Advection fog formation associated with atmospheric aerosols due to combustion-related pollutants

A large amount of pollutants in highly industrialized areas is produced by a photochemical reaction of NO _x and SO _x , which is a result of the production of energy-related fuel combustion. These pollutants provide the major source of condensation nuclei for the formation of fog in the areas of busy highways, airports, seaports, etc. The present study simulates how these pollutants affect the formation of advection fog. Both microphysical and macrophysical processes are considered in investigating the time dependent evolution of the spectra of condensation nuclei associated with both polluted and clean atmospheres during the time period of advection fog formation. In the first part of the series of this paper, the initial aerosol population concerns a monodisperse, multi-component aerosol model. The results show that both SO _x , and NO _x as condensation nuclei provide great contributions in the formation of advection fog.     

Effects of air pollution on the searching behaviour of an insect parasitoid

To assess the impact of air pollutants on the population dynamics of herbivores, the effects of pollutants on their natural enemies including predators, parasites, and pathogens must be evaluated in addition to direct effects and indirect effects mediated via the host plant. Insect parasitoids are an important group of such natural enemies providing many examples of partial or complete biological control of pest species. This study examined the effects of air pollutants (ozone (O₃), sulphur dioxide (SO₂), and nitrogen dioxide (NO₂)) on the searching behaviour of insect parasitoids. A series of experiments comprising short-term, closed chamber fumigations of O₃, SO₂, and NO₂ (100 nl l^?1) of the braconid parasitoid (Asobara tabida) and aggregated distributions of its host larvae (Drosophila subobscura) was set up. Analysis of chamber results showed that the proportion of hosts parasitised and the searching efficiency of the parasitoids were both significantly reduced with O₃ fumigation, but not with NO₂ or SO₂ fumigations. O₃ fumigation reduced percentage parasitism by approximately 10%. Parasitoids were able to avoid patches with no hosts, both in filtered air controls and when exposed to pollutants. However in the O₃ and NO₂ treatments they appeared less able to discriminate between different host densities, suggesting that pollutants may interfere with the olfactory responses of the parasitoids. These results indicate the potential for air pollutants, particularly O₃, to negatively influence the searching behaviour of parasitoids, and hence reduce the efficiency of natural enemy control of many pest species.     

A regional scale model for the calculation of episodic concentrations and depositions of acidifying components

An eulerian long-range transport model for the calculation of concentrations of SO₂, SO₄, NO _x , and NO₃ and wet and dry depositions of SO _x (sum of SO₂ and SO₄) and NO _y (sum of NO, NO₂ and NO₃) over Europe is presented. The model is developed in such a way that only routinely available, analyzed or prognostic meteorological fields are required as input data. In this way it is possible to obtain a forecast of the air quality during smog episodes. For evaluation of smog episodes the model provides a way to estimate the contributions of different sources and the effect of emission scenarios. The model has been evaluated for four winter and three summer episodes. The modeled concentrations of SO₂ and SO, are in agreement with the available measurements. A less good agreement is found for NO₂ and NO _x (sum of NO and NO₂) concentrations. For these components the model tends to underpredict the measured values.     

Approaching Cumulative Effects through Air Pollution Modelling

The research presented here represents a segment of a cumulative impact assessment of resource development in northeastern British Columbia. It considers point and area source emissions of sulphur and nitrogen oxides (SO₂ and NO _x , respectively), over a 2,156-km² area. With the exception of open burning, all emissions are from Upstream Oil and Gas (UOG) sector sources (SO₂, n?=?103; NO _x , n?=?250; area, n?=?25). AERMOD View? was used to estimate the maximum potential concentration and deposition of these pollutants over 1-h, 3-h, 24-h, and annual averaging periods. Results are compared with various thresholds and limits from the policy and scientific literature to assess the potential cumulative effects of these pollutants. Of the thresholds employed, exceedances of the 1-h and 24-h NO _x concentrations and the annual SO₂ concentration are predicted. There were no predicted exceedances of annual deposition thresholds (i.e., ??Critical Loads??). Maximum predicted concentrations vary between compounds and are related to boundary layer stability, elevation, and distance from sources. Comparison with nearby monitoring data indicated that predicted concentrations were reasonable and that AERMOD provides a useful tool for approaching the potential cumulative impacts of air pollution from multiple sources. While the accuracy of Gaussian-based annual deposition estimates is questioned, model enhancements that could extend the application to more comprehensive assessments are suggested. Lastly, the implications of predicted threshold violations for forest ecosystems and local forest-dependent First Nations communities are discussed.     

Effects of gaseous air pollutants on aphid performance on Scots pine and Norway spruce seedlings

Aphids are frequently found on conifers, but mass outbreaks are seldom reported. On trees stressed by air pollutants the natural resistance can be broken and insect attack combined with pollution stress may promote plant damages. To evaluate effects of air pollution on conifer aphids Scots pine and Norway spruce seedlings have been exposed to gaseous pollutants (O₃, SO₂ and NO₂) in growth chambers. The studied aphid species were Cinara pilicornis Hartig on Norway spruce, C. pinea (Mordv.) and Schizolachnus pineti Fabr. on Scots pine in SO₂ fumigations and S. pineti in O₃ and NO₂ fumigations. C. pilicornis nymphs had peaked dose response to SO₂ concentration. Both the first and third instar larvae of C. pilicornis showed highest mean relative growth rate (MRGR) at 100 ppb SO₂ concentration. MRGR of C. pinea peaked at 50 and 150 ppb SO₂ The response of S. pineti was more inconsistent During fumigation the peak MRGR of S. pineti was at 100 ppb and after exposure at 50 ppb SO₂. MRGR of S. pineti nymphs was not significantly affected during fumigation or after the end of fumigation experiment by 100 ppb O₃ or 100 ppb NO₂ or the mixtures. The results suggest that SO₂ affects more distinctively on aphid performance on conifers than O₃ or NO₂. Especially stem-feeding aphids on spruce can exploit physiological disturbance of host plant under pollution stress.     

Evaluation of extreme pollution episodes over Lithuania in 1980–1994

The investigation of SO₂, NO₂, benzo(a)pyrene (BP) and soot (C_el) has been carried out daily in the atmospheric air in the background station Preila (East shore of the Baltic Sea) since 1980. Over this period, daily concentrations of pollutants varied in the wide intervals in warm and cold period as well. From 15 years data typical episodes of highest and lowest concentrations of pollutants are chosen and analysed with respect to the air masses trajectories and meteorological conditions. The highest concentrations of SO₂, NO₂, BP, Cd were fixed, when the air masses passing Lithuania have been formed over Great Britain and Central Europe.     

Chemical Characterization of Acid Fog and Rain in Northern Japan Using Back Trajectory and Oblique Rotational Factor Analysis

Fog/cloud and rain water were collected at the mountainside of Hachimantai range in northern Japan and rain water was also collected at Akita City in order to investigate the air pollutant scavenging mechanism. The concentrations of various ions in these samples were analyzed, and the fog drop size and the wind direction were measured at each fog event. The fog at Hachimantai range had a very high total ion concentration, and was considerably acidified by non sea salt (nss-) SO₄ ^2? and NO₃ ^?, compared with the rain at Akita and all sites in Hachimantai range. Using the oblique rotational factor analysis, three factors were extracted as the air pollutants; A: (NH₄)₂SO₄+H₂SO₄, B: sea salts+HNO₃+H₂SO₄, C: NH₄NO₃+OH^?. These salts are well-known as the cloud condensation nuclei (CCN). Combining the factor analysis with the 72h back trajectory at 850hPa level, the contribution of Factor A was closely connected to the long-range transportation of anthropogenic or natural aerosol in air masses of continental origin.     

The Effect of Air Pollution on Yield and Quality of Mung Bean Grown in Peri-Urban Areas of Varanasi

There is growing concern that air pollution may have adverse impacts on crops in developing countries, yet this has been little studied. This paper addresses this issue, for a major leguminous crop of the Indian sub continent, examining the effect of air pollution in and around an Indian city. A field study was conducted using a gradient approach to elucidate the impact of air pollutants on selected production characteristics of Vigna radiata L. cv. Malviya Jyoti (mung bean) plants grown from germination to maturity at locations with differing concentrations of air pollutants around peri-urban and rural areas of Varanasi. The 6 -h daily mean SO₂, NO₂ and O₃ concentrations varied from 8.05 to 32.2 ppb, 11.7 to 80.1 ppb and 9.7 to 58.5 ppb, respectively, between the sites. Microclimatic conditions did not vary significantly between the sites. Changes in plant performance at different sites were evaluated with reference to ambient air quality status. Reductions in biomass accumulation and seed yields were highest at the site experiencing highest concentrations of all three gaseous pollutants. The magnitude of response indicated that at peri-urban sites SO₂, NO₂ and O₃ were all contributing to these effects, whereas at rural sites NO₂ and O₃ combinations appeared to have more influence. The quality of seed was also found to be negatively influenced by the ambient levels of pollutants. It is concluded that the air pollution regime of Varanasi City causes a major threat to mung bean plants, both in terms of yield and crop quality, with serious implications for the nutrition of the urban poor.     

A novel method to evaluate the phytotoxic potential of low ozone concentrations using poplar cuttings

Six-week-old rooted cuttings of Populus nigra L. ‘LOENEN’ and Populus maximowiczii Henri X Populus nigra L. ‘ROCHESTER’, differing in their phenomenological sensitivity to O₃, were submitted to low concentrations of O₃, NO_x, and SO₂. Exposure was performed in open top-chambers from 25.5. until 6.7.1988. Comparing the response of the two poplars by 77 biochemical criteria the macroscopic O₃- sensitivity of ‘LOENEN’ was clearly reflected in changes of the pool sizes of the different nonstructural carbohydrates, polyols, and phenolics of the leaf-lamina, petiole, shoot-axis, and roots. In contrast, both varieties revealed the same response to NO_x/SO₂-mixtures. It can be concluded that ‘LOENEN’ together with ‘ROCHESTER’-poplars as controls, are an appropriate system to specifically indicate O₃ in a mixture of air pollutants.     

Sulphur and nitrogen nutrition and misting effects on the response of bluegrass to ozone,sulphur dioxide,nitrogen dioxide or their mixture

Kentucky bluegrass (Poa pratensis L.) plants, cultivars Cheri, Merion and Touchdown were grown at complete nutrition or with low S or low N. Plants were exposed to 10 ppm (v/v) O₃ for 6 h d^?i, 15 pphm SO₂ continuously, 15 pphm NO₂ continuously, or their mixture at these concentrations for 10 days. The severity of injury was much increased by misting with deionized water for 5 min twice daily, especially with SO₂ and NO₂ single gas exposures. The misting did not have consistent effects on total S, total N, leaf area or fresh weight. Exposure to O₃ decreased leaf area without affecting S or N content, while SO₂ usually increased total S and, in some cases, increased total N. Exposure to NO₂ increased total N without affecting total S, and the mixture increased both total S and total N. Low S or low N usually enhanced the effect of SO₂ or NO₂, respectively. Leaf area and fresh weight were not as responsive to the treatments as total S and total N. Rainfall outdoors may be a major meteorological factor affecting plant injury response to gaseous pollutants.     

Manganese contamination in Montreal in relation with traffic density

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic derivative of manganese used as an additive in unleaded gasoline in Canada since 1977. Moreover, Canada is the only country in the world to have authorized the replacement of lead alkyls by MMT in gasoline. The purpose of the present study is to assess the importance of air contamination by Mn in relation to other air pollutants (gaseous and particulates), meteorological variables and traffic density. The concentration of both the gaseous (O₃, CO, NO, NO₂, SO₂) and the particulate pollutants (Mn, Pb, NO^? ₃, SO^?? ₄, TSP) had been measured by the Montreal Urban Community in 1990 at seven sampling stations located in high traffic and low traffic density areas. Data on the meteorological conditions during that same period were also used. Non-parametric correlation, ANOVA and discriminant analyses were used to compare gaseous and particulate pollutants found between both levels of traffic density. In almost 50% of the daily air samples measured in 1990, the Mn concentrations are higher than the urban background level estimated at 0.04 μg m^?3 and the variations of Mn concentrations are significantly correlated in time with traffic density. Moreover, Mn and TSP discriminate the best high and low traffic density areas. No significant differences have been observed between Pb, O₃ and SO₂ concentrations in both areas. These results should not be interpreted in terms of potential health effects since it is presently impossible to determine the fate of the Mn in the environment and its importance in terms of human exposure.     

Towards a Science-Based Integrated Ozone-Fine Particle Control Strategy

Epidemiology studies relating health effects to ambient levels of ozone and fine particles have led to the modification of standards in the United States for these pollutants (substitution of an 8-h standard for ozone at 80 ppbv, and addition of 24-h and annual standards for fine particles). The interrelationships of these pollutants in the atmosphere suggest the need for an integrated, science-based strategy for their control. Secondary ozone formation has been controlled through emission controls on VOC and NO_x precursors. Fine particles are secondary products largely resulting from the oxidation of precursors (SO₂, NO_x, and VOCs). The key intermediates in both types of secondary process are free radical species and the photochemically labile compounds that produce them in the atmosphere. However, due to the complex and nonlinear nature of the processes, reductions in precursors may lead to unexpected changes in ozone and fine particle formation rates. For example, reduction in NO_x emissions may reduce ozone and nitric acid levels, but lead also to increased rates of sulfate formation in clouds and increased ammonia availability for neutralization of acidic sulfate aerosols. Reductions of SO₂ may reduce aerosol sulfate levels in the summer, but have no effect in other seasons. Reductions in VOCs may reduce ozone levels in urban core areas, but not elsewhere. An integrated, regionally and seasonally specific, emission reduction strategy is needed to cost-effectively reduce both ozone and fine particle levels.     

Fine and Coarse Ionic Aerosol Components in Relation to Wet and Dry Deposition

The distribution of acidic andalkaline constituents (SO₄ ^2-,NO₃ ^-, Cl^-, NH₄ ⁺, Na⁺,K⁺, Ca²⁺) between the fine and coarseparticle range has been examined in an urban locationin Thessaloniki, N. Greece over an 8-month period. The chemistry of wet and dry deposition collected overthe same period was also examined. Statisticalassociations between species within each environmentalphase were investigated using correlation analysis.Use of principal component analysis was made toinvestigate compositional similarities betweenaerosol, deposited dust and rain. It was found thatSO₄ followed by NO₃, NH₄ and Caprevailed in fine aerosol. Sulphates and Ca were alsothe prevailing ions in the coarse particle fraction.Wet deposition was found to be the dominant depositionmechanism for all species. The high dry depositionrates observed for Ca and SO₄ suggest that mostof the dry deposited sulphate is in the form ofCaSO₄. Scavenging ratios of ionic speciesassociated with coarse aerosol were higher than thecorresponding ratios for fine particles. Principalcomponent analysis suggested that variations in ioniccomposition of fine aerosol could be interpretedprimarily by gas-to-particle neutralization reactionsinvolving atmospheric ammonia. In contrast, theinteraction between SO₂ and HNO₃ with Cacompounds seems to be the most likely factor that canexplain variations in wet and dry deposition ioniccontents.     

Casuarina and Eucalyptus response to single and multiple gaseous air pollutants

Casuarina cunninghamiana and Eucalyptus camadulensis (Egyptian var.) plants were exposed to 0.20 and 0.40 μL L^?1 O₃, SO₂ or NO₂ for 6 hr daily for 10 days. Eucalyptus plants were very sensitive to SO₂ and NO₂ and less sensitive to O₃. Casuarina plants were insensitive to the 3 gases. The rate of sorption of the 3 gases was estimated over a 10 day exposure to 0.20 μL L^?1 pollutant concentration singly and in a 3-gas mixture. Casuarina plants removed air pollutants more efficiently than Eucalyptus plants. Leaves of both species generally sorbed about the same volume of a given gas from the mixture and from the same single gas. The sorption rate over the 10 day exposure was almost constant after a higher sorption rate during the first day for both species.     

Bench Scale Evaluation of a Chemo-biochemical Process for Desulphurization of Gaseous Streams Containing Hydrogen Sulphide

Gases and suspended particulate matter are sampled and measured in situ at different sites within the city of Madrid to determinethe air pollution in the city. Lead concentrations in air are also determined. The information needed to assess levels of contaminants is obtained combining several analytical techniques,which provide real time concentration data of particles andgases. Particulate matter (PM), SO₂, CO, O₃, NO_x,NO₂, CH₄, total hydrocarbons and Pb were measured. Concentrations of pollutants are averaged over periods of hours,days, months and years. Variations of contaminant concentrationsin the last years are presented. Spatial and temporal distribution follows that of the traffic, the main source of pollution in Madrid City. Some specific measurements were carriedout to understand the influence of traffic emissions at themeasured site. Further, all measured concentrations never exceeded the European Union Directives.     

An Integrated Assessment Model for Fine Particulate Matter in Europe

Exposure to fine particles in the ambient air is recognized as a significant threat to human health. Two pathways contribute to the particle burden in the atmosphere: Fine particles originate from primary emissions, and secondary organic and inorganic particles are formed from the gas phase from the emissions of 'conventional' pollutants such as SO₂, NO_x, VOC and NH₃. Both types of particulate matter can be transported over long distances in the atmosphere. An integrated assessment model for particulate matter developed at IIASA addresses the relative importance of the different types of particulates, distinguishing primary and secondary particles and two size fractions. The model projects these emissions into the future and seeks cost-effective strategies for reducing health risks to population. The model integrates the control of primary emissions of fine particles with strategies to reduce the precursor emissions for the secondary aerosols. Preliminary results addressing the PM_2.5 fraction of both primary and secondary particulate matter indicate that in Europe the exposure to particulates will be significantly reduced as a side effect of the emission controls for conventional air pollutants (SO₂, NO_x, NH₃).     

Visibility Variation with Air Qualities in the Metropolitan Area in Southern Taiwan

Principal component analysis (PCA) was used to analyze variationsin visibility compared with (1) variations in meteorological variables in the period 1961 to 1998, and (2) criteria air pollutant (SO₂, CO, O₃, NO_x and PM₁₀) concentrations monitored between 1994 and 1998, in the Kaohsiungmetropolitan area. Whilst average visibility during the 1960'sexceeded 20km, it had deteriorated to 5–10 km in theperiod 1994 to 1998. PCA identified seven components witheigenvalues greater than one. The principal componentsidentified accounted for variability related to PM₁₀concentration, ozone-related pollutants, oil combustion,and traffic emissions. Furthermore, spatial and temporalvariations in PM₁₀ were consistent throughout thecity. Variation in SO₂ levels followed a similarpattern at Tsoying, Shanming, Chiankin and Chiancheng.Industrial pollution and traffic emissions, SO₂, COand NO_x, from the Hsiaokang area remained within thearea. However, similar patterns of SO₂ andNO_xat Fengshan and Jenwu indicate that industrial emissionsfrom the latter were probably transported to the former.Much of the first principal component is based onPM₁₀ variability, suggesting that, of the fivecriteria pollutants studied, PM₁₀ is the majorcontributor to visibility deterioration. It is known thatPM_2.5 concentration is more closely associated withvisibility changes than is PM₁₀. However, becausePM₁₀ and PM_2.5 are strongly associated inKaohsiung, a targeting reduction in PM₁₀ may imply areduction in visibility.     

A Computational Approach Based on GIS Technology for the Development of an Anthropogenic Emission Inventory of Gaseous Pollutants in Greece

This paper describes a computational system developed for the compilation of an anthropogenic emission inventory of gaseous pollutants for Greece. The inventory was developed using a geographical information system integrated with SQL programming language to provide high temporal gridded emission fields for CO, NO₂, NO, SO₂, NH₃ and 23 non-methane volatile organic compounds (NMVOCs) species for the reference year 2003. Activity and statistical data from national sources were used for the quantification of emissions from the road transport, the other mobile sources and machinery sectors and from range activities using top-down or bottom-up methodologies. Annual emission data from existing national and European emission databases were also used. The emission data were spatially and temporally disaggregated using source-specific spatiotemporal indicators. On national scale, the road transport sector produces about 60% of the annual CO and NMVOC total emissions, with gasoline vehicles being the main CO and NMVOC emissions source. The road transport is responsible for approximately half of the higher alkanes and for more than half of the ethene and toluene emissions. The maritime sector accounts for about 40% of the annual total NO_x emissions, most of which are emitted by the international shipping subsector, whilst SO₂ is emitted mainly by the energy sector. The evaluation of the emissions inventory suggests that it provides a good representation of the amounts of gaseous pollutants emitted on national scale and a good characterisation of the relative composition of CO and NO_x emission in the large urban centres.     

Acid deposition and ion leaching from a podzolic soil under hardwood forest

The contribution of atmospheric acids to cation leaching from a podzolic soil under mature maple-birch forest in central Ontario was examined during 1983. The movement of base cations was associated largely with NO₃ ^?, SO₄ ^2? and organic acid anions in surface soil horizons, with SO₄ ^2? and NO₃ ^? below the effective rooting zone, and SO₄ ^2? and HCO₃ ^? in streamflow. Mineral soil horizons could adsorb little additional SO₄ ^2? or associated cations at current soil solution SO₄ ^2? concentrations. Therefore it is concluded that the soil in situ lacks a strong affinity for SO₄ ^2?. Current annual inputs to the forest of SO₄ ^2? and NO₃ ^? in bulk precipitation (26.4 and 18.2 kg ha^?1, equivalent to 8.8 kg S and 4.1 kg N ha^?1 , respectively) contributed significantly to cation leaching from the soil. In order to maintain exchangeable cations in soil at current levels, a rate of weathering yielding 29.6, 5.0, 4.4 and 2.2 kg ha^?1 yr^?1 of Ca²⁺, Na⁺, Mg²⁺ and K⁺, respectively, would be required.     

Projections of SO2, NOx,NH3 and VOC Emissions in East Asia Up to 2030

Starting from an inventory of SO₂, NO_x, VOC and NH₃ emissions for the years 1990 and 1995 in East Asia (Japan, South and North Korea, China, Mongolia and Taiwan), the temporal development of the emissions of the four air pollutants is projected to the year 2030 based on scenarios of economic development. The projections are prepared at a regional level (prefectures or provinces of individual countries) and distinguish more than 100 source categories for each region. The emission estimates are presented with a spatial resolution of 1×1 degree longitude/latitude. First results suggest that, due to the emission control legislation taken in the region, SO₂ emissions would only grow by about 46 percent until 2030. Emissions of NO_x and VOC may increase by 95 and 65 percent, respectively, mainly driven by the expected increase in road traffic volume. Ammonia, mainly emitted from agriculture, is projected to double by 2030.