Trends of Air Pollution and Its Present Situation in Hiroshima Prefecture

The ambient concentration of SO₂, NOx and O_x in the atmosphere of Hiroshima, Fukuyama and Fuchu city which were monitored by the prefectural monitoring stations, are examined to give a picture of the typical air pollution at these sites. Results show that the yearly concentrations of SO₂ in these areas are significantly fall from 20 to 6 ppb during 1978–1996 when the NOx concentrations having no such significant change which varies from 40 to 30 ppb. The Photo-chemical Oxidant (Ox) increases annually at the rate of 0.3 ppb to 0.6 ppb in Hiroshima city only. To know the present situation of air pollution the Differential Optical Absorption Spectroscopy (DOAS) system is used in the city of Higashi Hiroshima. The daily average concentrations of SO₂, NO₂, O₃ and HONO measured during the period of August 1999 to March 2000 ranged from 1.4 ppb to 2.8 ppb, 13 ppb to 26.9 ppb, 21 ppb to 53.6 ppb and 1 ppb to 4.3 ppb respectively. The patterns of concentrations of NO₂ and O₃ measured by DOAS look similar to the seasonal patterns of NOx and Ox by the conventional system.     

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.     

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.     

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.     

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.     

Effects of ambient gaseous pollutants on photosynthesis,growth, yield and grain quality of selected crops grown at different sites varying in pollution levels

In recent decades, ambient gaseous pollution has increased due to anthropogenic activities worldwide. The studies to evaluate the adverse effects of ambient pollutants on commonly grown food crops are still limited, especially in Asian countries like Pakistan. The present study was conducted to measure the ambient pollutants in different sites of Faisalabad and their impact on growth and yield of wheat, mung bean and peas. Plants were grown in pots and placed at three sites named as control (Wire house of Government College University, Faisalabad), low pollution (LP) (Farm Area of Ayub Agricultural Research Institute) and high pollution (HP) (GT Chowk, Faisalabad) sites. Results showed that ambient ozone (O₃) concentration was highest at HP site followed by LP site and was below AOT40 in control site. Ambient pollutants caused foliar injury in crops and decreased plant height, leaf area, biomass and grain yield. Pollutants caused a reduction in photosynthetic pigments, stomatal conductance and net photosynthetic rate and grain protein contents in all three crops. In conclusion, the ambient O₃ level was highest at HP site, this current O₃ level and other pollutants decreased the growth and yield of important food crops.     

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.     

Monitoring Nitrogen Dioxide Levels in Urban Areas in Rawalpindi, Pakistan

Nitrogen dioxide is an important gaseous air pollutant. It plays a major role in atmospheric chemistry, particularly in the formation of secondary air pollutants, and contributes to environmental acidification. A comprehensive assessment of NO₂ levels in the atmosphere is required for developing effective strategies for control of air pollution and air quality improvement. Air pollution is a serious problem in all major cities of Pakistan and needs to be addressed to minimize detrimental effects on human health and urban vegetation. In this research, we focused on the monitoring of NO₂ levels in the urban environment of Rawalpindi city. Because of the lack of expensive continuous sampling devices and to get a good spatial coverage of the NO₂ concentrations in the study area, NO₂ passive samplers were exposed at 42 different sites within the city limits of Rawalpindi from January to December, 2008. Samplers were exchanged every 10 days and the associated meteorological conditions like temperature, wind speed, rainfall and relative humidity were also monitored. The average NO₂ concentration was found to be 27.46?±?0.32 ppb. The highest values of NO₂ were measured near to main roads and educational institutions due to intense flow of road vehicles. Moreover, the study showed that the values obtained for NO₂ for all sampling points exceeded the annual limit value set by World Health Organization. So, this is very important to take different steps to control this before it becomes a serious hazard for people living in those areas.     

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.     

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.     

Effects of ambient air pollution on wheat and rice yield in Pakistan

Open-top chambers ventilated with ambient or chiarcoal-filtered air were used to assess the impact of air pollution on the yield of local cultivars of wheat and rice, at a site on the outskirts of Lahore. At this location, 6-h mean O₃ concentrations reach 60 ppb in certain months, and annual mean NO₂ concentrations are 20–25 ppb. The experiments showed significant yield reduction in two successive seasons which ranged from 33% to 46% in wheat and from 37% to 51% in rice. The major yield parameter affected was the number of ears or panicles per plant, although there was also evidence of small effects on 1000 grain weight and on the number of grains per ear/panicle. These results have significance in terms of the maintenance of agricultural yields as pollution emissions rise in south and south-east Asia.     

Characterizing Groundwater Dynamics Based on Impact of Pulp and Paper Mill Effluent Irrigation and Climate Variability

Automated synoptic weather typing and robust orthogonal stepwise regression analysis (via principal components analysis) were applied together to develop within-weather-type air pollution prediction models for a variety of pollutants (specifically, carbon monoxide – CO, nitrogen dioxide – NO₂, ozone – O₃, sulphur dioxide – SO₂, and suspended particles – SP) for the period 1974–2000 in south-central Canada. The SAS robust regression procedure was used to limit the influence of outliers on air pollution prediction algorithms. Six-hourly Environment Canada surface observed meteorological data and 6-hourly US National Centers for Environmental Prediction (NCEP) reanalysis data of various weather elements were used in the analysis. The models were developed using two-thirds of the total years for meteorological and air pollution data; the remaining one-third (randomly selected) was used for model validation. Robust stepwise regression analysis was performed to analytically determine the meteorological variables that might be used to predict air pollution concentrations. There was a significant correlation between observed daily mean air pollution concentrations and model predictions. About 20, 50, and 80% of the 80 prediction models across the study area possessed R ² values ≥ 0.7, 0.6, and 0.5, respectively. The results of model validation were similar to those of model development, with slightly smaller model R ² values.     

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.     

Tropospheric Ozone in Alpine Forest Sites: Air Quality Monitoring and Statistical Data Analysis

Plants represent one of the major sinks for tropospheric ozone that, at high concentrations, can affect plants' physiological activity with consequent serious damage. A research project has been promoted by the Lombardy Foundation for the Environment to investigate the effects of air pollution on forest ecosystems. The areas of study are located on the southern slopes of the Italian Alps in two valleys, only 10 km apart, selected because of their different plant injury: Val Gerola and Val Masino. Air quality (O₃, NO_x, SO_x, VOC) and meteorological parameters were monitored during four summer seasons (1994-97) using automatic sampling devices providing hourly mean values for each variable. Data analysis showed very different ambient ozone concentrations at the two sites, with average concentration values observed in the more damaged valley (Val Gerola) twice those measured at the other site. Multivariate data analyses have been used to interpret the observed differences in long-term O₃ exposure between the two sites and to identify possible underlying processes.     

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.     

A modified nitrogen oxide-ozone photolytic cycle

Nitrogen Oxide-0₃ photolytic cycle is dependent upon the presence of NO in ambient air. From our air monitoring observations we have found that the NO concentration in the atmosphere is often zero (0 to 5 ppb). This suggests a need to modify/change the photolytic cycle. Linear regression analyses on the O₃ and NO₂ concentrations in ambient air, measured in real time were carried out. The predicted values of O₃ and NO₂ from these regression equations were close to the observed values. On the basis of these two observations a modified photolytic cycle, including some other components (such as HONO₂) is discussed.     

A Synoptic Climatological Approach to Assess Climatic Impact on Air Quality in South-central Canada. Part II: Future Estimates

Using within-weather-group air pollution prediction models developed in Part I of this research, this study estimates future air pollution levels for a variety of pollutants (specifically, carbon monoxide – CO, nitrogen dioxide – NO₂, ozone – O₃, sulphur dioxide – SO₂, and suspended particles – SP) under future climate scenarios for four cities in south-central Canada. A statistical downscaling method was used to downscale five general circulation model (GCM) scenarios to selected weather stations. Downscaled GCM scenarios were used to compare respective characteristics of the weather groups developed in Part I; discriminant function analysis was used to allocate future days from two windows of time (2040–2059 and 2070–2089) into one of four weather groups. In Part I, the four weather groups were characterised as hot, cold, air pollution-related, and other (defined as relatively good air quality and comfortable weather conditions). In estimating future daily air pollution concentrations, three future pollutant emission scenarios were considered: Scenario I – emissions decreasing 20% by 2050, Scenario II – future emissions remaining at the same level as at the end of the twentieth century, and Scenario III – emissions increasing 20% by 2050. The results showed that, due to increased temperatures, the average annual number of days with high O₃ levels in the four selected cities could increase by more than 40–100% by the 2050s and 70–200% by the 2080s (from the current areal average of 8 days) under the three pollutant emission scenarios. The corresponding number of low O₃ days could decrease by 4–10% and 5–15% (from the current areal average of 312 days). For the rest of the pollutants, future air pollution levels will depend on future pollutant emission levels. Under emission Scenarios II and III, the average annual number of high pollution days could increase 20–40% and 80–180%, respectively, by the middle and late part of this century. In contrast, under Scenario I, the average annual number of high pollution days could decrease by 10–65%.     

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.     

Improvements in Urban Air Quality: Case Studies from New York State, USA

Air quality levels vary over regions due to meteorological factors, proximity to sources, and local conditions (i.e., topography). The Northeast USA is subjected to pollution inputs from both local sources and those from the upwind Midwest USA that are transported by prevailing meteorological patterns. With the passage of the Clean Air Act in 1970 and the establishment of the National Ambient Air Quality Standards (NAAQS), national levels of air pollutants have declined significantly. Our study compared air quality time trends between five of the largest cities within New York State (Albany, Buffalo, New York City, Rochester, and Syracuse) and statewide means to national trends. Data were obtained from the NYS Department of Environmental Conservation (DEC) Bureau of Air Quality Surveillance for six criteria pollutants: carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ozone (O₃), particulate matter (PM_2.5), and lead (Pb). Regional Kendall tests found significant downward trends for each pollutant statewide from 1980 to 2007, while trends by city varied by decade and pollutant. The evaluation of historical trends of pollution in industrialized nations is useful in showing recent air quality improvements and also in the understanding what can be the result in air pollutant controls in those developing nations currently experiencing high levels of pollution.     

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.