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891.
Thuan-Quoc Thach Chit-Ming Wong King-Pan Chan Yuen-Kwan Chau G. Neil Thomas Chun-Quan Ou Lin Yang Joseph S.M. Peiris Tai-Hing Lam Anthony J. Hedley 《Atmospheric environment (Oxford, England : 1994)》2010,44(11):1437-1442
We assessed confounding of associations between short-term effects of air pollution and health outcomes by influenza using Hong Kong mortality and hospitalization data for 1996–2002.Three measures of influenza were defined: (i) intensity: weekly proportion of positive influenza viruses, (ii) epidemic: weekly number of positive influenza viruses ≥4% of the annual number for ≥2 consecutive weeks, and (iii) predominance: an epidemic period with co-circulation of respiratory syncytial virus <2% of the annual positive isolates for ≥2 consecutive weeks. We examined effects of influenza on associations between nitrogen dioxide (NO2), sulfur dioxide (SO2), particulate matter with aerodynamic diameter ≤10 μm (PM10) and ozone (O3) and health outcomes including all natural causes mortality, cardiorespiratory mortality and hospitalization. Generalized additive Poisson regression model with natural cubic splines was fitted to control for time-varying covariates to estimate air pollution health effects. Confounding with influenza was assessed using an absolute difference of >0.1% between unadjusted and adjusted excess risks (ER%).Without adjustment, pollutants were associated with positive ER% for all health outcomes except asthma and stroke hospitalization with SO2 and stroke hospitalization with O3. Following adjustment, changes in ER% for all pollutants were <0.1% for all natural causes mortality, but >0.1% for mortality from stroke with NO2 and SO2, cardiac or heart disease with NO2, PM10 and O3, lower respiratory infections with NO2 and O3 and mortality from chronic obstructive pulmonary disease with all pollutants. Changes >0.1% were seen for acute respiratory disease hospitalization with NO2, SO2 and O3 and acute lower respiratory infections hospitalization with PM10. Generally, influenza does not confound the observed associations of air pollutants with all natural causes mortality and cardiovascular hospitalization, but for some pollutants and subgroups of cardiorespiratory mortality and respiratory hospitalization there was evidence to suggest confounding by influenza. 相似文献
892.
S.R. Utembe M.C. Cooke A.T. Archibald M.E. Jenkin R.G. Derwent D.E. Shallcross 《Atmospheric environment (Oxford, England : 1994)》2010,44(13):1609-1622
A reduced chemical scheme (CRIv2-R5) which describes ozone formation from the tropospheric degradation of methane and 22 emitted non-methane hydrocarbons and oxygenated volatile organic compounds has been applied in a global-3D chemistry transport model (STOCHEM). The scheme, which contains 220 species in 609 reactions, has been used to simulate ozone and its precursors for the meteorological year of 1998 and the results have been compared with those from STOCHEM runs with its original chemistry. Compared with the original chemistry scheme, the degradation of a larger number of more reactive VOCs in the CRI scheme results in the formation (and their consequent transportation) of more NOx active reservoirs thus leading to formation of more ozone away from land-based sources. Conversely, the more reactive VOCs also lead to greater removal of OH in continental areas and greater formation of OH in marine environments. STOCHEM run with the CRI scheme simulates more ozone (by up to 10 ppb), which results in better agreement with observed vertical ozone profiles. The CRI scheme transforms the globally and annually integrated ozone budget for the considered year in STOCHEM from a net loss of ?55 Tg yr?1 to a net gain of +50 Tg yr?1. 相似文献
893.
T.M. McIntire O.S. Ryder P.L. Gassman Z. Zhu S. Ghosal B.J. Finlayson-Pitts 《Atmospheric environment (Oxford, England : 1994)》2010,44(7):939-944
It is commonly assumed that atmospheric oxidation of hydrocarbon particles or hydrocarbon coatings on particles leads to polar products and increased water uptake, altering atmospheric visibility and increasing the likelihood they will act as cloud condensation nuclei (CCN). We show here through laboratory experiments that increased water uptake depends on the 3-dimensional structure of the particles. Laboratory studies of particles formed during ozonolysis of surface-bound alkenes, present as terminally unsaturated self-assembled monolayers (C8= SAM) on a silica substrate, were carried out at room temperature and 1 atm pressure. SAMs were exposed to ~1013 O3 molecules cm?3 for 40 min and resultant particles were analyzed using single particle Fourier transform infrared micro-spectroscopy (micro-FTIR) and secondary ion mass spectroscopy (SIMS). Spectroscopy results show that –COOH and other polar groups are formed but are buried inside a hydrophobic shell, consistent with earlier observations (McIntire et al., 2005, Moussa et al., 2009) that water uptake does not increase after reaction of the terminal alkene with O3. These insights into the 3-D structure of particles formed on oxidation have important implications for the ability of secondary organic aerosols to act as CCN. In addition, the nature of the surface of the particles is expected to determine their uptake into biological systems such as the surface of the lungs. 相似文献
894.
B. Miljevic K.E. Fairfull-Smith S.E. Bottle Z.D. Ristovski 《Atmospheric environment (Oxford, England : 1994)》2010,44(18):2224-2230
Reactive oxygen species (ROS) and related free radicals are considered to be key factors underpinning the various adverse health effects associated with exposure to ambient particulate matter. Therefore, measurement of ROS is a crucial factor for assessing the potential toxicity of particles. In this work, a novel profluorescent nitroxide, BPEAnit, was investigated as a probe for detecting particle-derived ROS. BPEAnit has a very low fluorescence emission due to inherent quenching by the nitroxide group, but upon radical trapping or redox activity, a strong fluorescence is observed. BPEAnit was tested for detection of ROS present in mainstream and sidestream cigarette smoke. In the case of mainstream cigarette smoke, there was a linear increase in fluorescence intensity with an increasing number of cigarette puffs, equivalent to an average of 101 nmol ROS per cigarette based on the number of moles of the probe reacted. Sidestream cigarette smoke sampled from an environmental chamber exposed BPEAnit to much lower concentrations of particles, but still resulted in a clearly detectible increase in fluorescence intensity with sampling time. It was calculated that the amount of ROS was equivalent to 50 ± 2 nmol per mg of particulate matter; however, this value decreased with ageing of the particles in the chamber. Overall, BPEAnit was shown to provide a sensitive response related to the oxidative capacity of the particulate matter. These findings present a good basis for employing the new BPEAnit probe for the investigation of particle-related ROS generated from cigarette smoke as well as from other combustion sources. 相似文献
895.
S. Alfieri U. Amato M.F. Carfora M. Esposito V. Magliulo 《Atmospheric environment (Oxford, England : 1994)》2010,44(15):1866-1876
Quantifying trace gas emissions and the influence of surface exchange processes on the atmosphere is a necessary step towards the control of global greenhouse gas emissions and reliability of air quality models. This paper proposes a procedure based on the mass balance method and implemented on highly resolved aircraft data. It allows one to estimate surface exchanges on areas of several km2 and heterogeneous features exploiting the characteristics of convective boundary layer during steady state conditions that permit the estimation of emission/absorption terms as functions of advective fluxes only. A nonparametric approach is adopted and the fluxes on the surface of a virtual box surrounding the area of interest are reconstructed on the basis of scalar densities and wind vectors using Shepard functions. Two different techniques are also proposed to face lack of data on the top surface of the box. The method has been applied to experimental data coming from measurement campaigns on two different sites. It provides realistic estimates of the CO2 emission/absorption in the considered areas that are in good agreement with CO2 fluxes evaluated by Airborne Eddy Covariance and confirm the suitability of the proposed approach for the assessment of turbulent exchange of trace gases by composite landscapes. Uncertainties on the estimated emissions due to both propagation of the experimental error and interpolation have been quantified by bootstrap analysis as 6%. 相似文献
896.
897.
The effect of invertebrate predation pressure by the cladoceran Leptodora kindti on the population structure of Daphnia galeata and D. hyalina has been estimated by analyzing the occurrence frequency of the normal and spined morphotypes in Lake Baikal. It is shown
that the growth of L. kindti population density leads to an increase in the proportion of the spined morphotype, while that of that of the normal morphotype
decreases. 相似文献
898.
Distribution of 238U and 226Ra in soils and plants of an industrially polluted area are considered. The dependence between the biological uptake coefficients
(BUCs) for the plant species studied and the radionuclide concentrations in soil can be approximated by a decreasing power
function. Species differences in radionuclide uptake are demonstrated. 相似文献
899.
V. N. Orlov Yu. M. Borisov S. Yu. Irkhin A. A. Kovaleva 《Russian Journal of Ecology》2010,41(6):519-523
The distribution of three chromosome races (Moscow, Western Dvina, and Seliger) of the common shrew Sorex araneus L. in the zone of contact between their ranges in the Valdai Heights (32°00′ E, 57°00′ N) is discussed. The area co-inhabited
by all the three races is extremely small. Representatives of all the three races have been captured on only one trap line,
although there are no obstacles to the expansion of shrews. The extremely small area co-inhabited by the three races, as well
as the strictly parapatric distribution of the Moscow and Western Dvina races, may be related with competition forms such
as avoidance of contacts and separation of ecological niches. 相似文献
900.
James W. Rivers Philip S. Gipson Donald P. Althoff Jeffrey S. Pontius 《Environmental management》2010,45(2):203-216
Military training activities are known to impact individual species, yet our understanding of how such activities influence
animal communities is limited. In this study, we used long-term data in a case study approach to examine the extent to which
the local small landbird community differed between a site in northeast Kansas that experienced intensive disturbance from
military training activities (Ft. Riley Military Installation) and a similar, nearby site that experienced minimal human disturbance
(Konza Prairie Biological Station). In addition, we characterized how the regional pool of potential colonizers influenced
local community dynamics using Breeding Bird Survey data. From 1991 to 2001, most species of small terrestrial landbirds (73%)
recorded during breeding surveys were found at both sites and the mean annual richness at Ft. Riley (39.0 ± 2.86 [SD]) was
very similar to that of Konza Prairie (39.4 ± 2.01). Richness was maintained at relatively constant levels despite compositional
changes because colonizations compensated local extinctions at both sites. These dynamics were driven primarily by woodland
species that exhibited stochastic losses and gains and were present at a low local and regional abundance. Our results suggest
that military training activities may mimic natural disturbances for some species in this area because the small landbird
community did not differ markedly between sites with and sites without extensive human disturbance. Although our results suggest
that military training is not associated with large changes in the avian community, additional studies are needed to determine
if this pattern is found in other ecological communities. 相似文献