Interaction of ozone exposure and Fusarium subglutinans inoculation on growth and disease development of loblolly pine seedlings

Seedlings from ten half-sib families of loblolly pine (Pinus taeda) were exposed in open-top chambers to carbon-filtered air (CF), non-filtered air (NF), or air amended with ozone to 1.7 or 2.5 times ambient. After 105 days of exposure, half the seedlings within each family were wounded but not inoculated and half were wounded and inoculated with the pitch canker fungus, Fusarium subglutinans, to which five families were relatively resistant. After an additional 50 days of ozone treatment, seedling growth and canker development were recorded. Cankers were significantly (sigma < or = 0.05) smaller among resistant compared to susceptible families, and were significantly larger among seedlings receiving the highest (2.5) compared to the ambient (NF) ozone treatment. The wound scars of non-inoculated seedlings were also significantly larger among seedlings receiving the 2.5 compared to the NF treatment, but these dimensions did not differ significantly with seedling family or resistance. The weights of needles and large roots were significantly smaller at the 2.5 compared to the 1.7 ozone treatment for inoculated but not for non-inoculated seedlings; this resulted in a significant interaction for ozone and inoculation effects. Among resistant families, root weights were significantly smaller for inoculated seedlings. Diameter growth and dry weights of needles were significantly smaller among inoculated compared to non-inoculated seedlings, but did not differ between NF and 2.5 ozone treatments.     

Ozone exposure of field-grown winter wheat affects soil mesofauna in the rhizosphere

A 2-year open-top chamber experiment with field-grown winter wheat (Triticum aestivum L. cv. Astron) was conducted to examine the effects of ozone on plant growth and selected groups of soil mesofauna in the rhizosphere. From May through June in each year, plants were exposed to two levels of O₃: non-filtered (NF) ambient air or NF+ 40 ppb O₃ (NF+). During O₃ exposure, soil sampling was performed at two dates according to different plant growth stages. O₃ exposure reduced above- and below-ground plant biomass in the first year, but had little effect in the second year. The individual density of enchytraeids, collembolans and soil mites decreased significantly in the rhizosphere of plants exposed to NF+ in both years. Differences were highest around anthesis, i.e. when plants are physiologically most active. The results suggest that elevated O₃ concentrations may influence the dynamic of decomposition processes and the turnover of nutrients.     

Screening loblolly pine seedling responses to SO2 and O3: analysis of families differing in resistance to fusiform rust disease

Open pollinated families of loblolly pine differing in resistance to fusiform rust disease were screened in laboratory studies for responses to gaseous air pollutants. Twenty families were given acute exposures (2 fumigations for 4 h each) to SO(2) (0.4-1.0 ppm), O(3) (0.25 ppm), SO(2) (0.4-1.0 ppm) + O(3) (0.25 ppm) and control. Analyses of variance were performed to evaluate the treatment effects of these air pollutants on percent foliar injury, and to determine whether the families responded differentially to the air pollution treatments. Treatment effects were significant, with the combination treatment of SO(2) + O(3) producing a higher percentage of foliar injury than the controls; however, injury levels were very low and may not be of biological significance. Subsequently, twelve families were grown in two soil types for exposure to chronic levels of SO(2) (0.06 ppm), O(3) (0.07 ppm), SO(2) (0.06 ppm) + O(3) (0.07 ppm) and control. The families were then ranked for decreased primary shoot growth, shoot dry weight, root dry weight, total plant dry weight and root/shoot ratio after exposure to air pollution treatments. Air pollution treatments as a main effect were significant for only one of five growth parameters measured, that of primary shoot growth. The main effect of family, and the interaction of family and air pollution treatments, were significant for most growth parameters measured. In general, O(3) alone and in combination with SO(2) reduced growth more than SO(2) alone. Fumigation with O(3) reduced growth of two families in comparison with control groups, whereas SO(2) alone produced decreased growth in one family and stimulated growth in three families. Treatment with O(3) alone produced higher root/shoot ratios than fumigation with charcoal-filtered air in two families. Overall, families which were fast growers under control conditions maintained their ranking after exposure to air pollution. Families producing less growth in charcoal-filtered air also produced less growth under various air pollution regimes. Results indicated that these families exhibited a high degree of resistance to air pollution injury. Growth responses of seedlings may not reflect family differences in long-term productivity. No relationship was apparent between fusiform rust resistance and growth reductions due to air pollutants.     

Contribution of ambient ozone to Scots pine defoliation and reduced growth in the Central European forests: a Lithuanian case study

The study aimed to explore if changes in crown defoliation and stem growth of Scots pines (Pinus sylvestris L.) could be related to changes in ambient ozone (O₃) concentration in central Europe. To meet this objective the study was performed in 3 Lithuanian national parks, close to the ICP integrated monitoring stations from which data on meteorology and pollution were provided. Contribution of peak O₃ concentrations to the integrated impact of acidifying compounds and meteorological parameters on pine stem growth was found to be more significant than its contribution to the integrated impact of acidifying compounds and meteorological parameters on pine defoliation. Findings of the study provide statistical evidence that peak concentrations of ambient O₃ can have a negative impact on pine tree crown defoliation and stem growth reduction under field conditions in central and northeastern Europe where the AOT40 values for forests are commonly below their phytotoxic levels.     

The development of sulfur dioxide and ozone exposure profiles that mimic ambient conditions in the rural southeastern united states

A design for constructing experimental mixed-pollutant exposure profiles that reflect regional O₃ and SO₂ ambient air quality is described. The profiles were developed using hour-by-hour O₃ and SO₂ concentration data from monitoring sites in the southeastern United States where slash pine is indigenous. Only sites designated rural or remote, with co-monitored O₃ and SO₂, and at least 75% of the hourly values reported for the period April– October, were used. Each site was characterized by concentration, frequency of occurrence and duration of concentration values, length of time between episodes, and frequency of cooccurrence. A base profile, a 30-day hour-by-hour concentration regime, was constructed using averaged air quality characteristics from the selected sites. Using the base profile, additional regimes were constructed by increasing the concentration of all hourly values above a designated minimum, or by increasing the frequency of occurrence of selected hourly concentrations.     

Contrasting effects of ozone under different water supplies in two Mediterranean tree species

The effects of ozone (O₃) exposure under different water availabilities were studied in two Mediterranean tree species: Quercus ilex and Ceratonia siliqua. Plants were exposed to different O₃ concentrations in open top chambers (charcoal-filtered air (CF), non-filtered air (NF)) and non-filtered air plus 40 ppb_v of O₃ ((7:00–17:00 solar time) (NF+)) during 2 years, and to different water regimes (IR, sample irrigation, and WS, reduced water dose to 50%) through the last of those 2 years. AOT40 in the NF+ treatment was 59265 ppb_v h (from March 1999 to August 1999) while in the NF treatment, the AOT40 was 6727 ppb_v h for the same period. AOT40 was always 0 in the CF treatment. WS plants presented lower stomatal conductances and net photosynthetic rates, and higher foliar N concentrations than IR plants in both species. The irrigation treatment did not change the response trends to ozone in Q. ilex, the most sensitive species to O₃ ambient concentrations, but it changed those of C. siliqua, the least sensitive species, since its ozone-fumigated WS plants did not decrease their net photosynthetic rates nor their biomass accumulation as it happened to its ozone-fumigated IR plants. These results show interspecific variations in O₃ sensitivity under different water availabilities.     

Phenogenetic response of silver birch populations and half-sib families to elevated ozone and ultraviolet-B radiation at juvenile age

Phenogenetic response of silver birch populations and half-sib families to separate and combined elevated ozone (O₃) concentrations and ultraviolet-B (UV-B) radiation dozes was studied at juvenile age in the climatic chambers. Significant population and family effects were found for seedling height, lamina width, and leaf damage. The exposure to UV-B radiation decreased genetic variation at the stage of seed germination. Complex exposure to UV-B and O₃ caused an increase of genetic variation at the stage of intensive seedling growth: seedling height genetic variation in separate treatments increased from 23.7–38.6 to 33.7–65.7%, the increase for lamina width was from 10.2–13.9 to 13.6–31.8%. Different populations and families demonstrated differing response to elevated complex UV-B and O₃ exposure. Changes of genetic intra-population variation were population-specific. Such changes in genetic variation under the impact of stressors can alter adaptation, stability, and competitive ability of regenerating populations in a hardly predictive way.     

Indoor Fine Particles: The Role of Terpene Emissions from Consumer Products

Abstract

Consumer products can emit significant quantities of terpenes, which can react with ozone (O₃). Resulting byproducts include compounds with low vapor pressures that contribute to the growth of secondary organic aerosols (SOAs). The focus of this study was to evaluate the potential for SOA growth, in the presence of O₃, following the use of a lime-scented liquid air freshener, a pine-scented solid air freshener, a lemon-scented general-purpose cleaner, a wood floor cleaner, and a perfume. Two chamber experiments were performed for each of these five terpene-containing agents, one at an elevated O₃ concentration and the other at a lower O₃ concentration. Particle number and mass concentrations increased and O₃ concentrations decreased during each experiment. Experiments with terpene-based air fresheners produced the highest increases in particle number and mass concentrations. The results of this study clearly demonstrate that homogeneous reactions between O₃ and terpenes from various consumer products can lead to increases in fine particle mass concentrations when these products are used indoors. Particle increases can occur during periods of elevated outdoor O₃ concentrations or indoor O₃ generation, coupled with elevated terpene releases. Human exposure to fine particles can be reduced by minimizing indoor terpene concentrations or O₃ concentrations.     

Growth response of loblolly pine (Pinus taeda L.) seedlings to ozone fumigation

Twenty-two week-old Pinus taeda L. (loblolly pine) seedlings of 30 open-pollinated and five full-sib families, representing a wide range in geographic origin, were grown in charcoal-filtered (CF) air or CF-air supplemented with 160 or 320 nl liter(-1) ozone for 8 h day(-1), 4 days week(-1), for 9 weeks. Visible foliar injury (banded chlorosis, tip burn and premature senescence) was apparent in many families after 3 weeks in 320 nl liter(-1) and 6 weeks in 160 nl liter(-1) ozone. Decreases in relative height and root collar diameter growth rates, total dry weight, root dry weight, shoot dry weight, and root/shoot ratios were evident after 9 weeks of treatment with both 160 and 320 nl liter(-1) ozone. For relative height growth rates, family differences in response to ozone were observed. By the study's end, net photosynthesis rates were 15% less for the 320 nl liter(-1) ozone treatment as compared to the CF-air treatment. Total soluble sugar and total starch content of roots were not changed after 9 weeks of ozone exposure.     

Adaptation by Older Individuals Repeatedly Exposed to 0.45 Parts per Million Ozone for Two Hours

To test for an increased reaction to ozone (O₃) in older individuals following an initial exposure, and to test for adaptation and its duration, we exposed 10 men and 6 women (60-89 years old) in an environmental chamber to filtered air and 3 consecutive days of O₃ exposure (0.45 ppm), followed by a fourth O₃ exposure day after a two day hiatus. Subjects alternated 20-min exercise (minute ventilation = 27 L) and rest periods for 2 hours during each exposure. Subjects rated from one to five, 16 possible respiratory/exercise symptoms prior to and following the exposure. Pulmonary function tests were performed before, and during each rest period and following the exposure. Metabolic measurements were obtained during each exercise period. No significant changes in any symptom question occurred, in spite of a threefold increase in the total number of reported symptoms during O₃ exposure. Small but significant pre-to-post decrements on the first and second O₃ days in forced vital capacity (FVC—111 and 104 mL), forced expiratory volume in 1 (FEV₁—171 and 164 mL) and 3 seconds (FEV₃—185 and 172 mL) occurred without concomitant changes in any flow parameter of the forced expiratory maneuver. No differences in the group mean response in FVC, FEV₁, OR FEV₃ on the third or fourth day of O₃ exposure and the filtered air exposure were found. The observed changes were due to significant physiological changes in eight of the subjects. Unlike young subjects, no evidence of an increased pulmonary function response to a second consecutive O₃ exposure was observed. Changes in small airway response to O₃ (below 75 percent of FVC) without irritant receptor activation, would explain the observed pattern of response.     

The influence of ozone on atmospheric emissions of gaseous elemental mercury and reactive gaseous mercury from substrates

Experiments were performed to investigate the effect of ozone (O₃) on mercury (Hg) emission from a variety of Hg-bearing substrates. Substrates with Hg(II) as the dominant Hg phase exhibited a 1.7 to 51-fold increase in elemental Hg (Hg^o) flux and a 1.3 to 8.6-fold increase in reactive gaseous mercury (RGM) flux in the presence of O₃-enriched clean (50 ppb O₃; 8 substrates) and ambient air (up to ∼70 ppb O₃; 6 substrates), relative to clean air (oxidant and Hg free air). In contrast, Hg^o fluxes from two artificially Hg^o-amended substrates decreased by more than 75% during exposure to O₃-enriched clean air relative to clean air. Reactive gaseous mercury emissions from Hg^o-amended substrates increased immediately after exposure to O₃ but then decreased rapidly. These experimental results demonstrate that O₃ is very important in controlling Hg emissions from substrates. The chemical mechanisms that produced these trends are not known but potentially involve heterogenous reactions between O₃, the substrate, and Hg. Our experiments suggest they are not homogenous gas-phase reactions. Comparison of the influence of O₃ versus light on increasing Hg^o emissions from dry Hg(II)-bearing substrates demonstrated that they have a similar amount of influence although O₃ appeared to be slightly more dominant. Experiments using water-saturated substrates showed that the presence of high-substrate moisture content minimizes reactions between atmospheric O₃ and substrate-bound Hg. Using conservative calculations developed in this paper, we conclude that because O₃ concentrations have roughly doubled in the last 100 years, this could have increased Hg^o emissions from terrestrial substrates by 65–72%.     

Severity of SO2-lnduced Leaf Necrosis on Caribbean,Scots, and Virginia Pine Seedlings

Caribbean pine, an economically important tree of tropical lowlands, is at risk of SO₂ exposure in certain locales. Twenty-week old seedlings of Caribbean, Scots, and Virginia pine were exposed to 0.5, 1.0, and 2.0 ppm SO₂ (1300, 2600, and 5200 μm^?3, respectively) for 1, 2, 4, and 8 h in modified controlled-environment chambers. Severity of SO₂-induced leaf necrosis for each species was related to SO₂ concentration and exposure duration using a regression model. The three dose-response relationships differed in detail, but Caribbean pine seedlings were generally as sensitive to SO₂ as seedlings of the two highly sensitive temperate species. In addition, 173 4-wk-old Caribbean pine seedlings were exposed to 0.5 ppm SO₂ for 4 h. Over one-half of these seedlings exhibited some necrosis and over one-sixth had more than 5 percent of leaf surface necrotic. It is concluded that Caribbean pine seedlings are highly sensitive to acute doses of SO₂.     

The use of air quality forecasts to assess impacts of air pollution on crops: Methodology and case study

It has been reported that ambient ozone (O₃), either alone or in concurrence with acid rain precursors, accounts for up to 90% of US crop losses resulting from exposure to all major air pollutants. Crop damage due to O₃ exposure is of particular concern as ambient O₃ concentrations remain high in many major food-producing regions. Assessing O₃ damage to crops is challenging due to the difficulties in determining the reduction in crop yield that results from exposure to surface O₃, for which monitors are limited and mostly deployed in non-rural areas. This work explores the potential benefits of using operational air quality forecast (AQF) data to estimate rural O₃ exposure. Using the results from the first nationwide AQF as a case study, we demonstrate how the O₃ data provided by AQF can be combined with concurrent crop information to assess O₃ damages to soybeans in the United States. We estimate that exposure to ambient O₃ reduces the US soybean production by 10% in 2005.     

Effects of ozone on three open-pollinated families of Pinus taeda L. grown in two substrates

Seedlings from three open-pollinated loblolly pine (Pinus taeda L.) families grown in a mixture of commercial peat moss and grade 3 vermiculite (1:3 by volume) or a mixture of mineral soil and peat (1:1 by volume) were exposed to 0, 160 or 320 ppb ozone (O3) for 6h/day, 4 days/week for 8 weeks beginning 12 weeks after transplanting. Before exposures began, seedlings grown in the vermiculite-peat substrate were taller but smaller in diameter than those grown in the mineral soil-peat substrate. After 8 weeks of exposure, seedlings grown in the mineral soil-peat substrate were significantly larger in diameter and total biomass than those grown in the vermiculite-peat substrate. Primary needle and secondary needle injury increased with increasing O3 concentrations. Suppression of diameter growth, shoot weight and root weight was linear as O3 concentration increased. The effect of O3 on height or diameter growth or shoot biomass was not influenced by substrate type; but the suppression of root biomass due to O3 was dependent on substrate, with greater suppression in biomass occurring in the vermiculite-peat substrate. Foliar injury due to O3 was slightly greater in family 8-103, but growth suppression due to O3 was not significantly different among the families. Based on root biomass, response of seedlings to O3 was substrate-dependent.     

Variation of ozone concentrations in the ambient air of Baghdad

Measurements of ozone concentration in the ambient air of the city of Baghdad were carried out for the period October 1983 to October 1984. The O₃, probably of local origin, showed a typical diurnal and seasonal variation. Maximum daily 1-h O₃ concentrations higher than the international ambient air quality standards were observed regularly during the summer months. High O₃ concentrations during the night were also observed. Scatter diagrams were used to relate the O₃ concentrations with temperature, solar radiation and humidity.     

A system coupling hybrid biological method with UV/O<Subscript>3</Subscript> oxidation and membrane separation for treatment and reuse of industrial laundry wastewater

The possibilities of application of a three-step system combining hybrid biological treatment followed by advanced UV/O₃ oxidation with in situ generated O₃ and membrane separation (ultrafiltration (UF) and nanofiltration (NF)) to treat and reuse the wastewater from an industrial laundry are presented. By the application of a hybrid moving bed biofilm reactor (HMBBR), the total organic carbon concentration was reduced for about 90 %. However, since the HMBBR effluent still contained organic contaminants as well as high concentrations of inorganic ions and exhibited significant turbidity (8.2 NTU), its further treatment before a possible reuse in the laundry was necessary. The UV/O₃ pretreatment prior to UF was found to be an efficient method of the membrane fouling alleviation. During UF, the turbidity of wastewater was reduced below 0.3 NTU. To remove the inorganic salts, the UF permeate was further treated during NF. The NF permeate exhibited very low conductivity (27–75 μS/cm) and contained only small amounts of Ca²⁺ and Mg²⁺; thus ,it could be reused at any stage of the laundry process.     

Effects of ozone on growth, yield and leaf gas exchange rates of two Bangladeshi cultivars of wheat (Triticum aestivum L.)

To clarify the effects of O₃ on crop plants cultivated in Bangladesh, two Bangladeshi wheat cultivars (Sufi and Bijoy) were grown in plastic boxes filled with Andisol and exposed daily to charcoal-filtered air or O₃ at 60 and 100 nl l⁻¹ (10:00-17:00) from 13 March to 4 June 2008. The whole-plant dry mass and grain yield per plant of the two cultivars at the final harvest were significantly reduced by the exposure to O₃. Although there was no significant effect of O₃ on stomatal diffusive conductance to H₂O of flag leaf, net photosynthetic rate of the leaf was significantly reduced by the exposure to O_3. The sensitivity of growth, yield, yield components and leaf gas exchange rates to O₃ was not significantly different between the two cultivars. The results obtained in the present study suggest that ambient levels of O₃ may detrimentally affect wheat production in Bangladesh.     

Effects of ozone on growth, yield and leaf gas exchange rates of four Bangladeshi cultivars of rice (Oryza sativa L.)

To assess the effects of tropospheric O₃ on rice cultivated in Bangladesh, four Bangladeshi cultivars (BR11, BR14, BR28 and BR29) of rice (Oryza sativa L.) were exposed daily to charcoal-filtered air or O₃ at 60 and 100 nl l⁻¹ (10:00-17:00) from 1 July to 28 November 2008. The whole-plant dry mass and grain yield per plant of the four cultivars were significantly reduced by the exposure to O₃. The exposure to O₃ significantly reduced net photosynthetic rate of the 12th and flag leaves of the four cultivars. The sensitivity to O₃ of growth, yield and leaf gas exchange rates was not significantly different among the four cultivars. The present study suggests that the sensitivity to O₃ of yield of the four Bangladeshi rice cultivars is greater than that of American rice cultivars and is similar to that of Japanese rice cultivars and that O₃ may detrimentally affect rice production in Bangladesh.     

Air Quality Modeling of Interpollutant Trading for Ozone Precursors in an Urban Area

Abstract

Emission trading is a market‐based approach designed to improve the efficiency and economic viability of emission control programs; emission trading has typically been confined to trades among single pollutants. Interpollutant trading (IPT), as described in this work, allows for trades among emissions of different compounds that affect the same air quality end point, in this work, ambient ozone (O₃) concentrations. Because emissions of different compounds impact air quality end points differently, weighting factors or trading ratios (tons of emissions of nitrogen oxides (NO_x) equivalent to a ton of emissions of volatile organic compounds [VOCs]) must be developed to allow for IPT. In this work, IPT indices based on reductions in O₃ concentrations and based on reductions in population exposures to O₃ were developed and evaluated using a three‐dimensional gridded photochemical model for Austin, TX, a city currently on the cusp of nonattainment with the National Ambient Air Quality Standards for O₃ concentrations averaged over 8 hr. Emissions of VOC and NO_x from area and mobile sources in Austin are larger than emissions from point sources. The analysis indicated that mobile and area sources exhibited similar impacts. Trading ratios based on maximum O₃ concentration or population exposure were similar. In contrast, the trading ratios did exhibit significant (more than a factor of two) day‐to‐day variability. Analysis of the air quality modeling indicated that the daily variability in trading ratios could be attributed to daily variations in both emissions and meteorology.