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.     

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 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.     

Health effects associated with ozone and nitrogen dioxide exposure

Of the oxidants and nitrogenous compounds found in ambient air, O₃ and NO₂ are among those most thoroughy investigated. Large health data bases have been compiled in air quality criteria documents, which serve as the basis for review of primary (health) national ambient air quality standards (NAAQS) for each pollutant. When comparisons can be made, O₃ is generally more toxic than other photochemical oxidant species at or near ambient levels, although NO₂ does not appear to be of more concern with respect to carcinogenesis. Public health effects of concern for O₃ range from acute symptoms (e.g. cough) and decreased lung function to persistent functional changes and permanent scarring of lung tissue, a possible precursor to chronic lung disease. Impairment of immune defenses and increased susceptibility to lung infection have also been associated with O₃ exposure. Populations at greatest risk include exercising healthy persons, children, and those with preexisting lung disease. Nitrogen dioxide exhibits similar health effects but at higher concentrations. These effects include acute symptoms and lung function impairment, increased susceptibility to acute respiratory infection, and possibly conditions leading to chronic lung disease. Populations potentially at risk include children, asthmatics, and individuals who exercise in the presence of NO₂. Health effects data for O₃ and NO₂ are under consideration in the current review of both primary NAAQS.     

Ozone measurements in jet airliner cabin air

Ozone measured in cabin air on 14 flights over polar areas shows maximum concentrations during Spring. Ozone numbers close to atmospheric values were found in the air entering the cabin through the air conditioning system but a reduction to about half of this value takes place immediately within the cabin air. Aircraft with recirculating cabin air showed an additional reduction by about 25%. Maximum concentrations are considerably higher and the duration of such periods longer than those reported in FAA Technical Report ADS-5 in which, however, data from polar areas during O₃ maximum are missing. Ozone destruction effects within the pressurization system as claimed in the FAA report are doubtful. Although O₃ reduction occurs within the cabin air, the threshold value of 0.1 ppm. for breathing air was surpassed in about 75 % of the flight time (8 to 10 hr between Copenhagen and Seattle) and maximum concentrations (0.4 ppm during 4 hr and 0.6 ppm during 1 hr) were found to be close to critical values recommended by the Environmental Protection Agency. Assuming that no O₃ destruction takes place in the pressurization system, O₃ concentrations exceeding 1 ppm, can be expected to enter the cabin at flight levels for commercial flight on polar routes during Spring. Some experiences during periods of high O₃ concentrations were increasing irritation in the eyes and the respiratory tract, effects different from those associated with low humidity in cabin air.     

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.     

Field Data of Hydrogen Peroxide Concentrations in Urban and Mountain Air in Southwestern Poland

The concentrations of ambient gas-phase hydrogen peroxide were measured during the summer of 1998, 1999 and 2000. The experiments were performed in the city of Wroclaw and in the vicinity of Mount Szrenica, 1362 m a.s.l., Poland. Analysis was carried out by the chemiluminescence method. Typical mean ranges of 30 min H₂O₂ concentrations measured were 1.4–6.0 μg m^-3 at Mount Szrenica, whereas in the urban atmosphere H₂O₂ concentrations were in the range of 2.7–11.7 μg m^-3. In the case of the urban atmosphere, H₂O₂ concentrations were well correlated only with solar radiation and temperature. In the mountain air, H₂O₂ concentrations increased along with the increase of temperature, O₃, CO and the decrease of humidity. The diurnal variation was not only caused by photochemicalprocesses.     

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.     

Reduction in soybean yield after exposure to ozone and sulfur dioxide using a linear gradient exposure technique

A linear gradient field exposure system was modified from one originally described by Shinn et al. (1977) and used to expose field grown soybeans (Glycine max cv Hark) to a concentration gradient of a mixture of two gaseous pollutants: SO₂ and 0₃. Since this technique does not use enclosures, study plants experienced near ambient fluctuations in environmental conditions, including wind, and hence were exposed to widely fluctuating pollutant concentrations. Plants in the gradient system were exposed to both pollutants for 57 h on 12 days during the pod-filling period (31 August–17 September). Mean concentrations during the 57 h of exposure at the ‘high’ end of the gradient were 0.16 and 0.06 µl l^?1 (PPM) SO₂ and O₃, respectively, with 10 h at greater than 0.25 and 0.10 µl^?1 SO₂ and O₃, respectively. Total doses for these plants were estimated to be 9.0 and 3.5 µl^?1 · h SO₂ and O₃, respectively. Comparison with plants exposed to ambient air indicated that exposure to SO₂ and O₃ reduced total yield per plant and dry mass per bean by as much as 36 and 15 %, respectively. Since concurrent exposure to a much higher dosage of SO₂ alone (20.2 µl l^?1 · h) was observed in a separate experiment to have no significant effect on yield, 03, although present at moderately low levels, was probably responsible (alone or synergistically with SO₂) for the greatest reduction in seed size and yield.     

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.     

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.     

Oxygen and redox potential gradients in the rhizosphere of alfalfa grown on a loamy soil

Oxygen (O₂) supply and the related redox potential (E_H) are important parameters for interactions between roots and microorganisms in the rhizosphere. Rhizosphere extension in terms of the spatial distribution of O₂ concentration and E_H is poorly documented under aerobic soil conditions. We investigated how far O₂ consumption of roots and microorganisms in the rhizosphere is replenished by O₂ diffusion as a function of water/air‐filled porosity. Oxygen concentration and E_H in the rhizosphere were monitored at a mm‐scale by means of electroreductive Clark‐type sensors and miniaturized E_H electrodes under various matric potential ranges. Respiratory activity of roots and microorganisms was calculated from O₂ profiles and diffusion coefficients. pH profiles were determined in thin soil layers sliced near the root surface. Gradients of O₂ concentration and the extent of anoxic zones depended on the respiratory activity near the root surface. Matric potential, reflecting air‐filled porosity, was found to be the most important factor affecting O₂ transport in the rhizosphere. Under water‐saturated conditions and near field capacity up to –200 hPa, O₂ transport was limited, causing a decline in oxygen partial pressures (pO₂) to values between 0 and 3 kPa at the root surface. Aerobic respiration increased by a factor of 100 when comparing the saturated with the driest status. At an air‐filled porosity of 9% to 12%, diffusion of O₂ increased considerably. This was confirmed by E_H around 300 mV under aerated conditions, while E_H decreased to 100 mV on the root surface under near water‐saturated conditions. Gradients of pO₂ and pH from the root surface indicated an extent of the rhizosphere effect of 10–20 mm. In contrast, E_H gradients were observed from 0 to 2 mm from the root surface. We conclude that the rhizosphere extent differs for various parameters (pH, Eh, pO₂) and is strongly dependent on soil moisture.     

Growth of Pinus Taeda L. Seedlings varies with Family and ozone exposure level

Loblolly pine seedlings of five half-sib families were grown under ambient, subambient (approximately 0.6 × ambient), and elevated [ambient + 60 ppb O₃ (120 μg m^?3)] O₃ levels for one growing season in open-topped chambers. Diameter and height of the seedlings were measured periodically over the growing season, and above ground and below ground biomass were determined at harvest. Significant genetic differences were found in above ground volume (D ²H) 1 mo after 03 fumigation began and continued until harvest. Biomass of secondary needles and coarse and fine roots also differed significantly among families. Elevated O3 resulted in significantly decreased D ²H and secondary needle biomass relative to seedlings grown in ambient air. Seedlings receiving subambient O₃ levels were intermediate in size, but were not significantly different from seedlings fumigated at ambient O₃ levels. Root and stem biomass did not differ significantly among treatments. A significant interaction of O₃ and genotype was detected, suggesting that the response of loblolly pine to O₃ is influenced by genotype.     

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.     

Source regions of summertime ozone and haze episodes in the eastern United States

During the summer of 1979, the mobile Atmospheric Research Laboratory (ARL) was sited near the Louisiana Gulf Coast to monitor the concentrations of air contaminants in air masses moving northward from the Gulf. Using the ARL data in conjunction with O₃ and visibility measurements across the entire eastern United States as well as synoptic meteorological data and satellite photographs, major source areas were identified. The haze which was observed on the Louisiana Gulf Coast appears to be primarily due to aged sulfate aerosols. The evidence presented strongly suggests that the sulfates were largely due to SO₂ emissions in the northeastern and midwestern United States. The haze initially formed over and downwind of these source areas and was transported to the Gulf Coast area. In the last two episodes, the haze was subsequently transported back to the Midwest source region. Elevated levels of O₃ were also associated with the haze. Again, the Northeast and Midwest appear to be the most significant source areas for the regional O₃ episodes. Occasionally, O₃ formed from emissions in the east Texas area also appear to affect a large portion of the Gulf Coast. In addition, each episode appeared to have a significant stratospheric air component based on⁷Be measurements. All three episodes followed the passage of upper levels troughs which produce stratospheric intrusions due to tropopause folding.     

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.     

Carbon Isotope Composition, Macronutrient Concentrations, and Carboxylating Enzymes in Relation to the Growth of Pinus halepensis Mill. When Subject to Ozone Stress

We present here the effects of ambient ozone (O₃)-induced decline in carbon availability, accelerated foliar senescence, and a decrease in aboveground biomass accumulation in the Aleppo pine (Pinus halepensis Mill.). Aleppo pine seedlings were continuously exposed in open-top chambers for 39 months to three different types of O₃ treatments, which are as follows: charcoal-filtered air, nonfiltered air (NFA), and nonfiltered air supplemented with 40 ppb O₃ (NFA+). Stable carbon isotope discrimination (??) and derived time-integrated c _i/c _a ratios were reduced after an accumulated ozone exposure over a threshold of 40 ppb (AOT40) value from April to September of around 20,000 ppb·h. An AOT40 of above 67,000 ppb·h induced reductions in ribulose-1,5-biphosphate carboxylase/oxygenase activity, aboveground C and needle N and K concentrations, the C/N ratio, Ca concentrations in twigs under 3 mm, and the aerial biomass, as well as increases in needle P concentrations and phosphoenolpyruvate carboxylase (PEPC) activity and the N and K concentrations in twigs under 3 mm. Macronutrients losses, the limitations placed on carbon uptake, and increases in catabolic processes may be the causes of carbon gain diminution in leaves which was reflected as a reduction in aboveground biomass at tree level. Stimulation of PEPC activity, the consequent decreased ??, and compensation processes in nutrient distribution may increase O₃ tolerance and might be interpreted as part of Aleppo pine acclimation response to O₃.     

Oxidant effects on forest tree seedling growth in the Appalachian mountains

Long range transport of episodic concentrations of O₃ into the Appalachian Mountains of Virginia was recorded in the summer season of 1979 and 1980. Continuous monitoring of O₃ indicated monthly averages of ? 0.05 ppm O₃ and several periods averaged ? 0.08 ppm O₃. Open-top chambers were used to test the effect of ambient doses of the pollutant on the growth of 8 planted forest tree species native to the area. Height growth was suppressed for all species at the end of the second growing season when grown in open plots (no chamber) and ambient chambers compared to those grown in charcoal-filtered air supplied chambers. Height growth trends of open < ambient chamber < filtered air chamber were consistent. Virginia pine and green ash were significantly taller (p=0.10) when grown within filtered air chambers. Tulip poplar and green ash manifested purple stippling on the adaxial leaf surface and sweetgum developed purple coloration under open or ambient chamber conditions; other species exhibited no visible injury.     

Acid deposition at the summit of Mt. Fuji: Observations of gases,aerosols and precipitation in summer,1993 and 1994

Intensive observations of chemical species in aerosols, gases and other samples at the summit of Mt. Fuji and at Tarobo (at 1300m on the mountain'ts southern slope) was performed from July 28 to Aug. 3, 1993 and from July 25 to 30,1994. The most interesting observation was the abrupt increase in the sulfate concentration in aerosol collected in July, 1993 just after the typhoon (number 9306) passed the Japanese archipelago and the wind direction shifted from south to west. Chemical analysis indicated this aerosol was acidic. In contrast, the summit aerosol observed in 1994 was not acidic following a less dramatic rise in sulfate content. Back trajectory analyses were used to extrapolate from these measurement to an inventory of polluted air over the Asian Continent. The concentrations of gaseous SO₂ and HCl remained low during both observation periods, with some higher concentrations of NH₃.     

Effects of genotype on the response of Populus tremuloides michx. To ozone and nitrogen deposition

Elevated O₃ concentrations and N deposition levels co -occur in much of eastern United States. However, very little is known about their combined effects on tree growth. The effects of three O₃ treatments: charcoal-filtered air, non-filtered air and O₃, added at the rate of 80 ppb for 6 hr d^?1 3 d per week), four N deposition levels (0, 10, 20 and 40 kg ha^?1 yr^?1), and their interactions on growth of two Populus tremuloides clones in open-top chambers at two sites 600 km apart in Michigan were examined. Our results revealed a highly significant fertilization effect of the N treatments, even at the 10 kg ha^?1 yr^?1 rate. Ozone alone induced foliar injury, but not significant growth reductions. There was an indication that O₃ decreased growth at the O N level, but this decrease was reversed in all N treatments by the N fertilization effect. Further study is needed to more fully understand the combined effects of N deposition and O₃.