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PubMed2006

Evaluating effects of wind-induced pressure fluctuations on soil-atmosphere gas exchange at a landfill using stochastic modelling.

The impact of wind turbulence-induced pressure fluctuations at the soil surface on landfill gas transport and emissions to the atmosphere at an old Danish landfill site was investigated using stochastic modelling combined with soil property and gas transport data measured at the site. The impacts of soil physical properties (including air permeability and volumetric water content) and wind-induced pressure fluctuation properties (amplitude and temporal correlation) on landfill gas emissions to the atmosphere were evaluated. Soil-air permeability and pressure fluctuation amplitude were found to be the most important parameters. Wind-induced gas emissions were further compared with gas emissions caused by diffusion and by long-term pressure variations (due to passing weather systems). Here diffusion and wind-induced gas transport were found to be equally important with wind-induced gas transport becoming the most important at lower soil-air contents.

Air Pollutants↗

PubMed2005

Review of atmospheric water-soluble ionic species in Asia during 1998-2001.

Anthropogenic acid precursor emissions in Asia are increasing at a significant rate and this is expected to continue for the next several years. This paper comprises of studies that included sulfate, nitrate and ammonium around Asian countries (China, Korea, Japan and Taiwan) in recent years. The paper also provides the water-soluble ionic fine and coarse particulate concentrations in these Asian countries in recent years. Fine and coarse particulates in Taiwan (Kaohsiung and Talchung) and China (Nanjing and Shanghai) were found to have higher sulfate (average 18.68 and 15.75 microg/m3) and nitrate (average 12.77 and 7.71 microg/m3) concentrations than any other Asian country. The average sulfate concentrations for Japan and Korea were 7.31 and 5.84 microg/m3, respectively. The average nitrate concentrations for Japan and Korea were 6.73 and 4.65 microg/m3, respectively during the years 1998-2001. The different sample collection devices, analysis methods and pollutant concentrations are discussed in this study. The purpose of this study is to arrange the atmospheric water-soluble ionic species (SO4(2-) and NO3) investigations in the Asian region. The data obtained here can also help to understand the sources, concentrations, phase distribution and health impact of atmospheric water-soluble ionic species (SO4(2-) and NO3-) in other Asian regions.

Asia↗

PubMed1997

The influence of surface atmospheric conditions on the range and area reached by animal vocalizations.

Low-level vertical changes in temperature and wind exert powerful and predictable influences on the area ensonified by animal vocalizations. Computer modelling of low-frequency sound propagation in measured atmospheric conditions predicts that the calls of the savanna elephant at these frequencies can have ranges exceeding 10 km and that the calls will be highly directional in the presence of wind shear. Calling area is maximized under temperature inversions with low wind speeds. Calling area changes substantially over 24 h periods; on any given day, the calling area undergoes an expansion and contraction which may be as large as one order of magnitude. This cycle is modulated by topography, regional weather patterns, seasonality and possibly by climate variation. Similar influences affect the somewhat higher-frequency calls of lions and may be a selective pressure towards their crepuscular and nocturnal calling behaviour. Coyotes and wolves, which also live in areas with strong and prevalent nocturnal temperature inversions, show similar calling patterns, maximizing their chances of being heard over the longest possible distances. The pronounced dawn and evening vocalization peaks in other animals including birds, frogs and insects may reflect the same influences in combination with other factors which selectively limit high-frequency sound propagation. Atmospheric conditions therefore need to be taken into account in many field studies of animal behaviour. A simplified method for estimating sound propagation during field studies is presented.

Animals↗

PubMed2006

Interaction of the onset of spring and elevated atmospheric CO2 on ragweed (Ambrosia artemisiifolia L.) pollen production.

Increasing atmospheric carbon dioxide is responsible for climate changes that are having widespread effects on biological systems. One of the clearest changes is earlier onset of spring and lengthening of the growing season. We designed the present study to examine the interactive effects of timing of dormancy release of seeds with low and high atmospheric CO2 on biomass, reproduction, and phenology in ragweed plants (Ambrosia artemisiifolia L.), which produce highly allergenic pollen. We released ragweed seeds from dormancy at three 15-day intervals and grew plants in climate-controlled glass-houses at either ambient or 700-ppm CO2 concentrations, placing open-top bags over influorescences to capture pollen. Measurements of plant height and weight; inflorescence number, weight, and length; and days to anthesis and anthesis date were made on each plant, and whole-plant pollen productivity was estimated from an allometric-based model. Timing and CO2 interacted to influence pollen production. At ambient CO2 levels, the earlier cohort acquired a greater biomass, a higher average weight per inflorescence, and a larger number of influorescences; flowered earlier; and had 54.8% greater pollen production than did the latest cohort. At high CO2 levels, plants showed greater biomass and reproductive effort compared with those in ambient CO2 but only for later cohorts. In the early cohort, pollen production was similar under ambient and high CO2, but in the middle and late cohorts, high CO2 increased pollen production by 32% and 55%, respectively, compared with ambient CO2 levels. Overall, ragweed pollen production can be expected to increase significantly under predicted future climate conditions.

Ambrosia↗

PubMed1991

Global atmospheric changes.

Increasing concentrations of CO2 and other greenhouse gases in the atmosphere can be directly related to global warming. In terms of human health, because a major cause of increasing atmospheric concentrations of CO2 is the increased combustion of fossil fuels, global warming also may result in increases in air pollutants, acid deposition, and exposure to ultraviolet (UV) radiation. To understand better the impacts of global warming phenomena on human health, this review emphasizes the processes that are responsible for the greenhouse effect, air pollution, acid deposition, and increased exposure to UV radiation.

Acid Rain↗

PubMed2004

Characterization of atmospheric aerosols from infrared measurements: simulations, testing, and applications.

An inversion method for the characterization of atmospheric condensed phases from infrared (IR) spectra is described. The method is tested with both synthetic IR spectra and the spectra of particles that flow in a cryogenic flow tube. The method is applied to the IR spectra recorded by the Atmospheric Trace Molecule Spectroscopy instrument carried by the Space Shuttle during three missions in 1992, 1993, and 1994. The volume density and particle size distribution for sulfate aerosol are obtained as a function of altitude. The density and size distribution of ice particles in several cirrus clouds are also retrieved. The probable radius of the ice particles in the high-altitude (10-15-km) cirrus clouds is found to be approximately 6-7 microm.

Aerosols↗

PubMed2005

Off-axis cavity ringdown spectroscopy: application to atmospheric nitrate radical detection.

Atmospheric nitrate radicals (NO3) are detected using off-axis cavity ringdown spectroscopy (CRDS) for the first time to our knowledge with a room-temperature continuous-wave (cw) diode laser operating near 662 nm. A prototype instrument was constructed that achieved a 1sigma absorption sensitivity of 5 x 10(-10) cm(-1) Hz(-1/2), corresponding to a 1.4 part per trillion by volume 2sigma detection limit in 4.6 s at 80 degrees C. This sensitivity is a significant improvement over a recent implementation of off-axis cavity-enhanced absorption spectroscopy and comparable to that of the most advanced cw CRDS and pulsed CRDS applications for atmospheric detection of NO3. A comparison of measurements of ambient air in Fairbanks, Alaska, recorded with the off-axis CRDS instrument and a previously characterized conventional cw CRDS instrument showed good agreement (R2 = 0.97).

Air Pollutants↗

PubMed2005

Spectroscopic characterization of two different microwave (2.45 GHz) induced argon plasmas at atmospheric pressure.

A surface-wave-sustained discharge created by using a surfatron device in a tube open to the atmosphere can be used to maintain a microwave (2.45 GHz) plasma at atmospheric pressure at powers of less than 300 W. The TIA (Torche a Injection Axiale) is a device also producing a plasma that, moreover, permits us to work at high power (higher than 200 W and up to 1000 W). A study of the departure from the thermodynamic equilibrium existing in the argon plasmas created by both devices has been done by using optical emission spectroscopy techniques in order to characterize them and to evaluate their possible advantages when they are used for applied purposes.

Argon↗

PubMed1990

Increased release of the N-terminus of the atrial natriuretic factor prohormone with increasing absolute atmospheres of pressure in a hyperbaric chamber and reversal with oxygen therapy.

Increasing atmospheres of absolute pressure (ATA) on the cardiopulmonary system results in a marked diuresis. The present investigation was designed to determine if the diuresis observed with increasing ATA is associated with increased release of the N-terminus of the atrial natriuretic factor (ANF) prohormone that contains two potent diuresis-producing hormones consisting of amino acids (aa) 1-30 (pro ANF 1-30; long-acting sodium stimulator) and aa 31-67 (pro ANF 31-67; vessel dilator) of this 126 aa prohormone. Seven healthy volunteers (mean age, 31 years) had the circulating concentration of the N-terminus of the ANF prohormone evaluated at 1, 2, and 3 ATA in a monoplace hyperbaric chamber by two specific and sensitive radioimmunoassays that immunologically recognize (1) the whole 98 aa N-terminus and (2) the midportion of the N-terminus consistent with aa 31-67 (pro ANF 31-67). With increasing ATA from 1 (sea level) to 2 (equivalent to 33 feet of sea water), the circulating concentrations of both the whole N-terminus and pro ANF 31-67 increased threefold. At 3 ATA (66 feet of sea water), their circulating concentrations increased sixfold over their concentrations, at 1 ATA. With the addition of 100 percent O2 while at 3 and 2 ATA, the circulating concentrations of both the whole N-terminus and pro ANF 31-67 immediately decreased to their prehyperbaric ATA levels and remained there with further decompression to 1 ATA and removal of O2 supplementation. The increased circulating concentration of the N-terminus of the ANF prohormone containing two peptides with potent diuretic effects during increasing atmospheres of absolute pressure may help to explain the diuresis that has been observed with increasing ATA.

Adult↗

PubMed1994

Analysis of toxic gas produced by heating tar epoxy resin paint to assess work atmosphere.

Two male workers were acutely intoxicated with gas produced by heating tar epoxy resin paint, and developed peripheral neuropathy. To assess the work atmosphere, we analyzed the degradation products by GC-MS. The major toxic products emitted by heating tar epoxy resin were hydrogen cyanide, phenol, and benzene, as well as naphthalene. From 1 m2 of the surface of steel plates painted with tar epoxy resin, 2.4 g of hydrogen cyanide, 9.6 g of benzene, and 1.2 g of nephthalene were produced by heating at 1000 degrees C, At 700 degrees C, the amounts of phenol and p-isopropylphenol produced were 3.7 g and 0.57 g, respectively. Based on these results and the area of steel surface burned, the concentration of hydrogen cyanide, benzene, and phenol in the atmosphere of work environment was estimated to be 16, 64 and 24 mg/m3, respectively. Some of the symptoms of the workers including peripheral neuropathy might be related to the sole or cooperative action of the foregoing toxic chemicals mentioned above.

Adult↗

PubMed2006

Confirmation and efficacy tests against codling moth and oriental fruit moth in peaches and nectarines using combination heat and controlled atmosphere treatments.

Two high-temperature, forced air treatments under controlled atmosphere conditions, called CATTS for controlled atmosphere/temperature treatment system, were developed for control of all life stages of codling moth, Cydia pomonella (L.), and oriental fruit moth, Grapholita molesta (Busck), infesting peaches and nectarines (both Prunus spp.). These treatments were used in efficacy and confirmation tests to kill > 5,000 fourth instar oriental fruit moths and > 30,000 fourth instar codling moths with zero survivors. The treatments consist of linear heating rates of either 12 or 24 degrees C/h to a final chamber temperature under a 1% O2, 15% CO2, and > 90% RH atmosphere with air speed between 1.2 and 2.0 m/s. At a 12 degrees C linear chamber heating rate, treatment takes approximately 3 h to reach a final chamber temperature of 46 degrees C. The average lowest core temperatures of the fruit reached 43.8 degrees C within the last 30 min of the treatment. At a 24 degrees C linear chamber heating rate, it takes approximately 2.5 h to reach a final chamber temperature of 46 degrees C. The average lowest core temperatures of the fruit reached 44.6 degrees C for the last 15 min of the treatment. It also was determined that both treatments did not significantly alter the quality parameters that were evaluated to a degree that would have negatively influenced the marketability of the fruit. Positive benefits of treatment included a slower ripening of treated fruit and an inhibition of the loss of juiciness during storage in some cultivars. These treatments may be used to replacement to methyl bromide fumigation for conventional fruit or as a new treatment for organic fruit contingent upon importing country approval.

Animals↗

PubMed2006

Analytical functions to predict cosmic-ray neutron spectra in the atmosphere.

Estimation of cosmic-ray neutron spectra in the atmosphere has been an essential issue in the evaluation of the aircrew doses and the soft-error rates of semiconductor devices. We therefore performed Monte Carlo simulations for estimating neutron spectra using the PHITS code in adopting the nuclear data library JENDL-High-Energy file. Excellent agreements were observed between the calculated and measured spectra for a wide altitude range even at the ground level. Based on a comprehensive analysis of the simulation results, we propose analytical functions that can predict the cosmic-ray neutron spectra for any location in the atmosphere at altitudes below 20 km, considering the influences of local geometries such as ground and aircraft on the spectra. The accuracy of the analytical functions was well verified by various experimental data.

Algorithms↗

PubMed2005

Root exudation, phosphorus acquisition, and microbial diversity in the rhizosphere of white lupine as affected by phosphorus supply and atmospheric carbon dioxide concentration.

White lupine (Lupinus albus L.) was used as a phosphorus (P)-efficient model plant to study the effects of elevated atmospheric CO(2) concentrations on (i) P acquisition, (ii) the related alterations in root development and rhizosphere chemistry, and (iii) the functional and structural diversity of rhizosphere microbial communities, on a P-deficient calcareous subsoil with and without soluble P fertilization. In both +P (80 mg P kg(-1)) and -P treatments (no added P), elevated CO(2) (800 micromol mol(-1)) increased shoot biomass production by 20 to 35% and accelerated the development of cluster roots, which exhibit important functions in chemical mobilization of sparingly soluble soil P sources. Accordingly, cluster root formation was stimulated in plants without P application by 140 and 60% for ambient and elevated CO(2) treatments, respectively. Intense accumulation of citrate and increased activities of acid and alkaline phosphatases, but also of chitinase, in the rhizosphere were mainly confined to later stages of cluster root development in -P treatments. Regardless of atmospheric CO(2) concentrations, there was no significant effect on accumulation of citrate or on selected enzyme activities of C, N, and P cycles in the rhizosphere of individual root clusters. Discriminant analysis of selected enzyme activities revealed that mainly phosphatase and chitinase contributed to the experimental variance (81.3%) of the data. Phosphatase and chitinase activities in the rhizosphere might be dominated by the secretion from cluster roots rather than by microbial activity. Alterations in rhizosphere bacterial communities analyzed by denaturing gradient gel electrophoresis (DGGE) were related with the intense changes in root secretory activity observed during cluster root development but not with elevated CO(2) concentrations.

Atmosphere↗

PubMedDate not supplied

Atmospheric supply of trace elements studied by peat samples from ombrotrophic bogs.

Concentrations of Fe and 12 trace elements in peat from ombrotrophic bogs were used to estimate the atmospheric deposition of these elements on a temporal and spatial scale. Peat samples were collected at 21 different sites in Norway encompassing large geographical differences in marine influence and air pollution. The study demonstrates that surface peat is an excellent medium to study geographical differences in heavy metal deposition, provided that effects of the surface plant cover are properly considered. Long-range atmospheric transport of pollutants is the main source for As, Cd, Pb, Sb, and Zn, and to a lesser extent for Cu and Se. Biogenic emissions from the ocean appear to be the main source of Se to the peat. The metals Co, Cr, Fe, and Ni are mainly associated with wind-blown local soil dust. Surface enrichment of Mn, and in part Zn, is mainly caused by nutrient circulation between the surface peat and vascular plants growing on it. Deposition of marine salts appears to be the main reason for lower Mn concentrations in the peat near the coast.

Air Movements↗

PubMed1999

Effect of pH and CO2 on growth and toxin production by Clostridium botulinum in English-style crumpets packaged under modified atmospheres.

The effect of pH and CO2 on both growth of and toxin production by Clostridium botulinum in English-style crumpets, packaged under modified atmospheres was investigated using a 2 x 2 factorial experiment. English-style crumpets (water activity, 0.990; pH 6.5 and 8.3) were inoculated with C. botulinum spores types A and proteolytic B (500 spores/g), packaged in either 60% CO2 (balance N2) or 100% CO2, stored at ambient temperature (25 degrees C), and monitored daily for toxicity. Toxin was detected after 4 days in crumpets packaged in 60% CO2, irrespective of initial product pH. Toxin production was delayed 1.5 to 3 days in crumpets packaged under 100% CO2. Analysis of variance indicated a significant interaction effect of pH and %CO2 on time of earliest toxin detection. Delay of toxin production was greatest for high pH (8.3) crumpets. All products were organoleptically acceptable at the time of toxigenesis, and therefore, high moisture-high pH bakery products, if contaminated with spores of C. botulinum, could become hazardous if packaged in atmospheres containing CO2.

Atmosphere↗

PubMed2000

[Seasonal variation and influence of atmospheric pressure diurnal fluctuations on occurrence of acute complications in patients with stomach and duodenal ulcer].

Although there is rich literature concerning seasonal fluctuations of incidence of peptic ulcer, no one can find so many data on acute complications of this disease--bleedings and perforations. There is also only little information saying about the role of meteorological factors that can take part in occurrence of the mentioned complications. This study aimed to analyze the seasonal variation (in calendar months, quarters of the year and calendar seasons--winter, spring, summer, autumn) of peptic ulcer bleeding and perforations as well as the influence of atmospheric pressure diurnal fluctuations on the occurrence of these diseases. The conducted study was retrospective and based on data of patients admitted to III Department of General Surgery of the Jagiellonian University Medical School in Cracow. Altogether, from 1993 to 1997--26 patients with peptic gastroduodenal ulcer bleeding were admitted. 220 bleedings were endoscopically proven (6 patients did not agree for gastroscopy and were excluded from further analysis). 157 patients were treated because of peptic ulcer perforation at the same time and all of them underwent surgical procedure during which perforation was proven. The chi 2 test was used in order to verify our statistic hypothesis (p = 0.05). The examination did not show any significant seasonal variation of the studied complications. Neither hemorrhage nor perforation presented any seasonal prevalence. As for calendar months, quarters and calendar seasons (p > 0.01; p > 0.02; p > 0.02 respectively). However, the study confirmed the role of atmospheric pressure falls in the occurrence of both: bleeding and perforation of peptic ulcer (p < 0.001). 153 patients with bleeding were admitted on days with decreasing pressure, while 67 when pressure was going up. Similarly as for perforations--94 with falling down to 33 with growing up pressure.

Aged↗

PubMed2000

Photosynthetic acclimation to rising atmospheric carbon dioxide concentration.

With rising level of CO2 in the atmosphere plants are expected to be exposed to higher concentration of CO2. Since, CO2 is a substrate limiting photosynthesis particularly in C3 plants in the present atmosphere, the impact of elevated CO2 would depend mainly on how photosynthesis acclimates or adjusts to the long term elevated level of CO2. Photosynthetic acclimation is a change in photosynthetic efficiency of leaves due to long term exposure to elevated CO2. This change in photosynthetic efficiency could be a biochemical adjustment that may improve the overall performance of a plant in a high CO2 environment or it could be due to metabolic compulsions as a result of physiological dysfunction. Acclimation has generally become synonymous with the word response, if long term exposure to elevated CO2 decreases the photosynthesis rate (Pn) at a given CO2 level, it is called negative acclimation, if it stimulates Pn at a given CO2 level, it is called positive acclimation. Photosynthetic acclimation is clearly revealed by comparing Pn of ambient and elevated CO2 grown plants at same level of CO2. Species level differences in acclimation to elevated CO2 have been reported. The physiological basis of differential photosynthetic acclimation to elevated CO2 is discussed in relation to the regulation of photosynthesis and photosynthetic carbon partitioning at cellular level.

Adaptation, Physiological↗

PubMedDate not supplied

[Hypobaric nitrogen-oxygen atmosphere as a method of preventing altitude decompression sickness].

It has been shown experimentally that the development of altitude decompression disease at 250 and 180 mm Hg can be prevented by preliminary desaturation in the nitrogen-oxygen hypobaric atmosphere (60% N2 and 40% O2 at 550 mm Hg). This has been demonstrated in 38 experiments on 21 test subjects. The use of this atmosphere in space cabin prevents the development of decompression disease upon a decrease of the cabin pressure to 250 mm Hg and upon extravehicular activity in a space suit with 180--200 mm Hg.

Adult↗