Mature Thompson Seedless grapevines were exposed to charcoal-filtered air or ambient ozone in open-top field chambers near Fresno, CA. Chronic exposure to ambient ozone reduced net carbon dioxide assimilation rates an average of 9% through the season when compared to the filtered-air treatment. The initial slope of a carboxylation efficiency curve was less for the ambient ozone treatment compared to the filtered-air treatment. Individual leaves were exposed to ozone concentrations of 200, 400, or 600 ppb for 5 to 10 hours. No visual ozone damage was found. Exposure of leaves to 200 ppb ozone for 5 hours had no effect on photosynthesis. Photosynthesis was reduced approximately 50 to 80% respectively after 5 hours of exposure to 400 and 600 ppb ozone compared to the controls. There were no significant differences in vine-growth parameters, bud fruitfulness or yield between vines exposed to either filtered or ambient air. Net carbon dioxide assimilation rates for five of six potted grape cultivars exposed to 1.5 times ambient ozone concentrations were substantially less than for those grown in the charcoal-filtered air. The cultivar 'Barbera' had greater rates of photosynthesis at the higher ozone concentration.

The effects of long-term ozone fumigation on two common peatland plant species, a sedge Eriophorum vaginatum L. and a moss Sphagnum papillosum Lindb., were studied applying peatland microcosms. The peat cores with intact vegetation were cored from an oligotrophic pine fen and partially embedded into the soil of an open-air experimental field for four growing seasons. The open-air ozone exposure field consists of eight circular plots of which four were fumigated with elevated ozone concentration (doubled ambient) and four were ambient controls. The results showed that E. vaginatum and S. papillosum can tolerate ozone better than expected. Elevated ozone concentration did not affect overall relative length growth of E. vaginatum or S. papillosum. The leaf cross-section area of E. vaginatum leaves was 8% bigger in the ozone treatment compared to that in the ambient control. Ultrastuctural variables did not show any significant treatment effect in E. vaginatum or in S. papillosum. Total chlorophyll (a + b) concentration tended to increase in early growing season under ozone exposure. During the first growing season, elevated ozone concentration decreased methanol-extractable, UV-absorbing compounds in E. vaginatum. The results suggest that E. vaginatum and S. papillosum are ozone tolerant plant species and are likely able to cope with expected increase in tropospheric ozone concentration

Much has been written about the effects of ambient ozone on tree growth. Cause and effect has been established with seedlings in chambers. Results from multi-year studies with older tree seedlings, in open-top chambers, have been inconclusive, due to chamber effects. Extrapolation of results from chambers to trees in the forest is not possible. Predictive models for forest tree growth reductions caused by ozone have been developed, but not verified. Dendrochronological methods have been used to establish correlations between radial growth reductions in forest trees and ambient ozone exposure. The protective chemical ethylenediurea (EDU) has been used to protect tree seedlings from ozone injury. An experimental approach is advocated here that utilizes forest trees selected for sensitivity and non-sensitivity to ozone, dendrochronological methods, the protective chemical EDU, and monitoring data for ambient ozone, stomatal conductance, soil moisture potential, air temperature, PAR, etc. in long-term investigations to establish cause and effect relationships. - Progress is reviewed and an experimental approach is proposed to demonstrate a cause and effect relationship for ambient ozone and forest tree growth.

Solidago albopilosa Braun is an endangered species of goldenrod that is found in a very limited area of central Kentucky. The reasons for the limited distribution of this species are not known. The Daniel Boone National Forest was concerned that increased in ambient ozone might endanger the survival of this species. Little work has been done to assess the sensitivity of goldenrods to ozone and apparently none has been done on this endangered species. Plants were exposed to either ambient, half ambient or twice ambient concentrations of ozone for 39 days in mid summer using June 1992 data from Mammoth Cave National Park as ambient. Few statistically significant effects were found; however, consistent trends toward lower leaf and stem biomass, leaf area and less height growth in the higher ozone treatments were seen. Carbon allocation patterns appear to be different with plants in the higher treatment allocating more to reproductive structures. Net photosynthesis and leaf conductance were measured several days after fumigations ended and plants in the half ambient treatment had the lowest rates and plants in the highest treatment had the highest rate. No characteristics visible ozone injury was seen. This study suggests that ozone has little effect on Solidago albopilosa; however, concentrations used were quite low.

Physiological responses to ozone exposure over one growing season of four year-old potted ozone-tolerant white birch saplings were compared with saplings of six year-old open-soil-grown trees of the same birch variety that has been previously fumigated with ozone for five growing season. Both plant groups were exposed to ambient and elevated ozone concentrations under similar microclimatic conditions in a free air ozone exposure facility. Growth in foliage, net photosynthesis, stomatal conductance, starch and nutrient concentrations and differences in ozone responses between lower, middle and upper sections of the canopy were determined. Potted saplings showed no effect to elevated ozone concentration, while the open-soil-grown trees showed a 3 to 38 per cent reduction in shoot growth, a 22 per cent reduction in the number of overwintering buds, a 26-65 per cent decrease in net annual photosynthesis, 30 per cent reduction in starch, and a 20-23 per cent reduction in nitrogen concentration, as well as disturbances in stomatal conductance. Various explanations are offered for the higher ozone sensitivity of open-soil-grown trees, among them cumulative carry-over effects of multi-year exposure resulting in impaired bud formation, reduced capacity for photosynthetic compensation for ozone damage, and slower leaf senescence. The main conclusion was that in European white birch exposure period and plant size were the most important factors affecting ozone tolerance. 46 refs., 2 tabs., 6 figs.

The eastern Tennessee ridge-and-valley region has recently experienced tropospheric ozone levels that approach the national ambient air quality standards. The objective of this research was to characterize the atmospheric mixing height and vertical structure of ozone during morning and evening at a site within the ridge- and-valley. Historically, high ozone concentrations in eastern Tennessee occurred in summer months during hot, stagnant days. Thus, this study focused on periods when the region was under the influence of high pressure systems and elevated temperatures during July and August, 1995. Meteorological and ozone measurements were made during daytime and nighttime to provide information on the development and subsequent collapse of the mixing height during morning and evening, respectively; measurements were obtained using a tethered balloon sounding system. Morning profiles were characterized by growth of the mixing height and entrainment of upper ozone reservoirs. Evening profiles depicted reduction of the mixing height and growth of the nocturnal, stable boundary layer. Ground-level ozone concentrations decreased whereas ozone concentrations at greater heights (100-300 m) remained comparatively high. This study demonstrated that the entrainment of ozone reservoirs aloft played a significant, if not dominant, role in increased ozone concentrations at the surface. Experimental data were used to construct an alternative model for mixing heights in regions under meteorological conditions of elevated temperatures and high pressure systems.

Research examined the reaction of several major alfalfa cultivars to ozone fumigations in chambers using ozone concentrations simulating ambient levels observed in Massachusetts. These cultivars were all shown to be susceptible in varying degrees to such ozone stress. Further experiments showed that ozone at these concentrations not only reduced growth, but also altered photoassimilate partitioning. Greatest weight reductions occurred in roots, followed by leaves, and then stems. Ozone-stressed plants produced fewer leaves which weighed less per unit area than control leaves. Classic and functional growth analyses were used to examine such parameters as net assimilation rate and relative growth rate. Ozone-stressed plants fixed dry matter less efficiently than control plants, in terms of both leaf area and existing dry matter. In a final study, alfalfa was grown in the presence of isolates of pathogenic Fusarium, or to soil from a diseased alfalfa field, and concurrently fumigated with ozone. There was no significant interaction between pathogen and air pollutant, but each stress significantly reduced alfalfa growth independently.

...Ozone National Ambient Air Quality Standards: Scope and Methods Plan for Health Risk and Exposure Assessment and Ozone National Ambient Air Quality Standards: Scope and Methods Plan for Welfare Risk and Exposure...

Ozone damage has been causing concern in Northern Europe since the 1980s. It was, however, only during the last decade that the potential impacts of ozone have become an issue of concern. There is evidence that the ambient ozone concentrations found in Europe can cause a range of effects to vegetation, including visible leaf injury, growth and yield reductions, as well as altered sensitivity to biotic and abiotic stresses. Ozone pollution, unlike fluoride or sulphur dioxide pollution, leaves no elemental residue that can be detected by analytical techniques. Therefore, visible injury on needles and leaves is the only easily detectable evidence. Thus, even if visual injury does not include all the possible forms of injury to trees and natural vegetation, it may be a useful tool for detecting ozone injury in potentially sensitive species in Europe during extensive field surveys. Recently, ICP-Forest promoted a new standardised programme, dedicated to extensive ozone surveys in Europe based on the visual detection of injuries due to ozone. The main objective of the approach using passive biomonitoring is to provide information on the ozone injury distribution of the forest ecosystems in Europe (spontaneous vegetation and tree species) in a simple, feasible and statistically sound way. The essential basis for choosing visual injury is that many plant species respond to ambient levels of ozone pollution with distinct visible foliar symptoms. A field manual is being developed to help with the visual injury identification in the field, and the First Training Course was held in Spain in 2000, with the result of a common protocol for the first field survey to be done in 2001. Expected results are a map of Europe showing the ozone injury symptoms distribution in trees and understory vegetation. (orig.)

Tropospheric ozone is currently the third most important greenhouse gas, and also the most important gaseous air pollutant globally in terms of effects on vegetation world-wide. At present levels it poses a significant threat to crop yield and forest productivity of sensitive species, while background ozone concentrations are expected to increase further during the next decades. The potential importance of ozone in reducing carbon assimilation, and consequently in increasing atmospheric carbon dioxide concentrations, has been recognised. However, regional modelling studies are based on the impact of ozone on photosynthetic rates and above-ground growth, and do not consider effects of ozone on belowground carbon fluxes. The limited experimental data on the long-term effects of ozone on belowground carbon processes, mainly from arable crop and forest systems, are a major constraint to understanding the impacts of ozone on global carbon fluxes. Very little attention has been paid to ozone effects on peatland carbon dynamics, though northern peatlands store a third of the global soil organic carbon pool and are an important source of atmospheric methane. The aims of this study were to assess the long-term effects of elevated ozone on carbon dioxide and methane fluxes in temperate peatland mesocosms and to identify underlying plant, soil and microbial processes. Mesocosms from a wet heath (Isle of Skye, UK) with vegetation dominated by the peat moss Sphagnum papillosum and the sedge Schoenus nigricans have been exposed to ambient (control) and three elevated levels of ozone in open-top chambers from May 2008. Methane emission, carbon dioxide fluxes and relevant plant and soil variables were measured every 6 weeks (growing season) or 8 weeks (winter). Methane emissions were significantly reduced by elevated ozone over the first 18 months of the experiment. Ecosystem respiration only showed a significant increase in response to ozone in the second growing season, while gross photosynthesis has been enhanced by elevated ozone up till now. The latter may partly be explained by higher net biomass Sphagnum production observed at elevated ozone. Leaf biomass and stomatal conductance of Schoenus nigricans were not affected by ozone. Additional soil and plant data will be presented that may help unravel the mechanisms underling the observed changes in greenhouse gas fluxes. Hence, the results imply that increases in global background ozone concentrations that are predicted by models in the northern hemisphere over the 21st century may lead to a negative feedback on methane emissions from peatland ecosystems. This study will be continued with methane emission and high-frequency carbon dioxide flux measurements and more detailed process studies, including stable isotope tracer studies, providing key information for long-term predictions of ozone impacts on carbon dynamics in peatland ecosystems.

The purpose of the project was to investigate the importance, for Danish non-agricultural vegetation, of the gaseous air pollutants: Ozone, Sulphur Dioxide and Nitrogen Dioxide. Investigations were based on experiments in open-top chambers, where the climatic conditions are very close to those in the ambient surroundings. The air in the chambers were charcoal filtered, ambient, or added extra amounts of one er more of the three gasses to simulate elevated levels of the occurring variation. In the chamber bottoms the following plants were grown individually: Cladonia portentosa, Lotus corniculatus, Medicago lupulina, Empetrum nigrum, Calluna vulgaris, and finally, Fagus sylvatica, and Pices abies. Reindeer moss did not take up substantial amounts of nitrogen from the air. Fumigation with sulphur dioxide and nitrogen dixode, seems to cause washout of ions from the thallus. Ozone effects was observed, for the first time, on natural Danish herbs and shrubs. Large interspecific sensitivity variation was seen. For M. lupulina and C. vulgaris, the above-ground biomass increment was reduced by 40% and 25%, respectively, by a constant daytime additon of approximately 40 ppb ozone to the ambient concentrations. Neither L. corniculatus or E. nigrum seemed to be affected. P. abies was affected by the same ozone level, which caused disturbances to the growth of shoots and needles. Bud burst and shoot elongation was delayed, and a persistent reduction of needle length was found during two years experiments. F. sylvatica seemed to be very ozone sensitive, showing a marked reduced diameter increment and early senescense. (AB) 31 refs.

Studies were initiated to determine if Botrytis cinerea conidia remain viable when grown in vivo and in vitro in the presence of ambient ozone levels and whether ozonized conidia retain pathogenicity. Experimental materials and methods used are described.

...Source Review (NSR) State Implementation Plan (SIP); Antibacksliding of Major NSR SIP Requirements for the One-Hour Ozone National Ambient...Standards (NAAQS); Major Nonattainment NSR (NNSR) SIP Requirements for the 1997 Eight-Hour Ozone...

Ozone, an ambient pollutant, is transformed into other airborne pollutants in the indoor environment. In this dissertation, the type and amount of byproducts that result from ozone reactions with common indoor surfaces, surface residues, and vapors were determined, pollutant concentrations were related to occupant exposure, and frameworks were developed to predict byproduct concentrations under various indoor conditions. In Chapter 2, an analysis is presented of secondary organic aerosol formation from the reaction of ozone with gas-phase, terpene-containing consumer products in small chamber experiments under conditions relevant for residential and commercial buildings. The full particle size distribution was continuously monitored, and ultrafine and fine particle concentrations were in the range of 10 to>300 mu g m-3. Particle nucleation and growth dynamics were characterized.Chapter 3 presents an investigation of ozone reactions with aircraft cabin surfaces including carpet, seat fabric, plastics, and laundered and worn clothing fabric. Small chamber experiments were used to determine ozone deposition velocities, ozone reaction probabilities, byproduct emission rates, and byproduct yields for each surface category. The most commonly detected byproducts included C1?C10 saturated aldehydes and skin oil oxidation products. For all materials, emission rates were higher with ozone than without. Experimental results were used to predict byproduct exposure in the cabin and compare to other environments. Byproduct levels are predicted to be similar to ozone levels in the cabin, which have been found to be tens to low hundreds of ppb in the absence of an ozone converter. In Chapter 4, a model is presented that predicts ozone uptake by and byproduct emission from residual chemicals on surfaces. The effects of input parameters (residue surface concentration, ozone concentration, reactivity of the residue and the surface, near-surface airflow conditions, and byproduct yield) were explored. In Chapter 5, the reaction of ozone with permethrin, a residual insecticide used in aircraft cabins, to form phosgene is investigated. A derivatization technique was developed to detect phosgene at low levels, and chamber experiments were conducted with permethrin-coated cabin materials. It was determined that phosgene formation, if it occurs in the aircraft cabin, is not likely to exceed the relevant, health-based phosgene exposure guidelines.

Gas exchange characteristics of loblolly pine seedlings were measured in the third growing season of ozone fumigations to determine the effects of long-term ozone exposure on photosynthetic capacity. Light and CO{sub 2} response curves indicated significant decreases of 21% and 27%, respectively, in light-saturated and CO{sub 2}-saturated photosynthetic capacities at 2 {times} ambient ozone compared to charcoal-filtered (CF) air, approximately 0.5 {times} ambient ozone. Differences in the response curves suggest changes in light-harvesting and biochemical efficiencies as well as changes in the activity of RuBP carboxylase and the regeneration rate of RuBP. Chlorophyll and carotenoid conditions per unit leaf area were decreased at the high ozone treatment in older flushes. Stomatal resistance limited photosynthesis by about 29% in both CF and 2 {times} ambient ozone treated plants, suggesting that chronic ozone exposure did not affect stomatal control in loblolly pine.

In July 1997, EPA promulgated revised national ambient air quality standards (NAAQS) for ozone and particulate matter (PM). The new standards supplement existing ambient standards for ozone and PM. In the case of ozone, the new 8-hour standards are designed, over time, to replace the existing 1-hour ozone NAAQS. In the case of PM, the new standards will be focusing on the regulation of a new category of fine particles -- PM2.5. This paper will describe the legal and technical difficulties that EPA may encounter in its implementation of the revised ozone and PM standards. It evaluates EPA`s current program to phase in the new ozone standard over a period of many years, while at the same time trying to use the existence of the new ozone standards to press for regional reductions in ozone precursors. It also evaluates EPA`s program for phasing in the new NAAQS for PM2.5.

Beech seedlings were grown under different nitrogen fertilisation regimes (0, 20, 40, and 80 kg N ha{sup -1} yr{sup -1}) for three years and were fumigated with either charcoal-filtered (F) or ambient air (O{sub 3}). Nitrogen fertilisation increased leaf necroses, aphid infestations, and nutrient ratios in the leaves (N:P and N:K), as a result of decreased phosphorus and potassium concentrations. For plant growth, biomass accumulation, and starch concentrations, a positive nitrogen effect was found, but only for fertilisations of up to 40 kg N ha{sup -1} yr{sup -1}. The highest nitrogen load, however, reduced leaf area, leaf water content, growth, biomass accumulation, and starch concentrations, whereas soluble carbohydrate concentrations were enhanced. The ozone fumigation resulted in reduced leaf area, leaf water content, shoot growth, root biomass accumulation, and decreased starch, phosphorus, and potassium concentrations, increasing the N:P and N:K ratios. A combined effect of the two pollutants was detected for the leaf area and the shoot elongation, where ozone fumigation amplified the nitrogen effects. - The effects of nitrogen and ozone on growth, carbohydrate concentrations, and nutrients are mainly additive.

A field study was conducted to evaluate the impact of ambient ozone on mustard (Brassica campestris L. var. Kranti) plants grown under recommended and 1.5 times recommended NPK doses at a rural site of India using filtered (FCs) and non-filtered open top chambers (NFCs). Ambient mean O{sub 3} concentration varied from 41.65 to 54.2 ppb during the experiment. Plants growing in FCs showed higher photosynthetic rate at both NPK levels, but higher stomatal conductance only at recommended NPK. There were improvements in growth parameters and biomass of plants in FCs as compared to NFCs at both NPK levels with higher increments at 1.5 times recommended. Seed yield and harvest index decreased significantly only at recommended NPK in NFCs. Seed quality in terms of nutrients, protein and oil contents reduced in NFCs at recommended NPK. The application of 1.5 times recommended NPK provided protection against yield loss due to ambient O{sub 3}. - NPK level above recommended alleviates the adverse effects of ambient ozone on a tropical mustard cultivar.

Leaf ascorbic acid (ASA) level is thought to be an important trait conferring stress tolerance in plants, but definite evidence regarding its effectiveness in the breeding of stress tolerant crops is lacking. Therefore, the stress response of a rice TOS17 insertion mutant (ND6172) for a GDP-d-mannose-3',5'-epimerase gene, which is involved in ASA biosynthesis, was tested. Two fumigation experiments were conducted, in which rice plants (Oryza sativa L.) were exposed to (i) high ozone for ten days at the tillering stage (100 ppb, 7 h day^-^1); and (ii) to four different ozone concentrations ranging from charcoal filtered air to 2.5 times the ambient concentration for the entire growth season. The mutant ND6172 had around 20-30% lower ASA level than the wild-type (Nipponbare), and exhibited a...

The effects of ozone exposure during the cropping season on rice grain quality were investigated in chamber experiments employing four ozone treatments (charcoal filtered air, ambient, 2x ambient, and 2.5x ambient concentration) and six genotypes. The concentrations of protein and lipids in brown rice increased significantly in response to ozone, while starch concentration and thousand kernel mass decreased. Other parameters, including the concentrations of iron, zinc, phenolics, stickiness and geometrical traits did not exhibit significant treatment effects. Total brown rice yield, protein yield, and iron yield were negatively affected by ozone. Numerous genotypic differences occurred in the response to ozone, indicating the possibility of optimizing the grain quality in high ozone enviro...

The goals of the study were to: identify agencies, industries and associations that are collecting data on ambient ozone and its precursors, NOX and VOC in Alberta, compile a list of report and papers from Alberta on ambient ozone, ozone precursors and related photochemical products starting from the year 1980, provide a literature review on all papers and reports produced for Alberta, review and assess the information compiled, relating Alberta information to the national scene wherever possible, and comparing ambient ozone levels in Alberta to the proposed reference levels and Canada wide standards options for ground-level ozone. Calgary and Edmonton as cities in Alberta mostly act as ozone sinks because of reactions with nitric oxide emitted from urban sources. These chemical reactions produce other secondary air pollutants like peroxyactyl nitrate, nitric acid and particulate nitrate. A good urban database on ambient ozone exists in Alberta. The information is reliable and well recognized in the international scientific literature. Considering the current Canadian and Alberta objectives of one-hour of maximum ozone concentration of 82 ppb, there are no concerns about meeting this objective in Alberta cities except a few which surpassed the level during the last five years. Rural values of ozone concentrations are high compared with urban centres. The 24-hour Alberta objective for ozone is exceeded most of the time in rural Alberta compared with major cities.

The possible mechanisms by which the ozone reduces root growth and nodulation of soybean were investigated. Ozone did not appreciably penetrate the plant growth substrates nor did it oxidize soil organic matter to form compounds inhibitory to Rhizobium. When ozone was excluded fr...

The aim of the experiment was to test the sensitivity of grasses from a subarctic region to a range of different ultraviolet-B (UV-B, 280-320 nm) levels. Seedlings of Calamagrostis lapponica and tillers of Calamagrostis purpurea were grown for 50 days in a greenhouse at 4 different levels of UV-B{sub BE} radiation (no UV-B, ambient UV-B, UV-B corresponding to 15 and 25% ozone depletion, respectively, at 68 deg. N, northern Sweden on July 27th). In C. purpurea total plant dry weight was significantly reduced at the 15% level compared to all other treatments, whilst tiller number was reduced when compared to the non UV-B treatment only. Reduced growth at the 15% level was accompanied by significant increases in shoot to root ratio (S:R), leaf area ratio (LAR) and leaf weight ratio (LWR), which were due to changes in both specific leaf area (SLA) and root growth. Similarly, in C. lapponica there were reduction in total dry weight at the 15% level, although differences in partitioning were only observed in LWR which was significantly greater than in the non UV-B treatment. There was a difference in tiller number in C. lapponica between all treatments. A reduced number of tillers was observed with increasing UV-B exposure form zero UV-B to the 15% level, whilst tiller number was significantly higher at the 25% level than in all other treatments. In C. lapponica, differences were apparent in the amount of UV absorbing pigments. Plants exposed to ambient UV-B and the 15% level had significantly more UV-B absorbing compounds than those in the 25% and non UV-B treatments. All these results suggest that the 15% ozone depletion level was the most harmful to plant growth and few damaging effects were observed at the higher 25% ozone depletion level. (au) 30 refs.

The effects of foliar applications of ethylenediurea (EDU) on responses to ozone by field-grown bush bean (Phaseolus vulgaris L.) lines 'S156' (O{sub 3}-sensitive) and 'R123' (O{sub 3}-tolerant), and cultivars 'BBL 290' (O{sub 3}-sensitive) and 'BBL 274' (O{sub 3}-tolerant) were investigated during the 2001 and 2002 growing seasons. EDU was applied weekly to designated plants between primary leaf expansion and pod senescence. Results were compared with control plants at harvests made at pod maturation and pod senescence. In 2001, average hourly ambient O{sub 3} concentrations ranged between 41 and 59 ppb for a total of 303 h; in 2002, for 355 h. EDU applications prior to pod maturation significantly increased the number of marketable pods in 'R123', but not for the other cultivars. Harvests at pod senescence showed significant improvements in crop yield production in EDU-treated 'S156' plants, whereas for EDU-treated 'R123' plants significant reductions were determined in above-ground biomass and seed production. In contrast, results from 'BBL 290' and 'BBL 274' at both harvest points were inconclusive. Growth and reproductive responses of O{sub 3}-sensitive and O{sub 3}-tolerant bush bean plants to EDU applications varied, depending on developmental stages, duration of EDU applications, and fluctuations in ambient O{sub 3}. - Plant sensitivity to ozone, stage of plant development, number of applications of EDU and ambient ozone affect bean plant responses to EDU.

Rates of respiration by unifoliate leaves of pinto bean (Phaseolus vulgaris) plants, exposed to low levels of ozone, were partitioned into growth and maintenance components using a popular model of plant respiration. The mode can be written as R/W = G/sub R/(dW/dt)/W + m, where R/W is the leaf specific respiration rate, (dW/dt)/W is the leaf specific growth rate, G/sub R/ is the growth coefficient, and m is the maintenance coefficient. In controlled environment growth chamber experiments, plants were treated with one of two levels of ozone: 90 parts per billion (p.p.b., i.e., nl liter/sup -1/), for 6 h d/sup -1/ (+ ozone), or less than 15 p.p.b. (-ozone). The growth coefficient was not affected by ozone. The maintenance coefficient, however, was 10-15% larger in leaves of plants from the + ozone treatment, compared to the-ozone treatment. This difference in the maintenance coefficient was statistically significant. Open-top field chamber experiments were also conducted. As in the growth chamber experiments, ozone dose did not affect the growth coefficient, but increases in ozone resulted in significant increases in the maintenance coefficient. The results of these experiments suggest that one reason ozone inhibits plant growth and productivity is that maintenance respiration increases, probably in order to repair injury.

This report provides an evaluation of ground-level ozone pollution in Europe for April-September 2008, based on information submitted to the European Commission under Directive 2002/3/EC on ozone in ambient air. Since Members States have not yet finally validated the submitted data, the conclusions drawn in this report should be considered as preliminary. (au)

The U.S. Environmental Protection Agency (EPA) promulgates the National Ambient Air Quality Standards (NAAQS) on the basis of scientific information contained in air quality criteria documents. The previous ozone (O3) criteria document, Air Quality Criteria for Ozone and Other Ph...

Syncrude and Suncor have plans to develop new oil sands leases and to increase crude oil and bitumen recovery in the Athabasca oil sands region. A first air quality assessment was prepared as part of the Alberta Energy and Utilities Board application, in order to evaluate the emissions and potential impacts associated with the development. The Pembina Institute raised several issues with respect to potential future changes in ambient ozone levels as a result of the Aurora Mine operations. In response to these concerns, another more rigorous assessment was conducted to predict future ground-level ozone concentrations in the Fort McMurray area. This report includes: (1) ambient air quality guidelines for ozone, (2) emissions inventory for dispersion modelling, (3) dispersion modelling methodology, and (4) predicted ambient ozone concentrations. Ground level ozone (O{sub 3}) concentrations result from anthropogenically produced ozone, and from naturally occurring ozone. Ozone is not directly emitted to the atmosphere from industrial sources, but is formed as a result of chemical reactions between NO{sub x} and VOCs, which are emitted from industrial sources within the Athabasca oil sands region. NO{sub x} and VOC emissions associated with the Aurora Mine operation are predicted to increase hourly average ozone concentrations in the Fort McMurray area by only 0.001 ppm. 17 refs., 18 tabs., 5 figs.

Abstract The effect of ozonation as a method to reduce Bacillus cereus count in processed rice was investigated. Hundred grams of processed rice was exposed to gaseous ozone in an inert glass condenser at 20--3C and 50% relative humidity. Ozone concentrations of 0.1, 0.2, 0.3 and 0.4-ppm up to 7-h were used. Enumerations of B. cereus were done before ozonation treatment to establish the initial counts of B. cereus in processed rice. The experiments were done in an air-conditioned room and samples were then kept at ambient temperature pre- and post-ozonation to emulate normal conditions in rice storage facilities. Within 24-h, the ozonated samples were then enumerated by surface spread plating technique. Significant trends were observed in comparison with the non-ozonated rice samples. Non-...

The behavior of lower atmospheric ozone and ozone exchanges at the snow surface were studied using a suite of platforms during the Ocean-Atmosphere-Sea Ice-Snow (OASIS) Spring 2009 experiment at an inland, coastal site east of Barrow, Alaska. A major objective was to investigate if and how much chemistry at the snow surface at the site contributes to springtime ozone depletion events (ODEs). Between March 8 and April 16, seven ODEs, with atmospheric ozone dropping below 1.0 ppbv, were observed. The depth of the ozone-depleted layer was variable, extending from the surface to ?200–800 m. ODEs most commonly occurred during low wind speed conditions with flow coming from the Arctic Ocean. Two high-sensitivity ozone chemiluminescence instruments were used to accurately define the remaining sub-ppbv ozone levels during ODEs. These measurements showed variable residual ODE ozone levels ranging between 0.010 and 0.100 ppbv. During the most extended ODE, when ozone remained below 1.0 ppbv for over 78 h, these measurements showed a modest ozone recovery or production in the early afternoon hours, resulting in increases in the ozone mixing ratio of 0.100 to 0.800 ppbv. The comparison between high-sensitivity ozone measurements and BrO measured by longpath differential absorption spectroscopy (DOAS) during ODEs indicated that at low ozone levels formation of BrO is controlled by the amount of available ozone. Measurements of ozone in air drawn from below the snow surface showed depleted ozone in the snowpack, with levels consistently remaining <6 ppbv independent of above-surface ambient air concentrations. The snowpack was always a sink of ozone. Ozone deposition velocities determined from ozone surface flux measurements by eddy covariance were on the order of 0.01 cm s?1, which is of similar magnitude as ozone uptake rates found over snow at other polar sites that are not subjected to ODEs. The results from these multiple platform measurements unequivocally show that snow-atmosphere chemical exchanges of ozone at the measurement site do not exhibit a major contribution to ozone removal from the boundary layer and the formation of ODE.

In this study, ultraviolet (UV) ozone post treatment is proposed as an effective method of suppressing gate leakage current associated with the moisture absorption of lanthanum oxide (La2O3) films. It is considered that suppression effects come from the healing of oxygen vacancies in the film by the UV ozone post treatment, since the oxygen ambient annealing also shows similar suppression effects. As compared with the oxygen ambient annealing, however, the UV ozone treatment does not enhance the interface layer thickness between the La2O3 and Si substrates, whereas the oxygen ambient annealing does. Therefore, the UV ozone post treatment is an effective method of suppressing the moisture absorption of La2O3 films.   

Heated stainless steel inlets were optimized for the ozone removal and for the measurements of mono- and sesquiterpenes in ambient air. Five different inlets were used with different flows, temperatures and ozone and biogenic volatile organic compound (BVOC) concentrations. Both ozone removal capacities and recoveries of BVOCs were determined. Ozone and BVOCs were flushed through the inlet and recoveries were measured by an ozone monitor and adsorbent tube sampling of BVOCs with subsequent analysis with thermal desorption - gas chromatograph (GC) - mass spectrometer (MS). Recovery tests of BVOCs were conducted both with zero air and with ozone rich air. Inlets were optimized especially for online-GC and adsorbent tube measurements of mono- and sesquiterpenes. The results of this study show...

The effects of ozone and controlled-environment factors were investigated by exposing four tobacco varieties in fumigation chambers. The principal results of the investigations were: 1) ozone threshold of injury concentrations were defined for the four varieties; 2) a correlation was noted between ozone sensitivity and maturity of leaves; and 3) growth inhibition was correlated with severity of ozone exposure. The evidence presented strongly confirms earlier reports in which ozone was cited as the cause of weather fleck in tobacco. 93 references, 40 figures, 14 tables.

Quantification of ocular exposure to ultraviolet-B radiation (UV-B) has become an important public health issue, with reports that the ozone layer is being depleted worldwide. Ocular exposure to UV-B is determined by ambient UV-B levels, the duration of outdoor exposure, the proportion of ambient UV...

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 O{sub 3}: non-filtered (NF) ambient air or NF+ 40 ppb O{sub 3} (NF+). During O{sub 3} exposure, soil sampling was performed at two dates according to different plant growth stages. O{sub 3} 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 O{sub 3} concentrations may influence the dynamic of decomposition processes and the turnover of nutrients. - Ozone reduced the individual densities of enchytraeids, collembolans and soil mites in the rhizosphere of winter wheat indirectly via the plant-soil-system.

The effects of O{sub 3} on uptake and distribution of {sup 14}C within current-year foliage of 3-year-old loblolly pine (Pinus taeda L.) seedlings were studied using open-top exposure chambers that delivered ozone at three concentrations: sub-ambient O{sub 3} (charcoal-filtered air (CF)); ambient O{sub 3}(AMB); and twice-ambient O{sub 3} (2X). Seedlings were exposed to O{sub 3} from May to Oct. of 1987, 1988, and 1989. In July, Aug., and Sept. 1989, individual foliage fascicles were labeled with {sup 14}CO{sub 2}; harvested at 0, 0.5, 4, 24, and 48h after labeling; and analyzed for {sup 14}C in lipids and pigments, protein, starch, residue, sugars, organic acids, and amino acids. O{sub 3} affected initial (0 h) incorporation of {sup 14}C into different chemical fractions, and the relative distribution of {sup 14}C among fractions at specific points in time. Starch dynamics were particularly responsive to and negatively affected by O{sub 3}. In 2X treatments, only 39-46% of the initial (0 h) {sup 14}C incorporated into starch remained after 48h, compared with a range of 56-90% remaining in CF treatments. The percentage of {sup 14}C in the starch fraction after 48 h decreased by nearly three-fold in August from CF to 2X treatments (%total {sup 14}C in starch: 31% (CF), 17% (AMB), and 11% (2X)). The authors data indicated that foliar starch synthesis and/or retention was depressed by ozone exposure during late-season months, and supported the concept that O{sub 3} decreases growth by depleting carbohydrate reserves. Other findings will be discussed.

The solid phase microextraction (SPME) device with the polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used as a passive sampler for ambient ozone. Both O-2,3,4,5,6-(pentafluorobenzyl)hydroxylamine hydrochloride (PFBHA) and 1,2-di-(4-pyridyl)ethylene (DPE) were loaded onto the fiber before sampling. The SPME fiber assembly was then inserted into a PTFE tubing as a passive sampler. Known concentrations of ozone around the ambient ground level were generated by a calibrated ozone generator. Laboratory validations of the SPME passive sampler with the direct-reading ozone monitor were performed side-by-side in an exposure chamber at 25 deg. C. After exposures, pyriden-4-aldehyde was formed due to the reaction between DPE and ozone. Further on-fiber derivatizations between pyriden-4-aldehyde and PFBHA were followed and the derivatives, oximes, were then determined by portable gas chromatography with electron capture detector. The experimental sampling rate of the SPME ozone passive sampler was found to be 1.10 x 10{sup -4} cm{sup 3} s{sup -1} with detection limit of 58.8 {mu}g m{sup -3} h{sup -1}. Field validations with both SPME device and the direct-reading ozone monitor were also performed. The correlations between the results from both methods were found to be consistent with r = 0.9837. Compared with other methods, the current designed sampler provides a convenient and sensitive tool for the exposure assessments of ozone.

Increased drilling in urban areas overlying shale formations and its potential impact on human health through decreased air quality make it important to estimate the contribution of oil and gas activities to photochemical smog. Flares and compressor engines used in natural gas operations, for example, are large sources not only of NOx but also offormaldehyde, a hazardous air pollutant and powerful ozone precursor We used a neighborhood scale (200 m horizontal resolution) three-dimensional (3D) air dispersion model with an appropriate chemical mechanism to simulate ozone formation in the vicinity ofa hypothetical natural gas processing facility, based on accepted estimates of both regular and nonroutine emissions. The model predicts that, under average midday conditions in June, regular emissions mostly associated with compressor engines may increase ambient ozone in the Barnett Shale by more than 3 ppb beginning at about 2 km downwind of the facility, assuming there are no other major sources of ozone precursors. Flare volumes of 100,000 cubic meters per hour ofnatural gas over a period of 2 hr can also add over 3 ppb to peak 1-hr ozone somewhatfurther (>8 km) downwind, once dilution overcomes ozone titration and inhibition by large flare emissions of NOx. The additional peak ozone from the hypothetical flare can briefly exceed 10 ppb about 16 km downwind. The enhancements of ambient ozone predicted by the model are significant, given that ozone control strategy widths are of the order of a few parts per billion. Degrading the horizontal resolution of the model to 1 km spuriously enhances the simulated ozone increases by reducing the effectiveness of ozone inhibition and titration due to artificial plume dilution. PMID:22916444

The use of indoor ozone generators as air purifiers has steadily increased over the past decade. Many ozone generators are marketed to consumers for their ability to eliminate odors and microbial agents and to improve health. In addition to the harmful effects of ozone, recent studies have shown that heterogeneous and homogeneous reactions between ozone and some unsaturated hydrocarbons can be an important source of indoor secondary pollutants, including free radicals, carbonyls, carboxylic acids, and fine particles. Experiments were conducted in one apartment and two detached single-family dwellings in Austin, TX, to assess the effects of an ozone generator on indoor secondary organic aerosol concentrations in actual residential settings. Ozone was generated using a commercial ozone generator marketed as an air purifier, and particle measurements were recorded before, during, and after the release of terpenes from a pine oil-based cleaning product. Particle number concentration, ozone concentration, and air exchange rate were measured during each experiment. Particle number and mass concentrations increased when both terpenes and ozone were present at elevated levels. Experimental results indicate that ozone generators in the presence of terpene sources facilitate the growth of indoor fine particles in residential indoor atmospheres. Human exposure to secondary organic particles can be reduced by minimizing the intentional release of ozone, particularly in the presence of terpene sources. PRACTICAL IMPLICATIONS: Past studies have shown that ozone-initiated indoor chemistry can lead to elevated concentrations of fine particulate matter, but have generally been completed in controlled laboratory environments and office buildings. We explored the effects of an explicit ozone generator marketed as an air purifier on the formation of secondary organic aerosol mass in actual residential indoor settings. Results indicate significant increases in number and mass concentrations for particles <0.7 microns in diameter, particularly when an ozone generator is used in the presence of a terpene source such as a pine oil-based cleaner. These results add evidence to the potentially harmful effects of ozone generation in residential environments. PMID:16268833

We conducted four source apportionment simulations using the Community Multiscale Air Quality (CMAQ) photochemical grid modelling system in order to investigate and assess the relative importance of specific emissions sources and/or geographic regions on ambient ozone and PM air quality in the Alberta Oil Sands Region (AOSR). Local point and area sources, medium range transport of mobile sources and biogenic emissions were examined.The elimination of emissions from local stationary point sources reduced 8-h ozone concentrations and greatly reduces the PM2.5 concentrations in AOSR; similar results are seen in the local area source zero-out simulations but with less ozone and PM2.5 reductions than seen in the local point source zero-out run. Although the mobile source medium-range transport reduced 8-h ozone concentrations in the urban plume from Edmonton that results in some ozone and PM2.5 concentration reductions in the southern part of the AOSR, it has little effect on the elevated ozone and PM2.5 concentrations in the oil sands development area of the AOSR where the highest ozone and PM2.5 concentrations are estimated. The elimination of all anthropogenic emissions in Alberta so that only biogenic emissions remained resulted in large reductions in 8-h ozone concentrations in the AOSR, with the highest remaining ozone in the 50-52 ppb range occurring south of Fort McMurray; very low PM2.5 concentrations are also estimated across Alberta, including the AOSR, when anthropogenic emissions are eliminated in Alberta.

This monography first of all presents a geographical distribution of ozone for the territory of the Federal Republic of Germany, based on the results of rural measuring stations. The second part contains a comparison of ozone values, by growth areas, with the degree of forest decline, permitting to correlate the ozone concentration to the latter. Furthermore, the SO{sub 2} data measured for the territory of West Germany are given by geographic regions. They are not, however, correlated to forest decline. (orig.).

Ozone is found in urban and rural atmospheres and is produced from a variety of natural and man-made sources. Animal studies conducted at typical ambient levels result in reproducible morphological, biochemical and functional effects. Ozone damages type I epithelial cells, induces proliferation of type II cells and produces inflammation of the terminal bronchiolar-alveolar duct region. Ozone increases lung oxygen utilization and increases glutathione metabolism. Ozone increases airway resistance. The authors measured lactic dehydrogenase (LD) isoenzymes to ascertain the tissue giving rise to the increased LD activity in lavage. They also assayed acid phosphatase, alkaline phosphatase, creatine kinase activities, and protein levels since these parameters were increased in rat lung lavage after particulate exposure. They determined white cell differential and red cell morphology parameters because previous investigators reported that ozone increased neutrophil/lymphocyte ratio.

Which is the best standard for protecting plants from ozone? To answer this question, we must validate the standards by testing biological responses vs. ambient data in the field. A validation is missing for European and USA standards, because the networks for ozone, meteorology and plant responses are spatially independent. We proposed geostatistics as validation tool, and used durum wheat in central Italy as a test. The standards summarized ozone impact on yield better than hourly averages. Although USA criteria explained ozone-induced yield losses better than European criteria, USA legal level (75 ppb) protected only 39% of sites. European exposure-based standards protected > or =90%. Reducing the USA level to the Canadian 65 ppb or using W126 protected 91% and 97%, respectively. For a no-threshold accumulated stomatal flux, 22 mmol m(-2) was suggested to protect 97% of sites. In a multiple regression, precipitation explained 22% and ozone explained <0.9% of yield variability. PMID:19740583

Single and bi-metallic silver modified ZSM-5 catalysts were synthesized using three methods of preparation, characterized by different techniques: X-ray powder diffraction (XRD), scanning electron microscopy (SEM), nitrogen physisorption, X-ray fluorescence (XRF), inductively coupled plasma atomic emission spectrometry (ICP-AES) and tested in heterogeneous catalytic decomposition of ozone at ambient temperature. The highest degree of ozone decomposition was observed over 5Ag(Imp)-H(IE)-ZSM-5 catalyst, which exhibit 97% conversion and does not show any deactivation with the time. The method of preparation, amount of supported silver and the presence of modifiers as Cu, Ce, and Zr were found to be important for the ozone decomposition reaction.

This document provides guidance for the EPA Regional Offices to select and modify the ozone monitoring seasons designated for each State in the Code of Federal Regulations (40 CFR 58, Appendix D). Modifications to the original ozone monitoring seasons have been made periodically as new data and information became available; each of these changes has been incorporated into existing ambient air monitoring regulations. These seasons are important because they play a significant role in the estimation of annual ozone NAAQS exceedances and provide the basis for calculations in the Aerometric Information Retrieval System (AIRS) summary files. The monitoring seasons may also be tied to certain State emission regulations. With the 1997 revisions to the National Ambient Air Quality Standards (NAAQS) for ozone (i.e., the addition of a maximum 8-hour average ozone concentration of 0.08 ppm), it has become necessary to redefine the ozone monitoring season for purposes demonstrating attainment. The principal motivation is to develop an understanding of the characteristics of the ozone monitoring season based on the new standard. Another motivation for this guideline document is that reductions in required monitoring can result in considerable cost savings.

We investigated the effects of ozone and leaf senescence on steady-state stomatal conductance and stomatal response to light variation. Measurements were carried out in a free-air ozone exposure experiment on a representative deciduous broadleaved tree species in Japan (Fagus crenata). Both steady-state and dynamic stomatal response to light variation varied intrinsically with season due to leaf senescence. Ozone induced the decrease in steady-state leaf gas exchange and the sluggish stomatal closure progressively. These findings suggest that ozone reduces the ability of plants to adapt to a fluctuating light environment under natural conditions, and therefore impairs plant growth and ability to control water loss. PMID:22504428

Ozone dose-crop loss conversion functions for alfalfa (Medicago sativa, L. var. Moapa 69) yield reduction and defoliation were developed using standardized field plots within an ambient O/sub 3/ gradient in the South Coast Air Basin. Seasonal yields and defoliation values were tested with O/sub 3/ dose, average daily maximum temperature, average daily minimum temperature, and average daily relative humidity in regression analyses to determine significant functional relationships. Only the ambient O/sub 3/ dose variable was found to have a significant effect on alfalfa yield of defoliation. The ozone dose-crop loss conversion functions were calculated by converting the dose-response function to dose-percent reduction functions.

The effect of dissolved ozone on heat exchanger structural materials (carbon steel, stainless steel, copper and 70:30 copper nickel) has been studied in laboratory experiments, within the concentration range of 0.1--1.0 ppm. The biocidal efficacy of ozone on planktonic and sessile growth of Pseudomonas fluorescens was studied in quiescent and flow conditions. Ozone was able to kill the total number of planktonic bacteria in synthetic cooling water. However, ozone is only capable of inducing a partial reduction of bacterial numbers in the case of sessile bacteria. The electrochemical behavior of copper and 70:30 copper nickel is studied through voltamperometric and corrosion potential vs. time measurements. Dissolved ozone would be able to modify the structure of the oxide layer. The electrochemical behavior of carbon steel and stainless steel in ozonated solutions of similar concentrations is also analyzed.

Formaldehyde, an air contaminant found in many indoor air investigations, poses distinct occupational exposure hazards in certain job categories (e.g., mortuary science) but is also of concern when found or suspected in office buildings and homes. A variety of air-purifying devices (APDs) are currently available or marketed for application to reduce or remove concentrations of a variety of indoor air pollutants through the use of ozone as a chemical oxidant. An investigation was conducted to determine if concentrations of formaldehyde similar to those found in industrial hygiene evaluations of funeral homes could be reduced with the use of an ozone-generating APD. An ozone-generating APD was placed in an exposure chamber and formaldehyde-containing embalming solution was allowed to evaporate naturally, creating peak and mean chamber concentrations of 2.5 and 1.3 ppm, respectively. Continuous-reading instruments were used to sample for formaldehyde and ozone. Active sampling methods were also used to sample simultaneously for formaldehyde and a possible reactant product, formic acid. Triplicate measurements were made in each of three evaluations: formaldehyde alone, ozone alone, and formaldehyde and ozone combined. Concentrations of formaldehyde were virtually identical with and without 0.5 ppm ozone. No reduction in formaldehyde concentration was found during a 90-minute evaluation using ozone at this concentration with peak and average concentrations of approximately 2.5 and 1.3 ppm formaldehyde, respectively. The results of this investigation suggest that the use of ozone is ineffective in reducing concentrations of formaldehyde. Because ozone has demonstrated health hazards, and is a regulated air contaminant in both the occupational and ambient environment, the use of ozone as an air purification agent in indoor air does not seem warranted. 25 refs., 5 figs., 4 tabs.

ABSTRACT: Botrytis cinerea and Sclerotinia sclerotiorum are fungal pathogens that cause the decay of many fruits and vegetables. Ozone may be used as an antimicrobial agent to control the decay. The effect of gaseous ozone on spore viability of B. cinerea and mycelial growth of B. cinerea and S. sclerotiorum were investigated. Spore viability of B. cinerea was reduced by over 99.5% (P < 0.01) and height of the aerial mycelium was reduced from 4.7 mm in the control to less than 1 mm after exposure to 450 or 600 ppb ozone for 48 h at 20 degreeC. Sporulation of B. cinerea was also substantially inhibited by ozone treatments. However, ozone had no significant effect on mycelial growth of S. sclerotiorum in vitro. Decay and quality parameters including color, chlorophyll fluorescence (CF), and ...

3 days ago ... Their growth is closely recorded and compared. After they ... It is also found in plant and animal tissues, such as egg whites. ... Does the Radiation exposure effect seed germination without the protection of the ozone layer?

Commercially available corona discharge ozone generator, fitted onto industrial cooling tower, significantly reduces formation of scales (calcium carbonate) and corrosion. System also controls growth of algae and other microorganisms. Modification lowers cost and improves life of cooling system.

The published literature debates the extent to which naturally occurring stratospheric ozone intrusions reach the surface and contribute to exceedances of the U.S. National Ambient Air Quality Standard (NAAQS) for ground-level ozone (75 ppbv implemented in 2008). Analysis of ozonesondes, lidar, and surface measurements over the western U.S. from April to June 2010 show that a global high-resolution (?50 × 50 km2) chemistry-climate model (GFDL AM3) captures the observed layered features and sharp ozone gradients of deep stratospheric intrusions, representing a major improvement over previous chemical transport models. Thirteen intrusions enhanced total daily maximum 8-h average (MDA8) ozone to ?70–86 ppbv at surface sites. With a stratospheric ozone tracer defined relative to a dynamically varying tropopause, we find that stratospheric intrusions can episodically increase surface MDA8 ozone by 20–40 ppbv (all model estimates are bias corrected), including on days when observed ozone exceeds the NAAQS threshold. These stratospheric intrusions elevated background ozone concentrations (estimated by turning off North American anthropogenic emissions in the model) to MDA8 values of 60–75 ppbv. At high-elevation western U.S. sites, the 25th–75th percentile of the stratospheric contribution is 15–25 ppbv when observed MDA8 ozone is 60–70 ppbv, and increases to ?17–40 ppbv for the 70–85 ppbv range. These estimates, up to 2–3 times greater than previously reported, indicate a major role for stratospheric intrusions in contributing to springtime high-O3 events over the high-altitude western U.S., posing a challenge for staying below the ozone NAAQS threshold, particularly if a value in the 60–70 ppbv range were to be adopted.

Exposure to ambient levels of ozone (0.5 ppm) was shown to alter the pathogenesis of respiratory infection after aerosol infection of mice with influenza A virus. A semiquantitative method for determination of the sites of virus replication by direct immunofluorescence indicated that exposure to ozone reduced the involvement of respiratory epithelium in the infectious process and resulted in a less widespread infection of the alveolar parenchyma. Furthermore, the ozone-mediated alteration in viral antigen distribution was consistent with significantly reduced influenza disease mortality and prolonged survival time, but only when the oxidant was present during the course of infection. Reduced disease severity in ozone-exposed animals appeared to be independent of peak pulmonary virus titers, pulmonary interferon titers, and pulmonary and serum-neutralizing antibody titers. These studies suggested that the distribution of influenza virus in the murine lung was a key factor in disease severity.

A biomonitoring study using the ozone-sensitive bioindicator plant Nicotiana tabacum cv. Bel-W3 was conducted in the city of Valencia (eastern Spain) and surrounding areas in 2002. Plants were exposed to ambient air at seven sites, including four traffic-exposed urban sites, a large urban garden and a suburban and a rural station, for six consecutive 2-week periods using highly standardised methods. Foliar injury was registered at all stations in at least one of the exposure periods. The urban stations submitted to intense traffic showed lower ozone injury than the less traffic-exposed stations. Strong changes in the intensity of ozone injury were observed for the different exposure periods. Leaf injury was significantly related to both mean ozone values (24 and 12?h means) and cumulative ...

An emission inventory, covering the different source categories of ozone precursors in Sweden, has been performed. The emissions from each category, road traffic, working machinery, other mobile sources, wood combustion, energy production, industry, domestic use and pesticides, have been separated into 81 organic compounds and NO{sub x}. The emission data have been used in model simulations to predict the ozone formation due to the emission from different source categories. Four different ambient conditions have been treated. The results from this study indicate, as expected, that the road traffic is the single most important emitter of precursors significant in regional ozone production. POCP, or Photochemical Ozone Creation Potential, defined as the change in photochemical ozone production due to a change in the emission of that particular VOC, is used to compare different VOC in connection with ozone production. In this study the POCP was calculated for the whole group of compounds emitted from a specific source category. The results indicate that there is a big variety of ozone formation ability among source categories due to differences in composition, which clearly demonstrate the importance of a detailed description of the emissions. 48 refs, 5 figs, 6 tabs

Tropospheric ozone affects human health, plant health, regional air quality and Earth's climate. To understand regional ozone concentrations, sources of ozone precursors, atmospheric chemistry, meteorological transport and mechanical loss process including vegetation uptake have to be considered. In this study, we focus on ozone uptake and biogenic volatile organic carbon (BVOC) emissions that play a role in regional photochemical production of ozone and aerosols, by five varieties of citrus trees which are widely cultivated, including in California's Central Valley, where regional ground-level ozone concentrations frequently violate National Ambient Air Quality Standard during the summer. To measure ozone uptake and BVOC emissions, we performed branch enclosure tests in a greenhouse of the University of California at Berkeley. Fluxes of CO2 and H2O (LiCor-6262), O3 (Dasibi 1008), , and VOCs (GC-FID, GC-MS and PTR-MS) were determined by measuring concentrations in air entering and leaving the chamber. Temperature, humidity, PAR (Photosynthetically Active Radiation), leaf mass, and leaf area, were also recorded. . Greenhouse light and temperature conditions were maintained at levels similar to those found in summer in the Central Valley. The study objective is to improve BVOC emission inventories for California and O3 uptake rates for each of these citrus species, to improve understanding of plant-atmosphere interaction processes, and for modeling regional air quality.

...Implementation Plans; Connecticut; Infrastructure SIP for the 1997 8-Hour Ozone National Ambient...requires that each state adopt and submit a SIP for the implementation, maintenance and...each NAAQS promulgated by the EPA. This SIP is commonly referred to as an...

Air pollution control in the United States for five common pollutants--particulate matter, ground-level ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide--is based partly on the attainment of ambient air quality standards that represent a level of air pollution regarded as safe. Regulator...

Coneflower (Rudbeckia laciniata L.), crownbeard (Verbesina occidentalis L.), and tall milkweed (Asclepias exaltata L.) are wildflower species native to the Great Smoky Mountains National Park (USA) that are known to be sensitive to elevated ambient ozone concentrations. Natural populations of each ...

The present study compares the dynamics in carbon (C) allocation of adult deciduous beech (Fagus sylvatica) and evergreen spruce (Picea abies) during summer and in response to seven-year-long exposure with twice-ambient ozone (O3) concentrations (2 × O3). Focus was on the respira...

We examined the interactive effects of CO2 concentration and mean annual temperature on physiology, biochemistry and growth of Douglas fir seedlings. Seedlings were grown at ambient CO2 or ambient + 200 ppm CO2 and at ambient temperature or ambient + 4 ?C. Needle gas exchange m...

Stratospheric aerosol and ozone profiles obtained simultaneously from the lidar station at the University of L`Aquila (42.35{degrees}N, 13.33{degrees}E, 683m above sea level) during the first 6 months following the eruption of Mount Pinatubo are compared with corresponding nearby Stratospheric Aerosol and Gas Experiment (SAGE) II profiles. The agreement between the two data sets is found to be reasonably good. The temporal change of aerosol profiles obtained by both techniques showed the intrusion and growth of Pinatubo aerosols. In addition, ozone concentration profiles derived from an empirical time-series model based on SAGE II ozone data obtained before the Pinatubo eruption are compared with measured profiles. Good agreement is shown in the 1991 profiles, but ozone concentrations measured in January 1992 were reduced relative to time-series model estimates. Possible reasons for the differences between measured and model-based ozone profiles are discussed. 28 refs., 2 figs.

Some reactive volatile organic compounds (VOCs) are prone to degradation during sampling in an ozone-rich environment. A wide variety of different chemicals have been used to remove the ozone prior to sampling, but the possibility of interference by such chemicals with the sampled VOCs has not been thoroughly examined. In the present investigation, the retention/degradation of four terpenes (alpha-pinene, beta-pinene, 3-carene, and limonene) and isoprene together with some of their oxidation products (alpha-pinene oxide, nopinone, 4-acetyl-1-methylcyclohexene (AMCH), methylglyoxal, and methacrolein) has been studied, using various ozone-removing chemicals in an attempt to evaluate their potential as ozone scrubbers in the sampling of ambient air. The chemicals included in this first screening and their ozone-removing capacity are as follows: KI, MnO2, and Na2SO3 removed ozone for more than 24 h when exposed to 73-78 ppb (150-160 microg/m3) at a sampling flow rate of 500 mL/min. Silanized poly(1,4-phenylene sulfide) (PFS) removed ozone for 5 h, unsilanized PFS removed ozone for 1 h and 50 min, and Na2S2O3 removed ozone for 20 min. The recovery of the selected compounds with the different scrubbers was >95% for all compounds for KI; >95% for the terpenes oxidation products; >90% for the terpenes and isoprene for PFS; >90% for the terpenes and isoprene for MnO2 on copper nets, Na2SO3, and Na2S2O3; and carulite (a commercial mixture between MnO2, CuO, and Al2O3), CuO, and indigo carmine. PMID:11348086

Sustained cultivation of Bacillus thuringiensis (Bt) transgenic crops requires stable transgene expression under variable abiotic conditions. We studied the interactions of Bt toxin production and chronic ozone exposure in Bt cry1Ac-transgenic oilseed rape and found that the insect resistance trait is robust under ozone elevations. Bt Cry1Ac concentrations were higher in the leaves of Bt oilseed rape grown under elevated ozone compared to control treatment, measured either per leaf fresh weight or per total soluble protein of leaves. The mean relative growth rate of a Bt target herbivore, Plutella xylostella L. larvae was negative on Bt plants in all ozone treatments. On the non-transgenic plants, larval feeding damage was reduced under elevated ozone. Our results indicate the need for monitoring fluctuations in Bt toxin concentrations to reveal the potential of ozone exposure for altering dosing of Bt proteins to target and non-target herbivores in field environments experiencing increasing ozone pollution. - Elevated atmospheric ozone can induce fluctuations in insecticidal protein concentrations in transgenic plants.

Rooted cuttings of poplar (Populus nigra) and seedlings of beech (Fagus sylvatica) were exposed to ozone in open-top chambers for one growing season. Three treatments were applied: charcoal-filtered (CF), non-filtered (NF) and non-filtered air plus 30 ppb (nl l(-1)) ozone (NF+). Extra ozone was only added on clear days, from 09:00 until 17:00-20:00. The AOT40s (accumulated exposure over a threshold of 40 ppb), calculated from April to September were 4055 ppb.h for the NF and 8880 ppb.h for the NF+ treatments. For poplar ozone exposure caused highly significant reductions in growth rate, light-saturated net CO(2) assimilation rate, stomatal conductance, F(v)/F(m) and chlorophyll content. The largest effects were observed in August at which time ozone concentrations were elevated. A reduction was noticed in new leaf production, while accelerated ageing and visible damage to leaves caused high leaf losses. For beech the responses were similar but less pronounced: ozone exposure resulted in non-significant growth reductions, slight changes in light-saturated photosynthesis and accelerated leaf abscission. The chlorophyll content of beech leaves was not affected by the ozone treatments. The results confirmed previous observations that fast-growing tree species, such as most poplar species and hybrids, are more sensitive and responsive to tropospheric ozone than slower-growing species, such as beech. The growth reductions observed and reported here for beech were within the range of those reported in relationship to the AOT40 (accumulated exposure over a threshold of 40 ppb) critical level for ozone. PMID:15092884

Water soluble organic compounds (OCs), including naphthenic acids (NAs), are potentially toxic constituents of oil sands process-affected water (OSPW) that is generated during extraction of bitumen from Alberta oil sands. Ozonation can decrease concentrations of OCs in OSPW. However, effects of ozonated-OSPW on multicellular organisms are unknown. A 10-day and a chronic exposure of Chironomus dilutus to OSPW were conducted to assess effects on survival, growth, development, and behavior. Two separate batches of OSPW were treated with 30 or 80 mg ozone (O(3))/L. Wet body masses of larvae exposed to OSPW were 64 to 77% less than their respective controls (p < 0.001). However, both levels of ozonation significantly attenuated effects of OSPW on growth. Similarly, chronic exposure to untreated OSPW resulted in significantly less pupation than in the controls, with 31% and 71% less pupation of larvae exposed to the two batches of OSPW (p < 0.05). Emergence was significantly less for larvae exposed to OSPW, with 13% and 8% of larvae emerging, compared to 81% in controls (p < 0.0001). Both levels of ozonation of OSPW attenuated effects on emergence. These results suggest that OCs degraded by ozonation causes toxicity of OSPW toward C. dilutus, and that ozonation attenuates toxicity of OSPW. PMID:21992611

Transparent conductive tin oxide (TO, SnO2) films have been prepared by low pressure metal organic chemical vapor deposition (LP-MOCVD) from various mixtures of tetramethyltin (TMT) with oxygen and oxygen containing 2.96 to 5.1 mol% O3. The properties of TO films have been changed with the gas flow rate (oxygen, oxygen containing ozone) and the substrate temperature. The use of oxygen containing ozone instead of pure oxygen reduced substrate temperature significantly and the resistivity while maintaining the same growth rate. The films prepared using ozone showed resistivity ranging from 10-2 to 10-3 ?cm, and ranging mobility from 10.5 to 13.7 cm2/Vs.   

Photochemical ozone production is observed in March-September. Highest ozone concentrations and production efficiencies are observed in spring in the northern parts and in summer in the southern parts of the country. VOC concentrations are relatively low compared to continental areas in general. During the growing season a substantial part of the total reactive mass of VOCs is of biogenic origin. Large forest areas absorb ozone substantially, decreasing the ambient ozone concentrations in central and northern parts of Finland where long-range transport of ozone is relatively important compared to local production. The aim of the work conducted at Finnish Meteorological Institute has been to characterise concentrations of photochemically active species in the boundary layer and their photochemical formation and deposition including the effects on vegetation. Also interactions between the boundary layer and free troposphere of ozone have been studied. In the future, fluxes of both biogenic species and air pollutants will be measured and the models will be further developed so that the photochemical and micrometeorological processes could be better understood

Which is the best standard for protecting plants from ozone? To answer this question, we must validate the standards by testing biological responses vs. ambient data in the field. A validation is missing for European and USA standards, because the networks for ozone, meteorology and plant responses are spatially independent. We proposed geostatistics as validation tool, and used durum wheat in central Italy as a test. The standards summarized ozone impact on yield better than hourly averages. Although USA criteria explained ozone-induced yield losses better than European criteria, USA legal level (75 ppb) protected only 39% of sites. European exposure-based standards protected >=90%. Reducing the USA level to the Canadian 65 ppb or using W126 protected 91% and 97%, respectively. For a no-threshold accumulated stomatal flux, 22 mmol m{sup -2} was suggested to protect 97% of sites. In a multiple regression, precipitation explained 22% and ozone explained <0.9% of yield variability. - Geostatistics can be used as a tool for testing the effects of ozone standards on plant responses in the field.

A demonstration experiment is described that employs the ozone decomposition reaction at ambient conditions on Fe2O3 impregnated Fluidized Catalytic Cracking (FCC) catalyst. Using a two-dimensional see-through column the importance of interphase mass transfer is clearly illustrated by the significant difference in ozone conversion between the homogeneous and bubbling fluidization regimes. The principle is enhanced by simultaneous visual observation. Analysis of the conversion measurements at different superficial velocities clearly indicates the severity of interphase mass transfer in the bubbling regime and also shows how the mass transfer effect diminishes in the turbulent regime. The paper supplies detail on the demonstration equipment and gives guidelines on student interpretation possibilities

...population size and growth rate, and ambient...stress-related hormones (Thomas et al...animal. As shown in human psychoacoustics...annual population growth from the 2001 estimate...and some other human activities show that...annual population growth from the 2001...

Local governments, businesses and interested citizens comprise a regional ozone coalition (ROC) with a common interest in controlling ground level ozone in the Greater Cincinnati area which has as its aims: to attain an acceptable level of the gas, to teach its concerned members and citizens about the nature of the gas, its problematic aspects, its impact on the Greater Cincinnati area, how peak ozone values can be moderated, and via the introduction of a smog alert program to promote voluntary ozone containment actions and increase the public's understanding of the problem. This program gives the public a 24 hour in advance warning of the onset of ozone levels that can affect their health based on the following variables: the ambient temperature exceeding 85 degrees F, an excess of sunshine, SW winds that blow with velocities less than 10mph, no predicted rain, high ozone the day before, nitrogen oxides available in the morning, weather and ozone levels at measuring sites, a high pressure area locally, and day of the week. Some data is cited on smog alerts called in recent years, and factors in their costs. The program has had certain successes including: creating slogans to raise public awareness, provided a telephone information source, was called a model nationally, worked with the local bus company to get the public to use public transit, tested gasoline caps in automobiles, surveys supported the efforts at awareness and smog control, and there were no serious smog violations in recent years. An nitrogen oxide state implementation plan to reduce its transport was introduced by the United States EPA that provoked an alternative proposal by the state submitted to the courts. Its elements required a reduction in ozone emissions from power plants and introduction of a new air quality standard over time.

Pinto bean (Phaseolus vulgaris) plants were exposed to charcoal-filtered air with or without added low levels of ozone (90 nl/l). Dark respiration (CO{sub 2} efflux) by expanding primary leaves of the plants was measured and mathematically partitioned into growth and maintenance components. Growth respiration is associated with metabolism supplying energy and carbon skeletons for production of new phytomass. Maintenance respiration is associated with processes such as the turnover of labile molecules, the support of ion and metabolite gradients, and the acclimation to changing or stressful environments in existing phytomass. In the case of ozone stress, maintenance respiration includes the metabolic cost of repairing damaged cellular components. The growth respiration coefficient was unaffected by ozone, whereas the maintenance respiration coefficient increased 15%. Such a relative increase in maintenance respiration results in a diversion of energy and metabolic intermediates from growth processes. 21 refs., 1 fig., 1 tab.

Abstract in spanish Motivado por la importancia del control del medio ambiente se realiza un panel con los estudiantes de la especialidad de Tecnología de la Salud en el municipio de Matanzas, con el objetivo de fomentar en estos una conciencia ambientalista y de esta forma sensibilizar a los mismos, para ser defensores en la protección del medio ambiente y así elevar el conocimiento en cuanto a materia ambiental. Desde el triunfo revolucionario en 1959, la protección del medio ambiente (more) y el uso racional de los recursos naturales ha sido objetivo estratégico nacional. Y en medio de la difícil situación económica actual, los esfuerzos por encausar la recuperación económica y la protección ambiental con un enfoque integral, constituyen un importante desafío para los cubanos. La contaminación de ríos y arroyos por contaminantes químicos se ha convertido en uno de los problemas ambientales más graves de nuestra sociedad. El ozono es un contaminante que produce afectaciones a la salud. La explotación forestal debe ser realizada sobre la base de garantizar la repoblación. Son diversos los factores que determinan el crecimiento elevado de la población en los países subdesarrollados. La concentración de la población, la industria y el transporte automotor en zonas urbanas ha producido un desequilibrio ecológico con grave afectación a la higiene del ambiente. Cuba, a pesar de ser un país subdesarrollado, el crecimiento económico y la industrialización han llevado aparejadas medidas consecuentes para la protección del ambiente y el desarrollo sostenible. Los riesgos como consecuencia de los fenómenos naturales o provocados por las actividades humanas están íntimamente relacionados con la naturaleza de los mismos. En todos los casos se hacen necesario priorizar los servicios de saneamiento básico esenciales para garantizar la salud de la población . Abstract in english Due to the importance of the environmental control, we carried out a debate with the students of the specialty of Health Technologies in the municipality of Matanzas with the objective of forming an environmental awareness and inducing them to be defenders of the environmental protection, and also raising their knowledge on the environmental matters. Since the triumph of the Cuban revolution in 1959, environmental protection and rational use of the natural resources have (more) been a national strategic objective. Inserted in the current difficult economic situation, the efforts for achieving the economic recuperation and environmental protection through an integral approach are an important challenge for Cubans. Rivers and brooks contamination by chemical substances has become one of the most serious environmental problems in our society. Ozone is a contaminant producing health affections. Forestal exploitation should be carried on the bases of warranting repopulation. Several factors determine a high growth of population in the underdeveloped countries. The concentration of population, industries and auto transport in urban areas has produced an ecological disequilibrium with serious damage of the environmental hygiene. Although Cuba is an underdeveloped country, the economic growth and industrialization have been led together with tenacious measures to protect the environment and a sustainable development. Risks due to natural phenomena or caused by human activity are tightly related with their nature. In all the cases it is necessary to pay an especial attention to the services and measures guarantying the population health.

Two ecotypes of Arabidopsis thaliana, collected from Libya and Norway, were grown in the greenhouse under. UV-B doses of 0 and 10.5 kJ m[sup [minus]2] UV-B[sub BE]. The high UV-B dose simulated midsummer ambient conditions over Libya and a 40% reduction in stratospheric ozone over Norway. The Libyan ectotype, which originated from latitudes where solar UV-B is high, showed no UV-B induced damage to plant growth. However the Norwegian ecotype, which originated from latitudes where solar UV-B is low, showed a significant reduction in plant height, inflorescence weight, and rosette weight in response to enhanced UV-B. Although fruit and seed number for both ecotypes were unaffected by enhanced UV-B radiation the germination success of the seeds harvested from the irradiated Norwegian plants were significantly reduced. The two ecotypes also differed with respect to their accumulation of kaempferol, a putative UV-B protective filter. The Libyan ecotype increased kaempferol concentration by 38% over the 0 kJ treatment whereas the Norwegian ecotype increased by only 15%. These data suggest that, for these ecotypes, variation in UV-B sensitivity may be explained by the differential induction of UV-absorbing leaf pigments.

Ozone gas in an ambient pressure was blown to Cr2O3 powder. The higher oxides, CrO3, Cr2O5, Cr5O12, and Cr3O8, could be synthesized above 373 K. Both CrO3 and Cr2O5 were found by in situ X-ray diffraction measurements. It was known that they could be produced only at high pressure of oxygen and at high temperatures. The CrO3 formed was melted at 470 K in an ozone atmosphere and decomposed above 500 K. Because of thermal decomposition of ozone and the higher oxides, no higher oxides were formed above 660 K. The phase formation was discussed using the kinetic stability diagram.

The objective of this study was to estimate the association between ambient ozone levels and hospitalization for asthma/atopic dermatitis among children younger than 15 years old living in Seoul and Ulsan, Korea, in the years 2004-2005. Estimated relative risks of hospital admissions associated with an interquartile range (IQR) increase in ozone concentration were calculated using a generalized additive Poisson model. For childhood asthma, the effect of an ozone increase on the relative risks in Ulsan [1.21 (95% CI, 1.10-1.34)] was higher than that in Seoul [1.05 (95% CI, 0.99-1.11)]. The relative risks for childhood atopic dermatitis were also found to be higher in Ulsan [1.38 (95% CI, 0.80-2.36)] than in Seoul [1.28 (95% CI, 1.04-1.58)]. These results support previously reported findings...

Context: A human exposure-response (E-R) model previously demonstrated to accurately predict population mean FEV1 response to ozone exposure has been proposed as the foundation for future risk assessments for ambient ozone.Objective: Fit the original and related models to a larger data set with a wider range of exposure conditions and assess agreement between observed and population mean predicted values. Materials and methods: Existing individual E-R data for 23 human controlled ozone exposure studies with a wide range of concentrations, activity levels, and exposure patterns have been obtained. The data were fit to the original model and to a version of the model that contains a threshold below which no response occurs using a statistical program for fitting nonlinear mixed models. Resul...

Loss of symbiotic zooxanthellae, or “bleaching” is one of the first visible signs of thermal stress. Critical threshold temperatures for coral bleaching vary geographically, but can be expressed universally as fixed increments relative to the historical mean local summer maximum. Bleaching can be induced by short-term exposure (i.e. 1 2 days) at temperature elevations of 3°C to 4°C above normal summer ambient or by long-term exposure (i.e. several weeks) at elevations of 1°C to 2°C. Corals in both tropical and subtropical locations live at temperatures close to their lethal limits during the summer months. Temperature elevations above summer ambient, but still below the bleaching threshold, can impair growth and reproduction. Temperature and light interact synergistically; high light accelerates bleaching caused by elevated temperature. Bleaching susceptibility is correlated with respiration rate. Any factor that increases respiration (such as high incident light) accelerates bleaching at higher temperatures. Ultraviolet (UV) radiation is a detrimental factor associated with solar radiation. Increased UV due to thinning of the earth's protective ozone layer may aggravate bleaching and mortality caused by global warming. A warming trend in Hawaiian waters has been observed over the past decade. In 1986, 1987 and 1988 Hawaiian corals were perilously close to their bleaching threshold during the summer months, and localized bleachings did occur. In some cases, local warming of surface water on shallow reef flats exceeded this threshold temperature and caused localized coral bleaching. In other cases, heating of large mesoscale eddies in the lee of the larger islands apparently caused wide-scale bleaching of the most sensitive coral species ( Pocillopora meandrina) to depths of 20 m. A continuation of the warming trend in Hawaii would lead to mass bleachings similar to those observed recently in other geographic locations.

The wastewater purification was conducted both with pretreatment of the water with an ozone-air mixture containing 7-10 X 10/sub 3/ vol. % ozone for 300, 600, and 900 sec, and without pretreatment. The results of the experiments on the decomposition of phenol in an aqueous solution of the Candida tropicalis culture are presented. When conducting the treatment after pretreatment of the wastewater the ozone-air mixture, the utilization of phenol, and the growth of the yeast practically cease 16-20 hr earlier than in the control experiment. Here the residual concentration of phenol in the control experiment is 350 times greater than when treating water pretreated with ozone. At the same time, the rate of growth of the feed yeast increases by a factor of 1.5-1.7 after pretreatment of wastewater with an ozone-air mixture as compared to the control experiment without pretreatment. On the basis of the data we computed the economic effect of replacement of the culture of Pseudomonas species in the biological treatment facilities of the Novolipetsk IandSW with the Candida tropicalis culture (using pretreatment with ozone).

Antibiotic therapy administered for treatment of gram-negative bacterial infections can exert a negative effect in the form of endotoxin shock. Therefore, a sterilization method that releases little endotoxin is required. This in vitro study aimed to compare the amounts of endotoxin released from Escherichia coli exposed to antibiotics (aminobenzylpenicillin, kanamycin, oxytetracycline, sulfadimethoxine and enrofloxacin) or ozone. The bacterial growth and amount of endotoxin released were measured at specific time points. Compared with antibiotic treatment, ozone sterilization induced release of smaller amounts of endotoxin from the bacteria. Moreover, no major differences were observed when ozone was used against the purified endotoxin. We conclude that compared with antibiotic treatment, ozone sterilization may release smaller amounts of endotoxin.   

Considerable interest has recently been directed to the possible extrapulmonary effects caused by exposure to ambient ozone. As a result of ozone induced in vivo alteration of red cell function within human subjects, it has been hypothesized that individuals with an erythrocyte glucose-6-phosphate dehydrogenase (G-6-PD) deficiency would be at increased hemolytic risk to elevated ambient ozone exposure. In order to evaluate such an hypothesis in an experimental setting it would be of great value to have an appropriate animal model with erythrocyte G-6-PD activity similar to the absolute activity range found in the human population. While no such unique animal model is presently known, the literature has revealed that Dorset sheep have an erythrocyte G-6-PD activity comparable in absolute units to a human G-6-PD deficient. Based on this information, we evaluated the mechanisms by which sheep and human G-6-PD deficient red cells handle oxidant stress. We evaluated the effects of in vivo ozone exposure in Dorset sheep over a broad range of concentrations.

Three experiments examined the influence of ultraviolet-B radiation (UV-B; 280-320 nm) exposure on reproduction in Brassica rapa (Brassicacaeae). Plants were grown in a greenhouse under three biologically effective UV-B levels that stimulated either an ambient stratospheric ozone level (control), 16% ({open_quotes}low enhanced{close_quotes}), or 32% ({open_quotes}high enhanced{close_quotes}) ozone depletion levels at Morgantown, WV, USA in mid-March. In the first experiment,pollen production and viability per flower were reduced by {approx}50% under both enhanced UV-B levels relative to ambient controls. While plants under high-enhanced UV-B produced over 40% more flowers than plants under the two lower UV-B treatments, whole-plant production of viable pollen was reduced under low-enhanced UV-B to 34% of ambient controls. In the second experiment, the influence of source-plant UV-B exposure on in vitro pollen from plants was examined and whether source-plant UV-B exposure influenced in vitro pollen germination and viability. Pollen from plants under both enhanced-UV-B was reduced from 65 to 18%. Viability of the pollen from plants grown under both enhanced UV-B treatments was reduced to a much lesser extent: only from {approx}43 to 22%. Thus, ambient source-plant pollen was more sensitive to enhanced UV-B levels to fertilize plants growing under ambient-UV-B levels, and assessed subsequent seed production and germination. Seed abortion rates were higher in plants pollinated with pollen from the enhanced UV-B treatments, than from ambient UV-B. Despite this, seed yield (number and mass) per plant was similar, regardless of the UV-B exposure of their pollen source. Our findings demonstrate that enhanced UV-B levels associated with springtime ozone depletion events have the capacity to substantially reduce viable pollen production, and could ultimately reduce reproductive success of B. rapa. 37 refs., 4 figs., 2 tabs.

The Houston Regional Monitoring Corporation (HRM) has performed continuous ambient air quality and meteorological monitoring in the Ship Channel area of east Harris County since August 1981. The HRM monitoring network is one of the largest Environmental Protection Agency (EPA) approved Prevention of Significant Deterioration (PSD) monitoring network in the United States operated by an industrial group. As an adjunct to its monitoring. HRM has funded extensive meteorological and statistical analyses of ozone monitoring data in Harris County. One of the goals of these studies was to determine those meteorological conditions responsible for the formation of elevated ozone concentrations in Harris County. The analyses performed included the use of principal component analysis and cluster analysis. These analysis techniques have individually been applied to ozone and air quality research problems. The combined use of these techniques in this analysis, however, is a unique application of these statistical tools to an ozone air quality analysis. As a result of these analyses, a climatology of those episodes conducive to elevated ozone formation in Harris County was developed.

Large petrochemicalflares, common in the Houston Ship Channel (the Ship Channel) and other industrialized areas in the Gulfof Mexico region, emit hundreds to thousands of pounds per hour of highly reactive volatile organic compounds (HRVOCs). We employedfine horizontal resolution (200 mx200 m) in a three-dimensional (3D) Eulerian chemical transport model to simulate two historical Ship Channel flares. The model reasonably reproduced the observed ozone rise at the nearest monitoring stations downwind of the flares. The larger of the two flares had an olefin emission rate exceeding 1400 lb/hr. In this case, the model simulated a rate of increase in peak ozone greater than 40 ppb/hr over a 12 kmx12 km horizontal domain without any unusual meteorological conditions. In this larger flare, formaldehyde emissions typically neglected in official inventories enhanced peak ozone by as much as 16 ppb and contributed over 10 ppb to ambient formaldehyde up to approximately 8 km downwind of the flare. The intense horizontal gradients in large flare plumes cannot be simulated by coarse models typically used to demonstrate ozone attainment. Moreover even the relatively dense monitoring network in the Ship Channel may not be able to detect many transient high ozone events (THOEs) caused by industrial flare emissions in the absence of stagnant air recirculation or stalled sea breeze fronts, even though such conditions are unnecessary for the occurrence of THOEs. PMID:22916445

The roles of ozone and other oxidizing agents are discussed. The major polluting emissions are SO/sub 2/, NO, and volatile organic chemicals. In the usual ambient concentrations, these substances are relatively harmless. However, when SO/sub 2/ and NO are oxidized, they are converted into more acid, more toxic, substances. Oxidants, including OH, H/sub 2/O/sub 2/, HO/sub 2/, and organic peroxides, arise out of complex photochemistry that involves the ozone, the nitrogen oxides, and volatile organic chemicals. Were SO/sub 2/ the only pollutant, most of it would escape unchanged to the western Atlantic Ocean where it would be so diluted as to have no effect. At present about 35 percent of the SO/sub 2/ produced in the United States leaves the continent. In contrast, because of higher rates of reaction with oxidants, most of the NO is converted into nitric acid and deposited on land. The nitrogen oxides are involved in the production of ozone, some of which is naturally present. But particularly in urban settings where concentrations of NO/sub x/ are elevated and volatile organic chemicals such as those in gasoline are present, ozone concentrations may rise to levels deleterious to health. The Environmental Protection Agency has set standards for levels not to be exceeded, but nearly half of urban communities are not in compliance. The NO/sub x/ involved in the formation of urban ozone comes mostly from vehicular emissions.

The majority of humans rely on incidental sun exposure to maintain vitamin D sufficiency. Depending on where thresholds of vitamin D "sufficiency" are defined, it was recently stated that up to one billion people worldwide have suboptimal vitamin D levels (Bouillon, R., University of Leuven). Even in sunny southeast Queensland, the world's skin cancer capital, a 2006 study uncovered deficiency rates of up to 78% (at a threshold of 75 nmol/L of circulating 25-hydroxyvitamin D). Vitamin D regulates calcium absorption and inadequate levels are proven to result in osteomalacia, osteoporosis, rickets, bone pain and general skeletal weakness. Recent evidence also suggests vitamin D plays a preventative role in autoimmune diseases including numerous cancers, diabetes, schizophrenia, coronary heart disease, depression and other disorders. The most promising means of alleviating the worldwide burden of vitamin D deficiency seems to be by increased UV exposure. However, a much more mature understanding of UV exposures encountered in everyday life is required. This understanding is fundamentally founded in geophysics. UV exposures are strongly influenced by season/time of year, time of day, climate, location, pollution, aerosols and, importantly, ozone. In this work, we use computer simulations to obtain daily totals of vitamin D producing UV at numerous latitudes during one year. The ozone concentration is varied from 260 DU to 360 DU to determine the role of ozone variability on the ambient levels of vitamin D UV. Vitamin D synthesis is highly dependent on UVB. In our results, we demonstrate that this has important implications. Namely, vitamin D is strongly affected by ozone variability, since ozone filters UVB more strongly than UVA. Moreover, since erythema (sunburn) can occur at UVA wavelengths, ozone variation will more strongly affect vitamin D synthesis than erythema. Our results highlight that ozone monitoring is essential for understanding appropriate UV exposures for vitamin D health. We finally discuss implications for population health and how geophysics continues to play a vital role in addressing the widespread dilemma of vitamin D deficiency.

The disinfection of water containing the microorganism, Escherichia coli (E. coli) by exposure to a pulsed-discharge plasma generated above the water using a multineedle electrode (plasma-exposure treatment), and by sparging the off-gas of the pulsed plasma into the water (off-gas-sparging treatment), is performed in the ambient gases of air, oxygen, and nitrogen. For the off-gas-sparging treatment, bactericidal action is observed only when oxygen is used as the ambient gas, and ozone is found to generate the bactericidal action. For the plasma-exposure treatment, the density of E. coli bacteria decreases exponentially with plasma-exposure time for all the ambient gases. It may be concluded that the main contributors to E. coli inactivation are particle species produced by the pulsed plasma. For the ambient gases of air and nitrogen, the influence of acidification of the water in the system, as a result of pulsed-plasma exposure, may also contribute to the decay of E. coli density.   

The effect of water vapor and other pollutants on ozone monitoring instruments was investigated. Five UV-type and two chemiluminescence-type monitors were employed in this study. The results of the study indicate that in systems containing ozone, water vapor and zero air only, the UV-based monitors showed negligible effects due to humidity. On average, the UV monitors were within 0.5 percent of independently determined ozone values judged to be extremely accurate. The chemiluminescence-based monitors showed systematically higher readings than the UV monitors with added water vapor. The effect was found to be linear with water vapor concentration with an average positive deviation of 3.0 percent per percent H2O at 25 degrees C. For these measurement, ozone concentrations ranged from 85 to 320 ppbv and water concentrations from 1 to 3 percent (i.e., dew point temperatures from 9 to 24 degrees C). These results are largely in agreement with previous studies conducted to measure this interference, although the present study extends the range of water concentrations tested. Studies were also performed with a smog chamber with simulated polluted air (containing paraffinic, olefinic and aromatic hydrocarbon precursors) and varying relative humidities. Although the presence of water vapor did not appear to represent a substantial interference in these systems, a positive interference was observed with the UV monitors. This interference was likely a result of the presence of toluene and some of its aromatic photooxidation products (e.g., benzaldehyde), which can be partially removed from the reference stream by the ozone scrubber within the UV monitor. If the compound absorbs radiation at 254 nm, it is detected as ozone. However, when the results are scaled back to ambient concentrations of toluene and NO(x), the effect appears to be very minor (ca. 3 percent under the study conditions). It is concluded that under atmospheric conditions at moderate pollution and relative humidity levels, both types of instruments can give accurate measurements of the ozone concentration. These potential effects should be recognized when conducting ambient ozone measurements. PMID:15739516

The effect of ozone exposure on cytokine release was studied in alveolar macrophages (AM) from patients with chronic inflammatory lung disease. AM of 87 patients entered 99 exposure experiments (13 at 150 {mu}g, 32 at 300 {mu}g, 16 at 700 {mu}g, and 38 at 1000 {mu}g ozone/m{sup 3}). AM were exposed in a biphasic system consisting of membrane-culture insert of high porosity (transwell). AM were directly exposed to ozone for 1 h, followed by 4 h of culture covered with serum-free medium. The parameters were determined in culture supernatant by ELISA (interleukin (IL) 1{alpha}, {beta}, IL6, IL8, TNF{alpha}), by bioassay (TNF{alpha}), and by enzyme assay (LDH). By increased LHD activities in culture supernatants of ozone exposed AM, a significant cytotoxic effect was identified for ozone concentrations equal to or higher than 300 {mu}g/m{sup 3}. Spontaneous release of IL1{alpha}, {beta} and IL8 slightly increased after ozone exposure (p<0,05 at 150 {mu}g ozone). TNF was released in reduced quantities (p<0,05 at 300 {mu}g; p<0,01 at 1000 {mu}g ozone/m{sup 3}). Patients with chronic bronchitis, fibrosis, and sarcoidosis differed significantly in basic cytokine release of IL1{alpha}, IL1{beta}, IL8, and TNF, with sarcoidosis patients showing the highest levels of cytokines measured. Nevertheless, the ozone induced changes for the various cytokines were not significantly different between the above patient groups. The most obvious effect of ozone could be observed after additional stimulation of AMs with LPS. LPS induced secretion of TNF and IL6 were shown to be strongly inhibited by ozone, even at ambient concentrations (150 and 300 {mu}g/m{sup 3}). Little effect was seen regarding IL8, IL1{alpha}, and {beta}. The murine macrophage cell line J774A.1, which proved to respond to LPS stimulation in a similar reduction of TNF release after ozone exposure, was used as a model to study LPS receptor binding. After ozone exposure at 300 {mu}g/m{sup 3} LPS-FITC binding was reduced significantly demonstrating impaired receptor function, whereas detection of receptor by monoclonal anti-CD14-antibody was not altered significantly. In conclusion, ozone impairs macrophage functions even at ambient concentrations, which might interfere with host defence mechanisms. Some, but not all patients might therefore risk of aggravation of their respective disease. Response to ozone seemed to be influenced rather by the individual`s conditions than by the underlying disease. (orig.) [Deutsch] Unter der Fragestellung, ob und wie Ozon die Freisetzung von Entzuendungsmediatoren aus Alveolarmakrophagen (AM) bei Patienten mit chronisch entzuendlichen Lungenerkrankungen beeinflussen kann, wurden im Projekt die AM von 87 Patienten in 99 in vitro Expositionsexperimenten untersucht (13 bei 150 {mu}g, 32 bei 300 {mu}g, 16 bei 700 {mu}g und 38 bei 1000 {mu}g Ozon/m{sup 3}). Die AM wurden in Transwell-Membrankulturgefaessen exponiert und waren apikal der Gasphase 1 Stunde direkt ausgesetzt. Die Befeuchtung erfolgte kapillar von unten durch die poroese Membran hindurch. Nach weiteren 4 Stunden Kultur mit Medium bedeckt, wurden die Parameter im Kulturueberstand gemessen. Eine signifikant toxische Wirkung ist anhand der erhoehten LDH-Aktivitaet im Kulturueberstand der ozonexponierten AM ab 300 {mu}g/m{sup 3} nachweisbar. Von Patient zu Patient gab es fuer die einzelnen Parameter eine grosse individuelle Variabilitaet bezueglich Richtung und Hoehe der Ozonantwort. Die spontane Freisetzung von IL1 {alpha} und {beta} sowie IL8 zeigt im Mittel eine diskrete Zunahme nach Ozon (p<0,05 bei 150 {mu}g), waehrend fuer TNF zumeist eine Hemmung festzustellen ist (p<0,05 bei 300 {mu}g; p<0,01 bei 1000 {mu}g Ozon). Die Patientengruppen Sarkoidose, Fibrose und Bronchitis unterscheiden sich in ihrer Basisfreisetzung, wobei die AM von Sakroidosepatienten fuer die untersuchten Zytokine die hoechsten Sekretionsraten aufweisen. Die ozonbedingte Sekretionsaenderung zeigt keine signifikanten Unterschiede in Hoehe und Auslenkung zwischen den Patientengruppen. Der staerkste Ozoneffekt wird nach zusaetzlicher Aktivierung der AM mit LPS ermittelt. Man findet eine stark verminderte Freisetzung von TNF und IL6 bei allen untersuchten Ozonkonzentrationen. Die IL1 {alpha}-, {beta}- und IL8-Freisetzung wird dagegen wenig beeinflusst. Die murine Makrophagenzellinie J774A.1 zeigt nach 300 {mu}g Ozon und nachfolgender LPS-Stimulation eine TNF-Reduktion aehnlich den humanen AM. Eine funktionelle Schaedigung des LPS-Rezeptors (CD14) durch Ozon kann durch eine verminderte LPS-FITC-Bindung der ozonexponierten Zellen demonstriert werden. Der Nachweis des Rezeptors durch markierten anti-CD14-Antikoerper bleibt dagegen weitgehend unbeeintraechtigt. Zusammenfassend zeigen die Ergebnisse, dass Ozon auch bei umweltrelevanten Konzentrationen an AM funktionelle Schaeden hervorruft und die Zytokinfreisetzung moduliert, insbesondere nach zusaetzlicher Aktivierung durch LPS. Die Ozonantwort selbst scheint eher durch individuelle Faktoren als durch die Grunderkrankung der Patienten beeinflusst zu werden. (orig.)

The United States Environmental Protection Agency (USEPA) has recommended the use of the Urban Airshed Model (UAM), a grid-based photochemical model, for regulatory applications. One of the important parameters in applications of the UAM is the height of the mixed layer or the diffusion break. In this study, we examine the sensitivity of the UAM-predicted ozone concentrations to (a) a spatially invariant diurnal mixing height profile, and (b) a spatially varying diurnal mixing height profile for a high ozone episode of July 1988 for the New York Airshed. The 1985/88 emissions inventory used in the EPA`s Regional Oxidant Modeling simulations has been regridded for this study. Preliminary results suggest that the spatially varying case yields a higher peak ozone concentrations compared to the spatially invariant mixing height simulation, with differences in the peak ozone ranging from a few ppb to about 40 ppb for the days simulated. These differences are attributed to the differences in the shape of the mixing height profiles and its rate of growth during the morning hours when peak emissions are injected into the atmosphere. Examination of the impact of emissions reductions associated with these two mixing height profiles indicates that NO{sub x}-focussed controls provide a greater change in the predicted ozone peak under spatially invariant mixing heights than under the spatially varying mixing height profile. On the other hand, VOC-focussed controls provide a greater change in the predicted peak ozone levels under spatially varying mixing heights than under the spatially invariant mixing height profile.

We investigated the impacts of climate and land-use change on regional climate and surface ozone under the future IPCC A1B scenario in the greater Houston area. We applied the Weather Research and Forecasting (WRF) model with chemistry (WRF-CHEM) to the Houston area for current and future years. The high-resolution initial and boundary meteorological conditions for the WRF-CHEM model were obtained by running the WRF model at 12-km grid spacing driven by 6-hourly Community Climate System Model (CCSM) version 3 outputs. High- resolution land-use data from National Land Cover Dataset (NLCD) was used in the WRF-CHEM model coupled with an Urban Canopy Model (UCM). For future-year simulations, we implemented a detailed future urban land- use data based on projected population growth to investigate the effects of future land-use change on regional climate and ozone concentration. For the urban area, our simulation results indicate that the effect of climate change accounts for an increase of 2.6 ppb in daily maximum 8-hr ozone concentration and land-use change exerts more influence than climate change. The combined effect of climate change and land-use change can be up to 6.2 ppb. Predicted distribution of the number of extreme ozone days with the daily maximum 8-hr ozone concentration larger than 84 ppb is similar to the pattern of increases in ozone concentration. The increase in extreme ozone days can be up to 4-5 days in August in which land-use contributes to 2-3 days increase. We also find climate change and land-use change have different impacts in different regions. Additional sensitivity experiments on the impacts of anthropogenic emissions show that the impacts of future change in anthropogenic emissions are comparable with the effects of land-use change on ozone concentration.

Ozone, a secondary pollutant, is a strong oxidant that can pose a risk to human health. It is formed from a complex set of photochemical reactions involving nitrogen oxides (NOx) and volatile organic compounds (VOCs). Ambient measurements and air quality modeling of ozone and its precursors are important tools for support of regulatory decisions, and analyzing atmospheric chemical and physical processes. I worked on three methods to improve our understanding of photochemical ozone production in the Eastern U.S.: a new detector for NO2, a numerical experiment to test the sensitivity to the timing to emissions, and comparison of modeled and observed vertical profiles of CO and ozone. A small, commercially available cavity ring-down spectroscopy (CRDS) NO2 detector suitable for surface and aircraft monitoring was modified and characterized. The CRDS detector was run in parallel to an ozone chemiluminescence device with photolytic conversion of NO2 to NO. The two instruments measured ambient air in suburban Maryland. A linear least-squares fit to a direct comparison of the data resulted in a slope of 0.960+/-0.002 and R of 0.995, showing agreement between two measurement techniques within experimental uncertainty. The sensitivity of the Community Multiscale Air Quality (CMAQ) model to the temporal variation of four emissions sectors was investigated to understand the effect of emissions' daily variability on modeled ozone. Decreasing the variability of mobile source emissions changed the 8-hour maximum ozone concentration by +/-7 parts per billion by volume (ppbv). Increasing the variability of point source emissions affected ozone concentrations by +/-6 ppbv, but only in areas close to the source. CO is an ideal tracer for analyzing pollutant transport in AQMs because the atmospheric lifetime is longer than the timescale of boundary layer mixing. CO can be used as a tracer if model performance of CO is well understood. An evaluation of CO model performance in CMAQ was carried out using aircraft observations taken for the Regional Atmospheric Measurement, Modeling and Prediction Program (RAMMPP) in the summer of 2002. Comparison of modeled and observed CO total columns were generally in agreement within 5-10%. There is little evidence that the CO emissions inventory is grossly overestimated. CMAQ predicts the same vertical profile shape for all of the observations, i.e. CO is well mixed throughout the boundary layer. However, the majority of observations have poorly mixed air below 500 m, and well mixed air above. CMAQ appears to be transporting CO away from the surface more quickly than what is observed. Turbulent mixing in the model is represented with K-theory. A minimum Kz that scales with fractional urban land use is imposed in order to account for subgrid scale obstacles in urban areas and the urban heat island effect. Micrometeorological observations suggest that the minimum Kz is somewhat high. A sensitivity case where the minimum K z was reduced from 0.5 m2/s to 0.1 m2/s was carried out. Model performance of surface ozone observations at night increased significantly. The model better captures the observed ozone minimum with slower mixing, and increases ozone concentrations in the residual layer. Model performance of CO and ozone morning vertical profiles improves, but the effect is not large enough to bring the model and measurements into agreement. Comparison of modeled CO and O3 vertical profiles shows that turbulent mixing (as represented by eddy diffusivity) appears to be too fast, while convective mixing may be too slow.

We conducted a study to investigate the characteristics and determinants of ambient bacteria in Taipei, Taiwan from August 2004 to March 2005. We monitored ambient culturable bacteria in Shin-Jhuang City, an urban area in the Taipei metropolitan areas, using duplicate Burkard Portable Air Samplers with R2A agar. The average concentration of total bacteria was 1,986 colony-forming units per cubic meter of air (CFU/m3) (median = 780 CFU/m3) over the study period, with the highest level in autumn. Most bacterial taxa had similar seasonal variation, with higher concentrations in autumn and winter. During the study period, Gram negative rods and cocci were predominant. Multivariate analyses indicated that wind speed and wind direction significantly influenced ambient bacterial distribution. Temperature and relative humidity were also important environmental factors positively associated with ambient bacterial concentrations. We observed statistically significant relationships between ambient bacteria and air pollutants, including sulfur dioxide (SO2), ozone, particulate matter (aerodynamic diameter ?10 ?m (PM10)), methane and total hydrocarbons. The concentrations of methane and total hydrocarbons during the previous day were positively associated with total bacteria and Gram negative rods, respectively. Ozone level on the previous day had a negative relationship with Gram negative cocci. SO2 level with a 3-day lag was positively correlated with concentrations of both total bacteria and Gram negative cocci. In the future, more longitudinal studies are needed to confirm the relationships and possible mechanisms between ambient bacteria and meteorological factors, as well as to evaluate the ecological and health impacts of ambient bacteria.

Eastern white pine (Pinus strobus L.) has been described in the scientific literature as particularly sensitive to air pollution based on foliar injury symptoms, decreased growth, and increased mortality. Wide genotypic variability in tolerance of eastern white pine to air pollution has also been documented. Increment cores from 360 white pine were collected from a total of 24 sites in Tennessee, Virginia, Pennsylvania, Connecticut, Vermont, New Hampshire, and Maine as part of the FORAST (Forest Response to Anthropogenic Stress) project. The study analyzed the FORAST tree growth, air pollution, climate, and competition databases to determine if unexplained alterations in recent growth of white pine occur in a spatial/temporal pattern suggestive of air pollution effects. There is little evidence of widespread growth decline in this sample of white pine. Consistent with reports in the literature, regional mean BAI curves indicate growth has been constant or increasing from 1930 to 1980 for all regions sampled. However, a small proportion (9%) of the sample population exhibits post-1960 alterations in growth trends indicative of tree decline. Regional differences in tree age/size and recent stand dynamics obscured spatial patterns between incidence of tree decline and air pollution. Dendroclimatic analyses indicate white pine growth-climate relationships may have been altered at sites with high ozone exposure. Beginning in the 1950's, growth-climate correlations decrease markedly at high ozone exposure sites. However, the FORAST database has limitations that preclude a rigorous analysis of this potential ozone-climate interaction.

An experiment was performed to determine whether the presence of ozone modified the effects of acidity of simulated rain on growth and yield of soybean. Beeson, a type II cultivar, was grown in field chambers and exposed to simulated rain at 3 levels of acidity. Each level was ap...

sound environmental policy and economic investment decisions. NASAs' Earth .... post-event recovery. Space-based ... ing the growth of the now-famous Antarctic “ozone hole,” leading to the adoption by virtually all the ...... Argentina's SAC-C satellite will be launched by NASA.to form a constellation of land observing ...

The authors challenge those scientists who downplay the reality and importance of global environmental problems and contrast their anti-environmental rhetoric with the consensus view of the scientific community regarding such issues as population growth, desertification, food production, global warming, ozone depletion, acid rain and biodiversity loss.

The objective of this research is to study the effects of elevated ozone, carbon dioxide and their combination on ultrastructural, physiological and biochemical responses of Scots pine needles and how these effects are reflected to photosynthesis, carbohydrate and nutrient allocation and finally to shoot and root growth of trees. In addition the interactions of the studied trees and mycorrhizal fungi as well as insect herbivores are studied. The exposures have been running only for two growing periods and it seems necessary to continue the experiment over the third growing season in 1996. Since the analyses are partially incomplete, only preliminary conclusions are possible at the moment. The slightly increased shoot growth and needle width and increased amount of starch in chloroplasts point to the slight stimulating effect of elevated CO{sub 2} among the chamber treatments. Altogether the growth of the seedlings was best in the chamberless treatment indicating a negative chamber effect. The elevated ozone significantly increased the chlorotic mottling and overall yellowing of second year needles as well as caused increased density of chloroplast stroma and declined photosynthesis, all these responses being often related to ozone exposures. The ozone related responses appeared at both CO{sub 2} levels indicating no clear protection due to elevated CO{sub 2}. The ozone or carbon dioxide treatments were not able to significantly change nutrient concentrations, insect herbivory or carbon allocation among the secondary compounds of needles. A tendency of increased carbon allocation to fine roots due to ozone but not so clearly to CO{sub 2} was observed

Using the Atlanta metropolitan area as a case study, the authors examine the effects of urbanization and its associated heat island on urban ozone concentrations. Air quality data from Atlanta suggest that urban ozone concentrations are enhanced by increases in ambient temperature. Model calculations suggest that this enhancement is caused by the effect of temperature on the atmospheric chemistry of peroxyacetyl nitrate (PAN), as well as the temperature dependence of natural and anthropogenic hydrocarbon emissions. A comparison of summertime temperatures in Atlanta and a nearby rural station, suggests that Atlanta's temperature over the past 15 years has increased by about 2{degree}C due to urbanization and its concomitant intensification of the urban heat island. Numerical simulations using conditions of a typical summertime day in Atlanta suggest that this rise in temperature could have, (1) resulted in a significant increase in the net emissions of natural hydrocarbons in the area in spite of the loss of about 20% of the areas forests over the same period, and (2) negated the beneficial effects on summertime ozone concentrations that would have been obtained from a 50% reduction in anthropogenic hydrocarbon emissions. Because a NO{sub x}-based ozone abatement strategy appears to be less sensitive to temperature increases than does a hydrocarbon-based strategy, a NO{sub x} strategy may prove to be more effective in the future if temperatures continue to rise as a result of urbanization and the greenhouse effect.

The effects of acid precipitation and ozone on the composition of the ectomycorrhizal community of red spruce saplings were evaluated. In 1986, saplings were excavated from a site in Maine that had been clear-cut in 1979. Saplings were then potted in native soil and transported to Ithaca, New York. With the exception of an ambient control treatment, trees were grown in open-top chambers. Saplings were exposed to five levels of ozone and three levels of acid precipitation beginning in July 1987. Ectomycorrhizae were sampled in 1988 and 1991 after one and four years of treatment, respectively. Although the percentage of root tips infected by ectomycorrhizal fungi was not affected by treatments, a shift in the composition of the ectomycorrhizal community occurred in response to acid precipitation treatments for both sampling years. Among the seven ectomycorrhizal morphotypes identified, the percent composition of one morphotype increased and another decreased in response to higher rain acidity. Alone, ozone treatments did not influence ectomycorrhizal composition however, a significant interactive response to ozone and acid precipitation was observed in the organic soil horizon in 1988. Such shifts in the composition of the ectomycorrhizal community may indicate that the experimental trees were stressed by pollution treatments. 38 refs.

This study quantifies the national burden of disease attributed to particulate matter (PM) and ozone (O3) in ambient air in the United Arab Emirates (UAE), a rapidly growing nation in which economic development and climatic conditions pose important challenges for air quality management. Estimates of population exposure to these air pollutants are based on observed air quality data from fixed-site monitoring stations. We divide the UAE into small grid cells and use spatial-statistical methods to estimate the ambient pollutant concentrations in each cell based on the observed data. Premature deaths attributed to PM and O3 are computed for each grid cell and then aggregated across grid cells and over a year to estimate the total number of excess deaths attributable to ambient air pollution. ...

In this paper, we compare the open-path FTIR to the differential optical absorption spectroscopy (DOAS) approach in the Mid-Infrared region for the continuous retrieval of trace gases. After consideration of FTIR capabilities and results, we explore the potential for a compact quantum cascade laser (QCL) based DOAS system to continuously monitor ambient concentration levels of Ozone and Ammonia. Based on absorption spectra obtained from the HITRAN2000 database and processed within the GENSPECT environment, we find the optimal window for simultaneous retrieval of Ozone and Ammonia to be between 1045 (cm-1) and 1047 (cm-1). We further show that for a QCL-based transmitter with 0.1cm-1 spectral resolution and 10mW power and using nitrogen cooled MCT detector (D* ~ 1010 W-1m Hz1/2) in the receiver, it is possible to detect total path ambient concentrations of ozone and ammonia to within 10% accuracy using suitable targets of opportunity such as an building. Details of the optimal frequency sweeping methodology, optical path length, shot averaging, and SNR considerations are considered for comparison of the QCL-based standoff DOAS performance to more conventional open-path FTIR sensors.

Several crops and wildflowers were treated with natural air, filtered air and with different (realistic) ozone concentrations as well. The following parameters were investigated mainly: formation of stress ethylene; changes of cell and tissue structures detectable in light or electron microscope; diffusion resistance of leaves; growth and formation of necroses. The results show species specific differences in the sensitivity against ozone; the results were discussed under the following viewpoints: dose-effect-relation, early identification, standardization, representativeness, and diagnosis of symptoms. With 113 refs., 55 tabs., 72 figs.

This study considers potential impacts of increased use of diesel oxidation catalysts (DOCs) and catalyzed diesel particulate filters (DPFs) on ozone formation in the Dallas/ Fort Worth (DFW) area. There is concern that excess nitrogen dioxide (NO2) emissions from vehicles equipped with these devices could increase ambient ozone levels. The approach involved developing two scenarios for use of these devices, quantifying excess NO2 emissions in each scenario, and using a photochemical model to estimate the resulting ozone changes. In the "maximum penetration" scenario, DOC/DPF devices in a 2009 fleet of heavy-duty on-road trucks, school buses, and construction equipment were significantly increased by accelerating turnover of these vehicles and equipment to models that would require DOCs/DPFs. In the "realistic" scenario, current fractional usage of these devices was assessed for 2009. For both scenarios, excess NO2 emissions from DOCs/DPFs were estimated using U.S. Environmental Protection Agency's MOBILE6 and NONROAD emissions inventory modeling tools. The emissions analyses were used to adjust the DFW photochemical modeling emissions inventories and the Comprehensive Air Quality Model with extensions air quality model was rerun for the DFW area to determine the impact of these two scenarios on ozone formation. The maximum penetration scenario, which showed an overall reduction in oxides of nitrogen (NO(x)) because of the accelerated turnover of equipment to cleaner models, resulted in a net decrease in daily maximum 8-hr ozone of 4-5 parts per billion (ppb) despite the increase in NO2 emissions. The realistic scenario resulted in a small increase in daily maximum 8-hr ozone of less than 1 ppb for the DFW area. It was concluded that the excess NO2 emissions from DOC/DPF devices result in very small ozone impacts, particularly for the realistic scenario, in the DFW area. There are noticeable decreases in ozone for the maximum penetration scenario because NO(x) reductions associated with DOC/DPFs (i.e., accelerated fleet turnover) exert more influence than excess NO2. PMID:20842938

Atmospheric deposition of nitrogen (N) in California ecosystems is ecologically significant and highly variable, ranging from about 1 to 45 kg/ha/year. The lowest ambient concentrations and deposition values are found in the eastern and northern parts of the Sierra Nevada Mountains and the highest in parts of the San Bernardino and San Gabriel Mountains that are most exposed to the Los Angeles air pollution plume. In the Sierra Nevada Mountains, N is deposited mostly in precipitation, although dry deposition may also provide substantial amounts of N. On the western slopes of the Sierra Nevada, the majority of airborne N is in reduced forms as ammonia (NH3) and particulate ammonium (NH4+) from agricultural activities in the California Central Valley. In southern California, most of the N air pollution is in oxidized forms as nitrogen oxides (NOx), nitric acid (HNO3), and particulate nitrate (NO3-) resulting from fossil fuel combustion and subsequent complex photochemical reactions. In southern California, dry deposition of gases and particles provides most (up to 95%) of the atmospheric N to forests and other ecosystems. In the mixed-conifer forest zone, elevated deposition of N may initially benefit growth of vegetation, but chronic effects may be expressed as deterioration of forest health and sustainability. HNO3 vapor alone has a potential for toxic effects causing damage of foliar surfaces of pines and oaks. In addition, dry deposition of predominantly HNO3 has lead to changes in vegetation composition and contamination of ground- and stream water where terrestrial N loading is high. Long-term, complex interactions between N deposition and other environmental stresses such as elevated ozone (O3), drought, insect infestations, fire suppression, or intensive land management practices may affect water quality and sustainability of California forests and other ecosystems. PMID:12805794

Experiments were conducted in an 11 m3 environmental chamber to investigate secondaryparticles resulting from homogeneous reactions between ozone and alpha-pinene. Experimental results indicate that rapid fine particle growth occurs due to homogeneous reactions between ozone and alpha-pinene, and subsequent gas-to-particle partitioning of the products. A new indoor air quality model was used to predict dynamic particle mass concentrations based on detailed homogeneous chemical mechanisms and partitioning of semi-volatile products to particles. Chamber particle mass concentrations were estimated from measured particle size distributions and were in reasonable agreement with results predicted from the model. Both experimental and model results indicate that secondary particle mass concentrations incfrease substantially with lower air exchange rates. This is an interesting results, given a continuing trend toward more energy-efficient buildings. Seconary particle mass concentrations are also predictedc to increase with lower indoor temperatures, higher outdoor ozone concentrations, higher outdoor particle concentrations, and higher indoor alpha-pinene emissions rates.

A low-temperature ozone exposure technique was employed for the post-treatment of WO(x) nanorod thin films fabricated from hot-wire chemical vapor deposition (HWCVD) and ultrasonic spray deposition (USD) techniques. The resulting films were characterized with x-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy, UV-vis-NIR spectroscopy and x-ray photoelectron spectroscopy (XPS). The stoichiometry and surface crystallinity of the WO(x) thin films were subsequently modulated upon ozone exposure and thermal annealing without particle growth. The electrochromic performance was studied in a LiClO(4)-propylene carbonate electrolyte, and the results suggest that the low-temperature ozone exposure technique is superior to the traditional high-temperature thermal annealing (employed to more fully oxidize the WO(x)). The optical modulation at 670 nm was improved from 35% for the as-deposited film to 57% for the film after ozone exposure at 150?°C. The coloration efficiency was improved and the switching speed to the darkened state was significantly accelerated from 18.0 s for the as-deposited film to 11.8 s for the film after the ozone exposure. The process opens an avenue for low-temperature and cost-effective manufacturing of electrochromic films, especially on flexible polymer substrates. PMID:22653083

The chlorofluorocarbons (CFCs) were developed in the early 1920`s as replacements for the toxic refrigerants, like ammonia and sulfur dioxide. The CFCs are quickly released into the atmosphere from refrigerators and air conditioners that leak or during the refilling process, the production of foams, and the release of aerosol propellants. While the CFCs are non-toxic and unreactive in the lower atmosphere, they release chlorine in the upper atmosphere during photolysis and the chlorine reacts catalytically to destroy stratospheric ozone. One chlorine atom can destroy over 100,000 molecules of ozone until it is removed as HC1 from the stratosphere. The discovery of the Antarctic ozone hole in 1985 convinced public policy makers that the threat to the ozone layer was real. The Montreal Protocol for Substances that Destroy Ozone calls for the elimination of most CFCs by the end of the year 2000 and has been signed by over 100 countries. The worldwide reduction in the production by mandated and voluntary means are contributing to a reduction in the atmospheric growth rate of many CFCs. This talk will show this improvement in the atmospheric measurements from 7 stations ranging in latitude from 83{degrees}N to 90{degrees}S in the NOAA/CMDL halocarbon network. Besides mitigation by human activities, the ocean is a sink for some of the halocarbons included in the Montreal Protocol. The importance of this sink for atmospheric halocarbons will also be discussed using data from recent oceanographic expeditions.

This study investigated the impact of elevated ozone concentration ([O3]) on grain yield of rice in relation to the changes in spikelet formation, which plays a critical role in securing a sufficient number of spikelets per land area for a higher yield. Using a free air gas concentration enrichment (FACE) facility for O3 fumigation in China, two contrasting rice cultivars were exposed to either ambient (38ppb) or elevated [O3] (47ppb) from tillering stage to final harvest in 2008. A 23% increase in [O3] decreased grain yield of Yangdao6 and Shanyou63 by 6% and 27%, respectively. The yield loss was driven primarily by a decrease in the number of spikelets per panicle, rather than changes in the other yield components. The large reduction observed in panicle size of Shanyou63 under ozone str...

Abstract Climatology of tropospheric ozone (O3) and water vapour (H2O) over a metro city of Chennai in southern India has been presented based on the Measurements of OZone and water vapour by Airbus In-service AirCraft (MOZAIC) data during 1996-2001. The seasonal trends in mixing ratio of O3 are discussed in view of annual changes in the transport pattern, rainfall, and its relationship with ambient H2O. The vertical distributions of both O3 and H2O show large seasonal variations. The observed high mixing ratios of O3 in winter and spring months can be attributed to long-range transport of pollutants by the northwesterly winds associated with winter monsoon circulation. The lowest mixing ratio of 15 ppbv of O3 from July to September coincides with the summer monsoon circulation over Indian...

Council Directive 96/62/EC/ of 27 September 1996 on ambient air quality assessment and management (the Air Quality Framework Directive) provides a framework for future European Commission legislation on air quality. Annex 1 of the Air Quality Framework Directive lists sulphur dioxide, nitrogen dioxide, particulate matter (including PM){sub 10} and lead as the first priorities for action. The present proposals include limit values including target dates for attainment for these pollutants; fill in the details of requirements for assessment of concentrations, and provide for the dissemination of information about the pollutants to the public. The proposed Directive is only part of an integrated package of measures designed to combat problems of air pollution. Further proposals are now being developed for benzene, carbon monoxide and ozone, together with a strategy for reducing emissions of precursors of ozone. 30 refs.

A new analytical method was developed for the determination of formaldehyde in ambient air based on the use of a modified configuration of the Analyst passive sampler. It consists of a polyethylene cylinder filled with appropriate reactive adsorbent and a special anti-turbulence net which works as an ozone scrubber. The performance of a diffusive sampler depends critically on the selection and use of a suitable adsorbent and on environmental factors, such as temperature, humidity and the interference of oxidant species. In this study two adsorbent types were investigated: 2,4-dinitrophenylhydrazine (2,4-DNPH) coated silica gel and Florisil particles. Interference of ozone was removed by using a silver net upstream as an anti-turbulence device. The performance of this net was then compared ...

BACKGROUND: Hierarchical Bayesian methods have been used in previous papers to estimate national mean effects of air pollutants on daily deaths in time-series analyses. OBJECTIVES: To obtain maximum likelihood estimates of the common national effects of the criteria pollutants on mortality based on time-series data from up to 108 metropolitan areas in the U.S. METHODS: We used a subsampling bootstrap procedure to obtain the maximum likelihood estimates and confidence bounds for common national effects of the criteria pollutants, as measured by the percentage increase in daily mortality associated with a unit increase in daily 24-hour mean pollutant concentration on the previous day, while controlling weather and temporal trends. Five pollutants, PM10, ozone, CO, NO2, and SO2 were considered in single and multi-pollutant analyses. Flexible ambient concentration-response models for the pollutant effects were considered as well. Limited sensitivity analyses with different degrees of freedom for time trends were performed. RESULTS: In single pollutant models, we observed significant associations of daily deaths with all pollutants. The ozone coefficient was highly sensitive to the degree of smoothing of time trends. Among the gases, SO2 and NO2 were most strongly associated with mortality. The flexible ambient concentration-response curve for ozone showed evidence of non-linearity and a threshold at about 30 ppb. CONCLUSIONS: Differences between the results of our analyses and those reported from the Bayesian approach suggest that estimates of the quantitative impact of pollutants are dependent on choice of statistical approach, although results are not directly comparable because they are based on different data. Additionally, the estimate of the ozone-mortality coefficient depends on the amount of smoothing of time trends. PMID:23108284

Depletion of stratospheric ozone increases irradiance of terrestrial ultraviolet (UV) radiation at short wavelengths, which may be harmful to the human health. To understand quantitatively the risks caused by increasing UV radiation to the Finnish population, the actual UV exposure of the population has to be assessed. It was shown that the snow reflection increases the UV exposure to the face and eyes particularly in the northern Finland. In 1993 exceptionally low ozone levels persisted up to the end of May, which resulted in a theoretical increase in the annual UV dose ranging from 8 % to 13 % in Finland. The maximal increase in the measured erythemally effective dose rate was 34 % on 23 April, when compared with the theoretical normal value. During this study exposure models have been developed. The models have been combined them with Green`s radiation transfer model to estimate annual facial UV doses received by different groups of Finnish population. Also, an updated estimate for increase in skin cancer incidence due to the ozone depletion is presented. It is estimated that the maximal increase in UV doses caused by the depletion of the stratospheric ozone will be 12 % in the first years of the next century in Finland. This may result in increase in skin carcinomas by 20-30 % if the people do not improve their protection against solar UV radiation. At the moment the annual facial UV dose of the Finnish indoor worker varies from 3 % to 6 % of the annual ambient dose. In the worst case an outdoor worker may receive even 16% of the annual ambient dose. However, the doses received by indoor workers during vacation to an untanned skin may be more harmful due to the increased risk of malignant melanoma.

Net photosynthesis, dark respiration, and growth of Rumex patientia L. exposed to a ultraviolet irradiance (288-315 nanometers) simulating a 0.18 atm cm stratospheric ozone column were determined. The ultraviolet irradiance corresponding to this 38% ozone decrease from normal was shown to be an effective inhibitor of photosynthesis and leaf growth. The repressive action on photosynthesis accumulated through time whereas leaf growth was retarded only during the initial few days of exposure. Small increases in dark respiration rates occurred but did not continue to increase with longer exposure periods. A reduction in total plant dry weight and leaf area of approximately 50% occurred after 22 days of treatment, whereas chlorophyll concentrations remained unaltered. 29 references, 7 figures, 1 table.

The long-term and diurnal responses of photosystem II (PSII) performance to near-ambient UV-B radiation were investigated in High Arctic Betula nana. We conducted an UV exclusion experiment with five replicated blocks consisting of open control (no filter), photosynthetic active radiation and UV-B transparent filter control (Teflon), UV-B-absorbing filter (Mylar) and UV-AB-absorbing filter (Lexan). Ethylenediurea (EDU), a chemical normally used to protect plants against ozone injury, was sprayed on the leaves both in the field and in an additional laboratory study to investigate if EDU mitigated the effects of UV-B. Chlorophyll-a fluorescence induction curves were used for analysis of OJIP test parameters. Near-ambient UV-B radiation reduced across season maximum quantum yield (TRo /ABS = Fv /Fm ), approximated number of active PSII reaction center (RC/ABS) and the performance index (PIABS ), despite improved leaf screening against UV-B with higher content of UV-B-absorbing compounds and a lower specific leafarea. EDU application counteracted the negative impact of UV-B on TR(o) /ABS, RC/ABS and PI(ABS) . This indicates that the mechanisms behind UV-B and ozone damage share some common features. The midday depression was present in all treatments, but TR(o) /ABS and PI(ABS) were persistently lower in near-ambient UV-B compared to UV-B reduction. The recovery phase was particularly impaired in near-ambient UV-B and interactive effects between treatment × hour raised TRo /ABS, RC/ABS and PIABS higher in reduced UV-B compared to near-ambient UV-B. This demonstrates current solar UV-B to reduce the PSII performance both on a daily as well as a seasonal basis in this High Arctic species.

Maize and grain sorghum were grown for 39 d in sunlit environment-controlled chambers at 360 (ambient) and 720 (double-ambient, high) µmol mol-1 [CO2]. The most enhancement by high [CO2] on canopy photosynthesis (Pg), measured at 1,200 µmol m-2 s-1 solar PPFD, occurred at early plant growth stage, 1...

Growth and physiological response of plants was shown to be an effective tool for O{sub 3}-biomonitoring. - Relative sensitivity of five common Egyptian plant species namely, Senecio vulgaris, Malva parviflora, Sonchus oleraceus, Medicago sativa and Melilotus indicus to elevated levels of ozone has been studied. The plants were exposed to charcoal filtered air (CFA) and different levels of O{sub 3} (50 and 100 ppb) for 5 h per day. The studied parameters were recorded for five consecutive days after fumigation. The foliar injury varied significantly among species in a dose-dependent manner. Severe injury symptoms were recorded on the leaves of M. sativa. With the exception of M. parviflora, all species exhibited significant increases in the percentage reduction of the above-ground dry weight as a result of reductions in both leaf and stem dry weights. M. sativa showed a marked reduction in its relative growth rate at elevated levels of O{sub 3}. The extent of chlorophyll a destruction was higher in both M. sativa and S. oleraceus than in the other species tested. No differences in the sensitivity of chlorophylls a+b and carotenoids to ozone levels were recorded in this work. Percentage reduction of ascorbic acid was higher in M. sativa and S. oleraceus, compared with the other species studied. With respect to relative percentages of proline, there was a significant difference in the responses of plants to ozone. According to the ozone resistance (R%), measured as relative growth rate, the test species were arranged in the descending order: M. parviflora>M. Indicus>S. Vulgaris>S. Oleraceus>M. sativa. In M. sativa, both determinant and correlation coefficients are well reflected in the relationship between its physiological response, its performance and ozone levels, supporting its recommendation as a candidate for biomonitoring in Egypt.

Alfalfa (Medicago sativa) is an extremely important crop in California, ranking below number 1 cotton and number 2 grapes in dollar value. An air pollution effects experiment more nearly approximating 'field conditions' was initiated at the University of California San Joaquin Valley Research and Extension Center near Reedley in the spring of 1979. Ambient ozone concentrations reduced Moapa yields approximately 8 to 13% but had no measureable effect on variety WL-512. Exposure to a SO/sub 2/ concentration of 10 PPHM for six hours four times per week reduced yields by both varieties approximately 9%.

Abstract in english Foliar analysis of biochemical parameters were carried out in order to investigate the influence of air pollutants on two tropical tree species (Licania tomentosa (Benth.) and Bauhinia forfícata (Link.)). Special attention was given to tropospheric ozone due to the fact that concentration levels in the region were found to be up to 140 µg m-3 for a 4 h average time, which is well above the value that can cause injuries to orchides and tobacco (59 µg m-3). Other polluta (more) nts such as nitrogen and sulphur oxides were measured and their ambient concentrations were also associated to biochemical alterations in the investigated species.

Title I of the Clean Air act Amendments of 1990 significantly changed requirements for regulatory agencies to prepare state implementation plans that demonstrate attainment of the ozone National Ambient Air Quality Standards. State agencies now are required to submit plans that show how they will meet the standards by their attainment date. EPA has published a series of guidance documents to assist states in preparing their plans. In addition, the agency is developing software to assist states in projecting emissions and tracking reductions. This article summarizes the guidance documents and software program.

Background: Although ambient air pollution exposure has been linked with poor health in many parts of the world, no previous study has investigated the effect on morbidity in the city of Adelaide, South Australia. Objective: To explore the association between particulate matter (PM) and hospitalisations, including respiratory and cardiovascular admissions in Adelaide, South Australia. Methods: For the study period September 2001 to October 2007, daily counts of all-cause, cardiovascular and respiratory hospital admissions were collected, as well as daily air quality data including concentrations of particulates, ozone and nitrogen dioxide. Visibility codes for present weather conditions identified days when airborne dust or smoke was observed. The associations between PM and hospitalisatio...

A brief description is presented of the air quality, structure of current air pollution programs and future developments in air pollution control in the Republic of Korea. With the rapid increase of industrialization and urbanization during the 1970s, air pollution problems have become a primary social and public health concern. The major pollution sources are: increasing emissions for industrial processes; automobile exhaust emissions; and the combustion of coal briquettes, a domestic fuel which is used in more than 70% of the households. A summary is presented of air pollution measurement methods and ambient standards in Korea. Included are data for sulfur dioxide, carbon monoxide, nitrogen dioxide, total suspended particulates, ozone, and hydrocarbons.

Manufactured nanomaterials have become ubiquitous in science, industry, and medicine. Although electron microscopy and surface probe techniques have improved understanding of the physicochemical properties of nanomaterials, much less is known about what makes nanomaterials toxic. Particulate matter less than 2.5 mum in effective aerodynamic diameter is easily inhaled and taken deep into the lungs. The toxicity of inhaled particulate matter is related to its size and surface chemistry; for instance, the smaller the size of particles, the greater their specific surface area. The chemistry and toxicity of insoluble particles depends on their surface area, since chemical reactions may happen with the environment on the surface. Oxidation and reduction may occur on the surfaces of particles after they are produced. For instance, it is known that carbonaceous particles from vehicle exhaust and industrial emission may interact with reactive species like ozone in their ambient environment, altering the surface chemistry of the particles. Reaction with species in the environment may cause changes in the chemical functionality of the surface and change the toxic properties of the particles when they are inhaled. Furthermore, metals on the surface of inhalable particles can contribute to their toxicity. Much attention has been given to the presence of iron on the surfaces of inhalable particles in the environment. After particle inhalation, particles are endocytosed by alveolar macrophages in the immune response to foreign matter. They are exposed to hydrogen peroxide in the oxidative burst, which can cause the iron-mediated production of hydroxyl free radicals via the Fenton reaction, causing oxidative stress that leads to inflammation and cell death. The toxicity of particles that contain metals depends on the redox activity and bioavailability of the metals, the causes of thich have not yet been adequately explored. In this thesis, electron paramagnetic spectroscopy showed that carbon blacks contain free radical and other surface functionality as manufactured, and that exposure to ozone further functionalizes the surface. Samples of carbon black that have been exposed to ozone react with their ambient environment so that acid anhydride and cyclic ether functionality hydrolyze to form carboxylic acid functionality, observable by transmission Fourier transform infrared spectroscopy. Persistent free radical content, but not free radical content from ozone exposure, may mediate the toxic response of cells to carbon blacks in vitro. Results showed that macrophages exposed to carbon blacks that had been exposed to ozone were not less viable in vitro than macrophages exposed to carbon blacks as manufactured because the free radical content that resulted from ozone exposure was not persistent in an aqueous medium. Furthermore, concurrent exposure to ozonated carbon blacks and ozone was less lethal to macrophages than carbon black exposure alone, possibly because the ozone oxidatively preconditioned the macrophages to resist oxidative stress. The nature of redox-active iron species on the surface of iron-loaded synthetic carbon particles was explored. The particles had been shown in previous studies to provoke an inflammatory response involving the release of tumor necrosis factor (TNF)-alpha, which was correlated with their production of hydroxyl free radicals via the Fenton reaction in the presence of hydrogen peroxide. It was found that the source of bioavailable Fenton-active iron on the surfaces of the particles was fluoride species that were byproducts of a step in the synthetic process. Fluoride ligated the iron already on the surface, forming a complex that resisted precipitation in the biological medium and thus made the iron more bioavailable. The results of this thesis aim to clarify whether the size and surface chemistry of nanoparticles should be considered more closely as criteria with which to develop better environmental controls for occupational health. Permissible exposure limits to micrometer-size particulate matter in

The effects of ambient ozone (O{sub 3}) on plants was discussed. O{sub 3} is the most important phytotoxic air pollutant in North America and elsewhere, causing foliar injury or plant losses. Industrial activity has contributed to the increase in surface O{sub 3} concentrations. Transportation activities in urban centres and fossil fuel combustion in stationary sources have resulted in increases in emissions of oxides of nitrogen and volatile hydrocarbons which are the precursors for O{sub 3}. The atmospheric properties that are conducive for the transfer of O{sub 3} onto plant canopies, and crop properties that promote O{sub 3} uptake (absorbed dose) were discussed based on studies involving above ambient artificial O{sub 3} fumigations in field exposure chambers. Because of the questionable reliability of these results, it was recommended that experiments be performed in chamberless, ambient environments and that multi-point exposure-response models be used in establishing ambient air quality regulations to protect crops. Multi-point exposure-response models would consider the time lag in feedback and the extent of plant stress, repair or compensation that regulate the final crop biomass in response to highly variable ambient O{sub 3} exposures in time and space. 109 refs., 17 tabs., 7 figs.

This study presents an analysis of the relationship between ambient temperature, cod density, fishing mortality, prey fish biomass, and growth of North Sea cod (Gadus morhua) as estimated from survey catches during the period from 1983 to 2006. Growth of young cod was positively related to temperature; however, although temperature increased, distribution of 1-year-olds changed concurrently and no increase in length at age 1 occurred. Growth from age 1 to age 2 decreased as ambient biomass of sandeel and density of cod decreased, whereas growth of cod older than 2 years decreased with increasing density of cod and increased with increasing biomass of demersal fish prey. Though growth of juveniles was strongly positively correlated to ambient temperature, no indication of direct temperature limitation of growth of older North Sea cod was found.

Aims Information about how species respond to extreme environments, such as high UV-B radiation, is very useful in estimating natural ecosystem structure and functions in alpine areas. Our aim is to examine the effect of enhanced UV-B radiation on the fitness of an alpine meadow annual species on Qinghai-Tibet Plateau. Methods Plants of Cerastium glomeratum Thuill. were exposed to ambient (control) or ambient plus supplemental UV-B radiation (enhanced), simulating a 9% ozone depletion over Gannan, China (102degree53primeE, 34degree55primeN, 2900 m in altitude), up to leaf senescence and fruit maturation. Plant height, flower phenology, biomass allocation and reproductive parameters of the species were measured. Important findings Plant height in C. glomeratum was reduced by enhanced UV-B r...

Impacts of elevated ground-level ozone (O3) on nitrogen (N) uptake and allocation were studied on mature European beech (Fagus sylvatica L.) and Norway spruce (Picea abies [L.] Karst.) in a forest stand, hypothesizing that: (i) chronically elevated O3 limits nutrient uptake, and (ii) beech responds more sensitively to elevated O3 than spruce, as previously found for juvenile trees. Tree canopies were exposed to twice-ambient O3 concentrations (2 x O3) by a free-air fumigation system, with trees under ambient O3 serving as control. After 5 years of O3 fumigation, 15NH415NO3 was applied to soil, and concentrations of newly acquired N (Nlabelled) and total N (Ntotal) in plant compartments and soil measured. Under 2 x O3, Nlabelled and Ntotal were increased in the bulk soil and tended to be lo...

The effects of a continuing rise of ambient ozone on crop yield will seriously threaten food security in China. In the Yangtze River Delta, a rapidly developing and seriously air polluted region in China, innovative open-top chambers have been established to fumigate winter wheat and rice in situ with elevated O(3). Five years of study have shown that the yields of wheat and rice decreased with increasing O(3) concentration. There were significant relationships between the relative yield and AOT40 (accumulated hourly O(3) concentration over 40 ppb) for both winter wheat and rice. Winter wheat was more sensitive to O(3) than rice. O(3)-induced yield declines were attributed primarily to 1000-grain weight and harvest index for winter wheat, and attributed primarily to grain number per panicle and harvest index for rice. Control of ambient O(3) pollution and breeding of O(3) tolerant crops are urgent to guarantee food security in China. PMID:22892574

‘Food security’ has always been a prime issue for the development and progress of human civilization. However, in spite of all technological, scientific, and agricultural achievements the secure and affordable supply of safe and nutritious food to the population is still in an alarming state. In the year 2007 alone, the number of hungry people increased by 75 million and expected to reach to 1.2 billion worldwide by 2017. Among the various reasons responsible for rising food crisis, ‘global environmental change’ can be considered as one of the most critical factors today. Among the environmental factors, increasing tropospheric or surface level ozone (O3) levels has been recognized as a major cause for declining plant growth and crop yield. According to the IPCC (2007) report, concentration of tropospheric O3 is estimated to have increased from approximately 10 ppb prior in the industrial revolution to a current level of about 60 ppb during summer months, and is predicted to increase 20-40% more by 2050 in the industrialized countries of the Northern Hemisphere. Like other tropical countries, India is also under the severe threat of O3 pollution.The present review mainly focuses on the responses of rice (Oryza sativa L. cultivars - Malviya dhan 36 and Shivani) and wheat (Triticum aestivum L. cultivars - Sonalika and HUW 510) plants to elevated levels of O3-stress at Indian context through a combination of physiology and high-throughput proteomics analyses using open top chambers (OTCs). Experimental sets were prepared as: filtered chambers (FCs) with almost negligible O3, non-filtered chambers (NFCs) with ambient O3, non-filtered chambers with 10 ppb O3 fumigation (NFCLOs), and non-filtered chambers with 20 ppb O3 fumigation (NFCHOs). Notably, O3 causes significant induction in major cellular antioxidants, and negatively affects photosynthetic machinery in both rice and wheat plants. Proteomics analysis revealed that O3 strongly inhibits the expression of major photosynthetic and important energy metabolism proteins, and induced the defense or stress related proteins. Proteomics, writing simply, refers to the study of all the proteins in a cell, tissue or organism, and is part of three young, high-throughput ‘omics’ technologies of genomics (transcriptomics), proteomics, and metabolomics. Random Amplified Polymorphic DNA (RAPD) analysis also revealed significant damage in genome template stability of both the crops under O3 stress, hence indicating toward the mutagenic ability of O3.We believe that present results are a small but necessary step forward in developing O3-tolerant rice and wheat genotypes, which can be utilized in the future high O3 world for their optimum growth and yield.   

Two types of white exterior household paints - latex and oil base - were exposed for periods of up to 30 months at nine air monitoring sites in the St. Louis, Missouri area. Climatic and air quality data were recorded during the exposure period and were subjected to a rigorous evaluation to eliminate recording errors and to estimate missing values. Deterioration of the paints was measured during the exposure period by determining the rate of surface erosion. The latex paint had the highest erosion rate. Erosion rates of both paints were higher for southern exposures than for northern exposures indicating an effect of sunlight. The rate data were evaluated with respect to the possible effects of time-of-wetness, wind speed, temperature, and levels of total gaseous sulfur compounds, total gaseous oxides of nitrogen, and oxidants. Regression analysis indicated that of the ambient gaseous pollutants only oxides of nitrogen correlated significantly with erosion of the latex paint. The erosion of both paint films strongly correlated with the time of surface wetness. A possible effect of ozone on the latex paint was masked by strong covariances between ozone and temperature and between ozone and oxides of nitrogen.

It is well known that ozone and mercury depletion events occur in the Arctic during spring, around the time of polar sunrise. It has been suggested that halogen atoms, in particular bromine, play an important role in the onset of these depletion events, during which chlorine chemistry is also occurring. A variety of carbonyl compounds are produced when chlorine atoms react with VOCs, and destruction of aldehydes is seen as a result of bromine atom chemistry. Thus, these two halogen atoms impact the distribution of carbonyl compounds, and the ketone/aldehyde ratio is sensitive to the levels of chlorine and bromine that are present. During a field study in Barrow, Alaska, January - March of 2005, a variety of alkanes, ketones and aldehydes were measured using a preconcentrating autosampler-gas chromatograph-mass spectrometer from an inland site, and via Tenax-based sampling and GC-FID analysis in the vicinity of the Barrow lead. Additionally, ambient samples were collected in canisters and analyzed off-site, and the results from those canisters were used to evaluate the data collected with the instruments mentioned above. Here we discuss what can be learned about the sources and reactions of these compounds by examining the relationships between these species and ozone during a time period ranging from pre-polar sunrise, when ozone is not depleted, to post-polar sunrise, when substantial surface halogen chemistry is occurring.

The purpose of this project was to investigate the relationship of ambient air quality measurements between two analytical methods, referred to as the total oxidant method and the chemiluminescent method. These two well documented analytical methods were run simultaneously, side by side, at a site on the Houston ship channel. They were calibrated daily. The hourly averages were analyzed by regression techniques and the confidence intervals were calculated for the regression lines. Confidence intervals for point estimates were also calculated. These methods were used with all data sets with values greater than 10 parts per billion and again with values greater than 30 parts per billion. A regression line was also calculated for a second set of data for the preceding year. These data were generated before a chromium trioxide scrubber was installed to eliminate possible chemical interferences with the Kl method. The results show that in general the chemiluminescent ozone method tends to produce values as much as two times higher than the simultaneous total oxidant values. In one set of data collected an 80 ppb chemiluminescent ozone value predicted a value of 43.9 ppb total oxidant with a 95 percent confidence interval of 7.7 to 80.4 ppb. In the second set of data an 80 ppb chemiluminescent ozone value predicted a value of 78 ppb total oxidant with a 95 percent confidence interval of 0.4 to 156 ppb. Other statistical analyses confirmed that either measurement was a very poor predictor of the other.

To characterize the response of respiratory bronchioles (RBs) to chronic high ambient levels of ozone, bonnet monkeys were exposed for 90 days to 0, 0.4, or 0.64 ppm ozone (UV photometric standard; 3 monkeys/exposure). Morphologic changes in respiratory bronchiolar epithelium and interstitium were evaluated quantitatively at both the light and transmission electron microscopic levels. Significant changes in respiratory bronchioles following exposure included: a thicker wall and a narrower lumen, a thicker epithelial compartment and a much thicker interstitial compartment, shifts in epithelial cell populations with many more nonciliated bronchiolar epithelial cells and fewer squamous type I epithelial cells, larger nonciliated bronchiolar epithelial cells with a larger complement of cellular organelles associated with protein synthesis, greater amounts of both interstitial fibers and amorphous ground substance, greater numbers of interstitial smooth muscle cells per epithelial basal lamina surface area, and greater volumes of interstitial smooth muscle, macrophages, mast cells, and neutrophils per epithelial basal lamina surface area. These observations imply that chronic ozone exposure causes a concentration-dependent reactive peribronchiolar inflammatory response and an adaptive response consisting of hypertrophy and hyperplasia of the nonciliated bronchiolar cell.

Atmospheric new particle formation is a general phenomenon observed over coniferous forests. So far nucleation is either parameterised as a function of gaseous sulphuric acid concentration only, which is unable to explain the observed seasonality of nucleation events at different measurement sites, or as a function of sulphuric acid and organic molecules. Here we introduce different nucleation parameters based on the interaction of sulphuric acid and terpene oxidation products and elucidate the individual importance. They include basic trace gas and meteorological measurements such as ozone and water vapour concentrations, temperature (for terpene emission) and UV B radiation as a proxy for OH radical formation. We apply these new parameters to field studies conducted at conducted at Finnish and German measurement sites and compare these to nucleation observations on a daily and annual scale. General agreement was found, although the specific compounds responsible for the nucleation process remain speculative. This can be interpreted as follows: During cooler seasons the emission of biogenic terpenes and the OH availability limits the new particle formation while towards warmer seasons the ratio of ozone and water vapour concentration seems to dominate the general behaviour. Therefore, organics seem to support ambient nucleation besides sulphuric acid or an OH-related compound. Using these nucleation parameters to extrapolate the current conditions to prognosed future concentrations of ozone, water vapour and organic concentrations leads to a significant potential increase in the nucleation event number.

Mature vineyard-growing Concord grapevines (Vitis labrusca, Bailey) were sprayed with simulated acid rain solutions ranging from pH 2.5 to pH 5.5 both as acute treatments at anthesis and chronically throughout the season in 1980 and 1981. In 1981, eight additional varieties were also treated with simulated acid rain solutions at pH 2.75 and pH 3.25. With Concord in 1981, few foliar lesions on leaves were visible at pH 2.75. In contrast, many leaf lesions with decreased fruit soluble solids in the absence of acid rain leaf lesions at pH>2.5 remains unclear. Acute sprays (pH 2.75) at anthesis reduced pollen germination in four grape cultivars. However, fruit set was reduced in only one of these. Only the cultivars de Chaunac and Ives had reduced berry soluble solids with chronic weekly sprays at pH 2.75. Reduction in soluble solids was not associated with increased oxidant stipple (ozone injury) in Concord and de Chaunac cultivars, but this association was observed in Ives. There was no evidence that acid rain in combination with ozone increased oxidant stipple as occurs when ozone and SO/sub 2/ are combined. Grape yields were not influenced by acid rain treatments. There was no evidence that acid rain at ambient pH levels had negative effects on grape production or fruit quality.

The removal of fenitrothion (FT) pesticide residues from vegetables by immersion in ozone-microbubbled solution was demonstrated. FT-treated lettuce, cherry tomatoes, and strawberries were immersed in ozone-microbubbled, ozone-millibubbled, and dechlorinated water. After that the percentage of residual FT in the vegetables was determined. Residual FT was efficiently removed from lettuce by immersing it in ozone-microbubbled solution containing more than 1.0ppm dissolved ozone, or continuously generated ozone-microbubbled solution containing 2.0ppm dissolved ozone. Similarly, for cherry tomatoes and strawberries, the continuously generated ozone-microbubbled solution containing 2.0ppm dissolved ozone was highly effective. These results showed that ozone microbubbles effectively removed resi...

This study used a humidification system that adds dry steam to open-top field chambers to determine how relative-humidity affects plant responses to air pollutants in the field. There was a definite interaction between humidity and air pollution on leaf injury, with increasing humidity greatly increasing the amount of visible leaf necrosis and senescence from ozone. However, the injury interaction was not associated with any general interaction in terms of crop yield. Ozone caused visible injury to tomatoes, almonds, beans, and melons; reduced yield, growth, and biomass production for tomatoes and beans; and reduced physiological processes for tomatoes, beans, and almonds. Sulfur dioxide reduced growth and biomass production in wheat and lettuce, and yield for wheat. Humidification increased biomass production for tomatoes, carrots, onions, and beans, yield for carrots, onions, and lettuce, but decreased yields in beans.

This guide is intended to instruct Forest Health Monitors when collecting data on forest health indicators; site condition, growth and regeneration, crown condition, tree damage and mortality assessment, photosynthetically active radiation, vegetation structure, ozone bioindicator species, lichen community structure and field logistics. This guide contains information on measuring, observing and recording data related to the above listed forest health indicators. Pertinent quality assurance information is also included.

Forests of the central and southern Sierra Nevada in California have been subjected to chronic damage by ozone and other atmospheric pollutants for the past several decades. Until recently, pollutant exposure of northern Sierra Nevada forests has been mild but increasing population and changes in land use throughout the Sacramento Valley and Sierra Nevada foothills may lead to increased pollutant damage in these forests. Although, better documented in other regions of the United States, little is known regarding the potential for acidic precipitation damage to Sierra Nevada forests. Only recently have studies directed towards understanding the potential interactive effects of ozone and acidic precipitation been undertaken. A key issue in resolving potential regional impacts of pollutants on forests is the extent to which research results can be scaled across genotypes and life-stages. Most of the pollution research to date has been performed using seedlings with varying degrees of genetic control. It is important to determine if the results obtained in such studies can be extrapolated to mature trees and to different genetic sources. In this paper, we present results from a one-year study examining the interactive effects of foliar exposure to acidic rain and ozone on the growth of ponderosa pine (Pinus ponderosa), a conifer known to be sensitive to ozone. The response to pollutants is characterized for both seedlings and mature tree branches of three genotypes grown in a common environment.

Comparative growth rates of largemouth bass (Micropterus salmoides) from heated and ambient areas of Coffeen Lake, Illinois, were estimated by back calculation of lengths at annuli using transverse sections of otoliths and by recovery of marked fish after one growing season. Calculated lengths at otolith annuli were judged to be representative of the population growth, indicating that this technique was a reliable approach to obtaining growth information on largemouth bass from thermally affected environments. Growth of the Coffeen Lake population was more rapid than most other midwest populations. Fish recaptured in heated areas generally exhibited greater annual growth increments than those recaptured in ambient areas. Young largemouth bass (ages 1-4) from heated areas had significantly greater (P < 0.05) mean lengths than those from ambient areas according to back-calculated estimates. This was attributed to a longer growing season and earlier hatching time in thermally affected areas. 33 references, 6 figures, 3 tables.

We have conducted seasonal ambient and emission measurements of a series of biogenic VOCs such as monoterpenes (MT), sesquiterpenes (SQT), isoprene, methanol, methyl chavicol and acetaldehyde. Therefore a plant enclosure technique was applied in order to investigate a Central European spruce forest and its emissions responses to meteorological and environmental parameters. A healthy ?15m tall Norway spruce tree was selected and a vegetation enclosure technique was applied from April to November 2011. VOCs are measured by PTR-MS, while samples have also been analyzed with GC-MS (Gas Chromatography - Mass Spectrometry) techniques for intercomparison and identification of individual VOCs. E/N ratio was adjusted at 117Td[2] and the primary ion signal (H3O+) was continuously above 4×10^7cps, implying a high sensitivity to our measurements. Temperature, relative humidity, ozone, photosynthetic active radiation (PAR) and CO2 concentrations were continuously measured inside the plant cuvette. Meteorological and environmental parameters (radiation, atmospheric pressure, wind velocity, wind direction, temperature, O3, relative humidity, soil moisture, precipitation, global radiation, H2O, NO, NO2) were measured by HLUG (Hessian Agency for Environment and Geology) and DWD (German Weather Service), 50 meters away from the measuring site. In a peculiar season, which was characterized by a warm spring (temperature anomaly >40C), a wet summer (precipitation anomaly 126-150%) and an extremely dry autumn (precipitation anomaly light is also influencing MT emissions. On the contrary, SQT emissions showed similar temperature dependency for both day and night measurements. The beta factor showed a different behavior during the seasons for different compounds implying different driving forces and storage inside the tree. Especially for SQT, there are indications that a storage pool that is getting empty while moving towards winter. Interestingly, it has been found that SQT emissions are not only correlated with ambient temperature but also with high ambient ozone levels. In a wide range of meteorological conditions and ozone concentrations, we found different emission behavior when ozone values are exceeding a critical threshold. [1] Goldstein, A. H. and Galbally, I. E.: Known and unexplored organic constituents in the earth's atmosphere, Environ. Sci. Technol., 41, 1514-1521, 2007. [2] Kim, S., Karl, T., Helmig, D., Daly, R., Rassmusen, R. and Guether, A. : Measurement of atmospheric sesquiterpenes by proton transfer reaction-mass spectrometry (PTR-MS), Atmos. Meas. Tech., 2, 99-112, 2009. [3] Guenther, A.B., Zimmerman, P.R., Harley, P.C., Monson, R.K., Fall, R., 1993. Isoprene and monoterpene emission rate variability: model evaluations and sensitivity analyses, Journal of Geophysical Research., 98, 12609-12617, 1993.

The Community Multiscale Air Quality (CMAQ) and the Sparse Matrix Operator Kernel Emissions (SMOKE) modeling systems were used to simulate emissions and air quality in North Eastern Alberta where a rapid rise in oil sands development has caused air quality concerns over the last decade. The models were run on a 36/12/4 km domain for the four month period of May through August 2002. A model performance evaluation was conducted by comparing the CMAQ model estimates against ambient air quality measurements. In the Alberta oil sands region, the model tended to achieve or nearly achieve ozone model performance goals, albeit with an underestimation bias. The magnitudes of the observed PM2.5 concentrations were matched by the modeling system, except when the observed PM2.5 concentrations were influenced by emissions from forest fires in which case the model underestimated the observed PM2.5 concentrations. The CMAQ-estimated 4th highest daily maximum 8-hour ozone concentrations in the oil sands region were below the 65 ppb Canada Wide Standard (CWS) as well as the 58 ppb Alberta Management Plan Trigger Level. The highest estimated ozone concentrations occurred near the oil sands development area just north of Fort McMurray with values approaching, but below, the 58 ppb Management Plan Trigger Level; estimated ozone concentrations are much lower in the farther northern portions of the oil sands region. The acute (i.e., maximum 3-day value) SUM60 vegetative ozone exposure metric was mostly less than 100 ppb h, which is below the threshold of concern for crops. However, just north of Fort McMurray there were small areas where the acute SUM60 metric exceeded the 500-700 ppb h threshold of concern for crops with maximum values in plumes from sources in the oil sands mine area of ˜900 ppb h. The maximum chronic (three-month average) SUM60 ozone exposure metric was below the thresholds of concern. The CMAQ-estimated maximum 98th percentile 24-hour average PM2.5 concentration occurs in the mine area north of Fort McMurray and was below the CWS threshold (30 ?g m-3), however it was above the Alberta Management Plan Trigger Level (20 ?g m-3). The estimated 98th percentile 24- hour average PM2.5 concentrations were mostly in the 2-6 ?g m-3 range with regions of higher PM2.5 concentrations predicted just north of Fort McMurray in the oil sands development region.

Air quality impacts of volatile organic compound (VOC) and nitrogen oxide (NO(x)) emissions from major sources over the northwestern United States are simulated. The comprehensive nested modeling system comprises three models: Community Multiscale Air Quality (CMAQ), Weather Research and Forecasting (WRF), and Sparse Matrix Operator Kernel Emissions (SMOKE). In addition, the decoupled direct method in three dimensions (DDM-3D) is used to determine the sensitivities of pollutant concentrations to changes in precursor emissions during a severe smog episode in July of 2006. The average simulated 8-hr daily maximum O3 concentration is 48.9 ppb, with 1-hr O3 maxima up to 106 ppb (40 km southeast of Seattle). The average simulated PM2.5 (particulate matter with an aerodynamic diameter impact of decreased VOC emissions from biogenic, mobile, nonroad, and area sources on average 8-hr daily maximum O3 concentrations is up to 0.05 ppb decrease per % of emission change, each. Decreased emissions of VOCs decrease average PM2.5 concentrations in the entire modeling domain. In major cities, PM2.5 concentrations are more sensitive to emissions of VOCs from biogenic sources than other sources of VOCs. These results can be used to interpret the effectiveness of VOC or NO(x) controls over pollutant concentrations, especially for localities that may exceed National Ambient Air Quality Standards (NAAQS). Implications: The effect of NO(x) and VOC controls on ozone and PM2.5 concentrations in the northwestern United States is examined using the decoupled direct method in three dimensions (DDM-3D) in a state-of-the-art three-dimensional chemical transport model (CMAQ). NO(x) controls are predicted to increase PM2.5 and ozone in major urban areas and decrease ozone in more remote and forested areas. VOC reductions are helpful in reducing ozone and PM2.5 concentrations in urban areas. Biogenic VOC sources have the largest impact on O3 and PM2.5 concentrations. PMID:23155861

Nitrogen oxides (NO and NO2, collectively NOx) are critical intermediates in atmospheric chemistry. NOx abundance controls the levels of the primary atmospheric oxidants OH, NO3 and O3, and regulates the ozone production which results from the degradation of volatile organic compounds. NOx are also atmospheric pollutants in their own right, and NO2 is commonly included in air quality objectives and regulations. In addition to their role in controlling ozone formation, NOx levels affect the production of other pollutants such as the lachrymator PAN, and the nitrate component of secondary aerosol particles. Consequently, accurate measurement of nitrogen oxides in the atmosphere is of major importance for understanding our atmosphere. The most widely employed approach for the measurement of NOx is chemiluminescent detection of NO2* from the NO + O3 reaction, combined with NO2 reduction by either a heated catalyst or photoconvertor. The reaction between alkenes and ozone is also chemiluminescent; therefore alkenes may contribute to the measured NOx signal, depending upon the instrumental background subtraction cycle employed. This interference has been noted previously, and indeed the effect has been used to measure both alkenes and ozone in the atmosphere. Here we report the results of a systematic investigation of the response of a selection of NOx analysers, ranging from systems used for routine air quality monitoring to atmospheric research instrumentation, to a series of alkenes ranging from ethene to the biogenic monoterpenes, as a function of conditions (co-reactants, humidity). Experiments were performed in the European Photoreactor (EUPHORE) to ensure common calibration, a common sample for the monitors, and to unequivocally confirm the alkene (via FTIR) and NO2 (via DOAS) levels present. The instrument responses ranged from negligible levels up to 10 % depending upon the alkene present and conditions used. Such interferences may be of substantial importance for the interpretation of ambient NOx data, particularly for high-VOC, low-NOx environments such as remote forests.

Abstract in portuguese Plântulas de feijão das cultivares Fepagro 26, Guapo Brilhante, Iraí, Macotaço e US pinto 111 foram submetidas aos tratamentos com e sem adição de ozônio ao ar ambiente, com o objetivo de avaliar os efeitos da exposição sobre a fotossíntese, permeabilidade relativa a eletrólitos, abscisão foliar e biomassa das plântulas. A exposição ao ozônio causou decréscimos significativos na assimilação líquida de todas as cultivares, exceto na Iraí. Causou també (more) m um aumento significativo na permeabilidade relativa a eletrólitos da cultivar Pinto, mas apenas quando a AOT40 foi a mais elevada. Além disso, produziu uma antecipação significativa no tempo de abscisão foliar nas cultivares Pinto, Fepagro e Guapo. A variabilidade observada nas medidas de biomassa total, refletiu as limitações para se executar estudos de longo prazo em condições ambientais controladas, um dos principais desafios ainda por ser superado antes que se possa obter dados mais conclusivos sobre os danos em espécies cultivadas resultantes do enriquecimento do ozônio toposférico. Abstract in english Bean seedlings of Fepagro 26, Guapo Brilhante, Iraí, Macotaço and US Pinto 111 cultivars were submitted to treatments with or without addition of ozone to the ambient air, in order to evaluate the effects of exposure on photosynthesis, relative electrolyte leakage, foliar abscission and biomass of the seedlings. Exposure to ozone caused significant decreases in the net assimilation of all cultivars except Iraí. It also caused a significant increase in electrolyte leaka (more) ge from the Pinto cultivar, but only when AOT40 was the highest. It also produced significant anticipation in the time of foliar abscission in the Pinto, Fepagro and Guapo cultivars. The variability observed in the biomass measurements reflected the limitations to perform long-term controlled-environment studies, one of the major challengers yet to be overcome in order to obtain more conclusive data on damages induced on crop species resulting from tropospheric ozone enrichment.

Both Syncrude and Suncor have plans to develop new oil sands leases and to increase crude oil and bitumen recovery in the Athabasca oil sands region. In recognition of the effects that this will have on the environment, Suncor has proposed modifications to reduce SO{sub 2} emissions to the atmosphere, while Syncrude plans to develop additional ambient air quality, sulphur deposition and biomonitoring programs. This report discussed the ambient air quality monitoring that was undertaken in the Fort McMurray-Fort McKay airshed. Twelve continuous ambient air quality stations and 76 passive monitoring stations are maintained in the region. Environment Canada maintains eight precipitation monitoring stations in northern Alberta and Saskatchewan. Source characterization, ambient air quality and meteorology observations, air quality monitoring, and air quality data from continuous sulphur dioxide, hydrogen sulphide, nitrogen oxides, ozone, carbon monoxide, hydrocarbon, acid rain and particulates analyzers were reviewed. The documentation of all computer files used for the analysis of the air quality data is discussed in the Appendix. 47 refs., 39 tabs., 53 figs.

Pumpkin [Cucurbita pepo (L.) cv. Ambassador] plants were grown under either nonfiltered or filtered ambient air in open-top field chambers (OTCs) near the urban area of Milan, Northern Italy. The effects of ambient air pollution on the enzymatic detoxfication system of the leaves, both in terms of activity and isoform pattern were investigated. The data on air quality showed that ozone was the main phytotoxic pollutant present in ambient air, reaching a 7 h mean of 63 nL L{sup -1} and a maximum hourly peak of 104 nL L{sup -1} The peroxidase and catalase activities increased fourfold and twofold, respectively in the nonfiltered air plants In comparison to the filtered air ones. The peroxidase patterns were very modified in the polluted plants. In contrast no significant changes were found in the activity and isoenzyme pattern of superoxide dismutase. The data reported here suggest that in field-grown pumpkin plants exposed to ambient levels of photooxidants, a stimulation of the peroxddase-catalase detoxification system takes place. 32 refs., 3 figs., 3 tabs.

The effects of climate change (for 2050 compared to ambient climate) and change in climatic variability on soya bean growth and production at 3 sites in the EU have been calculated. These calculations have been done with both a simple growth model, SOYBEANW, and a comprehensive model, CROPGRO. Compa...

The effect of electrode rotation on the ozone generation process is presented. An ozonizer with an electrode rotating system might be one possible way to increase ozone-synthesis efficiency. The research presented shows that with electrode rotation the ozone-generation efficiency increases by about 15% compared to an ozonizer with a non-rotating electrode; discharge also becomes more homogenous.   

Ubiquitin-dependent proteolysis regulates multiple aspects of plant growth and development, but little is known about its role in ambient temperature-responsive flowering. In addition to being regulated by daylength, the onset of flowering in many plants can also be delayed by low ambient temperatures. Here, we show that HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 1 (HOS1), which encodes an E3 ubiquitin ligase, controls flowering time in response to ambient temperatures (16 and 23degreeC) and intermittent cold. hos1 mutants flowered early, and were insensitive to ambient temperature, but responded normally to vernalization and gibberellic acid. Genetic analyses suggested that this ambient temperature-insensitive flowering was independent of FLOWERING LOCUS C (FLC). Also, FLOWERING LOCU...

Spruce trees (Picea abies) kept in open-top chambers with charcoal-filtered and non-filtered air (sample size n=4) at the Edelmannshof site from 1987-1992 were studied to evaluate the impact of ambient air pollution on needle metabolism. Seasonal and diurnal variations in N-metabolism (soluble amino acids, protein, glutamine synthetase and glutamate dehydrogenase) and antioxidants (ascorbate, glutathione and different perioxidases) were investigated in the young needles till the end of the second vegetation period. Additionally, {delta} {sup 13}C-values were measured in needle samples from the Edelmannshof site and in needles of Pinus taeda exposed to different ozone concentrations in the Duke Forest, NC. There was an increase of the {delta}{sup 13}C-values in loblolly pine needles if ozone level increased. However, at the Edelmannshof site only a great variation between the trees could be found but no treatment effect. Based on all the data from 1988-1992 the typical seasonal curves of the different physiological parameters of the three groups (charcoal-filtered, non-filtered, ambient) were determined. There was no definite difference between the trees kept in chambers with charcoal-filtered and non-filtered air, but significant chamber effects on ascorbate and glutathione content. Moreover, great variations were found between the trees and the four years of exposure. Therefore physiological data were compared with the available values of the respective environmental conditions from 1989 till 1991 by regression analysis. It was found that components of the nitrogen metabolism and ascorbate content depended on the water supply and increased under water stress conditions. For soluble protein content r{sup 2} amounted to 0.62 indicating that water supply is a main factor influencing needle metabolism. It is concluded that the trees at the Delmannshof site are more affected by other environmental factors than by ambient air pollution. (orig.)

The Antarctic ozone hole and a general depletion of the stratospheric ozone layer cause increased levels of ultraviolet-B solar radiation (UV-B) over Tierra del Fuego, the southernmost tip of South America. For three consecutive growing seasons (1997-2000), we studied the biological impacts (morphology, physiology, demography and phenology) of natural UV-B radiation on a perennial Salicornia ambigua Michx. community in San Sebastian Bay (53 degrees S and 68 degrees W), Tierra del Fuego, Argentina. This is the first UV-B screening experiment on a subantarctic halophytic community. The shortwave UV-B spectrum (280 to 320 nm) was excluded by covering plots with UV-B blocking film (Mylar). These plots were compared to controls covered with UV-B transparent (Aclar) plastic screens, and unscreened plots. Shoot length in Salicornia was not affected by UV-B. Exposure to natural UV-B reduced biomass and density (by 17% and 38%, respectively). Concentration of UV-shielding pigments and cuticle thickness were both significantly higher (25-48% and 21-40%, respectively) in plants receiving ambient UV-B. The increase in cuticle thickness persisted throughout the growing season, whereas pigment concentration was higher at the beginning of the growing season. Also, the number of dead shoots was higher in plants exposed to UV-B. At the end of the growing season (March) shoot mortality was higher in plants exposed to ambient UV-B, and post-flowering senescence was 30 days earlier. Slight changes in the relative composition of Salicornia to Puccinellia were seen. The reduction observed in Salicornia shoot density under ambient UV-B was cumulative over time; 23% in the first growing-season, rising to 38% by the third growing-season. A similar incremental increase in pigment absorption at 305 nm was seen; 25% in the first and 48% in the third growing season. PMID:12962642

We analyzed secondary organic aerosol (SOA) data from a series of small-chamber experiments in which terpene-rich vapors from household products were combined with ozone under conditions analogous to product use indoors. Reagents were introduced into a continuously ventilated 198 L chamber at steady rates. Consistently, at the time of ozone introduction, nucleation occurred exhibiting behavior similar to atmospheric events. The initial nucleation burst and growth was followed by a period in which approximately stable particle levels were established reflecting a balance between new particle formation, condensational growth, and removal by ventilation. Airborne particles were measured with a scanning mobility particle sizer (SMPS, 10 to 400 nm) in every experiment and with an optical particle counter (OPC, 0.1 to 2.0 ?m) in a subset. Parameters for a three-mode lognormal fit to the size distribution at steady state were determined for each experiment. Increasing the supply ozone level increased the steady-state mass concentration and yield of SOA from each product tested. Decreasing the air-exchange rate increased the yield. The steady-state fine-particle mass concentration (PM1.1) ranged from 10 to> 300 mu g m-3 and yields ranged from 5percent to 37percent. Steady-state nucleation rates and SOA mass formation rates were on the order of 10 cm-3 s-1 and 10 mu g m-3 min-1, respectively.

Experiments were conducted to identify the emissions from the car air freshener and to identify the formation of ultra-fine particles and secondary gaseous compounds during the ozone-initiated oxidations with emitted volatile organic compounds (VOCs). The identified primary constituents emitted from the car air freshener in this study were a-pinene, b-pinene, p-cymene, and limonene. Formation of ultra-fine particles (4.4-160nm) was observed when ozone was injected into the chamber containing emitted monoterpenes from the air freshener. Particle number concentrations, particle mass concentrations, and surface concentrations were measured in time dependent experiments to describe the particle formation and growth within the chamber. The irritating secondary gaseous products formed during the...

In this study various two-stage processes were investigated for biological hydrogen production from olive mill wastewater (OMW) by Rhodobacter sphaeroides O.U.001. Two-stage processes consist of physicochemical pretreatment of OMW followed by photofermentation for hydrogen production. Explored pretreatment methods were chemical oxidation with ozone and Fenton's reagent, photodegradation by UV radiation, and adsorption with clay or zeolite. Among these different two-stage processes, strong chemical oxidants like ozone and Fenton's reagent have the highest color removal (90%). However, their effluents were observed to be unsuitable for both hydrogen production and bacterial growth. On the other hand, clay treatment method was selected as the optimum process that allows fast and low-cost trea...

MicroRNA398 targets two Cu/Zn superoxide dismutases (CSD1 and CSD2) in higher plants. Previous investigations revealed both decreased miR398 expression during high Cu2+ or paraquat stress and increased expression under low Cu2+ or high sucrose in the growth medium. Here, we show that additional abiotic stresses such as ozone and salinity also affect miR398 levels. Ozone fumigation decreased miR398 levels that were gradually restored to normal levels after relieved from the stress. Furthermore, miR398 levels decreased in Arabidopsis leaves infiltrated with avirulent strains of Pseudomonas syringae pv. tomato, Pst DC3000 (avrRpm1 or avrRpt2) but not the virulent strain Pst DC3000. To our knowledge, miR398 is the first miRNA shown to be down-regulated in response to biotic stress (P. syringae...

A novel approach to the large-scale and fast production of free-standing nanowires and microwires under ambient conditions is reported. The method is based on the interaction of a high power laser beam with a commercial ceramic substrate under a high-pressure gas jet under ambient conditions. Large quantities of amorphous Si-Al oxide nanowires were produced and characterized. An explanation for the growth of the nanowires based in the vapor-liquid-solid (VLS) mechanism is proposed. (orig.)