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.     

Effects of gaseous air pollutants on secondary chemistry of Scots pine and norway spruce seedlings

Plant secondary compounds have an important role in defense responses against herbivores and pathogens. This study summarises published and some unpublished data from a series of fumigation experiments where Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) seedlings were exposed to different concentrations of gaseous air pollutants, ozone (O₃), sulphur dioxide (SO₂) or nitrogen dioxide (NO₂), in growth chambers. Concentrations of monoterpenes, resin acids and total phenolics were studied. Overall, needle monoterpenes were not affected by pollutants. Only very high level of O₃ (600 ppb) decreased concentration of some individual monoterpenes in pine needles. O₃ did not have effect on concentrations of resin acids in pine needles. In contrast, the concentration of some individual resin acids increased in O₃-exposed pine shoots and in O₃-exposed needles of one spruce clone. The highest dose of SO₂ decreased concentrations of resin acids in pine needles, but low exposure levels did not have effects. However, SO₂ had no effects on the resin acids concentrations of spruce needles, except some minor individual compounds were affected in clonal spruces. Increased concentrations of resin acids was found in pine shoots exposed to NO₂. Total phenolics of needles were not affected by pollutants. These observations suggest that among secondary compounds there is variation in sensitivity to air pollutants and genetically different trees have different responses to air pollutants.     

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.     

SO2 Transformation in controlled atmosphere leading to the production of aerosol particles

The photochemical transformation of SO₂ and the generation of aerosol particles are investigated in a variety of atmospheres, with and without initial aerosols, in clean and polluted air, and with various pollutants. The pollutants in addition to the SO₂ include O₃, NO, NO₂ and water vapor in a variety of combinations. The most striking finding is, that only with the combination of SO₂, NO₂, and H₂O is the aerosol particle production large.     

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.     

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.     

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.     

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.     

Effects of ammonia,ammonium sulphate and sulphur dioxide on the frost sensitivity of scots pine (Pinus sylvestris L.).

The deterioration of forest vitality has been at least partly attributed to air pollution. Especially NH₃, originating from intensive livestock farming and locally deposited in high concentrations, may contribute to forest decline in The Netherlands. Therefore, the effect of NH₃ and SO₂ fumigations on cold stress and water stress of Pinus svlvestris were examined. P. sylvestris trees (3 yr old) were exposed to ambient air supplemented with several NH₃ concentrations, with SO₂ or a combination of NH₃ and SO₂.Tops of branches were then exposed to various subzero temperatures and the effect of air pollution on frost damage was examined. Neither ambient air, NH₃ or SO₂ significantly influenced from sensitivity at –4 or –7°C. Following freezing treatments of –10°C, the influence of NH₃ and SO₂ became apparent. The effect of the combination of these pollutants is synergistic. Exposure to NH₃ alone followed by freezing temperatures lower than –10°C resulted in more severe frost damage in early autumn and spring than in the winter. It also increased the susceptibility of P. sylvestris to water stress. A greater loss of water was observed in NH₃-fumigated needles following drought stress, suggesting increased cuticular transpiration. Bud burst and subsequent shoot growth was also strongly reduced by NH₃ fumigations.     

Effects of Sulfur Dioxide and Ozone on Ion Uptake of Spruce (Picea abies (L.) Karst.) Seedlings

Shoots of spruce (Picea abies (L.) Karst.) seedlings grown in solution culture were fumigated with sulfur dioxide or ozone, or with a combination of both for 60 days. Dry weights of the shoots exposed to O₃ and SO₂/O₃ were increased over the controls. Uptake rates of calcium, magnesium, potassium and nitrate from the nutrient solutions were altered in dependence on fumigation, time of exposure and stage of plant development. Uptake rates of all ions by the seedlings fumigated with SO₂ first increased, but later on decreased as compared to the control. Fumigation with O₃, or O₃ in combination with SO₂ affected uptake of the various nutrients differently. The effects of the pollutants on the concentrations of calcium and magnesium in the various parts of the seedlings indicate that the changes are not only due to altered water and ion uptake but may be related to various effects in ion transport and plant metabolism.     

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.     

Some measurements of air quality and precipitation in Saint John,N.B.

For the period of November 19 to 23, 1973, and July 13 to 23, 1974, air quality and precipitation measurements were made in and around Saint John, New Brunswick. For both periods it was found that SO₂ concentrations could be appreciable at several locations (with hourly maxima near 40 pphm). Sulfur dioxide fumigation from a power plant plume and H₂S concentrations near a Kraft process pulp and paper mill are discussed. For the July period, O₃, NO and NO₂ were measured in the background air as well as in air downwind of the city. The ambient concentrations were not unusually high, with the O₃ reaching levels up to 8 pphm (hourly average) on clear sunny days. Precipitation samples were collected on several occasions and the analyses indicate that concentrations of acid-forming species were not markedly different from those found in other Canadian cities.     

The effects of biocidal treatments on metabolism in soil—I. Fumigation with chloroform

This series of five papers is a study of how biocidal treatments influence metabolism in soil, directed particularly towards the flush of decomposition caused by fumigation, and designed to see if the size of this flush can be used as a measure of the soil biomass.Chloroform fumigation caused an immediate increase in the amounts of ammonium and organic C extracted from a soil by 1 N K₂SO₄. When the CHCl₃-treated soil was then inoculated with fresh soil and incubated for 10 days. it consumed 2·8 times more O₂, evolved 2·2 times more CO₂ and mineralised 7·3 times more N than an unfumigated soil. Extractable organic C decreased by about 40% when the fumigated soil was incubated for 10 days. A second fumigation given immediately after the first produced no further increase in the flush, but some recovery occurred if the soil was incubated between fumigations. However, this recovery was slow and incomplete; a second fumigation given 53 days after the first gave a flush only one-seventh the size of the first. Glucose (or ryegrass) added to the soil and allowed to decompose before fumigation increased the size of the flush. After a 52-day incubation, 29% of the C originally added as ¹⁴C labelled glucose remained in the soil; fumigation on the 52nd day increased the evolution of labelled CO₂ during the subsequent 10-day period by a factor of 8. Fumigation of a soil that had already been sterilized by 2·5 Mrads of gamma radiation increased the flush slightly; the amount of O₂ consumed in 10 days increased from 123 to 137 mg/100 g soil. It is proposed that the flush of decomposition following CHCl₃ fumigation is caused by the decomposition of killed organisms by the survivors (or by organisms added in the inoculum) and that organisms are more rapidly and completely attacked after exposure to CHCl₃ than after irradiation. On this hypothesis. 10% of the glucose C originally added to the soil was located in the soil biomass after 52 days.     

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.     

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.     

Simultaneous exposure of forest trees to pollutants and climatic stress

This paper describes a facility designed to simultaneously generate complex climatic and pollutant conditions for research into the effects of climate and air pollution on plants. The system, commissioned in 1985, consists of a set of 4 environmental chambers which are each equipped with four identical subchambers. These 4 subchambers are subjected to identical climatic conditions, but are equipped with independent gas supplies. The chambers are designed to operate within a temperature range of -20 to +40° C at a relative humidity of 20 to 95 % with an illumination system providing high light intensities at a spectrum very close to sunlight. A computer controlled fumigation system allows the injection of various gases singly and in combination at concentrations between 0.005 to l,000 ppm (SO₂, NO_x, O₃, CO₂, PAN).     

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.     

Physiological Effects of Exposure to Arsenic,Mercury, Antimony and Selenium in the Aquatic Moss Fontinalis antipyretica Hedw.

This study assessed the effect of ambient air pollution on leaf characteristics of white willow, northern red oak, and Scots pine. Willow, oak, and pine saplings were planted at sixteen locations in Belgium, where nitrogen dioxide (NO₂), ozone (O₃), sulfur dioxide (SO₂), and particulate matter (PM₁₀) concentrations were continuously measured. The trees were exposed to ambient air during 6 months (April–September 2010), and, thereafter, specific leaf area (SLA), stomatal resistance (R _s), leaf fluctuating asymmetry (FA), drop contact angle (CA), relative chlorophyll content, and chlorophyll fluorescence (F _v/F _m) were measured. Leaf characteristics of willow, oak, and pine were differently related to the ambient air pollution, indicating a species-dependent response. Willow and pine had a higher SLA at measuring stations with higher NO₂ and lower O₃ concentrations. Willow had a higher R _s and pine had a higher F _v/F _m at measuring stations with a higher NO₂ and lower O₃ concentrations, while oak had a higher F _v/F _m and a lower FA at measuring stations with a higher NO₂ and lower O₃ concentrations. FA and R _s of willow, oak, and pine, SLA of oak, and CA of willow were rather an indicator for local adaptation to the micro-environment than an indicator for the ambient air pollution.     

Seasonal Evolution of Levels of Gaseous Pollutants in an Urban Area (Ciudad Real) in Central-Southern Spain: A Doas Study

Long term continuous monitoring measurements of urban atmospheric concentrations of O₃, NO₂, NO, and SO₂ were performed for the first time in Ciudad Real, a city in central-southern Spain. The measurements were carried out using the differential optical absorption spectroscopy (DOAS) technique, with a commercial system (OPSIS, Lund-Sweden), covering the summer and winter seasons (from 21st July 2000 to 23rd March 2001). Mean levels of O₃, NO₂ and SO₂ monitored during this period were: 27 μg m^?3, 50 μg m^?3 and 7 μg m^?3 respectively. The highest hourly averaged value of O₃ (160 μg m^?3) was measured during the summer period, while NO₂ was enhanced in wintertime (highest values 90 μg m^?3). In the coldest period, when central heating installations were operating, SO₂ showed maximum levels of 20 μg m^?3. The daily, weekly and seasonal analysis of the data shows that photochemical air pollution dominates in this urban atmosphere and is strongly influenced by levels of motor traffic and domestic heating system emissions. These measurements were compared with other studies in Spain and Europe. Also, the long path averaged DOAS measurements were compared with in situ observations made in Ciudad Real, from 23rd August 2000 to 25th September 2000, using a mobile air pollution control station. All gas concentrations reported in this paper are below the WHO guidelines and the different thresholds introduced by the European Environmental Legislation.     

Air pollution measurements at the boulder atmospheric observatory

Pollution episodes of three distinct types were detected at the Boulder Atmospheric Observatory, which is a 300 m instrumented tower located in a rural area 25 km north of Denver and 20 km east of Boulder. Under stably stratified atmospheric conditions, usually at night or early morning, both power-plant-derived and general urban plumes were sampled. The powerplant plumes were characterized by SO₂ concentrations of 30 to 50 ppb in the plume centers, NO₂ maxima of 20 to 40 ppb on the plume edges, NO maxima of as much as 50 ppb in the plume centers, and the absence of O₃ from the plume centers. Light scattering (b _scat), principally due to coarse particles, was typically enhanced by 20 to 40%, relative to nominally clean air. The urban plumes typically contained NO₂ uniformly distributed throughout the affected air mass at 20 to 30 ppb, no detectable NO or SO₂, and O₃ present at concentrations less than half that in background air; b _scat was typically increased by a factor of 2 to 3. A third type of pollution episode, containing greatly increased concentrations of condensation nuclei, was observed during days when surface heating had apparently stimulated biological particle production. At these times the usual indicators of anthropogenic pollution were absent.