheric transport and transformation in the Northern Hemisphere. At the monitoring site at Station Nord the large and seasonally recurrent variations in the pollutant concentrations are testimony to the influence in this region of the phenomenon of Arctic Haze. These results can only be understood in terms of long range transport from distant pollution sources. The measurements also comprise a large number of particle-born elements. These results are used to build receptor models, which show that the ambient concentrations and their variations to a high degree can be explained by the influence of only four source types of both natural and anthropogenic nature. The challenging phenomena of atmospheric ozone and mercury depletion around Polar sunrise have been studied at Station Nord over several years. The results show that these two phenomena are closely connected, presumably through photochemical reactions with atmospheric halogens released from sea ice. A large-scale Eulerian model system for the Northern Hemisphere has been developed in this AMAP project. The validity of the model is illustrated by comparisons between measured and calculated air concentrations. The model has been used to calculate both the vertical distribution and the atmospheric depositions for several pollutants at various locations in Greenland and split into quantified contributions from different and geographically distant source areas. Mercury deposition estimates for the Northern Hemisphere are also presented. They show that the mercury depletion events are accompanied by very intense depositions to land and sea of reactive mercury that may seriously affect the Arctic ecosystems. Finally, measurement and model data are combined to demonstrate, despite considerable meteorological noise, that ambient air concentrations in North-eastern Greenland have decreased during the last decade. Quantified trends, attributable to emission reductions in distant source areas, are presented for several pollutants.

Air Movements↗
PubMed2005

Temporal and spatial variabilities of atmospheric polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and polycyclic aromatic hydrocarbons (PAHs) in the Canadian Arctic: results from a decade of monitoring.

The Northern Contaminants Program (NCP) baseline monitoring project was established in 1992 to monitor for persistent organic pollutants (POPs) in Arctic air. Under this project, weekly samples of air were collected at four Canadian and two Russian arctic sites, namely Alert, Nunavut; Tagish, Yukon; Little Fox Lake, Yukon; Kinngait, Nunavut; Dunai Island, Russia and Amderma, Russia. Selected POPs, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine (OC) pesticides, were analyzed in both the gas and particulate phases. This paper summarizes results obtained from this project in the past 5 years. Temporal trends were developed for atmospheric PCBs and OCs observed at Alert using a digital filtration (DF) technique. It was found that trends developed with 5 years of data (1993-1997) did not differ significantly from those determined with 7 years of data (1993-1999). This implies that with the DF technique, long-term trends can still be developed with less than 10 years of data. An acceleration in decline of OC and PCB air concentrations was noted in 1999 for some compounds, although the reason is unknown. Monitoring efforts must continue to assess the effect of this decline on the long-term trends of POPs in the Canadian Arctic. Occasional high trans-/cis-chlordane ratios and heptachlor air concentrations measured at Alert between 1995 and 1997 suggests sporadic fresh usage of chlordane-based pesticides. However, significant decreasing trends of chlordanes along with their chemical signatures has provided evidence that emission of old soil residues is replacing new usage as an important source to the atmosphere. Measurements of OC air concentrations conducted at Kinngait in 1994-1995 and 2000-2001 indicated faster OC removal at this location than at Alert. This may be attributed to the proximity of Kinngait to temperate regions where both biotic and abiotic degradation rates are faster. The PAH concentrations observed at Alert mimic those at mid-latitudes and are consistent with long-range transport to the Arctic, particularly for the lighter PAHs. A decline in particulate PAH was observed, similar to atmospheric sulphate aerosol and can be attributed to the collapse of industrial activity in the former Soviet Union between 1991 and 1995. Spatial comparisons of OC seasonality at Alert, Tagish, Dunai and Kinngait show elevated air concentrations of some compounds in spring. However, elevated spring concentrations were observed for different compounds at different sites. Potential causes are discussed. Further investigation in the atmospheric flow pattern in spring which is responsible for the transport of POPs into the Arctic is required. OC and PCB air concentrations at Alert were found to be influenced by two climate variation patterns, the North Atlantic Oscillation (NAO) and the Pacific North American (PNA) pattern. Planetary atmospheric patterns must be taken into account in the global prediction and modelling of POPs in the future.

Journal Article↗
PubMed2005

Impact of mercury atmospheric deposition on soils and streams in a mountainous catchment (Vosges, France) polluted by chlor-alkali industrial activity: the important trapping role of the organic matter.

Total atmospheric Hg contamination in a French mountainous catchment upstream from a chlor-alkali industrial site was assessed using Hg concentrations in the deepest soil horizon, in the stream bottom sediments, in river waters and in bryophytes. The natural background level of Hg content deriving from rock weathering was estimated to 32 ng g(-1) in the deepest soil layers. The soils appear to be Hg contaminated in two stages: atmospheric deposition and leaching through the soil profiles of Hg-organic matter complexes. The Hg enrichment factor (EF(Hg)(Sc)) which could be calculated by normalization to a conservative element like Sc, allows to estimate the major contribution (63% to 95%) of the atmospheric inputs, even in the upper part of the basin. This contribution may be attributed to diffuse regional atmospheric deposition of Hg and is mainly due to the geographic location of the chlor-alkali plant. This study shows for the first time that the mercury enrichment is proportional to the carbon content indicating that most of the atmospheric mercury deposition is trapped by the organic matter contained in the soils and in the stream sediments. The Hg stock in the soils of the upper catchment and the soil erosion contribution to the riverine Hg fluxes are estimated for the first time and allow to assess the Hg residence time. It indicates that Hg is trapped in the soils of such a polluted catchment for probably several thousand years.

Air Pollutants↗
PubMed2005

Observation of HOPG by STM and contact AFM in various gas atmospheres under pressures up to 1.1 MPa.

Apparatus comprising a scanning tunneling microscopy (STM) and an atomic force microscopy (AFM) has been developed for use under supra-atmospheres. Observations of highly oriented pyrolytic graphite (HOPG) were carried out by STM and contact AFM operating in air and various gas atmospheres (hydrogen, helium, neon and argon) under pressures up to 1.1 MPa. Atomic resolution images of the HOPG were obtained by STM in all the gas atmospheres studied. However, it was found that the presence of water vapor gave rise to a noise current at increased pressures. Using contact AFM, the atomic resolution in an argon atmosphere decreased with increasing pressure, while atomic images were obtained under the other gas atmospheres at 1.1 MPa.

Journal Article↗
PubMed2004

Incineration of healthcare wastes: management of atmospheric emissions through waste segregation.

The amount of atmospheric pollutants emitted through the incineration of healthcare wastes can be estimated using emission factors. Emission factors have been published without including sufficient information about the types of wastes incinerated. This paper reports the first emission factors estimated for the incineration of wastes segregated into different types according to the Portuguese legislation. One controlled-air incinerator without air pollution control devices was used in the research. The main objectives of the study were: (i) to estimate the emission factors for particulate matter, dioxins, heavy metals and gaseous pollutants, according to the type of waste incinerated; (ii) to evaluate the quality of atmospheric emissions; and (iii) to define a methodology for the management of atmospheric emissions, evaluating the influence of type of waste incinerated and of the segregation method used on the emitted amounts. It was concluded that: (i) when emission factors are not associated with the type of incinerated mixture, the utility of the emission factors is highly doubtful; (ii) without appropriate equipment to control atmospheric pollution, incineration emissions exceed legal limits, neglecting the protection of human health (the legal limit for pollutant concentrations could only be met for NO(x), all other concentrations were higher than the maximum allowed: dioxins, 93-710 times; Hg, 1.3-226 times; CO, 11-24 times; SO(2), 2-5 times; and HCl, 9-200 times); (iii) rigorous segregation methodologies must be used to minimize atmospheric emissions, and incinerate only those wastes that should be incinerated according to the law. A rigorous segregation program can result in a reduction of the amount of waste that should be incinerated by 80%. A reduction in the quantity of waste incinerated results in a reduction on the amounts of pollutants emitted: particulate matter, 98%; dioxins, 99.5%; As, Cd, Cr, Mn and Ni, respectively, 90%, 92%, 84%, 77% and 92%; Hg and Pb, practically eliminated; SO(2) and NO(x), 93%; and CO and HCl, more than 99%.

Air Pollution↗
PubMed2006

Mass balance for polycyclic aromatic hydrocarbons in the urban watershed of Le Havre (France): transport and fate of PAHs from the atmosphere to the outlet.

Polycyclic aromatic hydrocarbon (PAH) concentrations have been monitored simultaneously in ambient air, bulk atmospheric deposition and runoff waters during one year in a small urban watershed of the Seine river basin (France). PAH fluxes from the atmosphere to the outlet of the urban watershed have been calculated to establish a mass balance for PAHs. PAH flux in runoff waters was 5.2 kg km(-2) yr(-1) while PAH atmospheric deposition was 0.21 kg km(-2) yr(-1). The comparison between atmospheric input and output by runoff has shown the importance of street deposits that appeared to be the most important source of PAHs for surface waters in urban areas. PAH profiles in the various compartments showed the fate of PAHs in the air-water system: proportion of carcinogenic PAHs was more important in runoff waters (35%) than in bulk atmospheric deposition (22%) and air (6%).

Air Movements↗