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1.
《Atmospheric environment(England)》1983,17(7):1315-1329
This paper presents a mathematical model that describes the chemical composition and growth rate of atmospheric aerosols containing sulfate and nitrate, and that is applicable over the entire range of relative humidities. The model describes aerosols as consisting of an insoluble core, a soluble solid shell and an aqueous film. The chemical composition of the solid and aqueous aerosol phases in this model is governed by the following processes:
- 1.(1) the chemical equilibria between the ambient gas and the aerosol liquid phases and between the aerosol liquid and the soluble solid phases;
- 2.(2) the diffusion-limited condensation of H2SO4 and
- 3.(3) the liquid-phase chemical reaction of SO2. At low humidities the liquid phase may not be thermodynamically viable, in which case the model then treats the solid-phase/gas-phase equilibrium.
- 1.(1) precipitation of (NH4)2SO4 occurs at its point of deliquescence (i.e. at a relative humidity of close to 80%) even in the presence of other electrolytes;
- 2.(2) within the uncertainty of the thermodynamic data, the saturation products of NH3 and HNO3 for a liquid-coated aerosol and a dry aerosol are in agreement with each other;
- 3.(3) the aerosol concentrations correspond closely to (NH4) 2SO4 and NH4NO3 for both liquid and solid phases, i.e. NH4HSO4 is predicted to exist in negligible amounts under most conditions and
- 4.(4) the assumption of either an ideal internal mixture or an external mixture for dry sulfates and nitrate aerosols has little effect on model predictions.
2.
《Atmospheric environment(England)》1987,21(7):1623-1630
This paper is intended to be used by specialists engaged in air and precipitation quality management on regional and continental scales. Major goals are to establish definition, methodology and specific values of background air and precipitation quality for sulfur (S) and nitrogen (N) species to be used in practical applications of air resources management. Major findings are the following:
- 1.(a) 69% of SO2 and 63 % of NO2 concentration over Europe originate from continental scale anthropogenic sources,
- 2.(b) 15% of precipitation sulfate and 11% of precipitation nitrate over Europe are contributed by hemispheric background,
- 3.(c) hemispheric background pollution values for Europe were found as 1.25 μg (SO2-S)m−3, 0.80 μg (SO42−-S)m−3, 0.157 mg (SO42−-S)l−1 and 0.04 mg (NO3−-N)ℓ−1.
3.
《Atmospheric environment(England)》1986,20(6):1211-1215
In order to develop a diffusion denuder for the removal of NO2 from ambient atmospheric samples, a number of materials were screened for their ability to adsorb NO2:
- 1.(1) MgO;
- 2.(2) MnO2 on alpha-Al2O3;
- 3.(3) water-treated MnO2 on alpha-Al2O3; and
- 4.(4) MnO2 (activated).
4.
《Atmospheric environment(England)》1985,19(12):1995-2010
Arctic air chemistry observations made in Canada between 1979 and 1984 are discussed. The weekly average concentration of 25 aerosol constituents has been measured routinely at three locations. Anthropogenic pollution typified by SO42− and V has a persistent seasonal cycle. SO42− concentrations are similar at all three locations, although they tend to be somewhat higher at Alert than at Mould Bay and Igloolik. The seasonal variation of an aerosol constituent depends on its source. There are four distinctive seasonal variations for:
- 1.(i) anthropogenic constituents Cr, Cu, Mn, Ni, Pb, Sr, V, Zn, H+, NH4+, SO42−, NO3−,
- 2.(ii) halogens (excepting Cl) Br, I, F,
- 3.(iii) sea salt elements Na, Mg, Cl and
- 4.(iv) soil constituents Al, Ba, Ca, Fe and Ti. In the Arctic winter, the mean concentrations of anthropogenic aerosol constituents, except SO42−, are 2–4 times lower than annual mean concentrations in southern Sweden near a major source region. SO42− concentrations are only 30% lower mainly because of production from SO2. Light scattering (bscat) and SO42− observations indicate that the SO42− fraction of the fine particle mass fluctuates between 3 and 65% during the polluted winter months. Daily mean bsact, at Mould Bay that exceeds 50 × 10−6m−1 is associated with air originating from the northwest. The soluble major ion composition of aerosols during winter varies markedly with particle size. H+, NH4+ and SO42− dominate submicrometre particles while sea-salt ions Mg2+, Na+ and Cl− predominate in supermicrometre particles. Winter SO2 concentrations at Mould Bay and Igloolik ranged from 0.2 to 1.5 ppb
- 5.(v). The fraction of airborne S as SO2 ranged from 20 to 90% and peaked in late December-early January. The concentration of total NO3− (0.025–0.090 ppb(v)) is much lower than that of SO42− (0.3–1.2 ppb (v)).
5.
《Atmospheric environment(England)》1984,18(10):2261-2268
Precipitation chemistry data in North America and their associated uncertainties were reviewed by Hansen and Hidy (1982).1 Critical comments and corrections of that review are presented here, along with data which indicate that
- 1.(1) acid precipitation may not have been widespread in the eastern United States prior to 1930 and
- 2.(2) precipitation has become more acidified, especially in the midwestern and southeastern U.S. between the 1950s and the present.
- 1.(1) the accuracy of the yearly volume-weighted mean,
- 2.(2) regional among-site variability and
- 3.(3) temporal, among-year variability. For high quality samples, the pooled estimate for these three sources of variability is < 22 μeq ℓ−1 at the 95 % confidence interval. This value represents a convenient test for significant differences temporally or spatially in a region. Given the historical data available, many areas of the eastern U.S. show an increase in acidity of > 22 μeq ℓ−1 during the last three decades.
6.
《Atmospheric environment(England)》1985,19(4):659-667
Observations of annual wet deposition of sulfur made during 1980 at 62 stations in northeastern America are interpreted using a statistical long-range transport model. This work is meant to demonstrate the role of an empirical model in the analysis of observations. Our analysis points to the following conclusions:
- 1.(1) The parameters that represent the conversion of SO2 to SO4 and the wet and dry removal of sulfur are insensitive to concentration levels,
- 2.(2) the variation of the wet deposition field is closely related to the distribution of sulfur emissions and
- 3.(3) observations demand efficient wet scavenging of SO2.
7.
《Atmospheric environment(England)》1987,21(11):2435-2444
The frequency of co-occurrences for SO2NO2, SO2/O3 and O3/NO2 at rural and remote monitoring sites in the United States was characterized for the months of May-September for the years 1978–1982. Minimum hourly concentrations of 0.03 and 0.05 ppm of each gas were used as the criteria for defining a ‘co-occurrence’. The objectives of this study were to:
- 1.(1) identify the types of co-occurrence patterns and their frequency;
- 2.(2) identify whether the frequency of hourly simultaneous co-occurrences increased substantially when the minimum concentration was lowered (e.g. from 0.05 to 0.03 ppm) for each pollutant; and
- 3.(3) determine whether the frequency of co-occurrences showed large year-to-year variation.
- 1.(1) hourly simultaneous and daily simultaneous-only co-occurrences are fairly rare and
- 2.(2) when co-occurrences are present, complex-sequential and sequential-only co-occurrence patterns predominate.
8.
《Atmospheric environment(England)》1984,18(12):2609-2619
The derivation of a highly simplified parameterization of NOx chemistry for use with the AES Lagrangian trajectory model is described. Two versions, both employing essentially independent first-order kinetics are discussed:
- 1.(1) a one step mechanism: NO2→ inorganic nitrate and
- 2.(2) a somewhat more involved reaction scheme including PAN chemistry.
9.
《Atmospheric environment(England)》1984,18(10):2109-2124
The mathematical model presented in this paper describes in detail the gas-phase chemistry (80 reactions), gas-phase/liquid-phase equilibrium (12 equilibria) and liquid-phase chemistry (27 reactions and equilibria) of acid formation. The model is used to simulate acid formation under various conditions:
- 1.(1) nonprecipitating clouds in the Adirondacks,
- 2.(2) raining clouds in the Ohio River valley,
- 3.(3) night-time fog in the Los Angeles basin and
- 4.(4) night-time nonprecipitating clouds in the Los Angeles basin. Model calculations are compared with observed values of sulfate and nitrate formation. The model is used to analyze the relative importance of sulfate and nitrate formation pathways under these various conditions.
10.
《Atmospheric environment(England)》1987,21(3):469-477
Since emission regulations in Korea concentrate mainly on the limitation of pollutant concentration in the stack gas, it is difficult to achieve a desirable air quality in a heavily industralized city like Ulsan. To ensure a suitable air quality in the future, a total emission control method is proposed with a stack height formula of H = 10.6 q0.5, where H is the stack height (m) and q is the SO2 emission rate (m3 h−1 reduced to 0°C). The total emission permitted can be allocated to industries
- 1.(1) at an uniform reduction rate,
- 2.(2) by the formula Q = aQo0.925, where Q is the emission allowed (g s−1), a is a constant, and Qo is the emission before control (g s−1), or
- 3.(3) by using a linear programming technique.
11.
《Atmospheric environment(England)》1986,20(7):1501-1503
Evidence is presented to show that a serious leaf spot disease of potato which appeared each year in the Punjab since 1978 is primarily due to ozone:
- 1.(i) The symptoms of the leaf spot were similar to the ozone stipple of potato reported in the U.S.A.
- 2.(ii) Activated charcoal and ethylenediurea effectively controlled the spots.
- 3.(iii) Elevated ozone in the atmosphere was detected with the bioindicators Nicotiana tabacum var. Bel-W3 and potato variety Cherokee. This is the first report of ozone injury to a crop plant in India.
12.
《Atmospheric environment(England)》1986,20(8):1517-1521
The effect of (a) fixing the time interval between cleaning pulses or (b) fixing the maximum pressure drop at which cleaning is started, on the performance of the fabric filter was investigated.A maximum pressure drop value of 2500 Pa:
- 1.(a) minimized the effect of the filter medium resistance;
- 2.(b) reduced the energy consumption by the filter;
- 3.(c) minimized the dust emission from the fabric filter to the surrounding atmosphere.
13.
《Atmospheric environment(England)》1987,21(9):1995-2004
Volatile organic compound levels (VOCs) in breath, personal air, fixed outdoor air and drinking water samples were measured and compared for a probability sample of individuals in Los Angeles and Antioch/Pittsburg, California during 1984. In addition, comparisons were made between seasons (winter vs spring) in Los Angeles for individuals sampled in both seasons. The statistics presented to compare the sites and seasons were primarily percent measurable and concentration levels (e.g. sample medians). For most comparisons, 13 VOC levels were examined for breath, personal and outdoor air samples and four VOCs for water samples.In addition to the results for VOC levels, the paper also briefly describes
- 1.(i) the sampling procedures used to obtain the study participants
- 2.(ii) the collection of air, breath and water samples
- 3.(iii) selected results from the quality assurance procedures used in this study.
- 1.(i) higher in personal air samples than in breath or outdoor air samples,
- 2.(ii) higher in Los Angeles in the winter for air and breath than in the, spring,
- 3.(iii) higher in Los Angeles for air and breath than in Antioch/Pittsburg,
- 4.(iv) quite different for water as compared with air and breath.
- 1.(i) outdoor air vs breath in the winter in Los Angeles (where outdoor air levels were much higher than in the spring),
- 2.(ii) in personal air vs outdoor air in the upper tails of the concentration distribution (90th percentile) compared to the 50th percentile. For the water samples, relatively high concentrations were noted for chloroform, bromodichloromethane and dibromochloromethane.
14.
《Atmospheric environment(England)》1987,21(9):1989-1994
Application of micro spot and electron microscopy techniques to individual particles in a coastal urban site revealed the following:
- 1.(a) sulfate particles, some of them mixed, dominated the sub-μm (0.3–0.8 μm) size range;
- 2.(b) nitrates were found mostly in the μm size range, in the form of NaNO3.
15.
《Atmospheric environment(England)》1984,18(3):629-652
Historically, studies of the effects of the main phytotoxic gases (SO2, O3, NOx and HF) have focused on determining the threshold for onset of visible foliar injury. The current U.S.A. air quality standards to protect vegetation (500 ppb SO2 for 3 h and 120 ppb O3 for l h not to be exceeded more than once per annum) are good examples of the use of this information in the regulatory process. More recently, research has focused on determining the thresholds for effects on economically important yield parameters irrespective of foliar injury. The implication is that long-term seasonal or annual standards may be required to prevent yield losses particularly for the primary pollutants in diffuse-source regions and for secondary pollutants. This paper reviews the literature on thresholds for yield effects of SO2 and O3 and concludes that
- 1.(a) the current EEC standard for SO2 is adequate to protect most crops and trees and
- 2.(b) more work is required to determine whether the U.S.A. threshold for O3 effects are applicable to the climate and crops of Europe.
- 1.(a) when ‘hypothetical’ relationships are assumed in the absence of good data and
- 2.(b) when the linearity of dose-response relationships are presumed to justify the extrapolation from effects at high concentrations to lower ambient concentrations.
16.
《Atmospheric environment(England)》1986,20(2):361-366
Ozone fumigations that mimic ambient ozone distributions facilitate the development of links between
- 1.(1) vegetative effects results that are generated in the laboratory and the field and
- 2.(2) predictive effects models that depend upon ambient air quality data.
- 1.(a) the number of occurrences of hourly ozone concentrations equal to or above 0.07 ppm,
- 2.(b) the number of days of each episode,
- 3.(c) the number of days between episodes and
- 4.(d) the rate of rise and decline of the daily ozone concentrations.
17.
《Atmospheric environment(England)》1987,21(11):2473-2480
This Report describes a tour from 2 to 14 January 1986 in Delhi and New Delhi. The principal objectives were:
- 1.(1) To participate in the Indian Science Congress Meeting.
- 2.(2) To present a paper in the section on ‘Recent advances in numerical modelling of the disperion of atmospheric pollutants’ and make an appraisal of the value of the meeting and suggestions for future meetings.
- 3.(3) Discuss the research programme of the Centre for Advanced Studies in Atmospheric and Fluid Sciences of the Indian Institute of Technology with staff and research students and make recommendations for the future direction and development of this programme.
- 4.(4) Participate in seminars and discussions at the Centre. A general impression of the Indian air pollution scene is also given, and its relationship to past and present situations in other parts of the world is discussed.
18.
《Atmospheric environment(England)》1983,17(9):1837-1844
The growth of a single dust particle by vapour condensation is derived from Fick's diffusion equation after considering the conditions under which it may be used. The treatment is then extended to a polydisperse dust cloud, allowing for
- 1.(1) a constant cooling rate
- 2.(2) the depletion of the vapour by condensation
- 3.(3) the dependence of droplet vapour pressure on curvature and
- 4.(4) the variation of the diffusion coefficient with droplet size.
19.
《Atmospheric environment(England)》1983,17(11):2221-2229
Most current LRTAP models assume a linear relationship between sulphur emissions and predicted acidic concentrations, as well as the ability to superpose concentrations from different emission sources. This paper uses a non-linear chemistry model and control scenarios of 50% reductions in S, N and hydrocarbon (HC) emissions to examine the validity of these two assumptions at various downwind receptors. The model predicts that a 50% reduction in S emissions will lead to a 60–65% reduction in SO2 concentrations and a 25–40% reduction in H2SO4 concentrations, depending upon whether or not NOx and/or HC emissions are reduced by 50% at the same time. The non-linearities in the model predictions are due to complex interactions between NOx, HC, OH and HO2. Even when there was non-linearity in the individual S species (SO2 and SO4), there was little non-linearity in total airborne S. Adding the results of independent model predictions for different sources (superposition) might introduce errors due to
- 1.(1) chemical interactions between the emissions from the various sources
- 2.(2) overestimates of physical processes such as mixing in of ambient air.
20.
《Atmospheric environment(England)》1983,17(3):633-638
Precursor concentration distributions and the derived relationships which characterize the spatial distribution of emission sources in the Sydney airshed in 1975/6/7 are compared with precursor data obtained during the 1981/2 summer. The 1981/2 data shows that:
- 1.(i) NMHC point sources no longer dominate the character of Sydney's moring time urban air parcels and
- 2.(ii) morning time meteorology and/or overall 6:00–10:00 a.m. mass emission rates have changed, resulting in an increase in the frequency of occurrrence of moderate to high NHMC and NOx concentration events.