Abstract  Photosynthetic stimulation and stomatal conductance (Gs) depression in Quercus ilex leaves at a CO2 spring suggested no down-regulation. The insensitivity of Gs to a CO2 increase (from ambient 1500 to 2000 mu mol mol(-1)) suggested stomatal acclimation. Both responses are likely adaptations to the special environment Of CO2 Springs. At the CO2-enriched site, not at the control site, photosynthesis decreased 9% in leaves exposed to 2x ambient O-3 concentrations in branch enclosures, compared to controls in charcoal-filtered air. The stomatal density reduction at high CO2 was one-third lower than the concomitant Gs reduction, so that the O-3 uptake per single stoma was lower than at ambient CO2. No significant variation in monoterpene emission was measured. Higher trichome and mesophyll density were recorded at the CO2-enriched site, accounting for lower O-3 sensitivity. A long-term exposure to H2S, reflected by higher foliar S-content, and CO2 might depress the antioxidant capacity of leaves close to the vent and increase their O-3 sensitivity. (c) 2006 Elsevier Ltd. All rights reserved.

Abstract  The study examined air pollution tolerance indices ( APTI) of ten plant species around the Erhoike-Kokori oil exploration station of Delta state. Four physiological and biochemical parameters; leaf relative water content (RWC) ascorbic acid content ( AA), total leaf chlorophyll (TCh) and leaf extract pH were used to compute the APTI values. The result showed that combining variety of these parameters gave a more reliable result than those of individual parameter. The order of tolerance is as follows: Psidium guajava < Elaesis guineensis < Musa paradisiaca < Bambosa bambosa < Anacadium occidentale < Terminalia catappa < Manihot exculenta < Impereta cylindrical < Chromolaena odorata < Manifera indica.

Abstract  Maintaining healthy forests is the major objective for the Forest Service scientists and managers working for the U.S. Department of Agriculture. Air pollution, specifically ozone (O-3) and nitrogenous (N) air pollutants, may severely affect the health of forest ecosystems in the western U.S. Thus, the monitoring of air pollution concentration and deposition levels, as well as studies focused on understanding effects mechanisms, are essential for evaluation of risks associated with their presence. Such information is essential for development of proper management strategies for maintaining clean air, clean water, and healthy ecosystems on land managed by the Forest Service. We report on two years of research in the central Sierra Nevada of California, a semi-arid forest at elevations of 1100-2700 m. Information on O-3 and N air pollutants is obtained from a network of 18 passive samplers. We relate the atmospheric N concentration to N concentrations in streams, shallow soil water, and bulk deposition collectors within the Kings River Experimental Watershed. This watershed also contains an intensive site that is part of a recent Forest Service effort to calculate critical loads for N, sulfur, and acidity to forest ecosystems. The passive sampler design allows for extensive spatial measurements while the watershed experiment provides intensive spatial data for future analysis of ecosystem processes.

Abstract  Cutleaf coneflower (Rudbeckia laciniata L) seedlings were placed into open-top chambers in May, 2004 and fumigated for 12 wks. Nine chambers were fumigated with either carbon-filtered air (CF), nonfiltered air (NF) or twice-ambient (2x) ozone (O-3). Ethylenediurea (EDU) was applied as a foliar spray weekly at 0 (control), 200, 400 or 600 ppm. Foliar injury occurred at ambient (30%) and elevated O-3 (100%). Elevated O-3 resulted in significant decreases in biomass and nutritive quality. Ethylenediurea reduced percent of leaves injured, but decreased root and total biomass. Foliar concentrations of cell-wall constituents were not affected by EDU alone; however, EDU x O-3 interactions were observed for total cell-wall constituents and lignocellulose fraction. Our results demonstrated that O-3 altered the physiology and productivity of cutleaf coneflower, and although reducing visible injury EDU may be phytotoxic at higher concentrations. (C) 2008 Elsevier Ltd. All rights reserved.

Abstract  Critical levels to determine plant response to ozone (O-3) have been used in Europe since the 1980s, utilizing the concentration-based AOT40 to relate plant response to ambient O-3 exposure. More recently, there has been progress in Europe toward utilizing flux-based critical levels, because plant response is more closely related to O-3 uptake than to the amount of O-3 in ambient air. Flux-based critical levels are plant species specific; data for parameterization of flux-based critical levels models are lacking for most plant species. Although flux-based critical levels are now being used for a limited number of agricultural crops and tree species where data are available, the use of flux-based critical levels is limited by the lack of adequate consideration and incorporation of plant internal detoxification mechanisms in flux modeling. Critical levels have not been used in North America; however, recent interest in the U.S. and Canada for using critical loads for nitrogen and sulfur has generated interest in using critical levels for O-3. A major obstacle for utilization of critical levels in North America is that ambient air quality standards for O-3 in the U.S. and Canada are concentration based. It appears that cumulative exposure-based metrics, particularly when implemented with a quantification of peak concentrations and environmental variables, such as a drought index, are currently the most useful to relate O-3 to vegetation response. Because data are unavailable to quantify detoxification potential of vegetation, effective flux models are not available to determine plant response to O-3.

Abstract  Surface ozone concentration and surface air temperature was measured hourly at three coastal sites, four low elevation inland sites and two high elevation inland sites in southwestern Sweden. Diurnal ozone concentration range (DOR) and diurnal temperature range (DTR) were strongly correlated, both spatially and temporally, most likely because both depended on atmospheric stability. Accumulated ozone exposure above a threshold concentration of x nmol mol(-1) (AOTx) was estimated from time-integrated ozone concentration (as from diffusive sampling) and measures of ozone concentration variability. Two methods both estimated 24-h AOTx with high accuracy (modelling efficiencies >90% for x <= 40 nmol mol(-1)). Daytime (08:00-20:00) AOTx could not be equally well estimated. Estimates were better for lower AOT thresholds. Diffusive ozone concentration sampling, combined with hourly temperature monitoring, could be a valuable complement to ozone concentration monitoring with continuous instruments. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract  Surface ozone pollution may cause reductions in rice (Oryza sativa L.) yield. Ozone sensitivity in rice cultivars is often evaluated based on visible leaf injury at an early growth stage. However, it is not clear whether reduction in grain yield is related to visible injury. Therefore, visible damage and grain yield reduction were examined in Japanese and Asian rice cultivars exposed to ozone. In experiment 1, 3-week-old rice seedlings were exposed to ozone (min.: 20 nl center dot l-1, max.:120 nl center dot l-1) for 12 h in open-top chambers (OTCs). Visible leaf injury was quantified according to a leaf bronzing score. In experiment 2, rice plants were exposed to ozone in OTCs throughout the cropping season until grain harvest. Daily mean ozone concentrations were maintained at 2, 23, 28, 42, and 57 nl center dot l-1 with a regular diurnal pattern of exposure. After harvest, grain yield was determined. Based on visible injury to the uppermost fully expanded leaf, the indica cultivar 'Kasalath' was most tolerant, and the japonica cultivar 'Kirara 397' was most sensitive to ozone. However, grain yields for both 'Kasalath' and 'Kirara 397' were significantly decreased after ozone exposure. The indica cultivar 'Jothi' suffered severe injury after ozone exposure but had no reduction in grain yield. Therefore, ozone sensitivity of rice cultivars evaluated by visible injury did not coincide with that evaluated by the reductions in grain yield. These results suggest that mechanisms that induce acute leaf injury do not relate to chronic ozone toxicity that reduces yield.

Abstract  Global climatic change scenarios predict a significant increase in future tropospheric ozone (O-3) concentrations. The present investigation was done to assess the effects of elevated O-3 (70 and 100 ppb) on electron transport, carbon fixation, stomatal conductance and pigment concentrations in two tropical soybean (Glycine max L.) varieties, PK 472 and Bragg. Plants were exposed to O-3 for 4 h center dot day-1 from 10:00 to 14:00 from germination to maturity. Photosynthesis of both varieties were adversely affected, but the reduction was higher in PK 472 than Bragg. A comparison of chlorophyll a fluorescence kinetics with carbon fixation suggested greater sensitivity of dark reactions than light reactions of photosynthesis to O-3 stress. The O-3-induced uncoupling between photosynthesis and stomatal conductance in PK 472 suggests the reduction in photosynthesis may be attributed to a factor other than reduced stomatal conductance. An increase in internal CO2 concentration in both O-3-treated soybean varieties compared suggests that the reduction in photosynthesis was due to damage to the photosynthetic apparatus, leading to accumulation of internal CO2 and stomatal closure. The adverse impact of O-3 stress increased at higher O-3 concentrations in both soybean varieties leading to large reductions in photosynthesis. This study suggests that O-3-induced reductions in photosynthesis in tropical and temperate varieties are similar.

Abstract  in a nitrogen (N) saturated forest downwind from Los Angeles, California, the cumulative response to long-term background-N and N-amendment on black oak (Quercus kelloggii) was described in a below-average and average precipitation year. Monthly measurements of leaf and branch growth, gas exchange, and canopy health attributes were conducted. The effects of both pollutant exposure and drought stress were complex due to whole tree and leaf level responses, and shade versus full sun leaf responses. N-amended trees had lower late summer carbon (C) gain and greater foliar chlorosis in the drought year. Leaf water use efficiency was lower in N-amended trees in midsummer of the average precipitation year, and there was evidence of poor stomatal control in full sun. In shade, N-amendment enhanced stomata] control. Small differences in instantaneous C uptake in full sun, lower foliar respiration, and greater C gain in low light contributed to the greater aboveground growth observed. (c) 2005 Elsevier Ltd. All rights reserved.

Abstract  The main photo-physiological characteristics of Pinus tabulaeformis Carr. were analyzed in open-top chambers under elevated carbon dioxide and ozone concentrations. The results indicated that the leaves net photosynthetic rates (p < 0.05), Hill activity, Ca2+/Mg2+-ATPase activity, soluble sugar and starch contents all increased under elevated carbon dioxide concentration in whole growing season. While under elevated ozone concentration, the leaves net photosynthetic rates, Hill activity, Ca2+/Mg2+-ATPase activity, soluble sugar and starch contents all decreased. Under elevated carbon dioxide and ozone concentration, the leaves net photosynthetic rates, Hill activity, soluble sugar and starch contents all increased, but Ca2+-ATPase activity increased during the earlier growing season, decreased in later growing season, while Mg2+-ATPase activity responded contrarily.

Abstract  Northern forest trees are challenged to adapt to changing climate, including global warming and increasing tropospheric ozone (O-3) concentrations. Both elevated O-3 and temperature can cause significant changes in volatile organic compound (VOC) emissions as well as in leaf anatomy that can be related to adaptation or increased stress tolerance, or are signs of damage. Impacts of moderately elevated O-3 (1.3 x ambient) and temperature (ambient + 1 degrees C), alone and in combination, on VOC emissions and leaf structure of two genotypes (2.2 and 5.2) of European aspen (Populus tremula L.) were studied in an open-field experiment in summer 2007. The impact of O-3 on measured variables was minor, but elevated temperature significantly increased emissions of total monoterpenes and green leaf volatiles. Genotypic differences in the responses to warming treatment were also observed. a-Pinene emission, which has been suggested to protect plants from elevated temperature, increased from genotype 5.2 only. Isoprene emission from genotype 2.2 decreased, whereas genotype 5.2 was able to retain high isoprene emission level also under elevated temperature. Elevated temperature also caused formation of thinner leaves, which was related to thinning of epidermis, palisade and spongy layers as well as reduced area of palisade cells. We consider aspen genotype 5.2 to have better potential for adaptation to increasing temperature because of thicker photosynthetic active palisade layer and higher isoprene and a-pinene emission levels compared to genotype 2.2. Our results show that even a moderate elevation in temperature is efficient enough to cause notable changes in VOC emissions and leaf structure of these aspen genotypes, possibly indicating the effort of the saplings to adapt to changing climate.

Abstract  A three-part study was conducted to quantify the impact of landscaped vegetation on air quality in a rapidly expanding urban area in the and southeastern United States. The study combines in situ, plant-level measurements, a spatial emissions inventory, and a photochemical box model, Maximum plant-level basal emission rates were moderate: 18.1 mu gC gdw(-1) h(-1) (Washingtonia spp., palms) for isoprene and 9.56 mu gC gdw(-1) h(-1) (Fraxinus velutina, Arizona ash) for monoterpenes. Sesquiterpene emission rates were low for plant species selected in this study, with no measurement exceeding 0.1 mu gC gdw(-1) h(-1). The high ambient temperatures combined with moderate plant-level emission factors 2 resulted in landscape emission factors that were low (250-640 mu gC m(-2) h(-1)) compared to more mesic environments (e.g., the southeastern United States). The Regional Atmospheric Chemistry Mechanism (RACM) was modified to include a new reaction pathway for ocimene. Using measured concentrations of anthropogenic hydrocarbons and other reactive air pollutants (NO,, ozone), the box model employing the RACM mechanism revealed that these modest emissions could have a significant impact on air quality. For a suburban location that was downwind of the urban core (high NOx: low anthropogenic hydrocarbons), biogenic terpenes increased time-dependent ozone production rates by a factor of 50. Our study demonstrates that low-biomass density landscapes emit sufficient biogenic terpenes to have a significant impact on regional air quality. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract  The reaction of ozone (O3) with ?-pinene has been studied as a function of temperature and relative humidity and in the presence of wax surfaces that simulate a leaf surface. The objective was to determine whether the presence of a wax surface, in which ?-pinene could dissolve and form a high surface concentration, would lead to enhanced reaction with O3. The reaction of O3 itself with the empty stainless steel reactor and with aluminium and wax surfaces demonstrated an apparent activation energy of around 30 kJ mol?1 for all the surfaces, similar to that observed in long-term field measurements of O3 fluxes to vegetation. However, the absolute reaction rate was 14 times greater for aluminium foil and saturated hydrocarbon wax surfaces than for stainless steel, and a further 5 times greater for beeswax than hydrocarbon wax. There was no systematic dependence on either relative or absolute humidity for these surface reactions over the range studied (20?100% RH). Reaction of O3 with ?-pinene occurred at rates close to those predicted for the homogeneous gas-phase reaction, and was similar for both the empty reactor and in the presence of wax surfaces. The hypothesis of enhanced reaction at leaf surfaces caused by enhanced surface concentrations of ?-pinene was therefore rejected. Comparison of surface decomposition reactions on different surfaces as reported in the literature with the results obtained here demonstrates that the loss of ozone at the earth's surface by decomposition to molecular oxygen (i.e. without oxidative reaction with a substrate) can account for measured ?non-stomatal? deposition velocities of a few mm s?1. In order to quantify such removal, the effective molecular surface area of the vegetation/soil canopy must be known. Such knowledge, combined with the observed temperature-dependence, provides necessary input to global-scale models of O3 removal from the troposphere at the earth's surface.

Abstract  Experimental investigations of ozone (O(3)) effects on plants have commonly used short, acute [O(3)] exposure (>100 ppb, on the order of hours), while in field crops damage is more likely caused by chronic exposure (<100 ppb, on the order of weeks). How different are the O(3) effects induced by these two fumigation regimes? The leaf-level photosynthetic response of soybean to acute [O(3)] (400 ppb, 6 h) and chronic [O(3)] (90 ppb, 8 h d(-1), 28 d) was contrasted via simultaneous in vivo measurements of chlorophyll a fluorescence imaging (CFI) and gas exchange. Both exposure regimes lowered leaf photosynthetic CO(2) uptake about 40% and photosystem II (PSII) efficiency (F(q)'/F(m)') by 20% compared with controls, but this decrease was far more spatially heterogeneous in the acute treatment. Decline in F(q)'/F(m)' in the acute treatment resulted equally from decreases in the maximum efficiency of PSII (F(v)'/F(m)') and the proportion of open PSII centres (F(q)'/F(v)'), but in the chronic treatment decline in F(q)'/F(m)' resulted only from decrease in F(q)'/F(v)'. Findings suggest that acute and chronic [O(3)] exposures do not induce identical mechanisms of O(3) damage within the leaf, and using one fumigation method alone is not sufficient for understanding the full range of mechanisms of O(3) damage to photosynthetic production in the field.

Abstract  Isotopically labelled ozone (18O3) is an ideal tool to study the deposition of O3 to plants and soil, but no studies have made use of it due to the technical difficulties in producing isotopically enriched ozone. For 18O3 to be used in fumigation experiments, it has to be purified and stored safely prior to fumigations, to ensure that the label is present predominantly in the form of O3, and to make efficient use of isotopically highly enriched oxygen. We present a simple apparatus that allows for the safe generation, purification, storage, and release of 18O3. Following the purification and release of O3, about half (by volume) of the 18O is present in the form of O3. This means that for a given release of 18O3 into the fumigation system, a roughly identical volume of 18O2 is released. However, the small volume of this concurrent 18O2 release (100 nmol mol-1 in our experiment) results in only a minor shift of the much larger atmospheric oxygen pool, with no detectable consequence for the isotopic enrichment of either soil or plant materials. We demonstrate here the feasibility of using 18O as an isotopic tracer in O3 fumigations by exposing dry soil to 100 nmol mol-1 18O3 for periods ranging from 1 to 11 h. The 18O tracer accumulation in soil samples is measured using gas chromatography/isotope ratio mass spectrometry (GC/IRMS), and the results show a linear increase in 18O/16O isotope ratio over time, with significant differences detectable after 1 h of exposure. The apparatus is adapted for use with fumigation chambers sustaining flow rates of 1 m3 min-1 for up to 12 h, but simple modifications now allow larger quantities of O3 to be stored and continuously released (e.g. for use with open-top chambers or FACE facilities). Copyright © 2009 John Wiley & Sons, Ltd.

Abstract  This paper analyses the existence and relative strength of ozone (O3) sinks at the leaf level, in particular the implications for the partition of the O3 flux amongst the several physically, chemically and physiologically differing inner and outer surfaces of a leaf. We used a single-stomatal scale theoretical model to simulate the O3 transfer into leaves and estimate the flux partition. The theoretical scenarios were compared with experimental values from shoot-scale measurements of O3 flux onto Scots pine. The conditions where external sinks would prevent the stomatal diffusion involved the existence of very strong sinks at the external surfaces but yielded unrealistically high flux values. Only the possibility of a strong sink localized in the antechamber and/or pore could be of significance. Results also showed that in most instances a significant proportion of the total flux was generated by the external surfaces. For scenarios that consider strong scavenging in the mesophyll and weaker removal in the exterior, the proportion was about 60?80% for small stomatal apertures (?0.5 ?m), and 10?40% for larger apertures (?1.5 ?m). In these cases, however big the proportion of total flux is due to the external surfaces, the existence of sinks at the external surfaces does not prevent the diffusion through open and unoccluded stomata.

Abstract  Acute ozone is a model abiotic elicitor of oxidative stress in plants. In order to identify genes that are important for conferring ozone resistance or sensitivity we used two accessions of Medicago truncatula with contrasting responses to this oxidant. We used suppression subtraction hybridization (SSH) to identify genes differentially expressed in ozone-sensitive Jemalong and ozone-resistant JE154 following exposure to 300 nLL(-1) of ozone for 6h. Following differential screening of more than 2500 clones from four subtraction libraries, more than 800 clones were selected for sequencing. Sequence analysis of these clones identified 239 unique contigs. Fifteen novel genes of unknown functions were identified. A majority of the ozone responsive genes identified in this study were present in the Medicago truncatula EST collections. Genes induced in JE154 were associated with adaptive responses to stress, while in Jemalong, the gene ontologies for oxidative stress, cell growth, and translation were enriched. A meta-analysis of ozone responsive genes using the Genvestigator program indicated enrichment of ABA and auxin responsive genes in JE154, while cytokinin response genes were induced in Jemalong. In resistant JE154, down regulation of photosynthesis-related genes and up regulation of genes responding to low nitrate leads us to speculate that lowering carbon-nitrogen balance may be an important resource allocation strategy for overcoming oxidative stress. Temporal profiles of select genes using real-time PCR analysis showed that most of the genes in Jemalong were induced at the later time points and is consistent with our earlier microarray studies. Inability to mount an early active transcriptional reprogramming in Jemalong may be the cause for an inefficient defense response that in turn leads to severe oxidative stress and culminates in cell death.

Abstract  While exposure of C3 plants to elevated [CO2] would be expected to reduce production of reactive oxygen species (ROS) in leaves because of reduced photorespiratory metabolism, results obtained in the present study suggest that exposure of plants to elevated [CO2] can result in increased oxidative stress. First, in Arabidopsis and soybean, leaf protein carbonylation, a marker of oxidative stress, was often increased when plants were exposed to elevated [CO2]. In soybean, increased carbonyl content was often associated with loss of leaf chlorophyll and reduced enhancement of leaf photosynthetic rate (Pn) by elevated [CO2]. Second, two-dimensional (2-DE) difference gel electrophoresis (DIGE) analysis of proteins extracted from leaves of soybean plants grown at elevated [CO2] or [O3] revealed that both treatments altered the abundance of a similar subset of proteins, consistent with the idea that both conditions may involve an oxidative stress. The 2-DE analysis of leaf proteins was facilitated by a novel and simple procedure to remove ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) from soluble soybean leaf extracts. Collectively, these findings add a new dimension to our understanding of global change biology and raise the possibility that oxidative signals can be an unexpected component of plant response to elevated [CO2].

Abstract  Two field-growing silver birch (Betula pendula Roth) clones (clone 4 and 80) were exposed to elevated CO2 and O3 for three growing seasons (1999–2001). The phenolic compounds of naturally abscised leaf litter were analyzed in order to determine the possible CO2- and O3-induced changes in the litter quality. The potential litter-mediated CO2 and O3 effects on litter-feeding soil macrofauna (detritivore) performance were assessed in microcosm experiments, i.e., the relative growth rates (RGR) of Lumbricus terrestris and Porcellio scaber, the relative consumption rates (RCR) of P. scaber, and mortality of the test animals were measured. The leaf litter grown under elevated CO2 had increased concentrations (weight per mass unit) and contents (weight per leaf) of phenolic acids, flavonol glycosides, condensed tannins and total measured phenolics. Elevated O3 increased the concentrations of 3,4’-dihydroxypropiophenone 3-β-d-glucoside (DHPPG) and flavonoid aglycones but only under ambient CO2. However, elevated O3 effects on the content of some low-molecular-weight phenolic (LMWP) compounds (i.e. phenolic acids, DHPPG, flavonoid aglycones) and total LMWP changed over time emphasizing the importance of conducting long-term (>3 years) exposure studies. In general, RGR of young L. terrestris was affected by the litter quality changes induced by elevated CO2 and O3, as the animal growth rates were reduced when they were fed with CO2- and O3-exposed leaf litter of clone 80 in Experiment 1. P. scaber RCR or RGR responses to CO2- and O3-induced changes in litter quality were more variable and inconsistent, and neither were there any litter-mediated CO2 and O3 effects on animal mortality in these microcosm experiments. In conclusion, elevated CO2 has the potential to alter silver birch leaf litter quality, but the possible O3 effects on phenolic compounds and litter-mediated CO2 and O3 effects on detritivores are more difficult to validate.

Abstract  Changes to forest production drivers (light, water, temperature, and site nutrient) over the last 55 years have been documented in peer-reviewed literature. The main objective of this paper is to review documented evidence of the impacts of climate change trends on forest productivity since the middle of the 20th century. We first present a concise overview of the climate controls of forest production, provide evidence of how the main controls have changed in the last 55 years, followed by a core section outlining our findings of observed and documented impacts on forest productivity and a brief discussion of the complications of interpreting trends in net primary production (NPP). At finer spatial scales, a trend is difficult to decipher, but globally, based on both satellite and ground-based data, climatic changes seemed to have a generally positive impact on forest productivity when water was not limiting. Of the 49 papers reporting forest production levels we reviewed, 37 showed a positive growth trend, five a negative trend, three reported both a positive and a negative trend for different time periods, one reported a positive and no trend for different geographic areas, and two reported no trend. Forests occupy ?52% of the Earth's land surface and tend to occupy more temperature and radiation-limited environments. Less than 7% of forests are in strongly water-limited systems. The combined and interacting effects of temperature, radiation, and precipitation changes with the positive effect of CO2, the negative effects of O3 and other pollutants, and the presently positive effects of N will not be elucidated with experimental manipulation of one or a few factors at a time. Assessments of the greening of the biosphere depend on both accurate measurements of rates (net ecosystem exchange, NPP), how much is stored at the ecosystem level (net ecosystem production) and quantification of disturbances rates on final net biome production.

Abstract  OBJECTIVE: Air pollution can promote airway inflammation, posing significant health risks for children with chronic respiratory problems. However, it is unknown whether this process is reversible, so that limiting pollution will benefit these children. We measured the short-term response of allergic asthmatic children exposed to a real-life reduction in outdoor air pollution by using noninvasive biomarkers of airway inflammation and function. PATIENTS AND METHODS: Thirty-seven untreated allergic children with mild persistent asthma were recruited from a highly polluted urban environment and relocated to a less polluted rural environment. Air pollution, pollen counts, and meteorological conditions were carefully monitored at both sites. Nasal eosinophils, fractional exhaled nitric oxide, peak expiratory flow, and urinary leukotriene E(4) were measured first in the urban environment and then again 7 days after relocation to the rural environment. RESULTS: One week after relocation to the rural environment, we measured, on average, a fourfold decrease in nasal eosinophils and significant decrease in fractional exhaled nitric oxide. We also noted an improvement in lower airway function, reflected by highly significant increase in peak expiratory flow. In contrast, mean urinary leukotriene E(4) concentration remained unchanged after 1 week of exposure to the rural environment. CONCLUSIONS: Better air quality is associated with a rapid reduction of airway inflammation in allergic asthmatic children. Nasal eosinophils and fractional exhaled nitric oxide are sensitive indicators of this effect, and their rapid decline is paralleled by improved airway function measured by peak expiratory flow. Leukotriene synthesis has a more variable response to environmental modifications.

Abstract  Biogenic volatile organic compounds (VOCs), such as isoprene and alpha-/beta-pinene, are photo-oxidized in the atmosphere to non-volatile species resulting in secondary organic aerosol (SOA). The goal of this study was to examine time trends and diel variations of oxidation products of isoprene and alpha-/beta-pinene in order to investigate whether they are linked with meteorological parameters or trace gases. Separate day-night aerosol samples (PM(1)) were collected in a Scots pine dominated forest in southern Finland during 28 July-11 August 2005 and analyzed with gas chromatography/mass spectrometry (GC/MS). In addition, inorganic trace gases (SO(2), CO, NO(x), and O(3)), meteorological parameters, and the particle number concentration were monitored. The median total concentration of terpenoic acids (i.e., pinic acid, norpinic acid, and two novel compounds, 3-hydroxyglutaric acid and 2-hydroxy-4-isopropyladipic acid) was 65 ng m(-3), while that of isoprene oxidation products (i.e., 2-methyltetrols and C(5) alkene triols) was 17.2 ng m(-3). The 2-methyltetrols exhibited day/night variations with maxima during day-time, while alpha-/beta-pinene oxidation products did not show any diel variation. The sampling period was marked by a relatively high condensation sink, caused by pre-existing aerosol particles, and no nucleation events. In general, the concentration trends of the SOA compounds reflected those of the inorganic trace gases, meteorological parameters, and condensation sink. Both the isoprene and alpha-/beta-pinene SOA products were strongly influenced by SO(2), which is consistent with earlier reports that acidity plays a role in SOA formation. The results support previous proposals that oxygenated VOCs contribute to particle growth processes above boreal forest.

Abstract  Needles were collected from ponderosa and Jeffrey pine trees at three sites in the Sierra Nevada, and were assembled into 504 samples and grouped according to five dominant live needle conditions-green, winter fleck, sucking insect damage, scale insect damage, and ozone damage-and a random mixture. Reflectance and transmittance measurements of abaxial and adaxial surfaces were obtained at ca 0.3 nm spectral resolution from 400-800 nm, and binned to simulate Airborne Visible and Infrared Imaging Spectrometer (AVIRIS) data. There were no significant differences in optical properties between the two surfaces. Ozone-damaged needles were collected from Jeffrey pine trees at one site, and exhibited significantly different (family-wise ? = 0.01) reflectance and transmittance signatures-and significantly different signature slopes-at both spectral resolutions, from green and winter fleck needles from the same site. Ozone-damaged needles had significantly different (family-wise ? = 0.01) abaxial surface reflectance and reflectance slope signatures from all other groups of needles, at both spectral resolutions. In comparison with three chlorophyll reflectance indices, a new red fall index (RFI) provides high classification accuracies for ozone-damaged and non-ozone-damaged pine needles (overall acc. = 94%; ? = 59%). Thus, ozone-damaged Jeffrey pine needles have a unique spectral signature in relation to dominant needle conditions of ponderosa and Jeffrey pine trees.

Abstract  This report describes a unique collaboration among investigators from Europe, the United States, and Canada using existing data from three geographic areas and supported by HEI in collaboration with the European Commission. APHENA offered a large and diverse data set with which to address methodological as well as scientific issues about the relationships between PM10, ozone, and mortality and morbidity that were the subject of lively debates at the time the project was launched. Drs. Katsouyanni and Samet and their colleagues undertook a rigorous examination of time-series methods used to model the relationship between daily PM10 and ozone concentrations and daily mortality and hospital admissions. They sought to develop a standardized approach to the analysis of time series data at the city and regional level, to assess the consistency between relative rates of mortality and hospital admissions across Europe and North America when estimated using a common analytic protocol, and to explore possible explanations for any remaining variation in the results that analytic differences could not explain.

Abstract  BACKGROUND: Tumor necrosis factor (TNF)-alpha has a recognized role in respiratory pathophysiology. One genetic variant (G-308A) in the promoter region affecting the expression of this cytokine may contribute to airway inflammatory diseases, but the studies on bronchitic symptoms were still inconclusive. Because ozone produces oxidative stress, increased airway TNF, and inflammation, the associations of the TNF-308 polymorphism with bronchitic symptoms may vary by ambient ozone exposure. METHODS: We studied associations of TNF-308 genotype with bronchitic symptoms among asthmatic children in Children's Health Study. The association of TNF G-308A polymorphism with bronchitic symptoms was investigated and we also determined whether the associations vary with ambient ozone exposure. RESULTS: Asthmatic children with TNF-308 GG genotype had a significantly reduced risk of bronchitic symptoms with low-ozone exposure (adjusted OR: 0.53; 95% CI: 0.31-0.91). The risk was not reduced in children living in high-ozone communities (adjusted OR: 1.42; 95% CI: 0.75-2.70). This difference in genotypic effects between low- and high-ozone environments was statistically significant among asthmatics (P for interaction = 0.01), but insignificant among nonasthmatic children. CONCLUSION: Our findings suggest a role of gene-environmental interactions on the occurrence of bronchitic symptoms among children with asthma.