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At least 595 records · Page 33Linked to original sources
PubMed2003

[Characteristics of atmospheric CO2 variations and some affecting factors in urban area of Beijing].

The diurnal variation of the atmospheric CO2 at the urban area in Beijing displayed a very clear cycle, generally with the lowest value being recorded at about 15:00 local time and the highest in the nighttime. The differences between the maximums and the minimums ranged from 23.2 to 39.0 mumol.mol-1 in the four seasons and the ones of summer and fall were bigger than that of winter and spring. It showed a large seasonal cycle with a maximum in winter, from 421.5 to 441.0 mumol.mol-1, and a minimum in summer, between 367.4 and 371.6 mumol.mol-1. The peak-to-peak amplitude of atmospheric CO2 in Beijing, controlled mostly by the anthropogenic activities and seasonal variation of vegetation, was higher than that in Xinglong Station, Hebei Province and China Global Atmosphere Watch Baseline Observatory (Waliguan). The concentration of atmospheric CO2 in Beijing increased rapidly at a mean growth rate of 3.7%.a-1 from 1993 to 1995. After displaying a peak of 409.7 +/- 25.9 mumol.mol-1 in 1995, it decreased slowly.

Air↗
PubMed2004

Effect of atmospheric precipitation on the dissolved loads of the Dongjiang River, China.

The atmospheric precipitation plays an important role in influencing the river chemistry of the Dongjiang River. The atmospheric contribution to river water is estimated by reference to Cl concentration called Clref. The Clref of 41.97 micromol/L represents the highest chloride concentration of the rainwater inputs to river water, thus sea salts are responsible for total Cl concentration of the Dongjiang River. According to the principal compositions of precipitation and river water, two approaches-sea salt correction and precipitation correction were proposed in order to correct the contribution proportions of atmospheric precipitation on the solutes and to calculate chemical weathering rate. The results reflected that the atmospheric contribution ratios fluctuate from approximately 5% to approximately 20% of TDS (total dissolved solids) in the Dongjiang River. As compared with the other world watersheds, the lower dissolved ion contents and high runoff may result in the obvious influence of precipitation on river chemistry in the Dongjiang basin. The major elemental chemistry is mainly controlled by silicate weathering, with the anion HCO3- and cation Ca2+ and Na+ dominating the major compositions in this basin. The estimated chemical weathering rate of 15.78-23.48 t/(km2 x a) is only 40%-60% of a global average in the Dongjiang basin. Certainly, the estimated results are still under correction gradually because the effect of human activities on the precipitation chemistry has never been quantified in detail.

China↗
PubMedDate not supplied

[Seasonal dynamics of atmospheric methane oxidation in gray forest soils].

Seasonal fluctuations in the methane flow in the soil-atmosphere system were determined for gray forest soils of Central Russia. Consumption of atmospheric methane was found to exceed methane emission in gray forest soils under forest and in agrocenosis. The average annual rates of atmospheric methane consumption by the soil under forest and in agrocenosis were 0.026 and 0.008 mg CH4-C/(m2 h), respectively. The annual rate of atmospheric methane oxidation in the gray forest soils of Moscow oblast was estimated to be 0.68 kton. Seasonal fluctuations in the methane oxidation activity were due to changes in the hydrothermal conditions and in the reserves of readily decomposable organic matter and mineral nitrogen, as well as to changes in the activity of methane oxidizers.

Air↗
PubMed2004

[Preliminary study on HOx photochemical processes in urban atmosphere of Guangzhou City].

Simultaneous measurements of atmospheric hydroxyl radicals (OH) and other pollutants in Guangzhou city were carried out in July, 2000. The quantitative analysis of HOx reaction cycle during daytime in summer was made. The calculation results indicated that the total production rates of OH and HO2 were about 4.5 x 10(8) OH/(cm3 x s) and 3.8 x 10(8) HO2/(cm3 x s), respectively. The primary OH source in urban atmosphere was the photolysis of HONO, while the main OH sinks were the reactions of OH with VOCs, HCHO, NO2 and CO. The HOx chemistry in urban atmosphere is quite different from that in the remote clean atmosphere.

Air Pollutants↗
PubMed1997

[The development of a gas chromatograph used in gas analysis below atmospheric pressure].

During the process of setting up a carbon monoxide infrared laser generator, it's necessary to analyze the gaseous components produced in laser cavity under reduced pressure for understanding its charging regularity. In this paper a self-made gas chromatograph for analysis of some special gas mixtures is described. This instrument can analyze O2, N2, CO (with normal contents) and trace CO2 simultaneously below atmospheric pressure. The gas sample below atmospheric pressure was taken into a small piston cylinder and then compressed by pushing the piston for injection. The injected sample was carried by He into two parallel chromatographic columns and detected separately. The gases with normal contents were detected by a thermalconductivity detector (TCD) and the trace CO2 was detected by a He ionization detector (HeID). The detection sensitivity of CO2 is in the order of magnitude of 10(-6) V/V. The experimental results show that this instrument with advantages of simple design, easy operation and good stability is suitable for on-line analysis of gas samples below atmospheric pressure. We have successfully analyzed on-line the gaseous components produced in the laser cavity by using this equipment. The technique described here can be used for complete analysis of gas samples below atmospheric pressure in many other fields.

English Abstract↗
PubMed2006

Distribution of hydrogen, oxygen and carbon isotopes in the atmosphere of Croatia and Slovenia.

Monitoring of isotope distribution in the atmosphere included isotopes 2H, 3H and 18O in precipitation, and 13C and 14C in atmospheric CO2. This paper presents the results of atmospheric monitoring over Croatia and Slovenia overt the last few years. Monthly precipitations in Zagreb and Ljubljana had been collected since 1976 and 1981, respectively. Between 2000 and 2003 monitoring also included seven stations along the Adriatic coast. Tritium activity in precipitation shows seasonal variations that were most pronounced inland (at the continental stations Zagreb and Ljubljana) and were the smallest in the south Adriatic (Komiza and Dubrovnik). Mean annual tritium activity decreases from the north to the south Adriatic coast. Seasonal variations in delta2H and delta18O in precipitation follow the temperature variations at the sampling stations. Atmospheric CO2 was collected in Zagreb and Plitvice as a composite monthly sample. Both delta14C and delta13C showed seasonal variations. The mean annual 14C activities in Zagreb had been decreasing after the peak reached in the 1960s, and for the last three years the mean 14C activity (delta14C) remained about 30 per thousand.

Air↗
PubMedDate not supplied

[Atmospheric asbestos pollution in the urban environment: Milan, Casale Monferrato, Brescia, Ancona, Bologna and Florence].

The atmospheric concentrations of asbestos fibres were measured in 6 towns by long term sampling of air (3 weeks) and by counting at TEM both long and short fibres. Chrisotile and amphiboles were separately counted. For each town high traffic, low traffic and no traffic zones were considered as well as industrial areas and areas with possible and probable sources of asbestos pollution. For Milano the seasonal variations in atmospheric concentrations of asbestos fibres were also recorded in a central square. The maximum concentrations of total fibres was found in Milano (251.7 fibres/liter) and the minimum in Bologna (0.3 fibres/liter). Chrisotile and ultrashort fibres are the most frequent component of the atmospheric pollution. The fibre counts to which people is exposed are far below the levels at which it has been possible to detect risks in industry: however the possibility of a synergism between asbestos and other pollutants with consequent increase of the total carcinogenic potential of the polluted atmosphere cannot be ruled out. The control of the most active sources of asbestos dispersion must be considered in a correct balance between costs and social benefits.

Air Pollutants↗
PubMed2006

[Effect of elevated atmospheric O3 on arbuscular mycorrhizaL (AM) and its function].

In order to understand the possibility of AM in protecting crops from O3 pollution, simulated experiment was carried out to investigate effect of increased atmospheric O3 (0.02 microL x L(-1), 0.1 microL x L(-1) and 0.2 microL x L(-1)) on AM and its function. The results indicate that mycorrhizal colonization was slightly affected by elevated atmospheric O3, but spore and hypahe growth were significantly impacted. Spore number at high O3 level increased I times than that at ambient O3; hypahe length of AM at low and high O3 level decreased 48.7% and 85.6% than that at ambient O3, respectively. Root biomass, nodule number, horsebean pod and grain weight (excluding the treatment-- S + M) significantly decreased with elevated atmospheric O3, but they markedly increased after inoculation with AM fungi. Compared with the uninoculated treatment, nodule number increased by 2-5 times and grain weight of horsebean increased by 3-6 times after inoculation with AM fungi. Relative function of AM was slightly impacted by elevated atmospheric O3. Although indigenous microbes competed with inoculated AM fungi, inoculation with AM fungi could decrease the stress of O3 on plant, which was positive significant to alleviate crop loss resulted from O3 pollution.

Air Pollutants↗
PubMed1991

[Relationships between the pollen productions in sugi (Cryptomeria japonica D. Don) forests and the patterns of atmospheric scattering pollens in Toyama Prefecture--the example of Toyama Prefecture in 1990].

We investigated the geographical distribution of sugi (Cryptomeria Japonica D. Don) forests and the male flower-setting conditions of them in Toyama prefecture. The relationships between our findings and the atmospheric pollen scattering patterns were also studied. The results were as follows. 1. Atmospheric pollen counts and their scattering patterns were fairly easily explained by the geographical distribution of 30-year old sugi forests, the male flower-setting conditions and the first day pollen was scattered in those forests. 2. Total atmospheric counts and maximum sugi pollen peaks were significantly affected by the proximity of sugi forests at altitudes of less than 200 meter. 3. In the atmospheric pollen survey, the detected pollen counts decreased according to the distance between the observation sites and the sugi forests. And few pollen grains were observed from natural sugi forests growing at distances of 20 km to 30 km from the observation sites.

Air↗
PubMed1976

Survival of anaerobic bacteria during transportation. 1. Experimental investigations on the effect of evacuation of atmospheric air by flushing with carbon dioxide and nitrogen.

The effect of evacuation of atmospheric air during transportation on recovery of anaerobic bacteria was investigated. Evacuation of atmospheric air from glass tubes by flushing with pure carbon dioxide lowered the content of oxygen to about 0.4 per cent. Three B. fragilis strains and one strain of Fusobacterium mortiferum and of Peptostreptococcus anaerobius were investigated. Bacterial recovery was determined one hour and 24 hours after evacuation of atmospheric air by pure carbon dioxide and pure nitrogen, was compared to bacterial recovery from samples transported with free access to atmospheric air. Evacuation by pure carbon dioxide significantly improved the recovery of one B. fragilis strain after 24 hours of transportation and significantly impaired the recovery of Peptostreptococcus anaerobius after one hour of transportation, while evacuation by pure nitrogen significantly improved the recovery of Peptostreptococcus anaerobius after 24 hours of transportation. In all other cases, however, no statistically significant effect on bacterial recovery was found.

Air↗
PubMed1983

[Atmospheric pollution. Biological aspects and role of meteorologic factors in the distribution of respiratory hazards in the environment and relative prognostic and preventive measures].

The biometeorological factors underlying atmospheric pollution are discussed, together with its biological effects and its direct and indirect damage to human health. Damage is particularly likely when particularly adverse ambient and climatological conditions result in a massive and persistent concentration of contaminants in the ambient air. In this case, since the highly biologically interesting phenomenon of physicochemical reaction between pollutants and atmospheric components prevails over that of the dilution and dispersion of such contaminants, nature's major processes of removal and self-purification may be rendered nugatory and insufficiently prompt. The effects of atmospheric pollution, primarily with respect to urban background pollution, on human health make their appearance in the respiratory system, where there is a continuous relation between man and his environment throughout his life, in the form of immediate or short, medium and long-term damage. The desirability of preparing a meteorological map showing the distribution of the risk of atmospheric pollution is discussed. For this purpose, use could be made of meteorological data, and the hi-tech observations now made possible, inter alia, by the employment of satellites and aerospace data. A map of this kind would give more precise information concerning the part played by the weather in distributing the risk of respiratory damage caused by environmental pollution. It would also provide the knowledge required for the purpose of prediction and prevention in an organised struggle against such pollution. This would be of great social significance and value. Its practical applications could be enormous consequence to humanity.

Air Pollutants↗
PubMed1978

[Preservation of meats in a controlled atmosphere].

Commercializing meat sets problems more particularly connected with its organoleptic and microbiological qualities. As these qualities, resulting from biochemical and microbial effects, develop during the storage, the conditioning must precisely help their controlling. After examining their factors, the Author analyses the processes of conditioning which he classifies in three categories according to the techniques used and the desired finality (need to store at -1 degree C + 3 degrees C). 1. Conditioning under a steam-proof and gas pervious (O2-CO2) film. Composition of the internal atmosphere permanently close to that of the normal atmosphere. No change in the bright red colouring at the surface (oxymyoglobin). Microbial growth slowed down by refrigeration. Limited storage (a few days). Comminuted meat trade. 2. Conditioning under a totally steam--and gas--proof film. Internal atmospheric air under reduced volume and pressure ("vacuum-packed" meats). Internal changes during the storage: reduced rate O2; increased rate CO2 (cellular and microbial respirations). Surface becoming darker (absence of oxymyoglobin). Growth of the germs arrested (pathogenic and spoilage). However development of microaerophilic and acidophilic germs (in particular the lactic B.). Storage possibly extended to 8 weeks. Re-apparition of the red colour after oxygenation (opened package). Wholesale meat trade. 3. Conditioning under a film with properties close to that of (2 degrees). Initial constitution of an internal "artificial" atmosphere increased in O2 and CO2 (gas injection). No change in the bright red colouring (oxymyoglobin). Growth of the germs arrested (pathogenic and spoilage). Selection of an acidophilic aerobic flora including lactic B. and microbacterium. Storage until 12-15 days. Comminuted meat trade.

Carbon Dioxide↗
PubMed1994

[Amount of mercury from dental amalgam filling released into the atmosphere by cremation].

Mercury in dental amalgam filling is released into the atmosphere by cremation and is a suspected source of mercury pollution. The amount of mercury released was measured at three crematoriums. First, mercury levels in the atmosphere were measured. Mercury existed mainly in the gaseous form in ambient air. The concentration of atmospheric mercury at the three crematoriums (S, T and M) ranged from 4.3 to 19.7ng/m3, which was nearly identical to levels in our university surveyed as the control area and also to the levels of atmospheric mercury in general in Japan. Secondly, the amount of mercury release from T crematorium was estimated using official published statistical data in Japan and calculated as follows: sigma[(age specific number of dead that were cremated) x (the number of restored teeth by age category) x (mercury content per amalgam filling (0.6 g))] x (prevalence rate of restoration with amalgam). The amount of mercury released from this crematorium was estimated to be approximately 9.4 kg per year, or a daily release of 26 g into the ambient air. These results indicate that mercury release by cremation is similar to that from other man-made sources.

Air Pollutants↗
PubMed1996

Atmospheric stability and the dispersion of pesticides.

Applicators have long recognized that temperature inversions dramatically influence the behavior of pesticide material released into the atmosphere during pesticide application. This behavior can be explained in terms of the relationship between vertical atmospheric temperature gradients (stability) and atmospheric mixing (turbulence). This relationship is not intuitively obvious, but once it is understood, it provides the applicator with a tool to use for anticipating pesticide drift potential. The term inversion is synonymous with a stable thermal layer in the atmosphere. In stable thermal layers, mixing is suppressed and both dispersion and translation (or mean movement) of material is slow. This is typical of clear nights. Conversely, under clear, sunny conditions mixing is strong and dispersion is rapid. This situation indicates an unstable thermal layer.

Humidity↗
PubMed1997

[Comparison of predictive methods of Sugi (Cryptomeria) atmospheric pollen counts using mean temperature, solar radiation and male flowering index--an example of Toyama Prefecture].

The previous years mean temperature of July, total solar radiation of July and August and the male flowering index were used to predict atmospheric pollen counts. We examined the adaptability of these predictions and we get following results: 1. Following good harvest years of male flower, atmospheric pollen counts predicted by previous year's mean temperature of July and the total solar radiation of July and August are higher than the actual atmospheric pollen count. 2. Prediction of atmospheric pollen counts by factors within the previous five years are more exact because matured Cryptomeria forests are increasing yearly. 3. There are few errors in prediction by the flowering index because the flower index reflects the actual harvest of male flower.

Air↗
PubMedDate not supplied

Unique behavior of rubidium in mice under low oxygen atmosphere. Simultaneous tracing of Sc, Mn, Fe, Co, Zn, Se, Rb, Y, and Zr using off radioactive multitracer technique.

Relative tissue distributions of Sc, Mn, Fe, Co, Zn, Se, Rb, Y, and Zr tracers were studied in young mice housed under four different O2 atmospheres (10 percent, 20 percent, 80 percent, and 100 percent O2) using the radioactive multitracer technique developed at The Institute of Physical and Chemical Research (RIKEN). At 48 hr after injection of the multitracer, the tissue uptake rates were examined for 10 tissues (brain, cardiac muscle, lung, liver, spleen, pancreas, kidneys, skeletal muscle, bone, and blood) and expressed as the radioactivity percentage of the injected dose per gram of wet tissue (percent dose/g). Rubidium uptake rates for all soft tissues of mice housed under a 10 percent O2 atmosphere were found to be higher than those of the tissues of mice housed under the other three O2 atmospheres (20 percent, 80 percent, and 100 percent), but no difference was observed for the other elements (Sc, Mn, Fe, Co, Se, etc.) under any of the O2 atmospheres.

Animals↗
PubMed1998

[Experimental studies of the effects of atmospheric pollutants].

Experimental studies in man are an indispensable complement to epidemiological studies and experimental studies on animals. They aim at understanding the mechanisms of action of the main pollutants and at knowing their thresholds of triggering of the acute effects on the respiratory system. The studies made in man involve controlled exposure to different atmospheric pollutants, with measurement of the functional respiratory repercussions, studies of modification of the cells in broncho-alveolar lavage, as well as experimental protocols that combine inhalation of allergen and exposure to atmospheric pollutants by allergic subjects. The main results that are available are reported to distinguish those from normal subjects and those who are allergic. More recent protocols are based on exposure to concentrations that are close to atmospheric concentrations or those that are met in work places. The main data in the literature are reported in this journal and concern SO2 acid aerosols, dioxides of nitrogen, ozone and diesel particles. Pathogenic hypotheses concerning the undesirable effects of atmospheric pollutants on the respiratory system are considered.

Aerosols↗
PubMed1992

Minor constituents in the Martian atmosphere from the ISM/Phobos experiment.

Global Martian atmospheric results derived from the infrared imaging spectrometer ISM flown aboard the Phobos 2 Soviet spacecraft are presented. Over low altitude regions the expected CO mixing ratio of (8 +/- 3) x 10(-4) is measured. Variations of the 2.35-micrometers feature are inconsistent with this value over the Great Martian Volcanoes. If the 2.35-micrometers band is entirely attributable to carbon monoxide, the CO mixing ratio is typically depleted by a factor of 3 over these high altitude areas. Orography should play a major role in the existence of this CO "hole." If, however, these spectral variations at 2.35 micrometers are due to the surface composition, the fraction of the surface covered by the responsible mineral must smoothly decrease as the surface elevation decreases. This phenomenon implies a strong interaction between the surface and the atmosphere for the Great Martian Volcanoes. Diurnal behavior and latitudinal variations of water vapor are globally consistent with Viking measurements. During the Phobos observations, the water vapor amounts over the bright equatorial regions range around 11 pr-micrometers during the day. These amounts are slightly larger than those inferred from 1976 to 1979. The lack of global dust storms during 1988-1989 could explain the enhancement of H2O in the atmosphere.

Astronomy↗