WorldWideScience

Sample records for surface ozone levels

  1. Estimation of surface UV levels based on Meteor-3/TOMS ozone data

    Energy Technology Data Exchange (ETDEWEB)

    Borisov, Y.A. [Central Aerological Observatory, Moscow (Russian Federation); Geogdzhaev, I.V. [Moscow Inst. of Physics and Technology, Moscow (Russian Federation); Khattatov, V.U. [Central Aerological Observatory, Moscow (Russian Federation)

    1995-12-31

    The major consequence of ozone layer depletion for the environment is an increase of harmful ultraviolet (UV) radiation on the Earth surface and in the upper ocean. This implies the importance of environmental UV monitoring. Since the direct global monitoring is not currently possible, indirect estimations of surface UV levels may be used based on satellite ozone data (Madronich, S. 1992). Total Ozone Mapping Spectrometer (TOMS) on board the METEOR-3 satellite provided regular set of data for such estimates. During the time of its operation (August, 1991 - December, 1994) the instrument registered several ozone hole events over Antarctica, when ozone levels dropped by as much as 60 % from their unperturbed values. Probably even more alarming ozone depletions were observed over highly populated regions of middle latitudes of northern hemisphere. Radiative transfer modeling was used to convert METEOR-3/TOMS daily ozone values into regional and global maps of biologically active UV. Calculations demonstrate the effect on surface UV levels produced by ozone hole over Antarctica and ozone depletions over the territory of Russia (March, 1994). UV contour lines deviate from the normal appearance which is determined by growing southward solar elevation. UV contour lines are almost perpendicular to the ozone ones in the ozone depletions areas. The 30 % ozone depletion, over Siberia caused more than 30 % increase in noontime erythemal UV levels, which is equivalent to 10-15 degrees southward latitude displacement. Higher UV radiation increases were found in ozone hole over South America (October 1992) equivalent to about 20 degrees southward displacement

  2. The Ozone Problem | Ground-level Ozone | New England | US ...

    Science.gov (United States)

    2017-04-10

    Many factors impact ground-level ozone development, including temperature, wind speed and direction, time of day, and driving patterns. Due to its dependence on weather conditions, ozone is typically a summertime pollutant and a chief component of summertime smog.

  3. CONTRIBUTION TO INDOOR OZONE LEVELS OF AN OZONE GENERATOR

    Science.gov (United States)

    This report gives results of a study of a commonly used commercially available ozone generator, undertaken to determine its impact on indoor ozone levels. xperiment were conducted in a typical mechanically ventilated office and in a test house. he generated ozone and the in-room ...

  4. Effect of Ventilation Strategies on Residential Ozone Levels

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain S. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sherman, Max H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-01

    Elevated outdoor ozone levels are associated with adverse health effects. Because people spend the vast majority of their time indoors, reduction in indoor levels of ozone of outdoor origin would lower population exposures and might also lead to a reduction in ozone-associated adverse health effects. In most buildings, indoor ozone levels are diminished with respect to outdoor levels to an extent that depends on surface reactions and on the degree to which ozone penetrates the building envelope. Ozone enters buildings from outdoors together with the airflows that are driven by natural and mechanical means, including deliberate ventilation used to reduce concentrations of indoor-generated pollutants. When assessing the effect of deliberate ventilation on occupant health one should consider not only the positive effects on removing pollutants of indoor origin but also the possibility that enhanced ventilation might increase indoor levels of pollutants originating outdoors. This study considers how changes in residential ventilation that are designed to comply with ASHRAE Standard 62.2 might influence indoor levels of ozone. Simulation results show that the building envelope can contribute significantly to filtration of ozone. Consequently, the use of exhaust ventilation systems is predicted to produce lower indoor ozone concentrations than would occur with balanced ventilation systems operating at the same air-­exchange rate. We also investigated a strategy for reducing exposure to ozone that would deliberately reduce ventilation rates during times of high outdoor ozone concentration while still meeting daily average ventilation requirements.

  5. Surface ozone in the urban area of Manaus, Amazonas, Brazil

    Science.gov (United States)

    Souza, R. A. F. D.; Costa, P. S.; Silva, C.; Godoi, R. M.; Martin, S. T.; Tota, J.; Barbosa, H. M.; Pauliquevis, T.; Ferreira De Brito, J.; Artaxo, P.; Manzi, A. O.; Wolf, S. A.; Cirino, G. G.

    2014-12-01

    When nitrogen oxides from vehicle and industrial emissions mix with volatile organic compounds from trees and plants with exposure to sunlight, a chemical reaction occurs contributing to ground-level ozone pollution. The preliminary results of the surface ozone study in urban area of Manaus, Amazonas State, Brazil, are presented for the first intensive operating period (IOP1) of the GoAmazon experiment (February/March 2014). Photochemical ozone production was found to be a regular process, with an afternoon maximum of the ozone mixing ratio of lower than 20 ppbv for cloudy days or clear sky weather. Typical ozone concentrations at mid-day were low (about 10 ppb). On the other hand, several high-value ozone episodes with surface ozone mixing ratios up to three times larger were registered during the dry season of 2013 (September/October). At the beginning of the wet season, the ozone concentration in Manaus decreased significantly, but diurnal variations can be found during the days with rainfall and other fast changes of meteorological conditions. Possible explanations of the nature of pulsations are discussed. Photochemical ozone production by local urban plumes of Manaus is named as a first possible source of the ozone concentration and biomass burning or power plant emissions are suggested as an alternative or an additional source.

  6. Nicotiana tabacum as model for ozone - plant surface reactions

    Science.gov (United States)

    Jud, Werner; Fischer, Lukas; Wohlfahrt, Georg; Tissier, Alain; Canaval, Eva; Hansel, Armin

    2015-04-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants, responsible for global crop losses with associated economic costs of several billion dollars per year. The ensuing injuries have been related to the uptake of ozone through the stomatal pores and oxidative effects damaging the internal leaf tissue. A striking question of current research is the environment and plant specific partitioning of ozone loss between gas phase, stomatal or plant surface sink terms. Here we show results from ozone fumigation experiments using various Nicotiana Tabacum varieties, whose surfaces are covered with different amounts of unsaturated diterpenoids exuded by their glandular trichomes. Exposure to elevated ozone levels (50 to 150 ppbv) for 5 to 15 hours in an exceptionally clean cuvette system did neither result in a reduction of photosynthesis nor caused any visible leaf damage. Both these ozone induced stress effects have been observed previously in ozone fumigation experiments with the ozone sensitive tobacco line Bel-W3. In our case ozone fumigation was accompanied by a continuous release of oxygenated volatile organic compounds, which could be clearly associated to their condensed phase precursors for the first time. Gas phase reactions of ozone were avoided by choosing a high enough gas exchange rate of the plant cuvette system. In the case of the Ambalema variety, that is known to exude only the diterpenoid cis-abienol, ozone fumigation experiments yield the volatiles formaldehyde and methyl vinyl ketone (MVK). The latter could be unequivocally separated from isomeric methacrolein (MACR) by the aid of a Selective Reagent Ion Time-of-Flight Mass Spectrometer (SRI-ToF-MS), which was switched every six minutes from H3O+ to NO+ primary ion mode and vice versa. Consistent with the picture of an ozone protection mechanism caused by reactive diterpenoids at the leaf surface are the results from dark-light experiments. The ozone loss obtained from the

  7. Surface ozone and carbon monoxide levels observed at Oki, Japan: regional air pollution trends in East Asia.

    Science.gov (United States)

    Sikder, Helena Akhter; Suthawaree, Jeeranut; Kato, Shungo; Kajii, Yoshizumi

    2011-03-01

    Simultaneous ground-based measurements of ozone and carbon monoxide were performed at Oki, Japan, from January 2001 to September 2002 in order to investigate the O(3) and CO characteristics and their distributions. The observations revealed that O(3) and CO concentrations were maximum in springtime and minimum in the summer. The monthly averaged concentrations of O(3) and CO were 60 and 234 ppb in spring and 23 and 106 ppb in summer, respectively. Based on direction, 5-day isentropic backward trajectory analysis was carried out to determine the transport path of air masses, preceding their arrival at Oki. Comparison between classified results from present work and results from the year 1994-1996 was carried out. The O(3) and CO concentration results of classified air masses in our analysis show similar concentration trends to previous findings; highest in the WNW/W, lowest in N/NE and medium levels in NW. Moreover, O(3) levels are higher and CO levels are lower in the present study in all categories. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Effect of pesticides on surface ozone concentration

    International Nuclear Information System (INIS)

    Farag, S.A.; Rizk, H.F.S.; Elbahnasawy, R.M.; Meleigy, M.I.

    1992-01-01

    A comparative study through seasonal variation of surface ozone concentration was carried out recently (1991-1992) at a background area free from expected urban pollutants (Shebin ElKom) and industrial and urban areas (Cairo). Surface ozone concentrations in ppb were generally lower in such area compared with urban or industrial areas studied through the comparative seasonal variations. Notable smog values (>100 ppb) of hourly surface ozone concentrations appeared during summer season in this rural area; during this season, some pesticides were sprayed over cotton and other crops fields in near by agricultural areas. The unexpected jump in the values of diurnal concentrations of surface ozone in that area may be due to the photochemical reactions of these organic pesticides in the atmosphere. 1 fig, 3 tab

  9. Surface ozone characterization at Larsemann Hills and Maitri, Antarctica.

    Science.gov (United States)

    Ali, Kaushar; Trivedi, D K; Sahu, S K

    2017-04-15

    Data are analyzed in terms of daily average ozone, its diurnal variation and its relation with meteorological parameters like dry bulb temperature (T), wet bulb temperature (T w ), atmospheric pressure and wind speed based on measurement of these parameters at two Indian Antarctic stations (Larsemann Hills, and Maitri) during 28th Indian Scientific Expedition of Antarctica (ISEA) organized during Antarctic summer of the year 2008-09. The work has been carried out to investigate summer time ozone level and its day-to-day and diurnal variability at these coastal locations and to highlight possible mechanism of ozone production and destruction. The result of the analysis indicates that daily average ozone concentration at Larsemann Hills varied from ~13 and ~20ppb with overall average value of ~16ppb and at Maitri, it varied from ~16 and ~21ppb with overall average value of ~18ppb. Photochemistry is found to partially contribute occasionally to the surface layer ozone at both the stations. Lower concentration of ozone at Maitri during beginning of the observational days may be due to destruction of ozone through activated halogens, whereas higher ozone on latter days may be due to photochemistry and advective transport from east to south-east areas. Ozone concentration during blizzard episodes at both the stations is reduced due to slow photochemical production of ozone, its photochemical removal and removal through deposition of ozone molecules on precipitation particles. Diurnal variation of ozone at Larsemann Hills and Maitri has been found to be absent. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Coincident Observations of Surface Ozone and NMVOCs over Abu Dhabi

    Science.gov (United States)

    Abbasi, Naveed; Majeed, Tariq; Iqbal, Mazhar; Tarasick, David; Davies, Jonathan; Riemer, Daniel; Apel, Eric

    2016-07-01

    The vertical profiles of ozone are measured coincidently with non-methane volatile organic compounds (NMVOCs) at the meteorological site located at the Abu Dhabi international airport (latitude 24.45N; longitude 54.22E) during the years 2012 - 2014. Some of the profiles show elevated surface ozone >95 ppbv during the winter months (December, January and February). The ground-level NMVOCs obtained from the gas chromatography-flame ionization detection/mass spectrometry system also show elevated values of acetylene, ethane, propane, butane, pentane, benzene, and toluene. NMVOCs and ozone abundances in other seasons are much lower than the values in winter season. NMVOCs are emitted from an extensive number of sources in urban environments including fuel production, distribution, and consumption, and serve as precursor of ozone. Transport sources contribute a substantial portion of the NMVOC burden to the urban atmosphere in developed regions. Abu Dhabi is located at the edge of the Arabian Gulf and is highly affected by emissions from petrochemical industries in the neighboring Gulf region. The preliminary results indicate that wintertime enhancement in ozone is associated with large values of NMVOCs at Abu Dhabi. The domestic production of surface ozone is estimated from the combination of oxygen recombination and NMVOCs and compared with the data. It is estimated that about 40-50% of ozone in Abu Dhabi is transported from the neighbouring petrochemical industries. We will present ozone sounding and NMVOCs data and our model estimates of surface ozone, including a discussion on the high levels of the tropospheric ozone responsible for contaminating the air quality in the UAE. This work is supported by National Research Foundation, UAE.

  11. The impacts of surface ozone pollution on winter wheat productivity in China--An econometric approach.

    Science.gov (United States)

    Yi, Fujin; Jiang, Fei; Zhong, Funing; Zhou, Xun; Ding, Aijun

    2016-01-01

    The impact of surface ozone pollution on winter wheat yield is empirically estimated by considering socio-economic and weather determinants. This research is the first to use an economic framework to estimate the ozone impact, and a unique county-level panel is employed to examine the impact of the increasing surface ozone concentration on the productivity of winter wheat in China. In general, the increment of surface ozone concentration during the ozone-sensitive period of winter wheat is determined to be harmful to its yield, and a conservative reduction of ozone pollution could significantly increase China's wheat supply. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Impact of the 2008 Global Recession on air quality over the United States: Implications for surface ozone levels from changes in NOx emissions

    Science.gov (United States)

    Tong, Daniel; Pan, Li; Chen, Weiwei; Lamsal, Lok; Lee, Pius; Tang, Youhua; Kim, Hyuncheol; Kondragunta, Shobha; Stajner, Ivanka

    2016-09-01

    Satellite and ground observations detected large variability in nitrogen oxides (NOx) during the 2008 economic recession, but the impact of the recession on air quality has not been quantified. This study combines observed NOx trends and a regional chemical transport model to quantify the impact of the recession on surface ozone (O3) levels over the continental United States. The impact is quantified by simulating O3 concentrations under two emission scenarios: business-as-usual (BAU) and recession. In the BAU case, the emission projection from the Cross-State Air Pollution Rule is used to estimate the "would-be" NOx emission level in 2011. In the recession case, the actual NO2 trends observed from Air Quality System ground monitors and the Ozone Monitoring Instrument on the Aura satellite are used to obtain "realistic" changes in NOx emissions. The model prediction with the recession effect agrees better with ground O3 observations over time and space than the prediction with the BAU emission. The results show that the recession caused a 1-2 ppbv decrease in surface O3 concentration over the eastern United States, a slight increase (0.5-1 ppbv) over the Rocky Mountain region, and mixed changes in the Pacific West. The gain in air quality benefits during the recession, however, could be quickly offset by the much slower emission reduction rate during the post-recession period.

  13. Impact of the 2008 Global Recession on Air Quality over the United States: Implications for Surface Ozone Levels from Changes in NOx Emissions

    Science.gov (United States)

    Tong, Daniel; Pan, Li; Chen, Weiwei; Lamsal, Lok; Lee, Pius; Tang, Youhua; Kim, Hyuncheol; Kondragunta, Shobha; Stajner, Ivanka

    2016-01-01

    Satellite and ground observations detected large variability in nitrogen oxides (NOx) during the 2008 economic recession, but the impact of the recession on air quality has not been quantified. This study combines observed NOx trends and a regional chemical transport model to quantify the impact of the recession on surface ozone (O3) levels over the continental United States. The impact is quantified by simulating O3 concentrations under two emission scenarios: business-as-usual (BAU) and recession. In the BAU case, the emission projection from the Cross-State Air Pollution Rule is used to estimate the would-be NOx emission level in 2011. In the recession case, the actual NO2 trends observed from Air Quality System ground monitors and the Ozone Monitoring Instrument on the Aura satellite are used to obtain realistic changes in NOx emissions. The model prediction with the recession effect agrees better with ground O3 observations over time and space than the prediction with the BAU emission. The results show that the recession caused a 12ppbv decrease in surface O3 concentration over the eastern United States, a slight increase (0.51ppbv) over the Rocky Mountain region, and mixed changes in the Pacific West. The gain in air quality benefits during the recession, however, could be quickly offset by the much slower emission reduction rate during the post-recession period.

  14. Transboundary Contributions To Surface Ozone In California's Central Valley

    Science.gov (United States)

    Post, A.; Faloona, I. C.; Conley, S. A.; Lighthall, D.

    2014-12-01

    Rising concern over the impacts of exogenous air pollution in California's Central Valley has prompted the establishment of a coastal, high altitude monitoring site at the Chews Ridge Observatory (1550 m) approximately 30 km east of Point Sur in Monterey County, under the auspices of the Monterey Institute for Research in Astronomy. Two and a half years of continuous ozone data are presented in the context of long-range transport and its potential impact on surface air quality in the San Joaquin Valley (SJV). Past attempts to quantify the impact of transboundary ozone on surface levels have relied on uncertain model estimates, or have been limited to weekly ozonesonde data. Here, we present an observationally derived quantification of the contribution of free tropospheric ozone to surface sites in the San Joaquin Valley throughout three ozone seasons (June through September, 2012-2014). The diurnal ozone patterns at Chews Ridge, and their correlations with ozone aloft over the Valley, have been presented previously. Furthermore, reanalysis data of geopotential heights indicate consistent flow from Chews Ridge to the East, directly over the SJV. In a related airborne project we quantify the vertical exchange, or entrainment, rate over the Southern SJV from a series of focused flights measuring ozone concentrations during peak photochemical hours in conjunction with local meteorological data to quantify an ozone budget for the area. By applying the entrainment rates observed in that study here we are able to quantify the seasonal contributions of free tropospheric ozone measured at Chews Ridge to surface sites in the San Joaquin Valley, and compare prior model estimates to our observationally derived values.

  15. Ozone Control Strategies | Ground-level Ozone | New ...

    Science.gov (United States)

    2017-09-05

    The Air Quality Planning Unit's primary goal is to protect your right to breathe clean air. Guided by the Clean Air Act, we work collaboratively with states, communities, and businesses to develop and implement strategies to reduce air pollution from a variety of sources that contribute to the ground-level ozone or smog problem.

  16. A climatological study of rural surface ozone in central Greece

    Directory of Open Access Journals (Sweden)

    P. D. Kalabokas

    2004-01-01

    Full Text Available Recent studies show that surface ozone levels at rural sites in Greece are generally high when compared with rural ozone measurements at northern European sites. The area of SE Europe, including Greece, is not very well monitored regarding rural ozone in comparison to central and northern Europe. In order to have the best possible picture of the rural surface ozone climatology in the area, based on the available data-sets of long-term continuous monitoring stations, the 10-year measurement records (1987-1996 of the Athens peripheral station of Liossia, (12 km N of the city center and the urban background station of Geoponiki (3 km W as well as the 4-year record (1996-1999 of the rural station of Aliartos (100 km NW of Athens, are analyzed in this paper. The data for Liossia and Geoponiki stations are screened for cases of strong airflow from rural areas (N-NE winds stronger than 5 m/s. The variation characteristics of the average rural ozone afternoon levels (12:00-18:00, with the best vertical atmospheric mixing, are mainly examined since these measurements are expected to be representative of the broader area. In all three stations there is a characteristic seasonal variation of rural ozone concentrations with lowest winter afternoon values at about 50 μg/m3 in December-January and average summer afternoon values at about 120 μg/m3 in July-August, indicating that high summer values are observed all over the area. The rural summer afternoon ozone values are very well correlated between the three stations, implying spatial homogeneity all over the area but also temporal homogeneity, since during the 13-year period 1987-1999 the rural afternoon ozone levels remained almost constant around the value of 120 μg/m3.

  17. Sensitivity analysis of ground level ozone in India using WRF-CMAQ models

    NARCIS (Netherlands)

    Sharma, Sumit; Chatani, Satoru; Mahtta, Richa; Goel, Anju; Kumar, Atul|info:eu-repo/dai/nl/333244869

    2016-01-01

    Ground level ozone is emerging as a pollutant of concern in India. Limited surface monitoring data reveals that ozone concentrations are well above the prescribed national standards. This study aims to simulate the regional and urban scale ozone concentrations in India using WRF-CMAQ models.

  18. Global Ozone Distribution relevant to Human Health: Metrics and present day levels from the Tropospheric Ozone Assessment Report (TOAR)

    Science.gov (United States)

    Fleming, Z. L.; Doherty, R. M.; von Schneidemesser, E.; Cooper, O. R.; Malley, C.; Colette, A.; Xu, X.; Pinto, J. P.; Simpson, D.; Schultz, M. G.; Hamad, S.; Moola, R.; Solberg, S.; Feng, Z.

    2017-12-01

    Using stations from the TOAR surface ozone database, this study quantifies present-day global and regional distributions of five ozone metrics relevant for both short-term and long-term human exposure. These metrics were explored at ozone monitoring sites globally, and re-classified for this project as urban or non-urban using population densities and night-time lights. National surface ozone limit values are usually related to an annual number of exceedances of daily maximum 8-hour running mean (MDA8), with many countries not even having any ozone limit values. A discussion and comparison of exceedances in the different ozone metrics, their locations and the seasonality of exceedances provides clues as to the regions that potentially have more serious ozone health implications. Present day ozone levels (2010-2014) have been compared globally and show definite geographical differences (see Figure showing the annual 4th highest MDA8 for present day ozone for all non-urban stations). Higher ozone levels are seen in western compared to eastern US, and between southern and northern Europe, and generally higher levels in east Asia. The metrics reflective of peak concentrations show highest values in western North America, southern Europe and East Asia. A number of the metrics show similar distributions of North-South gradients, most prominent across Europe and Japan. The interquartile range of the regional ozone metrics was largest in East Asia, higher for urban stations in Asia but higher for non-urban stations in Europe and North America. With over 3000 monitoring stations included in this analysis and despite the higher densities of monitoring stations in Europe, north America and East Asia, this study provides the most comprehensive global picture to date of surface ozone levels in terms of health-relevant metrics.

  19. 21 CFR 801.415 - Maximum acceptable level of ozone.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Maximum acceptable level of ozone. 801.415 Section... level of ozone. (a) Ozone is a toxic gas with no known useful medical application in specific, adjunctive, or preventive therapy. In order for ozone to be effective as a germicide, it must be present in a...

  20. The impacts of surface ozone pollution on winter wheat productivity in China – An econometric approach

    International Nuclear Information System (INIS)

    Yi, Fujin; Jiang, Fei; Zhong, Funing; Zhou, Xun; Ding, Aijun

    2016-01-01

    The impact of surface ozone pollution on winter wheat yield is empirically estimated by considering socio-economic and weather determinants. This research is the first to use an economic framework to estimate the ozone impact, and a unique county-level panel is employed to examine the impact of the increasing surface ozone concentration on the productivity of winter wheat in China. In general, the increment of surface ozone concentration during the ozone-sensitive period of winter wheat is determined to be harmful to its yield, and a conservative reduction of ozone pollution could significantly increase China's wheat supply. - Highlights: • We examine the impacts of the surface ozone exposure on winter wheat yield in China. • An econometric method is used to measure the ozone impacts. • The results conclude that surface ozone is harmful to winter wheat yield in China. • We confirm that stress conditions such as drought and air particles can mitigate the adverse effect of ozone. - Surface ozone pollution is harmful to winter wheat yield in China by considering socio-economic determinants, weather, and other stress conditions like drought and air particles.

  1. Summertime state-level source-receptor relationships between nitrogen oxides emissions and surface ozone concentrations over the continental United States.

    Science.gov (United States)

    Tong, Daniel Q; Mauzerall, Denise L

    2008-11-01

    Interstate transport of ozone (O3) and its precursors can contribute substantially to state-level surface o3 concentrations, making it difficult for some states to meet the National Ambient Air Quality Standards (NAAQS) for O3 by limiting only their own emissions. We analyze the effect of interstate transport on surface O3 in each continental U.S. state in July 1996 using the community multiscale air quality (CMAQ) model. By examining the difference between a baseline simulation and perturbation simulations in which each state's nitrogen oxides (NOx) emissions are removed, we establish for the first time a summertime source-receptor matrix for all 48 continental states. We find that for 16 (20) states at least one neighboring state's NOx emissions are responsible for a larger increase in monthly mean peak 8 h (all-hour) O3 concentrations than the state's own emissions. For over 80% of the contiguous states, interstate transport is more importantthan local emissions for summertime peak O3 concentrations. Our source-receptor matrices indicate that the geographic range of the clean air interstate rule (CAIR) was sufficient to address interstate transport of O3 in most of the states included in the program. However, the exclusion of Texas, which has particularly large NOx emissions, from the CAIR O3 program left emission sources uncontrolled that contribute more than 1 ppbv to the July mean of peak 8 h O3 concentrations in over a dozen states.

  2. Impact of East Asian Summer Monsoon on Surface Ozone Pattern in China

    Science.gov (United States)

    Li, Shu; Wang, Tijian; Huang, Xing; Pu, Xi; Li, Mengmeng; Chen, Pulong; Yang, Xiu-Qun; Wang, Minghuai

    2018-01-01

    Tropospheric ozone plays a key role in regional and global atmospheric and climate systems. In East Asia, ozone can be affected both in concentration level and spatial pattern by typical monsoon climate. This paper uses three different indices to identify the strength of East Asian summer monsoon (EASM) and explores the possible impact of EASM intensity on the ozone pattern through synthetic and process analysis. The difference in ozone between three strong and three weak monsoon years was analyzed using the simulations from regional climate model RegCM4-Chem. It was found that EASM intensity can significantly influence the spatial distribution of ozone in the lower troposphere. When EASM is strong, ozone in the eastern part of China (28°N - 42° N) is reduced, but the inverse is detected in the north and south. The surface ozone difference ranges from -7 to 7 ppbv during the 3 months (June to August) of the EASM, with the most obvious difference in August. Difference of the 3 months' average ozone ranges from -3.5 to 4 ppbv. Process analysis shows that the uppermost factor controlling ozone level during summer monsoon seasons is the chemistry process. Interannual variability of EASM can impact the spatial distribution of ozone through wind in the lower troposphere, cloud cover, and downward shortwave radiation, which affect the transport and chemical formation of ozone. The phenomenon should be addressed when considering the interaction between ozone and the climate in East Asia region.

  3. Multi-scale modeling study of the source contributions to near-surface ozone and sulfur oxides levels over California during the ARCTAS-CARB period

    Directory of Open Access Journals (Sweden)

    M. Huang

    2011-04-01

    Full Text Available Chronic high surface ozone (O3 levels and the increasing sulfur oxides (SOx = SO2+SO4 ambient concentrations over South Coast (SC and other areas of California (CA are affected by both local emissions and long-range transport. In this paper, multi-scale tracer, full-chemistry and adjoint simulations using the STEM atmospheric chemistry model are conducted to assess the contribution of local emission sourcesto SC O3 and to evaluate the impacts of transported sulfur and local emissions on the SC sulfur budgetduring the ARCTAS-CARB experiment period in 2008. Sensitivity simulations quantify contributions of biogenic and fire emissions to SC O3 levels. California biogenic and fire emissions contribute 3–4 ppb to near-surface O3 over SC, with larger contributions to other regions in CA. During a long-range transport event from Asia starting from 22 June, high SOx levels (up to ~0.7 ppb of SO2 and ~1.3 ppb of SO4 is observed above ~6 km, but they did not affect CA surface air quality. The elevated SOx observed at 1–4 km is estimated to enhance surface SOx over SC by ~0.25 ppb (upper limit on ~24 June. The near-surface SOx levels over SC during the flight week are attributed mostly to local emissions. Two anthropogenic SOx emission inventories (EIs from the California Air Resources Board (CARB and the US Environmental Protection Agency (EPA are compared and applied in 60 km and 12 km chemical transport simulations, and the results are compared withobservations. The CARB EI shows improvements over the National Emission Inventory (NEI by EPA, but generally underestimates surface SC SOx by about a factor of two. Adjoint sensitivity analysis indicated that SO2 levels at 00:00 UTC (17:00 local time at six SC surface sites were influenced by previous day maritime emissions over the

  4. Chemical analysis and surface morphology of enamel following ozone application with different concentrations and exposure times

    Directory of Open Access Journals (Sweden)

    Iman I. Elsayad

    2011-04-01

    Full Text Available This study aimed to determine the effect of different ozone concentrations applied with different exposure times on the chemical composition and the surface morphology of enamel. Twenty human mandibular molars were divided into four groups according to ozone concentration and exposure times. Group A received 90 μg of ozone/ml oxygen for 1 min, group B received 90 μg of ozone/ml oxygen for 2 min, group C received 120 μg of ozone/ml oxygen for 1 min and group D received 120 μg of ozone/ml oxygen for 2 min. The ozone source was from a medical ozone generator equipped with a device to adjust the concentration. Buccal surfaces of teeth were tested before and after ozone application so that each tooth served as a control for itself, using Environmental Scanning Electron Microscope (ESEM connected to an Electron Dispersive Analytical X-ray (EDAX. Changes in calcium and phosphorus percentage levels were recorded and the Ca/P ratio was calculated. The values were statistically analyzed using the one-way ANOVA test with a level of significance set at P ⩽ 0.05. No statistical significant difference was found between the control and the tested groups in minerals content or ratio as P > 0.05. ESEM images showed enamel surface roughness with 2 min ozone exposure times. High ozone concentration with prolonged exposure time does not change the chemical composition of enamel. Applying ozone for 2 min alters the surface morphology of enamel causing variable degrees of roughness. Using high ozone concentrations with prolonged exposure times for caries reversal or prevention and for bleaching may be contraindicated if this changes the surface morphology of enamel.

  5. Analysis of the Impact of Wildfire on Surface Ozone Record in the Colorado Front Range

    Science.gov (United States)

    McClure-Begley, A.; Petropavlovskikh, I. V.; Oltmans, S. J.; Pierce, R. B.; Sullivan, J. T.; Reddy, P. J.

    2015-12-01

    Ozone plays an important role on the oxidation capacity of the atmosphere, and at ground-level has negative impacts on human health and ecosystem processes. In order to understand the dynamics and variability of surface ozone, it is imperative to analyze individual sources, interactions between sources, transport, and chemical processes of ozone production and accumulation. Biomass burning and wildfires have been known to emit a suite of particulate matter and gaseous compounds into the atmosphere. These compounds, such as, volatile organic compounds, carbon monoxide, and nitrogen oxides are precursor species which aid in the photochemical production and destruction of ozone. The Colorado Front Range (CFR) is a region of complex interactions between pollutant sources and meteorological conditions which result in the accumulation of ozone. High ozone events in the CFR associated with fires are analyzed for 2003-2014 to develop understanding of the large scale influence and variability of ozone and wildfire relationships. This study provides analysis of the frequency of enhanced ozone episodes that can be confirmed to be transported within and affected by the fires and smoke plumes. Long-term records of surface ozone data from the CFR provide information on the impact of wildfire pollutants on seasonal and diurnal ozone behavior. Years with increased local fire activity, as well as years with increased long-range transport of smoke plumes, are evaluated for the effect on the long-term record and high ozone frequency of each location. Meteorological data, MODIS Fire detection images, NOAA HYSPLIT Back Trajectory analysis, NOAA Smoke verification model, Fire Tracer Data (K+), RAQMS Model, Carbon Monoxide data, and Aerosol optical depth retrievals are used with NOAA Global Monitoring Division surface ozone data from three sites in Colorado. This allows for investigation of the interactions between pollutants and meteorology which result in high surface ozone levels.

  6. Surface ozone in China: present-day distribution and long-term changes

    Science.gov (United States)

    Xu, X.; Lin, W.; Xu, W.

    2017-12-01

    Reliable knowledge of spatio-temporal variations of surface ozone is highly needed to assess the impacts of ozone on human health, ecosystem and climate. Although regional distributions and trends of surface ozone in European and North American countries have been well characterized, little is known about the variability of surface ozone in many other countries, including China, where emissions of ozone precursors have been changing rapidly in recent decades. Here we present the first comprehensive description of present-day (2013-2017) distribution and long-term changes of surface ozone in mainland China. Recent ozone measurements from China's air quality monitoring network (AQMN) are analyzed to show present-day distributions of a few ozone exposure metrics for urban environment. Long-term measurements of ozone at six background sites, a rural site and an urban are used to study the trends of ozone in background, rural and urban air, respectively. The average levels of ozone at the AQMN sites (mainly urban) are close to those found at many European and North American sites. However, ozone at most of the sites shows very large diurnal and seasonal variations so that ozone nonattainment can occur in many cities, particularly those in the North China Plain (NCP), the south of Northeast China (NEC), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), and the Sichuan Basin-Chongqing region (SCB). In all these regions, particularly in the NCP, the maximum daily 8-h average (MDA8) ozone concentration can significantly exceed the national limit (75 ppb). High annual sum of ozone means over 35 ppb (SOMO35) exist mainly in the NCP, NEC and YRD, with regional averages over 4000 ppb·d. Surface ozone has significantly increased at Waliguan (a baseline site in western China) and Shangdianzi (a background site in the NCP), and decreased in winter and spring at Longfengshan (a background site in Northeast China). No clear trend can be derived from long-term measurements

  7. Seasonal changes in surface ozone over South Korea

    Directory of Open Access Journals (Sweden)

    Hyun-Chae Jung

    2018-01-01

    Full Text Available Recently, the surface ozone concentration in the Korean peninsula has been increasing more rapidly than in the past, and seasonal changes are appearing such as increases in the number of ozone alerts in springtime. We examined changes in the timing of annual maximum South Korean O3 levels by fitting a sine function to data from 54 air-quality monitoring sites over a 10-year period (2005–2014. The analytical results show that the date of maximum ozone concentration at 23 points in the last 10 years has been advanced by about 2.1 days per year (E-sites, while the remaining 31 points have been delayed by about 2.5 days per year (L-sites. We attribute these differences to seasonal O3 changes: E-sites show a larger increase in O3 level in March–April (MA than in June–July (JJ, while L-sites show a larger increase in JJ than in MA. Furthermore, these shifts are significantly larger in magnitude than those reported for Europe and North America. We also examined one possible reason for these seasonal differences: the relationship between O3 and precursors such as NO2 and CO. E-sites showed a rapid decrease in NO2 (NO concentration in MA over the last decade. As a result, the ozone concentration at E-sites seems to have increased due to the absence of ozone destruction by NOx titration in early spring. In L-Sites, the concentrations of ozone precursors such as NO2 and CO in JJ showed a smaller decrease than those at other sites. Therefore, in L-sites, relatively large amounts of ozone precursors were distributed in JJ, implying that more ozone was generated. We suggest that shifts in the South Korean O3 seasonal cycle are due to changes in early spring and summer NO2 (NO and CO levels; this should be tested further by modeling studies.

  8. Climate Change Impacts on Projections of Excess Mortality at 2030 using Spatially-Varying Ozone-Temperature Risk Surfaces

    Science.gov (United States)

    Wilson, Ander; Reich, Brian J.; Nolte, Christopher G.; Spero, Tanya L.; Hubbell, Bryan; Rappold, Ana G.

    2017-01-01

    We project the change in ozone-related mortality burden attributable to changes in climate between a historical (1995–2005) and near-future (2025–2035) time period while incorporating a nonlinear and synergistic effect of ozone and temperature on mortality. We simulate air quality from climate projections varying only biogenic emissions and holding anthropogenic emissions constant, thus attributing changes in ozone only to changes in climate and independent of changes in air pollutant emissions. We estimate nonlinear, spatially-varying, ozone-temperature risk surfaces for 94 US urban areas using observed data. Using the risk surfaces and climate projections we estimate daily mortality attributable to ozone exceeding 40 ppb (moderate level) and 75 ppb (US ozone NAAQS) for each time period. The average increases in city-specific median April-October ozone and temperature between time periods are 1.02 ppb and 1.94°F; however, the results varied by region. Increases in ozone due to climate change result in an increase in ozone-mortality burden. Mortality attributed to ozone exceeding 40 ppb increases by 7.7% (1.6%, 14.2%). Mortality attributed to ozone exceeding 75 ppb increases by 14.2% (1.6%, 28.9%). The absolute increase in excess ozone mortality is larger for changes in moderate ozone levels, reflecting the larger number of days with moderate ozone levels. PMID:27005744

  9. Effects of ozone-vegetation coupling on surface ozone air quality via biogeochemical and meteorological feedbacks

    Science.gov (United States)

    Sadiq, Mehliyar; Tai, Amos P. K.; Lombardozzi, Danica; Martin, Maria Val

    2017-02-01

    Tropospheric ozone is one of the most hazardous air pollutants as it harms both human health and plant productivity. Foliage uptake of ozone via dry deposition damages photosynthesis and causes stomatal closure. These foliage changes could lead to a cascade of biogeochemical and biogeophysical effects that not only modulate the carbon cycle, regional hydrometeorology and climate, but also cause feedbacks onto surface ozone concentration itself. In this study, we implement a semi-empirical parameterization of ozone damage on vegetation in the Community Earth System Model to enable online ozone-vegetation coupling, so that for the first time ecosystem structure and ozone concentration can coevolve in fully coupled land-atmosphere simulations. With ozone-vegetation coupling, present-day surface ozone is simulated to be higher by up to 4-6 ppbv over Europe, North America and China. Reduced dry deposition velocity following ozone damage contributes to ˜ 40-100 % of those increases, constituting a significant positive biogeochemical feedback on ozone air quality. Enhanced biogenic isoprene emission is found to contribute to most of the remaining increases, and is driven mainly by higher vegetation temperature that results from lower transpiration rate. This isoprene-driven pathway represents an indirect, positive meteorological feedback. The reduction in both dry deposition and transpiration is mostly associated with reduced stomatal conductance following ozone damage, whereas the modification of photosynthesis and further changes in ecosystem productivity are found to play a smaller role in contributing to the ozone-vegetation feedbacks. Our results highlight the need to consider two-way ozone-vegetation coupling in Earth system models to derive a more complete understanding and yield more reliable future predictions of ozone air quality.

  10. Airborne lidar measurements of surface ozone depletion over Arctic sea ice

    Directory of Open Access Journals (Sweden)

    J. A. Seabrook

    2013-06-01

    Full Text Available A differential absorption lidar (DIAL for measurement of atmospheric ozone concentration was operated aboard the Polar 5 research aircraft in order to study the depletion of ozone over Arctic sea ice. The lidar measurements during a flight over the sea ice north of Barrow, Alaska, on 3 April 2011 found a surface boundary layer depletion of ozone over a range of 300 km. The photochemical destruction of surface level ozone was strongest at the most northern point of the flight, and steadily decreased towards land. All the observed ozone-depleted air throughout the flight occurred within 300 m of the sea ice surface. A back-trajectory analysis of the air measured throughout the flight indicated that the ozone-depleted air originated from over the ice. Air at the surface that was not depleted in ozone had originated from over land. An investigation into the altitude history of the ozone-depleted air suggests a strong inverse correlation between measured ozone concentration and the amount of time the air directly interacted with the sea ice.

  11. Variability of surface ozone with cloud coverage over Kolkata, India

    Indian Academy of Sciences (India)

    Critical analysis of experimental surface ozone data and cloud coverage is reported over Kolkata during the period January 2011 to December 2011. Significant relationship between these two parameters is observed. Analysis shows that the trend of surface ozone concentration and cloud coverage follow opposite ...

  12. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    International Nuclear Information System (INIS)

    Marinov, Daniil; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine; Guerra, Vasco

    2013-01-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1–5 Torr and discharge currents ∼40–120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O 3 * , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O 3 * is strongly coupled with those of atomic oxygen and O 2 (a 1 Δ g ) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established. (paper)

  13. Ozone kinetics in low-pressure discharges: vibrationally excited ozone and molecule formation on surfaces

    Science.gov (United States)

    Marinov, Daniil; Guerra, Vasco; Guaitella, Olivier; Booth, Jean-Paul; Rousseau, Antoine

    2013-10-01

    A combined experimental and modeling investigation of the ozone kinetics in the afterglow of pulsed direct current discharges in oxygen is carried out. The discharge is generated in a cylindrical silica tube of radius 1 cm, with short pulse durations between 0.5 and 2 ms, pressures in the range 1-5 Torr and discharge currents ˜40-120 mA. Time-resolved absolute concentrations of ground-state atoms and ozone molecules were measured simultaneously in situ, by two-photon absorption laser-induced fluorescence and ultraviolet absorption, respectively. The experiments were complemented by a self-consistent model developed to interpret the results and, in particular, to evaluate the roles of vibrationally excited ozone and of ozone formation on surfaces. It is found that vibrationally excited ozone, O_3^{*} , plays an important role in the ozone kinetics, leading to a decrease in the ozone concentration and an increase in its formation time. In turn, the kinetics of O_3^{*} is strongly coupled with those of atomic oxygen and O2(a 1Δg) metastables. Ozone formation at the wall does not contribute significantly to the total ozone production under the present conditions. Upper limits for the effective heterogeneous recombination probability of O atoms into ozone are established.

  14. Responses of Surface Ozone Air Quality to Anthropogenic Nitrogen Deposition

    Science.gov (United States)

    Zhang, L.; Zhao, Y.; Tai, A. P. K.; Chen, Y.; Pan, Y.

    2017-12-01

    Human activities have substantially increased atmospheric deposition of reactive nitrogen to the Earth's surface, inducing unintentional effects on ecosystems with complex environmental and climate consequences. One consequence remaining unexplored is how surface air quality might respond to the enhanced nitrogen deposition through surface-atmosphere exchange. We combine a chemical transport model (GEOS-Chem) and a global land model (Community Land Model) to address this issue with a focus on ozone pollution in the Northern Hemisphere. We consider three processes that are important for surface ozone and can be perturbed by addition of atmospheric deposited nitrogen: emissions of biogenic volatile organic compounds (VOCs), ozone dry deposition, and soil nitrogen oxide (NOx) emissions. We find that present-day anthropogenic nitrogen deposition (65 Tg N a-1 to the land), through enhancing plant growth (represented as increases in vegetation leaf area index (LAI) in the model), could increase surface ozone from increased biogenic VOC emissions, but could also decrease ozone due to higher ozone dry deposition velocities. Meanwhile, deposited anthropogenic nitrogen to soil enhances soil NOx emissions. The overall effect on summer mean surface ozone concentrations show general increases over the globe (up to 1.5-2.3 ppbv over the western US and South Asia), except for some regions with high anthropogenic NOx emissions (0.5-1.0 ppbv decreases over the eastern US, Western Europe, and North China). We compare the surface ozone changes with those driven by the past 20-year climate and historical land use changes. We find that the impacts from anthropogenic nitrogen deposition can be comparable to the climate and land use driven surface ozone changes at regional scales, and partly offset the surface ozone reductions due to land use changes reported in previous studies. Our study emphasizes the complexity of biosphere-atmosphere interactions, which can have important

  15. Global Model Comparison with NOAA Observed Surface Ozone to Understand Transport in the Arctic

    Science.gov (United States)

    Petropavlovskikh, I. V.; McClure-Begley, A.; Tummon, F.; Tilmes, S.; Yudina, A.; Crepinsek, S.; Uttal, T.

    2016-12-01

    The Arctic region is rapidly gaining interest and support for scientific studies to help understand and characterize the processes, sources, and chemical composition of the Arctic environment. In order to understand the Arctic climate system and the changes that are occurring, it is imperative to know the behavior and impact of atmospheric constituents. As a secondary pollutant which impacts the oxidation capacity and radiative forcing of the atmosphere, ozone is an imperative species to characterize. Global atmospheric models help to confirm and understand the influence of long-distance transport on local ozone conditions. This analysis highlights the winter season when ozone conditions are not being driven by photochemical influence, and transport is the prevalent means of ozone variation. In order to ensure adequate representation of ozone conditions and source regions, model comparison verifies the ability of models to represent the behavior of ozone at the surface. Ozone mixing ratios observed from Barrow, Alaska and Summit, Greenland, are critical observations to provide fundamental knowledge of the behavior and trends of ground-level ozone in the Arctic. The observed surface ozone and wind data are compared against two different global climate-chemistry models to assess the ability for models to simulate surface ozone in the arctic region. The CCM SOCOL (Modeling tools for studies of Solar Climate Ozone Links) and Community Earth System Model (CESM1) CAM4-chem are compared to observational measurements. Comparisons between the model and observations are used as the first step in understanding of the long-range transport contribution to ozone variability in the boundary layer of the Arctic environment. An improvement in agreement between observations and chemistry-climate hind cast is found when the model is forced with reanalysis wind conditions.

  16. Ozone-surface interactions: Investigations of mechanisms, kinetics, mass transport, and implications for indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, Glenn Charles [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    -7, 10-5, and 10-5 respectively. To understand how internal surface area influences the equivalent reaction probability of whole carpet, a model of ozone diffusion into and reaction with internal carpet components was developed. This was then used to predict apparent reaction probabilities for carpet. He combines this with a modified model of turbulent mass transfer developed by Liu, et al. to predict deposition rates and indoor ozone concentrations. The model predicts that carpet should have an equivalent reaction probability of about 10-5, matching laboratory measurements of the reaction probability. For both carpet and duct materials, surfaces become progressively quenched (aging), losing the ability to react or otherwise take up ozone. He evaluated the functional form of aging and find that the reaction probability follows a power function with respect to the cumulative uptake of ozone. To understand ozone aging of surfaces, he developed several mathematical descriptions of aging based on two different mechanisms. The observed functional form of aging is mimicked by a model which describes ozone diffusion with internal reaction in a solid. He shows that the fleecy nature of carpet materials in combination with the model of ozone diffusion below a fiber surface and internal reaction may explain the functional form and the magnitude of power function parameters observed due to ozone interactions with carpet. The ozone induced aldehyde emissions, measured from duct materials, were combined with an indoor air quality model to show that concentrations of aldehydes indoors may approach odorous levels. He shows that ducts are unlikely to be a significant sink for ozone due to the low reaction probability in combination with the short residence time of air in ducts.

  17. Influences of the boundary layer evolution on surface ozone ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... A chemical box model simulation indicates about 17% reduction in the daytime ozone levels during the conditions of suppressed PBL in comparison with those of higher PBL conditions. On a few occasions, substantially elevated ozone levels (as high as 90 ppbv) were observed during late evening hours, ...

  18. Meteorologically-adjusted trend analysis of surface observed ozone at three monitoring sites in Delhi, India: 2007-2011

    Science.gov (United States)

    Biswas, J.; Farooqui, Z.; Guttikunda, S. K.

    2012-12-01

    It is well known that meteorological parameters have significant impact on surface ozone concentrations. Therefore it is important to remove the effects of meteorology on ozone concentrations to correctly estimate long-term trends in ozone levels due to the alterations in precursor emissions. This is important for the development of effectual control strategies. In this study surface observed ozone trends in New Delhi are analyzed using Komogorov-Zurbenko (KZ) filter, US EPA ozone adjustment due to weather approach and the classification and regression tree method. The statistical models are applied to the ozone data at three observational sites in New Delhi metropolitan areas, 1) Income Tax Office (ITO) 2) Sirifort and 3) Delhi College of Engineering (DCE). The ITO site is located adjacent to a traffic crossing, Sirifort is an urban site and the DCE site is located in a residential area. The ITO site is also influenced by local industrial emissions. DCE has higher ozone levels than the other two sites. It was found that ITO has lowest ozone concentrations amongst the three sites due to ozone titrating due to industrial and on-road mobile NOx emissions. The statistical methods employed can assess ozone trends at these sites with a high degree of confidence and the results can be used to gauge the effectiveness of control strategies on surface ozone levels in New Delhi.

  19. Ground-level Ozone (Smog) Information | New England | US ...

    Science.gov (United States)

    2017-09-05

    Ground-level ozone presents a serious air quality problem in New England. In 2008, EPA revised the ozone standard to a level of 0.075 parts per million, 8-hour average. Over the last 5 years (2006 through 2010), there have been an average of 31 days per summer when New England's air exceeded this standard.

  20. The TOAR database on observations of surface ozone (and more)

    Science.gov (United States)

    Schultz, M. G.; Schröder, S.; Cooper, O. R.; Galbally, I. E.; Petropavlovskikh, I. V.; von Schneidemesser, E.; Tanimoto, H.; Elshorbany, Y. F.; Naja, M. K.; Seguel, R. J.

    2017-12-01

    In support of the first Tropospheric Ozone Assessment Report (TOAR) a relational database of global surface ozone observations has been developed and populated with hourly measurement data and enhanced metadata. A comprehensive suite of ozone data products including standard statistics, health and vegetation impact metrics, and trend information, are made available through a common data portal and a web interface. These data form the basis of the TOAR analyses focusing on human health, vegetation, and climate relevant ozone issues. Cooperation among many data centers and individual researchers worldwide made it possible to build the world's largest collection of in-situ hourly surface ozone data covering the period from 1970 to 2015. By combining the data from almost 10,000 measurement sites around the world with global metadata information, new analyses of surface ozone have become possible, such as the first globally consistent characterisations of measurement sites as either urban or rural/remote. Exploitation of these global metadata allows for new insights into the global distribution, and seasonal and long-term changes of tropospheric ozone and they enable TOAR to perform the first, globally consistent analysis of present-day ozone concentrations and recent ozone changes with relevance to health, agriculture, and climate. This presentation will provide a summary of the TOAR surface observations database including recent additions of ozone precursor and meteorological data. We will demonstrate how the database can be accessed and the data can be used, and we will discuss its limitations and the potential for closing some of teh remaining data gaps.

  1. Influences of the boundary layer evolution on surface ozone ...

    Indian Academy of Sciences (India)

    Considering the importance of tropical tropo- sphere, attempts have been made for the measure- ment of ozone and precursors along with meteoro- logical parameters over the Indian region in which the roles of chemistry and meteorology in control- ling the ozone levels have been examined over this region (e.g., Naja and ...

  2. Surface Ozone Dynamics in the Kola Peninsula Region

    Science.gov (United States)

    Beloglazov, M. I.; Karpechko, A. Yu.; Nikulin, G. N.; Roumjantsev, S. A.

    Measurements of surface ozone from the centre of the Murmansk Region (Apatity, Kola peninsula) and its southern part (Kovda, White Sea coast) give a picture of the behaviour of this air component on the Kola peninsula and surrounding vicinity. Simultaneous measurements in Apatity and Kovda have shown that the ozone concentration in Apatity is roughly twice as much as in Kovda. This fact may be explained by the local wind circulation and the presence of bromine near the coast of the Kola Peninsula. An inverse correlation is found between the ozone and nitrogen oxide concentrations from observations near motorways in Apatity. A decrease of nitrogen oxide concentration accompanies the growth of ozone on average. Thus, Apatity is a northern city in which the air pollution by traffic emissions decreases the ozone content.

  3. Damages of surface ozone: evidence from agricultural sector in China

    Science.gov (United States)

    Yi, Fujin; McCarl, Bruce A.; Zhou, Xun; Jiang, Fei

    2018-03-01

    This study measures the damages that surface ozone pollution causes within the Chinese agricultural sector under 2014 conditions. It also analyzes the agricultural benefits of ozone reductions. The analysis is done using a partial equilibrium model of China’s agricultural sector. Results indicate that there are substantial, spatially differentiated damages that are greatest in ozone-sensitive crop growing areas with higher ozone concentrations. The estimated damage to China’s agricultural sector range is between CNY 1.6 trillion and 2.2 trillion, which for comparison is about one fifth of 2014 agricultural revenue. When considering concentration reduction we find a 30% ozone reduction yields CNY 678 billion in sectoral benefits. These benefits largely fall to consumers with producers losing as the production gains lead to lower prices.

  4. Ozone Decomposition on the Surface of Metal Oxide Catalyst

    Directory of Open Access Journals (Sweden)

    Batakliev Todor Todorov

    2014-12-01

    Full Text Available The catalytic decomposition of ozone to molecular oxygen over catalytic mixture containing manganese, copper and nickel oxides was investigated in the present work. The catalytic activity was evaluated on the basis of the decomposition coefficient which is proportional to ozone decomposition rate, and it has been already used in other studies for catalytic activity estimation. The reaction was studied in the presence of thermally modified catalytic samples operating at different temperatures and ozone flow rates. The catalyst changes were followed by kinetic methods, surface measurements, temperature programmed reduction and IR-spectroscopy. The phase composition of the metal oxide catalyst was determined by X-ray diffraction. The catalyst mixture has shown high activity in ozone decomposition at wet and dry O3/O2 gas mixtures. The mechanism of catalytic ozone degradation was suggested.

  5. The influence of meteorological factors and biomass burning on surface ozone concentrations at Tanah Rata, Malaysia

    Science.gov (United States)

    Toh, Ying Ying; Lim, Sze Fook; von Glasow, Roland

    2013-05-01

    The surface ozone concentrations at the Tanah Rata regional Global Atmosphere Watch (GAW) station, Malaysia (4°28‧N, 101°23‧E, 1545 m above Mean Sea Level (MSL)) from June 2006 to August 2008 were analyzed in this study. Overall the ozone mixing ratios are very low; the seasonal variations show the highest mixing ratios during the Southwest monsoon (average 19.1 ppb) and lowest mixing ratios during the spring intermonsoon (average 14.2 ppb). The diurnal variation of ozone is characterised by an afternoon maximum and night time minimum. The meteorological conditions that favour the formation of high ozone levels at this site are low relative humidity, high temperature and minimum rainfall. The average ozone concentration is lower during precipitation days compared to non-precipitation days. The hourly averaged ozone concentrations show significant correlations with temperature and relative humidity during the Northeast monsoon and spring intermonsoon. The highest concentrations are observed when the wind is blowing from the west. We found an anticorrelation between the atmospheric pressure tide and ozone concentrations. The ozone mixing ratios do not exceed the recommended Malaysia Air Quality Guidelines for 1-h and 8-h averages. Five day backward trajectories on two high ozone episodes in 07 August 2006 (40.0 ppb) and 24 February 2008 (45.7 ppb) are computed using the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to investigate the origin of the pollutants and influence of regional transport. The high ozone episode during 07 August 2006 (burning season during southwest monsoon) is mainly attributed to regional transport from biomass burning in Sumatra, whereas favourable meteorological conditions (i.e. low relative humidity, high temperature and solar radiation, zero rainfall) and long range transport from Indo-China have elevated the ozone concentrations during 24 February 2008.

  6. Surface ozone scenario at Pune and Delhi during the decade of 1990s

    Indian Academy of Sciences (India)

    there is no trend whatsoever in the variation of surface ozone concentration at Delhi. Minimum value of surface ozone occurs before sunrise and maximum in the afternoon hours. Regression ... Introduction. Surface ozone is of immense societal concern due to .... in the presence of high concentration of ozone precursor ...

  7. Tropospheric Ozone Assessment Report: Database and Metrics Data of Global Surface Ozone Observations

    Directory of Open Access Journals (Sweden)

    Martin G. Schultz

    2017-10-01

    Full Text Available In support of the first Tropospheric Ozone Assessment Report (TOAR a relational database of global surface ozone observations has been developed and populated with hourly measurement data and enhanced metadata. A comprehensive suite of ozone data products including standard statistics, health and vegetation impact metrics, and trend information, are made available through a common data portal and a web interface. These data form the basis of the TOAR analyses focusing on human health, vegetation, and climate relevant ozone issues, which are part of this special feature. Cooperation among many data centers and individual researchers worldwide made it possible to build the world's largest collection of 'in-situ' hourly surface ozone data covering the period from 1970 to 2015. By combining the data from almost 10,000 measurement sites around the world with global metadata information, new analyses of surface ozone have become possible, such as the first globally consistent characterisations of measurement sites as either urban or rural/remote. Exploitation of these global metadata allows for new insights into the global distribution, and seasonal and long-term changes of tropospheric ozone and they enable TOAR to perform the first, globally consistent analysis of present-day ozone concentrations and recent ozone changes with relevance to health, agriculture, and climate. Considerable effort was made to harmonize and synthesize data formats and metadata information from various networks and individual data submissions. Extensive quality control was applied to identify questionable and erroneous data, including changes in apparent instrument offsets or calibrations. Such data were excluded from TOAR data products. Limitations of 'a posteriori' data quality assurance are discussed. As a result of the work presented here, global coverage of surface ozone data for scientific analysis has been significantly extended. Yet, large gaps remain in the surface

  8. Ultraviolet-Ozone Cleaning of Semiconductor Surfaces

    Science.gov (United States)

    1992-01-01

    streptococcus faecalis ) in water. UV/ozone has been used for the breakdown of PCBs (33). A combination of UV, ozone and hydrogen peroxide is used in...quartz tube that was evacuated and then backfilled with oxygen. The samples were irradiated with UV light from a medium -pressure mercury lamp that...five percent of the output of these lamps is at 184.9-nm. Medium - and high-pressure UV lamps (17) generally have a much higher output in the short

  9. Surface ozone in the White Mountains of California

    Science.gov (United States)

    Joel Burley; Andrzej Bytnerowicz

    2011-01-01

    Surface ozone concentrations are presented for four high-elevation sites along a northesouth transect along the spine of the White Mountains and a fifth site located at lower elevation approximately 15 km to the west on the floor of the Owens Valley. The ozone data, which were collected from mid-June through mid-October of 2009, include results from two sites, White...

  10. Climate change impacts on projections of excess mortality at 2030 using spatially varying ozone-temperature risk surfaces.

    Science.gov (United States)

    Wilson, Ander; Reich, Brian J; Nolte, Christopher G; Spero, Tanya L; Hubbell, Bryan; Rappold, Ana G

    2017-01-01

    We project the change in ozone-related mortality burden attributable to changes in climate between a historical (1995-2005) and near-future (2025-2035) time period while incorporating a non-linear and synergistic effect of ozone and temperature on mortality. We simulate air quality from climate projections varying only biogenic emissions and holding anthropogenic emissions constant, thus attributing changes in ozone only to changes in climate and independent of changes in air pollutant emissions. We estimate non-linear, spatially varying, ozone-temperature risk surfaces for 94 US urban areas using observed data. Using the risk surfaces and climate projections we estimate daily mortality attributable to ozone exceeding 40 p.p.b. (moderate level) and 75 p.p.b. (US ozone NAAQS) for each time period. The average increases in city-specific median April-October ozone and temperature between time periods are 1.02 p.p.b. and 1.94 °F; however, the results varied by region. Increases in ozone because of climate change result in an increase in ozone mortality burden. Mortality attributed to ozone exceeding 40 p.p.b. increases by 7.7% (1.6-14.2%). Mortality attributed to ozone exceeding 75 p.p.b. increases by 14.2% (1.6 28.9%). The absolute increase in excess ozone mortality is larger for changes in moderate ozone levels, reflecting the larger number of days with moderate ozone levels.

  11. Characterizing changes in surface ozone levels in metropolitan and rural areas in the United States for 1980-2008 and 1994-2008

    Science.gov (United States)

    Lefohn, Allen S.; Shadwick, Douglas; Oltmans, Samuel J.

    2010-12-01

    In this analysis, we characterize urban and rural ozone (O 3) trends across the US for the periods 1980-2008 (29 years) and 1994-2008 (15 years) using three exposure metrics, which summarize daily O 3 concentrations to reflect different ways O 3 may affect human health and vegetation. We observe that a statistically significant trend at a specific monitoring site, using one exposure metric, does not necessarily result in a similar trend using the other two metrics. The two most common trends among the monitoring sites are either a continuation of negative trending over the 29-year period or a shift from negative to no trend status, indicating a leveling off of the trending. Very few sites exhibit statistically significant increases in the exposure indices. In characterizing the statistically significant changes in the distribution of hourly average O 3, we observe subtle statistically significant changes in the lower part of the distribution (i.e., below 50 ppb) that are not necessarily captured by the trending patterns associated with the three exposure metrics. Using multisite data from 12 metropolitan cities, we find that as the frequency of higher hourly average concentrations is reduced, the lower hourly average concentrations also move upward toward the mid-level values. The change in the number of the hourly average concentrations in the lower range is consistent with decreased NO scavenging. We recommend assessing possible subtle shifts in O 3 concentrations by characterizing changes in the distribution of hourly average concentrations by month. Identifying statistically significant monthly changes in the mid- and low-level hourly average concentrations may provide important information for assessing changes in physical processes associated with global climate change, long-range transport, and the efficacy of models used for emission and risk reductions. Our results indicate that it is important to investigate the change in the trending pattern with time (e

  12. Ground-level ozone: Our new environmental policy

    International Nuclear Information System (INIS)

    Schiff, H.

    1991-01-01

    The environmental problem of ground level ozone is discussed, and the Canadian strategy for dealing with it is explained. Ozone in the troposphere can cause serious health problems in susceptible persons, and is estimated to cause up to $70 million in crop damage per year. The Canadian Council of Ministers of the Environment (CCME) Plan calls for less than 82 ppB by volume of ozone in any one-hour period in all areas of Canada by 2005. Three areas of Canada regularly exceed this value: the Lower Frazer valley in British Columbia, Saint John in New Brunswick, and the Windsor-Quebec corridor along the lower Great Lakes and the St. Lawrence River. Ozone is formed by a photochemical reaction of ammonia gases, nitrogen oxides, hydrogen sulfide or sulfur dioxide. Historically, ozone control has concentrated on controlling hydrocarbon emissions, but to little effect. In most locations close to large cities, ozone production is nitrogen oxide-limited, and the most recent models predict that the best strategy for ozone reduction requires the simultaneous reduction of both hydrocarbons and nitrogen oxides. The CCME Management Plan suggests that the 82 ppB ozone target will require a reduction of 40-50% in nitrogen oxide emissions. The Windsor end of the Windsor-Quebec corridor is dominated by transport of ozone and precursors from the USA, particularly Detroit and Cleveland, so Canadian controls alone are unlikely to solve the problem. For the rest of the corridor, nitrogen oxide control is likely to be most effective in urban areas. 1 fig

  13. Assessing control strategies for ground level ozone

    Science.gov (United States)

    Sule, Neelesh Vijay

    2009-12-01

    Developing cost effective control strategies for ozone has been a challenge to air quality modelers. Conventionally, the control strategies are applied across-the board to the region. The main aim of this research was to develop a Decision-Making Framework (DMF) for evaluating and optimizing the selection of ozone control strategies. Conventional across-the-board reductions conduct emission reductions uniformly throughout the region and throughout the day. By contrast, this dissertation studied targeted reductions, in which emission sources of various types are reduced at various times and locations. The proposed DMF comprised of four phases: (1) Initialization, (2) Mining, (3) Metamodeling, and (4) Optimization. This DMF was tested on a DFW 2009 future case episode which was based on a 10-day episode from August 13-22, 1999. 612 emission variables were identified in three source categories viz. point, area (includes non-road) and line (on-road). The emission control regions and time periods along with ozone monitoring regions and time periods were defined. The control strategy emission reductions and costs were also identified in this stage. Initially a Latin hypercube experimental design was setup to organize 30 sets of emission reduction scenarios to be modeled using the photochemical model CAMx. Data mining reduced the number of variables to a maximum of 126. A second Latin hypercube was setup to organize another 30 emission reduction scenarios for the significant variables identified by data mining. Metamodels were developed for ozone from the 60 CAMx runs using linear regression models constructed with the stepwise model selection method. Stepwise regression further reduced the number of variables. The metamodels were implemented in optimization as a surrogate for time-intensive CAMx modeling. Appropriate constraints were calculated for each metamodel to ensure that it satisfied EPA's MAT. The optimization was formulated to find the most cost effective

  14. Ozone time scale decomposition and trend assessment from surface observations

    Science.gov (United States)

    Boleti, Eirini; Hueglin, Christoph; Takahama, Satoshi

    2017-04-01

    Emissions of ozone precursors have been regulated in Europe since around 1990 with control measures primarily targeting to industries and traffic. In order to understand how these measures have affected air quality, it is now important to investigate concentrations of tropospheric ozone in different types of environments, based on their NOx burden, and in different geographic regions. In this study, we analyze high quality data sets for Switzerland (NABEL network) and whole Europe (AirBase) for the last 25 years to calculate long-term trends of ozone concentrations. A sophisticated time scale decomposition method, called the Ensemble Empirical Mode Decomposition (EEMD) (Huang,1998;Wu,2009), is used for decomposition of the different time scales of the variation of ozone, namely the long-term trend, seasonal and short-term variability. This allows subtraction of the seasonal pattern of ozone from the observations and estimation of long-term changes of ozone concentrations with lower uncertainty ranges compared to typical methodologies used. We observe that, despite the implementation of regulations, for most of the measurement sites ozone daily mean values have been increasing until around mid-2000s. Afterwards, we observe a decline or a leveling off in the concentrations; certainly a late effect of limitations in ozone precursor emissions. On the other hand, the peak ozone concentrations have been decreasing for almost all regions. The evolution in the trend exhibits some differences between the different types of measurement. In addition, ozone is known to be strongly affected by meteorology. In the applied approach, some of the meteorological effects are already captured by the seasonal signal and already removed in the de-seasonalized ozone time series. For adjustment of the influence of meteorology on the higher frequency ozone variation, a statistical approach based on Generalized Additive Models (GAM) (Hastie,1990;Wood,2006), which corrects for meteorological

  15. Variability of surface ozone with cloud coverage over Kolkata, India

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 124; Issue 2. Variability of surface ozone with cloud coverage over Kolkata, India. D Ghosh ... Engineering, Jadavpur University, Jadavpur, Kolkata 700 032, India. Department of Atmospheric Sciences, Calcutta University, 92, A.P.C. Road, Kolkata 700 009, India.

  16. Surface ozone exposures measured at clean locations around the world.

    Science.gov (United States)

    Lefohn, A S; Krupa, S V; Winstanley, D

    1990-01-01

    For assessing the effects of air pollution on vegetation, some researchers have used control chambers as the basis of comparison between crops and trees grown in contemporary polluted rural locations and those grown in a clean environment. There has been some concern whether the arbitrary ozone level of 0.025 ppm and below, often used in charcoal-filtration chambers to simulate the natural background concentration of ozone, is appropriate. Because of the many complex and man-made factors that influence ozone levels, it is difficult to determine natural background. To identify a range of ozone exposures that occur at 'clean' sites, we have calculated ozone exposures observed at a number of 'clean' monitoring sites located in the United States and Canada. We do not claim that these sites are totally free from human influence, but rather than the ozone concentrations observed at these 'clean' sites may be appropriate for use by vegetation researchers in control chambers as pragmatic and defensible surrogates for natural background. For comparison, we have also calculated ozone exposures observed at four 'clean' remote sites in the Northern and Southern Hemispheres and at two remote sites (Whiteface Mountain, NY and Hohenpeissenberg, FRG) that are considered to be more polluted. Exposure indices relevant for describing the relationship between ozone and vegetation effects were applied. For studying the effects of ozone on vegetation, the higher concentrations are of interest. The sigmoidally-weighted index appeared to best separate those sites that experienced frequent high concentration exposures from those that experienced few high concentrations. Although there was a consistent seasonal pattern for the National Oceanic and Atmospheric Administration (NOAA) Geophysical Monitoring for Climate Change (GMCC) sites indicating a winter/spring maximum, this was not the case for the other remote sites. Some sites in the continental United States and southern Canada

  17. BUV/Nimbus-4 Level 2 Compressed Ozone Profile Data V005 (BUVN4L2CPOZ) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus-4 BUV Level 2 Compressed Ozone Profile Data collection or CPOZ contains total ozone, reflectivities, ozone mixing ratios and layer ozone amounts measured...

  18. Regional trend analysis of surface ozone observations from monitoring networks in eastern North America, Europe and East Asia

    Science.gov (United States)

    Chang, K. L.; Petropavlovskikh, I. V.; Cooper, O. R.; Schultz, M.; Wang, T.

    2017-12-01

    Surface ozone is a greenhouse gas and pollutant detrimental to human health and crop and ecosystem productivity. The Tropospheric Ozone Assessment Report (TOAR) is designed to provide the research community with an up-to-date observation-based overview of tropospheric ozone's global distribution and trends. The TOAR Surface Ozone Database contains ozone metrics at thousands of monitoring sites around the world, densely clustered across mid-latitude North America, western Europe and East Asia. Calculating regional ozone trends across these locations is challenging due to the uneven spacing of the monitoring sites across urban and rural areas. To meet this challenge we conducted a spatial and temporal trend analysis of several TOAR ozone metrics across these three regions for summertime (April-September) 2000-2014, using the generalized additive mixed model (GAMM). Our analysis indicates that East Asia has the greatest human and plant exposure to ozone pollution among investigating regions, with increasing ozone levels through 2014. The results also show that ozone mixing ratios continue to decline significantly over eastern North America and Europe, however, there is less evidence for decreases of daytime average ozone at urban sites. The present-day spatial coverage of ozone monitors in East Asia (South Korea and Japan) and eastern North America is adequate for estimating regional trends by simply taking the average of the individual trends at each site. However the European network is more sparsely populated across its northern and eastern regions and therefore a simple average of the individual trends at each site does not yield an accurate regional trend. This analysis demonstrates that the GAMM technique can be used to assess the regional representativeness of existing monitoring networks, indicating those networks for which a regional trend can be obtained by simply averaging the trends of all individual sites and those networks that require a more

  19. Strategy for reducing ozone levels in the northeast United States

    International Nuclear Information System (INIS)

    Bradley, M.

    1992-01-01

    In the northeast USA, ozone episodes are frequent during the summer; most of these episodes last 3-4 days. The duration and frequency of these episodes is mainly determined by weather conditions. The persistence of ozone episodes in the region is explained by the fact that emissions of ozone precursors (nitrogen oxides (NOx) and volatile organic compounds (VOC)) are like those of other regions of the USA affected by acute ozone problems. The population density, industry, and use of automobiles are other factors contributing to the difficulty of maintaining acceptable ozone levels. The ozone problem is especially severe in the New York metropolitan area and most of New Jersey. Strategies for combating ozone precursors have relied entirely on reducing emissions of VOCs, while little has been done to reduce NOx, except for automobile emissions. The Clean Air Act of 1990 provides for significant reductions of NOx and VOC from mobile sources and insists on VOC emissions reductions from stationary sources. In California, stricter emission standards for VOC and NOx have been implemented for new vehicles, requiring wider use of low- or zero-emission vehicles. The Northeast States for Coordinated Air Use Management (NESCAUM) organization, formed by the state agencies responsible for air quality, is aiding the northeast states to evaluate the advantages of adopting California standards for vehicles. Twelve northeast states propose to adopt the Californian low-emission vehicle program and are examining other options such as reformulated gasolines, improved maintenance and verification programs, and measures to reduce the number of miles travelled. 1 fig., 1 tab

  20. Variability of surface ozone with cloud coverage over Kolkata, India

    Indian Academy of Sciences (India)

    3Department of Atmospheric Sciences, Calcutta University, 92, A.P.C. Road, Kolkata 700 009, India. ∗. Corresponding author. e-mail: .... 2004). Kolkata also experiences substan- tial level of pollution from automobiles (Mallik et al. ... from Ozone Monitoring Instrument (OMI) onboa rd the Aura satellite. This study employs the ...

  1. Report card on low level ozone in urban areas

    International Nuclear Information System (INIS)

    Onischak, M.

    1994-01-01

    It has been four years since the Clean Air Act was amended in November of 1990. Much work has been done in this time, and the country is beginning to see real air quality benefits. Although these changes have not completely licked the urban ozone problem yet, they have made a lot of progress. All of the urban areas which have been required to reduce their ozone levels have done a good job of lowering their emissions. While the urban areas have not all been able to meet every federal deadline, the areas have all been able to achieve the control milestones before the mandatory Clean Air Act sanctions have taken effect. Some areas are even ready to declare their ozone problems solved

  2. Report card on low level ozone in urban areas

    Energy Technology Data Exchange (ETDEWEB)

    Onischak, M.

    1994-12-31

    It has been four years since the Clean Air Act was amended in November of 1990. Much work has been done in this time, and the country is beginning to see real air quality benefits. Although these changes have not completely licked the urban ozone problem yet, they have made a lot of progress. All of the urban areas which have been required to reduce their ozone levels have done a good job of lowering their emissions. While the urban areas have not all been able to meet every federal deadline, the areas have all been able to achieve the control milestones before the mandatory Clean Air Act sanctions have taken effect. Some areas are even ready to declare their ozone problems solved.

  3. Effect of ambient levels of ozone on photosynthetic components and ...

    African Journals Online (AJOL)

    Effect of ambient levels of ozone on photosynthetic components and radical scavenging system in leaves of African cowpea varieties. ... The O3-induced significant reduction in catalase activity was observed in Blackeye at vegetative and reproductive growth stages; and in Asontem at reproductive growth stage. On the other ...

  4. Ozone-surface reactions in five homes: surface reaction probabilities, aldehyde yields, and trends.

    Science.gov (United States)

    Wang, H; Morrison, G

    2010-06-01

    Field experiments were conducted in five homes during three seasons (summer 2005, summer 2006 and winter 2007) to quantify ozone-initiated secondary aldehyde yields, surface reaction probabilities, and trends any temporal over a 1.5-year interval. Surfaces examined include living room carpets, bedroom carpets, kitchen floors, kitchen counters, and living room walls. Reaction probabilities for all surfaces for all seasons ranged from 9.4 x 10(-8) to 1.0 x 10(-4). There were no significant temporal trends in reaction probabilities for any surfaces from summer 2005 to summer 2006, nor over the entire 1.5-year period, indicating that it may take significantly longer than this period for surfaces to exhibit any 'ozone aging' or lowering of ozone-surface reactivity. However, all surfaces in three houses exhibited a significant decrease in reaction probabilities from summer 2006 to winter 2007. The total yield of aldehydes for the summer of 2005 were nearly identical to that for summer of 2006, but were significantly higher than for winter 2007. We also observed that older carpets were consistently less reactive than in newer carpets, but that countertops remained consistently reactive, probably because of occupant activities such as cooking and cleaning. Ozone reactions taking place at indoor surfaces significantly influence personal exposure to ozone and volatile reaction products. These field studies show that indoor surfaces only slowly lose their ability to react with ozone over several year time frames, and that this is probably because of a combination of large reservoirs of reactive coatings and periodic additions of reactive coatings in the form of cooking, cleaning, and skin-oil residues. When considering exposure to ozone and its reaction products and in the absence of dramatic changes in occupancy, activities or furnishings, indoor surface reactivity is expected to change very slowly.

  5. Nocturnal surface ozone enhancement over Portugal during winter: Influence of different atmospheric conditions

    KAUST Repository

    Kulkarni, Pavan S.

    2016-09-24

    Four distinct nocturnal surface ozone (NSO) enhancement events were observed, with NSO concentration exceeding 80μg/m3, at multiple ozone (O3) monitoring stations (32 sites) in January, November and December between year 2000–2010, in Portugal. The reasonable explanation for the observed bimodal pattern of surface ozone with enhanced NSO concentration during nighttime has to be transport processes, as the surface ozone production ceases at nighttime. Simultaneous measurements of O3 at multiple stations during the study period in Portugal suggest that horizontal advection alone cannot explain the observed NSO enhancement. Thus, detailed analysis of the atmospheric conditions, simulated with the Weather Research and Forecasting (WRF) model, were performed to evaluate the atmospheric mechanisms responsible for NSO enhancement in the region. Simulations revealed that each event occurred as a result of one or the combination of different atmospheric processes such as, passage of a cold front followed by a subsidence zone; passage of a moving surface trough, with associated strong horizontal wind speed and vertical shear; combination of vertical and horizontal transport at the synoptic scale; formation of a low level jet with associated vertical mixing below the jet stream. The study confirmed that large-scale flow pattern resulting in enhanced vertical mixing in the nocturnal boundary layer, plays a key role in the NSO enhancement events, which frequently occur over Portugal during winter months. © 2016 Elsevier Ltd

  6. Relationship between surface, free tropospheric and total column ozone in 2 contrasting areas in South-Africa

    CSIR Research Space (South Africa)

    Combrink, J

    1995-04-01

    Full Text Available Measurements of surface ozone in two contrasting areas of South Africa are compared with free tropospheric and Total Ozone Mapping Spectrometer (TOMS) total column ozone data. Cape Point is representative of a background monitoring station which...

  7. Surface ozone measurements in the southwest of the Iberian Peninsula (Huelva, Spain).

    Science.gov (United States)

    Carnero, Jose A Adame; Bolívar, Juan P; de la Morena, Benito A

    2010-02-01

    Photochemical ozone pollution of the lower troposphere (LT) is a very complex process involving meteorological, topographic emissions and chemical parameters. Ozone is considered the most important air pollutant in rural, suburban and industrial areas of many sites in the world since it strongly affects human health, vegetation and forest ecosystems, and its increase during the last decades has been significant. In addition, ozone is a greenhouse gas that contributes to climate change. For these reasons, it is necessary to carry out investigations that determine the behaviour of ozone at different locations. The aim of this work is to understand the levels and temporal variations of surface ozone in an industrial-urban region of the Southwest Iberian Peninsula. The study is based on ozone hourly data recorded during a 6-year period, 2000 to 2005 at four stations and meteorological data from a coastal station. The stations used were El Arenosillo and Cartaya--both coastal stations, Huelva--an urban site and Valverde--an inland station 50 km away from the coastline. The general characteristics of the ozone series, seasonal and daily ozone cycles as well as number of exceedances of the threshold established in the European Ozone Directive have been calculated and analysed. Analysis of the meteorological data shows that winter-autumn seasons are governed by the movement of synoptic weather systems; however, in the spring-summer seasons, both synoptic and mesoescale conditions exist. Average hourly ozone concentrations range from 78.5 +/- 0.1 microg m(-3) at Valverde to 57.8 +/- 0.2 microg m(-3) at Huelva. Ozone concentrations present a seasonal variability with higher values in summer months, while in wintertime, lower values are recorded. A seasonal daily evolution has also been found with minimum levels around 08:00 UTC, which occurs approximately 1-1.5 h after sunrise, whereas the maximum is reached at about 16:00 UTC. Furthermore, during summer, the maximum value

  8. Surface ozone scenario at Pune and Delhi during the decade of 1990s

    Indian Academy of Sciences (India)

    Transport mechanism is also understood to have contributed significantly to the total concentration of ozone. Inverse relationship obtained between surface ozone concentration and relative humidity indicates that major photochemical paths for removal of ozone become effective when humidity increases at these locations.

  9. Investigating ozone-induced decomposition of surface-bound permethrin for conditions in aircraft cabins.

    Science.gov (United States)

    Coleman, B K; Wells, J R; Nazaroff, W W

    2010-02-01

    The reaction of ozone with permethrin can potentially form phosgene. Published evidence on ozone levels and permethrin surface concentrations in aircraft cabins indicated that significant phosgene formation might occur in this setting. A derivatization technique was developed to detect phosgene with a lower limit of detection of 2 ppb. Chamber experiments were conducted with permethrin-coated materials (glass, carpet, seat fabric, and plastic) exposed to ozone under cabin-relevant conditions (150 ppb O(3), 4.5/h air exchange rate, means of material-balance modeling indicates that the upper limit on the phosgene level in aircraft cabins resulting from this chemistry is approximately 1 microg/m(3) or approximately 0.3 ppb. It was thus determined that phosgene formation, if it occurs in aircraft cabins, is not likely to exceed relevant, health-based phosgene exposure guidelines. Phosgene formation from ozone-initiated oxidation of permethrin in the aircraft cabin environment, if it occurs, is estimated to generate levels below the California Office of Environmental Health Hazard Assessment acute reference exposure level of 4 microg/m(3) or approximately 1 ppb.

  10. Assessing spatial occurrence of ground level ozone around coal mining areas of Chandrapur District, Maharashtra, India.

    Science.gov (United States)

    Salve, Pradeep R; Satapathy, Deepty Ranjan; Katpatal, Yashwant B; Wate, Satish R

    2007-10-01

    Stratospheric input and photochemical ozone formation in the troposphere are the two main sources determining the ozone levels in the surface layer of the atmosphere. Because of the importance of ozone in controlling the atmospheric chemistry and its decisive role in the heat balance of atmosphere, leading to climate change, the examination of its formation and destruction are of great interest. This study characterized the distribution of Ground level Ozone (GLO) in Chandrapur district is lying between 19 degrees 25'N to 20 degrees 45'N and 78 degrees 50'E to 80 degrees 10'E. Continuous ozone analyzer was used to quantify GLO at thirteen locations fixed by Global Positioning System (GPS) during the winter of 2005-2006. The daily GLO at all the locations ranged between 6.4 and 24.8 ppbv with an average and standard deviation of 14.9 +/- 6.5 ppbv. The maximum and minimum concentration occurs during 1300-1600 h and 0300-0500 h may be due to high solar radiation facilitating photochemical production of O(3) and downward mixing from the overlying air mass and in situ destruction of ozone by deposition and/or the reaction between O(3) and NO. GIS based spatial distribution of GLO in Chandrapur district is indicates that the central core of the district and southern sites experienced elevated levels of GLO relative to the northern and western areas. The sites near by Chandrapur city are particularly affected by elevated GLO. The average variation of GLO with temperature shows a significant correlation of r = 0.55 indicating a direct relationship between GLO and temperature. Similarly an attempt has been made to compare the GLO monitored data in Chandrapur district with the reported values for other locations in Indian cities. This generated database helps regulatory agencies to identify locations where the natural resources and human health could be at risk.

  11. RNA-Seq study reveals genetic responses of diverse wild soybean accessions to increased ozone levels.

    Science.gov (United States)

    Waldeck, Nathan; Burkey, Kent; Carter, Thomas; Dickey, David; Song, Qijian; Taliercio, Earl

    2017-06-29

    Ozone is an air pollutant widely known to cause a decrease in productivity in many plant species, including soybean (Glycine max (L.) Merr). While the response of cultivated soybean to ozone has been studied, very little information is available regarding the ozone response of its wild relatives. Ozone-resistant wild soybean accessions were identified by measuring the response of a genetically diverse group of 66 wild soybean (Glycine soja Zucc. and Sieb.) accessions to elevated ozone levels. RNA-Seq analyses were performed on leaves of different ages from selected ozone-sensitive and ozone-resistant accessions that were subjected to treatment with an environmentally relevant level of ozone. Many more genes responded to elevated ozone in the two ozone-sensitive accessions than in the ozone-resistant accessions. Analyses of the ozone response genes indicated that leaves of different ages responded differently to ozone. Older leaves displayed a consistent reduction in expression of genes involved in photosynthesis in response to ozone, while changes in expression of defense genes dominated younger leaf tissue in response to ozone. As expected, there is a substantial difference between the response of ozone-sensitive and ozone-resistant accessions. Genes associated with photosystem 2 were substantially reduced in expression in response to ozone in the ozone-resistant accessions. A decrease in peptidase inhibitors was one of several responses specific to one of the ozone resistant accessions. The decrease in expression in genes associated with photosynthesis confirms that the photosynthetic apparatus may be an early casualty in response to moderate levels of ozone. A compromise of photosynthesis would substantially impact plant growth and seed production. However, the resistant accessions may preserve their photosynthetic apparatus in response to the ozone levels used in this study. Older leaf tissue of the ozone-resistant accessions showed a unique down-regulation of

  12. Convective storms and non-classical low-level jets during high ozone level episodes in the Amazon region: An ARM/GOAMAZON case study

    Science.gov (United States)

    Dias-Junior, Cléo Q.; Dias, Nelson Luís; Fuentes, José D.; Chamecki, Marcelo

    2017-04-01

    In this work, we investigate the ozone dynamics during the occurrence of both downdrafts associated with mesoscale convective storms and non-classical low-level jets. Extensive data sets, comprised of air chemistry and meteorological observations made in the Amazon region of Brazil over the course of 2014-15, are analyzed to address several questions. A first objective is to investigate the atmospheric thermodynamic and dynamic conditions associated with storm-generated ozone enhancements in the Amazon region. A second objective is to determine the magnitude and the frequency of ground-level ozone enhancements related to low-level jets. Ozone enhancements are analyzed as a function of wind shear, low-level jet maximum wind speed, and altitude of jet core. Strong and sudden increases in ozone levels are associated with simultaneous changes in variables such as horizontal wind speed, convective available potential energy, turbulence intensity and vertical velocity skewness. Rapid increases in vertical velocity skewness give support to the hypothesis that the ozone enhancements are directly related to downdrafts. Low-level jets associated with advancing density currents are often present during and after storm downdrafts that transport ozone-enriched air from aloft to the surface.

  13. A model study of the Eastern Mediterranean ozone levels during the hot summer of 2007

    Science.gov (United States)

    Hodnebrog, Ø.; Solberg, S.; Stordal, F.; Svendby, T. M.; Simpson, D.; Gauss, M.; Hilboll, A.; Pfister, G. G.; Turquety, S.; Richter, A.; Burrows, J. P.; Denier van der Gon, H. A. C.

    2012-03-01

    The hot summer of 2007 in Southeast Europe has been studied using two regional atmospheric chemistry models; WRF-Chem and EMEP MSC-W. The region was struck by three heat waves and a number of forest fire episodes, greatly affecting air pollution levels. We have focused on ozone and its precursors using state-of-the-art inventories for anthropogenic, biogenic and forest fire emissions. The models have been evaluated against measurement data, and processes leading to ozone formation have been quantified. Heat wave episodes are projected to occur more frequently in a future climate, and therefore this study also makes a contribution to climate change research. The plume from the Greek forest fires in August 2007 is clearly seen in satellite observations of CO and NO2 columns, showing extreme levels of CO in and downwind of the fires. Model simulations reflect the location and influence of the fires relatively well, but the modelled magnitude of CO in the plume core is too low. Most likely, this is caused by underestimation of CO in the emission inventories, suggesting that the CO/NOx ratios of fire emissions should be re-assessed. Moreover, higher maximum values are seen in WRF-Chem than in EMEP MSC-W, presumably due to differences in plume rise altitudes as the first model emits a larger fraction of the fire emissions in the lowermost model layer. The model results are also in fairly good agreement with surface ozone measurements. Biogenic VOC emissions reacting with anthropogenic NOx emissions are calculated to contribute significantly to the levels of ozone in the region, but the magnitude and geographical distribution depend strongly on the model and biogenic emission module used. During the July and August heat waves, ozone levels increased substantially due to a combination of forest fire emissions and the effect of high temperatures. We found that the largest temperature impact on ozone was through the temperature dependence of the biogenic emissions, closely

  14. Estimating contribution of wildland fires to ambient ozone levels in National Parks in the Sierra Nevada, California

    Science.gov (United States)

    Haiganoush K. Preisler; Shiyuan (Sharon) Zhong; Annie Esperanza; Timothy J. Brown; Andrzej Bytnerowicz; Leland Tarnay

    2010-01-01

    Data from four continuous ozone and weather monitoring sites operated by the National Park Service in Sierra Nevada, California, are used to develop an ozone forecasting model and to estimate the contribution of wildland fires on ambient ozone levels. The analyses of weather and ozone data pointed to the transport of ozone precursors from the Central Valley as an...

  15. BUV/Nimbus-4 Level 3 Ozone Zonal Means V005 (BUVN4L3ZMT) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus-4 BUV Level 3 Ozone Zonal Means collection or ZMT contains total ozone, reflectivities, and ozone mixing ratios averaged in 10 degree latitude zones...

  16. Semiconductor Sensors Application for Definition of Factor of Ozone Heterogeneous Destruction on Teflon Surface

    Directory of Open Access Journals (Sweden)

    Nataliya V. Finogenova

    2003-12-01

    Full Text Available In our paper we present the results of our research, which was carried out by means of semiconductor sensor techniques (SCS, which allowed evaluating heterogeneous death-rate of ozone (γ Teflon surface. When ozone concentration is near to Ambient Air Standard value, γ is assessed to be equal to 6,57*10-7. High technique response provide possibility to determine ozone contents in the air media and the percentage of ozone, decomposed on the communication surfaces and on the surfaces of installation in the low concentration range (1–100 ppb.

  17. Effects of trans-Eurasian transport of anthropogenic pollutants on surface ozone concentrations over China

    Science.gov (United States)

    Liu, J.; Li, X.; Mauzerall, D. L.; Emmons, L. K.; Horowitz, L. W.; Guo, Y.; Tao, S.

    2015-12-01

    Due to a lack of industrialization in Western China, surface air there was, until recently, believed to be relatively unpolluted. However, recent measurements and modeling studies have found high levels of ozone (O3) there. Based on the state-of-the-science global chemical transport model MOZART-4, we identify the origin, pathway, and mechanism of trans-Eurasian transport of air pollutants to Western China in 2000. MOZART-4 generally simulates well the observed surface O3 over inland areas of China. Simulations find surface ozone concentrations over Western China on average to be about 10 ppbv higher than Eastern China. Using sensitivity studies as well as a fully-tagged approach, we find that anthropogenic emissions from all Eurasian regions except China contribute 10-15 ppbv surface O3 over Western China, superimposed upon a 35-40 ppbv natural background. Transport from European anthropogenic sources to Northwestern China results in 2-6 ppbv O3 enhancements in spring and summer. Indian anthropogenic sources strongly influence O3 over the Tibetan Plateau during the summer monsoon. Transport of O3 originating from emissions in the Middle East occasionally reach Western China and increase surface ozone there by about 1-4 ppbv. These influences are of similar magnitude as trans-Pacific and transatlantic transport of O3 and its precursors, indicating the significance of trans-Eurasian ozone transport in hemispheric transport of air pollution. Our study further indicates that mitigation of anthropogenic emissions from Europe, the Indian subcontinent, and the Middle East could benefit public health and agricultural productivity in Western China.

  18. Impacts of Climate Change on Surface Ozone and Intercontinental Ozone Pollution: A Multi-Model Study

    Science.gov (United States)

    Doherty, R. M.; Wild, O.; Shindell, D. T.; Zeng, G.; MacKenzie, I. A.; Collins, W. J.; Fiore, A. M.; Stevenson, D. S.; Dentener, F. J.; Schultz, M. G.; hide

    2013-01-01

    The impact of climate change between 2000 and 2095 SRES A2 climates on surface ozone (O)3 and on O3 source-receptor (S-R) relationships is quantified using three coupled climate-chemistry models (CCMs). The CCMs exhibit considerable variability in the spatial extent and location of surface O3 increases that occur within parts of high NOx emission source regions (up to 6 ppbv in the annual average and up to 14 ppbv in the season of maximum O3). In these source regions, all three CCMs show a positive relationship between surface O3 change and temperature change. Sensitivity simulations show that a combination of three individual chemical processes-(i) enhanced PAN decomposition, (ii) higher water vapor concentrations, and (iii) enhanced isoprene emission-largely reproduces the global spatial pattern of annual-mean surface O3 response due to climate change (R2 = 0.52). Changes in climate are found to exert a stronger control on the annual-mean surface O3 response through changes in climate-sensitive O3 chemistry than through changes in transport as evaluated from idealized CO-like tracer concentrations. All three CCMs exhibit a similar spatial pattern of annual-mean surface O3 change to 20% regional O3 precursor emission reductions under future climate compared to the same emission reductions applied under present-day climate. The surface O3 response to emission reductions is larger over the source region and smaller downwind in the future than under present-day conditions. All three CCMs show areas within Europe where regional emission reductions larger than 20% are required to compensate climate change impacts on annual-mean surface O3.

  19. Surface ozone seasonality under global change: Influence from dry deposition and isoprene emissions at northern mid-latitudes

    Science.gov (United States)

    Clifton, O.; Paulot, F.; Fiore, A. M.; Horowitz, L. W.; Malyshev, S.; Shevliakova, E.; Correa, G. J. P.; Lin, M.

    2017-12-01

    Identifying the contributions of nonlinear chemistry and transport to observed surface ozone seasonal cycles over land using global models relies on an accurate representation of ozone uptake by vegetation (dry deposition). It is well established that in the absence of ozone precursor emission changes, a warming climate will increase surface ozone in polluted regions, and that a rise in temperature-dependent isoprene emissions would exacerbate this "climate penalty". However, the influence of changes in ozone dry deposition, expected to evolve with climate and land use, is often overlooked in air quality projections. With a new scheme that represents dry deposition within the NOAA GFDL dynamic vegetation land model (LM3) coupled to the NOAA GFDL atmospheric chemistry-climate model (AM3), we simulate the impact of 21st century climate and land use on ozone dry deposition and isoprene emissions. This dry deposition parameterization is a version of the Wesely scheme, but uses parameters explicitly calculated by LM3 that respond to climate and land use (e.g., stomatal conductance, canopy interception of water, leaf area index). The parameterization includes a nonstomatal deposition dependence on humidity. We evaluate climatological present-day seasonal cycles of ozone deposition velocities and abundances with those observed at northern mid-latitude sites. With a set of 2010s and 2090s decadal simulations under a high climate warming scenario (RCP8.5) and a sensitivity simulation with well-mixed greenhouse gases following RCP8.5 but air pollutants held at 2010 levels (RCP8.5_WMGG), we examine changes in surface ozone seasonal cycles. We build on our previous findings, which indicate that strong reductions in anthropogenic NOx emissions under RCP8.5 cause the surface ozone seasonal cycle over the NE USA to reverse, shifting from a summer peak at present to a winter peak by 2100. Under RCP8.5_WMGG, we parse the separate effects of climate and land use on ozone dry

  20. Surface modification of carbon nanohorns by helium plasma and ozone treatments

    Science.gov (United States)

    Lin, Zaw; Iijima, Toru; Selvam Karthik, Paneer; Yoshida, Mitsunobu; Hada, Masaki; Nishikawa, Takeshi; Hayashi, Yasuhiko

    2017-01-01

    In this paper, we describe the effects of helium plasma and ozone treatments on the dispersibility of carbon nanohorns (CNHs) in water. The experimental setups have been designed to efficiently generate helium plasma and ozone by dielectric barrier discharge at atmospheric pressure. After being treated with ozone, the oxygen-containing functional groups were introduced to the surface of CNHs, and are responsible for better dispersion. Helium plasma treatment was performed separately and it resulted in hydroxyl functional groups on the surface of CNHs. It was also found that the sizes of CNHs in water were smaller after ozone treatment. However, plasma-treated CNHs were bigger than ozone treated CNHs. The dispersed CNHs modified by ozone treatment were stable for more than three months without precipitation. In contrast, though helium plasma treatment introduced hydroxyl groups to the surface of CNHs, the dispersibility decreased and the flocculation of CNHs was observed in a few minutes.

  1. The lake breeze-ground-level ozone connection in eastern Wisconsin: a climatological perspective

    Science.gov (United States)

    Lennartson, G. Jay; Schwartz, Mark D.

    2002-09-01

    The Lake Michigan Air Quality Region (LMAQR) experiences exceedances of the 1 h health standard for ozone numerous times each summer. Previous short-term investigations have revealed that the lake breeze circulation is connected with very high levels of ozone in eastern Wisconsin (EWI). Findings from one of the more recent short-term research efforts have led to the development of a generalized conceptual model that details the role that the lake breeze circulation plays in transporting ozone-rich air of the Lake Michigan conduction layer onshore to EWI. Short-term studies, however, are limited by the small number of cases examined. To understand the ozone-lake breeze relationship from a climatological perspective, we analysed the spatial and temporal pattern of 1 h ozone exceedances in EWI during the months of May through to September, over the period 1985-99. Further, we used Laird et al.'s recently developed technique for discriminating lake breeze days to determine which exceedance-days over the period of our climatology occurred in association with lake breezes.Our results show: (1) a decrease in both magnitude and frequency of exceedances of the 1 h ozone standard in EWI with increasing distance from the lakeshore; (2) a positive correlation between average onset time of the initial exceedance-hour and a site's distance from Lake Michigan; (3) a very high percentage of initial exceedance-hours occurring in association with southeasterly surface air flow; and (4) exceedances occurring in association with lake breezes 82.1% of the time at near-shore sites.Collectively, our findings provide strong evidence that the lake breeze circulation is closely associated with the distribution of ozone in EWI in both space and time. Moreover, our results show that the lake breeze circulation is directly associated with a significant proportion of the exceedances of the 1 h ozone standard in EWI-particularly at near-shore sites. Thus, mandated reductions in regional

  2. Fractal and variability analysis of simulations in ozone level due to oxides of nitrogen and sulphur

    Science.gov (United States)

    Bhardwaj, Rashmi; Pruthi, Dimple

    2017-10-01

    Air pollution refers to the release of pollutants into the air. These pollutants are detrimental to human the planet as a whole. Apart from causing respiratory infections and pulmonary disorders, rising levels of Nitrogen Dioxide is worsening ozone pollution. Formation of Ground-level ozone involves nitrogen oxides and volatile gases in the sunlight. Volatile gases are emitted from vehicles primarily. Ozone is harmful gas and its exposure can trigger serious health effects as it damages lung tissues. In order to decrease the level of ozone, level of oxides leading to ozone formation has to be dealt with. This paper deals with the simulations in ozone due to oxides of nitrogen and sulphur. The data from Central Pollution Control Board shows positive correlation for ozone with oxides of sulphur and nitrogen for RK Puram, Delhi in India where high concentration of ozone has been found. The correlation between ozone and sulphur, nitrogen oxides is moderate during summer while weak during winters. Ozone with nitrogen and sulphur dioxide follow persistent behavior as Hurst exponent is between 0.5 and 1. The fractal dimension for Sulphur dioxide is 1.4957 indicating the Brownian motion. The behavior of ozone is unpredictable as index of predictability is close to zero.

  3. Influence of baseline ozone on surface air quality in the western U.S

    Science.gov (United States)

    Jaffe, D. A.; Downey, N.

    2011-12-01

    As the ozone air quality standard is made more stringent, cities, counties and states will need a better understanding of the sources of ozone. While Eulerian models can provide important indications of the sources, they are often challenged by episodic emissions (eg wildfires), interannual variability and/or coarse model resolution. These challenges are especially problematic in the western United States. Thus we need improved tools to directly use available observations to better understand and identify ozone sources. In this study we examine the relationship between measured free tropospheric/baseline ozone and surface ozone at several receptor sites in the western U.S. Our focus is on air quality sites in the Pacific Northwest and Rocky Mtn region that exceed current or new air quality standards that have been proposed. Elevated sites in the Rocky Mtns are exposed to high ozone from the free troposphere. Significant interannual variations occur in spring, due to variations in baseline ozone, and in summer, due to variations in wildfires. In the Rocky Mtn region there are significant correlations between the surface and free tropospheric mixing ratios using both daily and monthly means for spring and summer months (see Jaffe 2011; DOI: 10.1021/es1028102). This implies that free tropospheric ozone mixes down and frequently contributes to elevated ozone at the surface. In the Pacific Northwest, we are using data from suburban and rural monitoring locations to identify ozone from local and non-local sources. The approach for both the Rocky Mtn and Pacific Northwest sites is to develop a statistical model for ozone using all available observations, (e.g. PM, meteorology, satellite data and trajectories) to quantify the variable contribution from baseline ozone. The statistical model can then be evaluated against actual observations of baseline ozone. The statistical model can also be useful to help identify "exceptional events" as defined by the US EPA.

  4. Variations of surface ozone concentration across the Klang Valley, Malaysia

    Science.gov (United States)

    Latif, Mohd Talib; Huey, Lim Shun; Juneng, Liew

    2012-12-01

    Hourly air quality data covering the period 2004-2008 was obtained from the Air Quality Division, the Department of Environment (DOE) through long-term monitoring by Alam Sekitar Sdn. Bhd. (ASMA) were analysed to investigate the variations of surface ozone (O3) in the Klang Valley, Malaysia. A total of nine monitoring stations were selected for analysis in this study and the results show that there are distinct seasonal patterns in the surface O3 across the Klang Valley. A high surface O3 concentration is usually observed between January and April, while a low surface O3 concentration is found between June and August. Analysis of daily variations in surface O3 and the precursors - NO, NO2, CO, NMHC and UVb, indicate that the surface O3 photochemistry in this study area exhibits a positive response to the intensity and wavelength in UVb while being influenced by the concentration of NOx, particularly through tritration processes. Although results from our study suggested that NMHCs may influence the maximum O3 concentration, further investigation is required. Wind direction during different monsoons was found to influence the concentration of O3 around the Klang Valley. HYSPLIT back trajectories (-72 h) were used to indicate the air-mass transport patterns on days with high concentrations of surface O3 in the study area. Results show that 47% of the high O3 days was associated with the localized circulation. The remaining 32% and 22% were associated with mid-range and long-range transport across the South China Sea from the northeast.

  5. Ozone decay on stainless steel and sugarcane bagasse surfaces

    Science.gov (United States)

    Souza-Corrêa, Jorge A.; Oliveira, Carlos; Amorim, Jayr

    2013-07-01

    Ozone was generated using dielectric barrier discharges at atmospheric pressure to treat sugarcane bagasse for bioethanol production. It was shown that interaction of ozone molecules with the pretreatment reactor wall (stainless steel) needs to be considered during bagasse oxidation in order to evaluate the pretreatment efficiency. The decomposition coefficients for ozone on both materials were determined to be (3.3 ± 0.2) × 10-8 for stainless steel and (2.0 ± 0.3) × 10-7 for bagasse. The results have indicated that ozone decomposition has occurred more efficiently on the biomass material.

  6. Global impacts of surface ozone changes on crop yields and land use

    NARCIS (Netherlands)

    Chuwah, Clifford; van Noije, Twan; van Vuuren, Detlef P.|info:eu-repo/dai/nl/11522016X; Stehfest, Elke; Hazeleger, Wilco

    2015-01-01

    Exposure to surface ozone has detrimental impacts on vegetation and crop yields. In this study, we estimate ozone impacts on crop production and subsequent impacts on land use in the 2005-2050 period using results of the TM5 atmospheric chemistry and IMAGE integrated assessment model. For the crops

  7. Global impacts of surface ozone changes on crop yields and land use

    NARCIS (Netherlands)

    Chuwah, C.D.; Noije, van Twan; Vuuren, van Detlef P.; Stehfest, Elke; Hazeleger, Wilco

    2015-01-01

    Exposure to surface ozone has detrimental impacts on vegetation and crop yields. In this study, we estimate ozone impacts on crop production and subsequent impacts on land use in the 2005-2050 period using results of the TM5 atmospheric chemistry and IMAGE integrated assessment model. For the

  8. Ozonation of benzothiazole saturated-activated carbons: Influence of carbon chemical surface properties

    International Nuclear Information System (INIS)

    Valdes, H.; Zaror, C.A.

    2006-01-01

    The combined or sequential use of ozone and activated carbon to treat toxic effluents has increased in recent years. However, little is known about the influence of carbon surface active sites on ozonation of organic adsorbed pollutants. This paper presents experimental results on the effect of metal oxides and oxygenated surface groups on gaseous ozonation of spent activated carbons. Benzothiazole (BT) was selected as a target organic compound in this study due to its environmental concern. Activated carbons with different chemical surface composition were prepared from a Filtrasorb-400 activated carbon. Pre-treatment included: ozonation, demineralisation, and deoxygenation of activated carbon. Ozonation experiments of BT saturated-activated carbons were conducted in a fixed bed reactor loaded with 2 g of carbon samples. The reactor was fed with an O 2 /O 3 gas mixture (2 dm 3 /min, 5 g O 3 /h), for a given exposure time, in the range 10-120 min, at 298 K and 1 atm. Results show that extended gaseous ozonation of activated carbon saturated with BT led to the effective destruction of the adsorbate by oxidation reactions. Oxidation of BT adsorbed on activated carbon seemed to occur via both direct reaction with ozone molecules, and by oxygen radical species generated by catalytic ozone decomposition on metallic surface sites

  9. Surface Ozone Measured at GLOBE Schools in the Czech Republic: A Demonstration of the Importance of Student Contribution to the Larger Science Picture

    Science.gov (United States)

    Pippin, Margaret R.; Creilson, John K.; Henderson, Bryana L.; Ladd, Irene H.; Fishman, Jack; Votapkova, Dana; Krpcova, Ilona

    2008-01-01

    GLOBE (Global Learning and Observations to Benefit the Environment) is a worldwide hands-on, primary and secondary school-based education and science program, developed to give students a chance to perform real science by making measurements, analyzing data, and participating in research in collaboration with scientists. As part of the GLOBE Surface Ozone Protocol and with the assistance of the TEREZA Association in the Czech Republic, schools in the Czech Republic have been making and reporting daily measurements of surface ozone and surface meteorological data since 2001. Using a hand-held ozone monitor developed for GLOBE, students at several Czech schools have generated multiyear data records of surface ozone from 2001 to 2005. Analysis of the data shows surface ozone levels were anomalously high during the summer of 2003 relative to other summers. These findings are consistent with measurements by the European Environment Agency that highlights the summer of 2003 as having exceptionally long-lasting and spatially extensive episodes of high surface ozone, especially during the first half of August. Further analysis of the summer s prevailing meteorology shows not only that it was one of the hottest on record, a finding also seen in the student data, but the conditions for production of ozone were ideal. Findings such as these increase student, teacher, and scientist confidence in the utility of the GLOBE data for engaging budding scientists in the collection, analysis, and eventual interpretation of the data for inquiry-based education.

  10. The effect of ozone on nicotine desorption from model surfaces:evidence for heterogeneous chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Destaillats, Hugo; Singer, Brett C.; Lee, Sharon K.; Gundel, LaraA.

    2005-05-01

    Assessment of secondhand tobacco smoke exposure using nicotine as a tracer or biomarker is affected by sorption of the alkaloid to indoor surfaces and by its long-term re-emission into the gas phase. However, surface chemical interactions of nicotine have not been sufficiently characterized. Here, the reaction of ozone with nicotine sorbed to Teflon and cotton surfaces was investigated in an environmental chamber by monitoring nicotine desorption over a week following equilibration in dry or humid air (65-70 % RH). The Teflon and cotton surfaces had N{sub 2}-BET surface areas of 0.19 and 1.17 m{sup 2} g{sup -1}, and water mass uptakes (at 70 % RH) of 0 and 7.1 % respectively. Compared with dry air baseline levels in the absence of O{sub 3}, gas phase nicotine concentrations decrease, by 2 orders of magnitude for Teflon after 50 h at 20-45 ppb O{sub 3}, and by a factor of 10 for cotton after 100 h with 13-15 ppb O{sub 3}. The ratios of pseudo first-order rate constants for surface reaction (r) to long-term desorption (k) were r/k = 3.5 and 2.0 for Teflon and cotton surfaces, respectively. These results show that surface oxidation was competitive with desorption. Hence, oxidative losses could significantly reduce long-term re-emissions of nicotine from indoor surfaces. Formaldehyde, N-methylformamide, nicotinaldehyde and cotinine were identified as oxidation products, indicating that the pyrrolidinic N was the site of electrophilic attack by O{sub 3}. The presence of water vapor had no effect on the nicotine-O{sub 3} reaction on Teflon surfaces. By contrast, nicotine desorption from cotton in humid air was unaffected by the presence of ozone. These observations are consistent with complete inhibition of ozone-nicotine surface reactions in an aqueous surface film present in cotton but not in Teflon surfaces.

  11. Climate-driven ground-level ozone extreme in the fall over the Southeast United States.

    Science.gov (United States)

    Zhang, Yuzhong; Wang, Yuhang

    2016-09-06

    Ground-level ozone is adverse to human and vegetation health. High ground-level ozone concentrations usually occur over the United States in the summer, often referred to as the ozone season. However, observed monthly mean ozone concentrations in the southeastern United States were higher in October than July in 2010. The October ozone average in 2010 reached that of July in the past three decades (1980-2010). Our analysis shows that this extreme October ozone in 2010 over the Southeast is due in part to a dry and warm weather condition, which enhances photochemical production, air stagnation, and fire emissions. Observational evidence and modeling analysis also indicate that another significant contributor is enhanced emissions of biogenic isoprene, a major ozone precursor, from water-stressed plants under a dry and warm condition. The latter finding is corroborated by recent laboratory and field studies. This climate-induced biogenic control also explains the puzzling fact that the two extremes of high October ozone both occurred in the 2000s when anthropogenic emissions were lower than the 1980s and 1990s, in contrast to the observed decreasing trend of July ozone in the region. The occurrences of a drying and warming fall, projected by climate models, will likely lead to more active photochemistry, enhanced biogenic isoprene and fire emissions, an extension of the ozone season from summer to fall, and an increase of secondary organic aerosols in the Southeast, posing challenges to regional air quality management.

  12. Influences of the boundary layer evolution on surface ozone ...

    Indian Academy of Sciences (India)

    (1998) showed that the change in tropical ozone is highly sensitive to climate forcing in the tropics. Considering the importance of tropical tropo- sphere, attempts have been made for the measure- ment of ozone and precursors along with meteoro- logical parameters over the Indian region in which the roles of chemistry and ...

  13. Investigation of ozone zero phenomenon using new electrode and surface analysis technique

    Science.gov (United States)

    Taguchi, M.; Ochiai, Y.; Kawagoe, R.; Kato, Y.; Teranishi, K.; Suzuki, S.; Itoh, H.

    2011-07-01

    Results of our experimental investigation on the ozone zero phenomenon suggested us the importance of the electrode surface condition. This means that the main cause of the phenomenon, that is, temporal decrease of ozone concentration at the outlet of DBD type ozone generator and the recovery characteristics from the phenomenon are considered as the surface reaction process, which are influenced strongly by the surface condition. The surface condition is never constant during the ozone generation and varies gradually or remarkably with time depending on the experimental conditions. Therefore we have been continued to make clear the cause of the phenomenon, for example, the reproducibility of the phenomenon, using new electrodes and together with the surface analysis technique etc. In this paper, we describe on the above results and discussion.

  14. Baseline levels and trends of ground level ozone in Canada and the United States

    Directory of Open Access Journals (Sweden)

    E. Chan

    2010-09-01

    Full Text Available A statistical method was developed to extract baseline levels of ground level ozone in Canada and the US, and to quantify the temporal changes of baseline ozone levels on annual, seasonal, diurnal and decadal scales for the period 1997 to 2006 based on ground-level observations from 97 non-urban monitoring sites. Baseline ozone is defined here as ozone measured at a given site in the absence of strong local influences. The quantification of baseline levels involved using a Principal Component Analyses (PCA to derive groups of commonly-varying sites in contiguous regions by season, followed by using backward air parcel trajectories to systematically select ozone mixing ratios associated with the baseline condition in each of the PCA-derived regions. Decadal trends were estimated by season for each of the regions using a generalized linear mixed model (GLMM.

    Baseline ozone mixing ratios determined by this method were found to vary geographically and seasonally. For the 1997–2006 period, baseline mixing ratios were calculated for annual and seasonal periods in seven regions of North America based on multi-site multi-year averages of the baseline data sets. The annual average (±1 standard deviation baseline mixing ratios for the regions are as follows: Continental Eastern Canada=30±9 ppb, Continental Eastern US=30±10 ppb, Coastal Eastern Canada=27±9 ppb, Coastal Western Canada=19±10 ppb; Coastal Western US=39±10 ppb, Continental Western Canada=28±10 ppb and Continental Western US=46±7 ppb. Trends in the baseline mixing ratios were also found to vary by season and by geographical region. On a decadal scale, increasing baseline ozone trends (temperature-adjusted were observed in all seasons along the Pacific coasts of Canada and the US, although the trends in California were not statistically significant. In the coastal zone of Pacific Canada, positive

  15. Temporal and Spatial Variation in, and Population Exposure to, Summertime Ground-Level Ozone in Beijing.

    Science.gov (United States)

    Zhao, Hui; Zheng, Youfei; Li, Ting; Wei, Li; Guan, Qing

    2018-03-29

    Ground-level ozone pollution in Beijing has been causing concern among the public due to the risks posed to human health. This study analyzed the temporal and spatial distribution of, and investigated population exposure to, ground-level ozone. We analyzed hourly ground-level ozone data from 35 ambient air quality monitoring sites, including urban, suburban, background, and traffic monitoring sites, during the summer in Beijing from 2014 to 2017. The results showed that the four-year mean ozone concentrations for urban, suburban, background, and traffic monitoring sites were 95.1, 99.8, 95.9, and 74.2 μg/m³, respectively. A total of 44, 43, 45, and 43 days exceeded the Chinese National Ambient Air Quality Standards (NAAQS) threshold for ground-level ozone in 2014, 2015, 2016, and 2017, respectively. The mean ozone concentration was higher in suburban sites than in urban sites, and the traffic monitoring sites had the lowest concentration. The diurnal variation in ground-level ozone concentration at the four types of monitoring sites displayed a single-peak curve. The peak and valley values occurred at 3:00-4:00 p.m. and 7:00 a.m., respectively. Spatially, ground-level ozone concentrations decreased in gradient from the north to the south. Population exposure levels were calculated based on ground-level ozone concentrations and population data. Approximately 50.38%, 44.85%, and 48.49% of the total population of Beijing were exposed to ground-level ozone concentrations exceeding the Chinese NAAQS threshold in 2014, 2015, and 2016, respectively.

  16. Cyclone-induced surface ozone and HDO depletion in the Arctic

    Science.gov (United States)

    Zhao, Xiaoyi; Weaver, Dan; Bognar, Kristof; Manney, Gloria; Millán, Luis; Yang, Xin; Eloranta, Edwin; Schneider, Matthias; Strong, Kimberly

    2017-12-01

    Ground-based, satellite, and reanalysis datasets were used to identify two similar cyclone-induced surface ozone depletion events at Eureka, Canada (80.1° N, 86.4° W), in March 2007 and April 2011. These two events were coincident with observations of hydrogen deuterium oxide (HDO) depletion, indicating that condensation and sublimation occurred during the transport of the ozone-depleted air masses. Ice clouds (vapour and crystals) and aerosols were detected by lidar and radar when the ozone- and HDO-depleted air masses arrived over Eureka. For the 2007 event, an ice cloud layer was coincident with an aloft ozone depletion layer at 870 m altitude on 2-3 March, indicating this ice cloud layer contained bromine-enriched blowing-snow particles. Over the following 3 days, a shallow surface ozone depletion event (ODE) was observed at Eureka after the precipitation of bromine-enriched particles onto the local snowpack. A chemistry-climate model (UKCA) and a chemical transport model (pTOMCAT) were used to simulate the surface ozone depletion events. Incorporating the latest surface snow salinity data obtained for the Weddell Sea into the models resulted in improved agreement between the modelled and measured BrO concentrations above Eureka. MERRA-2 global reanalysis data and the FLEXPART particle dispersion model were used to study the link between the ozone and HDO depletion. In general, the modelled ozone and BrO showed good agreement with the ground-based observations; however, the modelled BrO and ozone in the near-surface layer are quite sensitive to the snow salinity. HDO depletion observed during these two blowing-snow ODEs was found to be weaker than pure Rayleigh fractionation. This work provides evidence of a blowing-snow sublimation process, which is a key step in producing bromine-enriched sea-salt aerosol.

  17. Surface Monitoring Data for PM2.5 and Ozone

    Data.gov (United States)

    Washington University St Louis — AIRNOW is an EPA program in collaboration with the States to gather and distribute hourly near-realtime data from several hundred continuous PM2.5 and ozone monitors.

  18. Surface Ozone Variability and Trends over the South African Highveld from 1990 to 2007

    Science.gov (United States)

    Balashov, Nikolay V.; Thompson, Anne M.; Piketh, Stuart J.; Langerman, Kristy E.

    2014-01-01

    Surface ozone is a secondary air pollutant formed from reactions between nitrogen oxides (NOx = NO + NO2) and volatile organic compounds in the presence of sunlight. In this work we examine effects of the climate pattern known as the El Niño-Southern Oscillation (ENSO) and NOx variability on surface ozone from 1990 to 2007 over the South African Highveld, a heavily populated region in South Africa with numerous industrial facilities. Over summer and autumn (December-May) on the Highveld, El Niño, as signified by positive sea surface temperature (SST) anomalies over the central Pacific Ocean, is typically associated with drier and warmer than normal conditions favoring ozone formation. Conversely, La Niña, or negative SST anomalies over the central Pacific Ocean, is typically associated with cloudier and above normal rainfall conditions, hindering ozone production. We use a generalized regression model to identify any linear dependence that the Highveld ozone, measured at five air quality monitoring stations, may have on ENSO and NOx. Our results indicate that four out of the five stations exhibit a statistically significant sensitivity to ENSO at some point over the December-May period where El Niño amplifies ozone formation and La Niña reduces ozone formation. Three out of the five stations reveal statistically significant sensitivity to NOx variability, primarily in winter and spring. Accounting for ENSO and NOx effects throughout the study period of 18 years, two stations exhibit statistically significant negative ozone trends in spring, one station displays a statistically significant positive trend in August, and two stations show no statistically significant change in surface ozone.

  19. Climate and emission changes contributing to changes in near-surface ozone in Europe over the coming decades: results from model studies.

    Science.gov (United States)

    Engardt, Magnuz; Bergström, Robert; Andersson, Camilla

    2009-12-01

    We used an off-line, regional, model of atmospheric transport and chemistry to investigate current and future levels of near-surface ozone and accumulated ozone exposure over a threshold of 40 ppb(v) (AOT40) in Europe. To describe the current situation and enable an evaluation of the model's performance we simulated a number of years around 2000. To assess changes in ozone concentrations due to possible emission changes in Europe, the model was run with the meteorology of the early 2000s and precursor emissions from a set of Clean Air for Europe (CAFE) emissions scenarios. By extrapolation of the observed increase in near-surface O3 at coastal locations in northwest Europe we constructed model boundaries that were used to simulate the impact of increasing hemispheric background in 2020. To assess changes in ozone concentrations due to climate change, the model was run with recent (2000) emissions but using meteorology from a regional climate model simulating a control (1961-1990) and a future (2021-2050) climate. The results indicate that climate change will have a small impact on ozone concentrations and AOT40 in the Nordic countries. Changes in hemispheric background concentrations and changes in precursor emissions in Europe will have a larger effect on ozone in Northern Europe. The situation is quite different in southern Europe, where climate change is expected to result in a very large increase in near-surface ozone concentrations.

  20. OZONATION BYPRODUCTS: IDENTIFICATION OF BROMOHYDRINS FROM THE OZONATION OF NATURAL WATERS WITH ENHANCED BROMIDE LEVELS

    Science.gov (United States)

    When ozone is used in the treatment of drinking water, it reacts with both inorganic and organic compounds to form byproducts. f bromide is present, it may be oxidized to hydrobromous acid, which may than react with natural organic matter to form brominated organic compounds. he ...

  1. Responses of surface ozone air quality to anthropogenic nitrogen deposition in the Northern Hemisphere

    Science.gov (United States)

    Zhao, Yuanhong; Zhang, Lin; Tai, Amos P. K.; Chen, Youfan; Pan, Yuepeng

    2017-08-01

    Human activities have substantially increased atmospheric deposition of reactive nitrogen to the Earth's surface, inducing unintentional effects on ecosystems with complex environmental and climate consequences. One consequence remaining unexplored is how surface air quality might respond to the enhanced nitrogen deposition through surface-atmosphere exchange. Here we combine a chemical transport model (GEOS-Chem) and a global land model (Community Land Model, CLM) to address this issue with a focus on ozone pollution in the Northern Hemisphere. We consider three processes that are important for surface ozone and can be perturbed by the addition of atmospheric deposited nitrogen - namely, emissions of biogenic volatile organic compounds (VOCs), ozone dry deposition, and soil nitrogen oxide (NOx) emissions. We find that present-day anthropogenic nitrogen deposition (65 Tg N a-1 to the land), through enhancing plant growth (represented as increases in vegetation leaf area index, LAI, in the model), could increase surface ozone from increased biogenic VOC emissions (e.g., a 6.6 Tg increase in isoprene emission), but it could also decrease ozone due to higher ozone dry deposition velocities (up to 0.02-0.04 cm s-1 increases). Meanwhile, deposited anthropogenic nitrogen to soil enhances soil NOx emissions. The overall effect on summer mean surface ozone concentrations shows general increases over the globe (up to 1.5-2.3 ppbv over the western US and South Asia), except for some regions with high anthropogenic NOx emissions (0.5-1.0 ppbv decreases over the eastern US, western Europe, and North China). We compare the surface ozone changes with those driven by the past 20-year climate and historical land use changes. We find that the impacts from anthropogenic nitrogen deposition can be comparable to the climate- and land-use-driven surface ozone changes at regional scales and partly offset the surface ozone reductions due to land use changes reported in previous studies

  2. Outdoor and indoor ozone level: A potential impact on human health

    Directory of Open Access Journals (Sweden)

    Valuntaitė Vaida

    2015-01-01

    Full Text Available Background/Aim. Air pollution outside and inside is still one of the most sensitive issues. The aim of this study was to assess the ozone level in ambient air and working premises in terms of its possible influence on human health. Methods. The study was based on the results obtained in Lithuanian conditions. Continuous ozone measurement data from the rural monitoring station in Preila over the period 1995-2011 were analyzed. More than 180,000 hourly values were examined according to the requirements in the Directive 2008/50/EC. The World Health Organization (WHO and European Union indicators the Sum of Ozone Means Over 35 ppb (SOMO 35, the maximum daily 8-hour mean concentration of ozone higher than 100 and 120 μg/m3 were estimated. Indoor ozone concentrations in copying and welding rooms were evaluated. The ozone concentration was measured with the ozone analyzer O341M. Results. The frequency distribution of ozone hourly concentrations at the Preila station showed that less than 1% of the data were higher than 120 μg/m3 and 6% of them higher than 100 μg/m3, that could have the adverse effect on human health, during 1995-2011. The investigations made in working premises showed that near a copying machine the ozone concentration can reach 330 μg/m3, however in the room, i.e. 0.5 m from the machine, the average ozone concentration during automatic copying was 165 μg/m³ and during manual copying it was 50 μg/m³. Measurements in a welding room showed that the ozone concentration was in the range of 380-1,850 μg/m3 at the distance of 25 cm from the electrode and at the distance of 1 m from the source the ozone concentration decreased 2.5 times. Conclusion. The danger of the ambient ozone level to human health practically was not observed in Lithuanian conditions. However, almost 6% of the data exceed the new WHO guideline of 100 μg/m3 during the measurement time. Indoor ozone during welding reached a higher level than during copying that

  3. Distribution and urban-suburban differences in ground-level ozone and its precursors over Shenyang, China

    Science.gov (United States)

    Liu, Ningwei; Ren, Wanhui; Li, Xiaolan; Ma, Xiaogang; Zhang, Yunhai; Li, Bingkun

    2018-03-01

    Hourly mixing ratio data of ground-level ozone and its main precursors at ambient air quality monitoring sites in Shenyang during 2013-2015 were used to survey spatiotemporal variations in ozone. Then, the transport of ozone and its precursors among urban, suburban, and rural sites was examined. The correlations between ozone and some key meteorological factors were also investigated. Ozone and O x mixing ratios in Shenyang were higher during warm seasons and lower during cold ones, while ozone precursors followed the opposite cycle. Ozone mixing ratios reached maximum and minimum values in the afternoon and morning, respectively, reflecting the significant influence of photochemical production during daytime and depletion via titration during nighttime. Compared to those in downtown Shenyang, ozone mixing ratios were higher and the occurrence of peak values were later in suburban and rural areas downwind of the prevailing wind. The differences were most significant in summer, when the ozone mixing ratios at one suburban downwind site reached a maximum value of 35.6 ppb higher than those at the downtown site. This suggests that photochemical production processes were significant during the transport of ozone precursors, particularly in warm seasons with sufficient sunlight. Temperature, total radiation, and wind speed all displayed positive correlations with ozone concentration, reflecting their important role in accelerating ozone formation. Generally, the correlations between ozone and meteorological factors were slightly stronger at suburban sites than in urban areas, indicating that ozone levels in suburban areas were more sensitive to these meteorological factors.

  4. Analysis of surface ozone using a recurrent neural network.

    Science.gov (United States)

    Biancofiore, Fabio; Verdecchia, Marco; Di Carlo, Piero; Tomassetti, Barbara; Aruffo, Eleonora; Busilacchio, Marcella; Bianco, Sebastiano; Di Tommaso, Sinibaldo; Colangeli, Carlo

    2015-05-01

    Hourly concentrations of ozone (O₃) and nitrogen dioxide (NO₂) have been measured for 16 years, from 1998 to 2013, in a seaside town in central Italy. The seasonal trends of O₃ and NO₂ recorded in this period have been studied. Furthermore, we used the data collected during one year (2005), to define the characteristics of a multiple linear regression model and a neural network model. Both models are used to model the hourly O₃ concentration, using, two scenarios: 1) in the first as inputs, only meteorological parameters and 2) in the second adding photochemical parameters at those of the first scenario. In order to evaluate the performance of the model four statistical criteria are used: correlation coefficient, fractional bias, normalized mean squared error and a factor of two. All the criteria show that the neural network gives better results, compared to the regression model, in all the model scenarios. Predictions of O₃ have been carried out by many authors using a feed forward neural architecture. In this paper we show that a recurrent architecture significantly improves the performances of neural predictors. Using only the meteorological parameters as input, the recurrent architecture shows performance better than the multiple linear regression model that uses meteorological and photochemical data as input, making the neural network model with recurrent architecture a more useful tool in areas where only weather measurements are available. Finally, we used the neural network model to forecast the O₃ hourly concentrations 1, 3, 6, 12, 24 and 48 h ahead. The performances of the model in predicting O₃ levels are discussed. Emphasis is given to the possibility of using the neural network model in operational ways in areas where only meteorological data are available, in order to predict O₃ also in sites where it has not been measured yet. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Effective UV/Ozone irradiation method for decontamination of hydroxyapatite surfaces

    Directory of Open Access Journals (Sweden)

    Keisuke Yasuda

    2017-08-01

    Full Text Available The purpose of this study was to establish whether UV/ozone (O3 irradiation method can effectively decontaminate hydroxyapatite surfaces, including those modified by the treatment with 30% phosphoric acid solution through morphological and chemical surface analyses (surface roughness, X-ray photoelectron spectroscopy and wettability, and to evaluate the in vitro response of osteoblast-like MC3T3-E1 cells to the modified hydroxyapatite surface decontaminated via this method. The amount of carbon and the contact angle of hydroxyapatite surfaces were significantly decreased by UV/O3 irradiation that lasted for ≥ 5 and ≥ 3 min, respectively (P 0.05. MC3T3-E1 cell proliferation, differentiation (as assessed by relative ALP and OCN mRNA levels, and mineralisation were significantly promoted on irradiated surfaces (P < 0.05. These findings show that UV/O3 irradiation for ≥ 5 min significantly decontaminated H3PO4-modified hydroxyapatite surface, improved its wettability, and facilitated osteoblast growth and function.

  6. The role of Br2 and BrCl in surface ozone destruction at polar sunrise.

    Science.gov (United States)

    Foster, K L; Plastridge, R A; Bottenheim, J W; Shepson, P B; Finlayson-Pitts, B J; Spicer, C W

    2001-01-19

    Bromine atoms are believed to play a central role in the depletion of surface-level ozone in the Arctic at polar sunrise. Br2, BrCl, and HOBr have been hypothesized as bromine atom precursors, and there is evidence for chlorine atom precursors as well, but these species have not been measured directly. We report here measurements of Br2, BrCl, and Cl2 made using atmospheric pressure chemical ionization-mass spectrometry at Alert, Nunavut, Canada. In addition to Br2 at mixing ratios up to approximately 25 parts per trillion, BrCl was found at levels as high as approximately 35 parts per trillion. Molecular chlorine was not observed, implying that BrCl is the dominant source of chlorine atoms during polar sunrise, consistent with recent modeling studies. Similar formation of bromine compounds and tropospheric ozone destruction may also occur at mid-latitudes but may not be as apparent owing to more efficient mixing in the boundary layer.

  7. Why do Models Overestimate Surface Ozone in the Southeastern United States?

    Science.gov (United States)

    Travis, K.; Jacob, D.; Fisher, J. A.; Kim, S.; Marais, E. A.; Zhu, L.; Yu, K.; Miller, C. E.; Yantosca, R.; Payer Sulprizio, M.; Thompson, A. M.; Wennberg, P. O.; Crounse, J.; St Clair, J. M.; Cohen, R. C.; Laughner, J.; Dibb, J. E.; Hall, S. R.; Ullmann, K.; Wolfe, G.; Pollack, I. B.; Peischl, J.; Neuman, J. A.; Zhou, X.

    2016-12-01

    Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx = NO + NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0.25°×0.3125° horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NO­x from the US Environmental Protection Agency (EPA) is too high in the Southeast and nationally by a factor of 2. This finding is based on SEAC4RS observations of NOx and its oxidation products, surface network observations of nitrate wet deposition fluxes, and OMI satellite observations of tropospheric NO2 columns. Upper tropospheric NO2 from lightning makes a large contribution to the satellite observations that must be accounted for when using these data to estimate surface NOx emissions. We find that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft, and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NOx oxidation products. However, the model is still biased high by 8±13 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone decrease from 1.5 km to the surface that GEOS-Chem does not capture. This may be caused by excessively dry conditions in the model, representing another

  8. Surface ozone variation at Bhubaneswar and intra-corelationship ...

    Indian Academy of Sciences (India)

    transport of airmass from mainly Indo-Gangetic Plains (IGP) and western part of Indian peninsula, a major industrial hub. In other seasons, wind ... 1164. P S Mahapatra et al. processes. Downward transport of the ozone-rich ... izer and food processing industries along with ther- mal power plants have been set-up in the ...

  9. Estimating contribution of wildland fires to ambient ozone levels in National Parks in the Sierra Nevada, California.

    Science.gov (United States)

    Preisler, Haiganoush K; Zhong, Shiyuan Sharon; Esperanza, Annie; Brown, Timothy J; Bytnerowicz, Andrzej; Tarnay, Leland

    2010-03-01

    Data from four continuous ozone and weather monitoring sites operated by the National Park Service in Sierra Nevada, California, are used to develop an ozone forecasting model and to estimate the contribution of wildland fires on ambient ozone levels. The analyses of weather and ozone data pointed to the transport of ozone precursors from the Central Valley as an important source of pollution in these National Parks. Comparisons of forecasted and observed values demonstrated that accurate forecasts of next-day hourly ozone levels may be achieved by using a time series model with historic averages, expected local weather and modeled PM values as explanatory variables. Results on fire smoke influence indicated occurrence of significant increases in average ozone levels with increasing fire activity. The overall effect on diurnal ozone values, however, was small when compared with the amount of variability attributed to sources other than fire.

  10. HIRDLS/Aura Level 3 Ozone (O3) Zonal Fourier Coefficients V007

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Ozone (O3) Zonal Fourier Coefficients" version 7 data product (H3ZFCO3) contains the entire mission (~3 years) of HIRDLS data expressed as...

  11. Why do Models Overestimate Surface Ozone in the Southeastern United States?

    Science.gov (United States)

    Travis, Katherine R.; Jacob, Daniel J.; Fisher, Jenny A.; Kim, Patrick S.; Marais, Eloise A.; Zhu, Lei; Yu, Karen; Miller, Christopher C.; Yantosca, Robert M.; Sulprizio, Melissa P.; hide

    2016-01-01

    Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx = NO + NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0.25 deg. x 0.3125 deg. horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NOx from the US Environmental Protection Agency (EPA) is too high. This finding is based on SEAC4RS observations of NOx and its oxidation products, surface network observations of nitrate wet deposition fluxes, and OMI satellite observations of tropospheric NO2 columns. Our results indicate that NEI NOx emissions from mobile and industrial sources must be reduced by 30-60%, dependent on the assumption of the contribution by soil NOx emissions. Upper tropospheric NO2 from lightning makes a large contribution to satellite observations of tropospheric NO2 that must be accounted for when using these data to estimate surface NOx emissions. We find that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft, and reproduces the observed ozone production efficiency in the boundary layer as derived from a 15 regression of ozone and NOx oxidation products. However, the model is still biased high by 8 +/- 13 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone

  12. Why do Models Overestimate Surface Ozone in the Southeastern United States?

    Science.gov (United States)

    Travis, Katherine R.; Jacob, Daniel J.; Fisher, Jenny A.; Kim, Patrick S.; Marais, Eloise A.; Zhu, Lei; Yu, Karen; Miller, Christopher C.; Yantosca, Robert M.; Sulprizio, Melissa P.; Thompson, Anne M.; Wennberg, Paul O.; Crounse, John D.; St Clair, Jason M.; Cohen, Ronald C.; Laughner, Joshua L.; Dibb, Jack E.; Hall, Samuel R.; Ullmann, Kirk; Wolfe, Glenn M.; Pollack, Illana B.; Peischl, Jeff; Neuman, Jonathan A.; Zhou, Xianliang

    2018-01-01

    Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx ≡ NO + NO2) and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0.25°×0.3125° horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI) for NOx from the US Environmental Protection Agency (EPA) is too high. This finding is based on SEAC4RS observations of NOx and its oxidation products, surface network observations of nitrate wet deposition fluxes, and OMI satellite observations of tropospheric NO2 columns. Our results indicate that NEI NOx emissions from mobile and industrial sources must be reduced by 30–60%, dependent on the assumption of the contribution by soil NOx emissions. Upper tropospheric NO2 from lightning makes a large contribution to satellite observations of tropospheric NO2 that must be accounted for when using these data to estimate surface NOx emissions. We find that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft, and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NOx oxidation products. However, the model is still biased high by 8±13 ppb relative to observed surface ozone in the Southeast US. Ozonesondes launched during midday hours show a 7 ppb ozone decrease

  13. Why do models overestimate surface ozone in the Southeast United States?

    Directory of Open Access Journals (Sweden)

    K. R. Travis

    2016-11-01

    Full Text Available Ozone pollution in the Southeast US involves complex chemistry driven by emissions of anthropogenic nitrogen oxide radicals (NOx  ≡  NO + NO2 and biogenic isoprene. Model estimates of surface ozone concentrations tend to be biased high in the region and this is of concern for designing effective emission control strategies to meet air quality standards. We use detailed chemical observations from the SEAC4RS aircraft campaign in August and September 2013, interpreted with the GEOS-Chem chemical transport model at 0.25°  ×  0.3125° horizontal resolution, to better understand the factors controlling surface ozone in the Southeast US. We find that the National Emission Inventory (NEI for NOx from the US Environmental Protection Agency (EPA is too high. This finding is based on SEAC4RS observations of NOx and its oxidation products, surface network observations of nitrate wet deposition fluxes, and OMI satellite observations of tropospheric NO2 columns. Our results indicate that NEI NOx emissions from mobile and industrial sources must be reduced by 30–60 %, dependent on the assumption of the contribution by soil NOx emissions. Upper-tropospheric NO2 from lightning makes a large contribution to satellite observations of tropospheric NO2 that must be accounted for when using these data to estimate surface NOx emissions. We find that only half of isoprene oxidation proceeds by the high-NOx pathway to produce ozone; this fraction is only moderately sensitive to changes in NOx emissions because isoprene and NOx emissions are spatially segregated. GEOS-Chem with reduced NOx emissions provides an unbiased simulation of ozone observations from the aircraft and reproduces the observed ozone production efficiency in the boundary layer as derived from a regression of ozone and NOx oxidation products. However, the model is still biased high by 6 ± 14 ppb relative to observed surface ozone in the Southeast US. Ozonesondes

  14. Impacts of urban land-surface forcing on ozone air quality in the Seoul metropolitan area

    Directory of Open Access Journals (Sweden)

    Y.-H. Ryu

    2013-02-01

    Full Text Available Modified local meteorology owing to heterogeneities in the urban–rural surface can affect urban air quality. In this study, the impacts of urban land-surface forcing on ozone air quality during a high ozone (O3 episode in the Seoul metropolitan area, South Korea, are investigated using a high-resolution chemical transport model (CMAQ. Under fair weather conditions, the temperature excess (urban heat island significantly modifies boundary layer characteristics/structures and local circulations. The modified boundary layer and local circulations result in an increase in O3 levels in the urban area of 16 ppb in the nighttime and 13 ppb in the daytime. Enhanced turbulence in the deep urban boundary layer dilutes pollutants such as NOx, and this contributes to the elevated O3 levels through the reduced O3 destruction by NO in the NOx-rich environment. The advection of O3 precursors over the mountains near Seoul by the prevailing valley-breeze circulation in the mid- to late morning results in the build-up of O3 over the mountains in conjunction with biogenic volatile organic compound (BVOC emissions there. As the prevailing local circulation in the afternoon changes to urban-breeze circulation, the O3-rich air masses over the mountains are advected over the urban area. The urban-breeze circulation exerts significant influences on not only the advection of O3 but also the chemical production of O3 under the circumstances in which both anthropogenic and biogenic (natural emissions play important roles in O3 formation. As the air masses that are characterized by low NOx and high BVOC levels and long OH chain length are advected over the urban area from the surroundings, the ozone production efficiency increases in the urban area. The relatively strong vertical mixing in the urban boundary layer embedded in the

  15. Preliminary SEM Observations on the Surface of Elastomeric Impression Materials after Immersion or Ozone Disinfection

    Science.gov (United States)

    Prombonas, Anthony; Yannikakis, Stavros; Karampotsos, Thanasis; Katsarou, Martha-Spyridoula; Drakoulis, Nikolaos

    2016-01-01

    Introduction Surface integrity of dental elastomeric impression materials that are subjected to disinfection is of major importance for the quality of the final prosthetic restorations. Aim The aim of this qualitative Scanning Electronic Microscopy (SEM) study was to reveal the effects of immersion or ozone disinfection on the surface of four dental elastomeric impression materials. Materials and Methods Four dental elastomeric impression material brands were used (two vinyl polysiloxane silicones, one polyether, and one vinyl polyether silicone). Total of 32 specimens were fabricated, eight from each impression material. Specimens were immersion (0.525% sodium hypochlorite solution or 0.3% benzalkonium chloride solution) or ozone disinfected or served as controls and examined with SEM. Results Surface degradation was observed on several speci-mens disinfected with 0.525% sodium hypochlorite solution. Similar wavy-wrinkling surface structures were observed in almost all specimens, when treated either with 0.3% benzalkonium chloride solution or ozone. Conclusion The SEM images obtained from this study revealed that both immersion disinfectants and ozone show similar impression material surface alterations. Ozone seems to be non-inferior as compared to immersion disinfectants, but superior as to environmental protection. PMID:28208993

  16. Surface ozone in the Southern Hemisphere: 20 years of data from a site with a unique setting in El Tololo, Chile

    Science.gov (United States)

    Anet, Julien G.; Steinbacher, Martin; Gallardo, Laura; Velásquez Álvarez, Patricio A.; Emmenegger, Lukas; Buchmann, Brigitte

    2017-05-01

    The knowledge of surface ozone mole fractions and their global distribution is of utmost importance due to the impact of ozone on human health and ecosystems and the central role of ozone in controlling the oxidation capacity of the troposphere. The availability of long-term ozone records is far better in the Northern than in the Southern Hemisphere, and recent analyses of the seven accessible records in the Southern Hemisphere have shown inconclusive trends. Since late 1995, surface ozone is measured in situ at "El Tololo", a high-altitude (2200 m a.s.l.) and pristine station in Chile (30° S, 71° W). The dataset has been recently fully quality controlled and reprocessed. This study presents the observed ozone trends and annual cycles and identifies key processes driving these patterns. From 1995 to 2010, an overall positive trend of ˜ 0.7 ppb decade-1 is found. Strongest trends per season are observed in March and April. Highest mole fractions are observed in late spring (October) and show a strong correlation with ozone transported from the stratosphere down into the troposphere, as simulated with a model. Over the 20 years of observations, the springtime ozone maximum has shifted to earlier times in the year, which, again, is strongly correlated with a temporal shift in the occurrence of the maximum of simulated stratospheric ozone transport at the site. We conclude that background ozone at El Tololo is mainly driven by stratospheric intrusions rather than photochemical production from anthropogenic and biogenic precursors. The major footprint of the sampled air masses is located over the Pacific Ocean. Therefore, due to the negligible influence of local processes, the ozone record also allows studying the influence of El Niño and La Niña episodes on background ozone levels in South America. In agreement with previous studies, we find that, during La Niña conditions, ozone mole fractions reach higher levels than during El Niño conditions.

  17. First observations of surface ozone concentration from the summit region of Mount Everest

    Science.gov (United States)

    Semple, John L.; Moore, G. W. K.

    2008-10-01

    The extreme height of Mount Everest is such that its summit region may periodically be in the lower stratosphere. In this regard it provides a unique location for observing the exchange of ozone between the upper troposphere and lower stratosphere. Here we report the first surface ozone measurements from the summit region of Mount Everest. Simultaneous measurements were recorded at different elevations on the north side from base camp (5676 m) to the summit (8848 m) during May 2005. The concentrations measured were as high as 70 ppb. Meteorological diagnostics suggest that the stratosphere as well as the long range transport of polluted tropospheric air masses from South East Asia are sources of the observed ozone. There is evidence that the source region for ozone in the vicinity of Mount Everest may vary with the onset of the summer monsoon.

  18. Modeling of regional climate change effects on ground-level ozone and childhood asthma.

    Science.gov (United States)

    Sheffield, Perry E; Knowlton, Kim; Carr, Jessie L; Kinney, Patrick L

    2011-09-01

    The adverse respiratory effects of ground-level ozone are well established. Ozone is the air pollutant most consistently projected to increase under future climate change. To project future pediatric asthma emergency department visits associated with ground-level ozone changes, comparing 1990s to 2020s. This study assessed future numbers of asthma emergency department visits for children aged 0-17 years using (1) baseline New York City metropolitan area emergency department rates; (2) a dose-response relationship between ozone levels and pediatric asthma emergency department visits; and (3) projected daily 8-hour maximum ozone concentrations for the 2020s as simulated by a global-to-regional climate change and atmospheric chemistry model. Sensitivity analyses included population projections and ozone precursor changes. This analysis occurred in 2010. In this model, climate change could cause an increase in regional summer ozone-related asthma emergency department visits for children aged 0-17 years of 7.3% across the New York City metropolitan region by the 2020s. This effect diminished with inclusion of ozone precursor changes. When population growth is included, the projections of morbidity related to ozone are even larger. The results of this analysis demonstrate that the use of regional climate and atmospheric chemistry models make possible the projection of local climate change health effects for specific age groups and specific disease outcomes, such as emergency department visits for asthma. Efforts should be made to improve on this type of modeling to inform local and wider-scale climate change mitigation and adaptation policy. Copyright © 2011 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  19. Description of the surface water filtration and ozone treatment system at the Northeast Fishery Center

    Science.gov (United States)

    A water filtration and ozone disinfection system was installed at the U.S. Fish and Wildlife Service's Northeast Fishery Center in Lamar, Pennsylvania to treat a surface water supply that is used to culture sensitive and endangered fish. The treatment system first passes the surface water through dr...

  20. Reaction rates of ozone and terpenes adsorbed to model indoor surfaces.

    Science.gov (United States)

    Springs, M; Wells, J R; Morrison, G C

    2011-08-01

    Reaction rates and reaction probabilities have been quantified on model indoor surfaces for the reaction of ozone with two monoterpenes (Δ(3) -carene and d-limonene). Molar surface loadings were obtained by performing breakthrough experiments in a plug-flow reactor (PFR) packed with beads of glass, polyvinylchloride or zirconium silicate. Reaction rates and probabilities were determined by equilibrating the PFR with both the terpene and the ozone and measuring the ozone consumption rate. To mimic typical indoor conditions, temperatures of 20, 25, and 30°C were used in both types of experiments along with a relative humidity ranging from 10% to 80%. The molar surface loading decreased with increased relative humidity, especially on glass, suggesting that water competed with the terpenes for adsorption sites. The ozone reactivity experiments indicate that higher surface loadings correspond with higher ozone uptake. The reaction probability for Δ(3) -carene with ozone ranged from 2.9 × 10(-6) to 3.0 × 10(-5) while reaction probabilities for d-limonene ranged from 2.8 × 10(-5) to 3.0 × 10(-4) . These surface reaction probabilities are roughly 10-100 times greater than the corresponding gas-phase values. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially for lower volatility terpenoids. At present, it is unclear how important heterogeneous reactions will be in influencing indoor concentrations of terpenes, ozone and their reaction products. We observe that surface reaction probabilities were 10 to 100 times greater than their corresponding gas-phase values. Thus indoor surfaces do enhance effective reaction rates and adsorption of terpenes will increase ozone flux to otherwise low-reactivity surfaces. Extrapolation of these results to typical indoor conditions suggests that surface conversion rates may be substantial relative to gas-phase rates, especially

  1. Inter-annual variability of surface ozone at coastal (Dumont d'Urville, 2004–2014 and inland (Concordia, 2007–2014 sites in East Antarctica

    Directory of Open Access Journals (Sweden)

    M. Legrand

    2016-07-01

    Full Text Available Surface ozone has been measured since 2004 at the coastal East Antarctic site of Dumont d'Urville (DDU, and since 2007 at the Concordia station located on the high East Antarctic plateau. This paper discusses long-term changes, seasonal and diurnal cycles, as well as inter-annual summer variability observed at these two East Antarctic sites. At Concordia, near-surface ozone data were complemented by balloon soundings and compared to similar measurements done at the South Pole. The DDU record is compared to those obtained at the coastal site of Syowa, also located in East Antarctica, as well as the coastal sites of Neumayer and Halley, both located on the coast of the Weddell Sea in West Antarctica. Surface ozone mixing ratios exhibit very similar seasonal cycles at Concordia and the South Pole. However, in summer the diurnal cycle of ozone is different at the two sites with a drop of ozone in the afternoon at Concordia but not at the South Pole. The vertical distribution of ozone above the snow surface also differs. When present, the ozone-rich layer located near the ground is better mixed and deeper at Concordia (up to 400 m than at the South Pole during sunlight hours. These differences are related to different solar radiation and wind regimes encountered at these two inland sites. DDU appears to be the coastal site where the impact of the late winter/spring bromine chemistry is the weakest, but where the impact of elevated ozone levels caused by NOx snow emissions from the high Antarctic plateau is the highest. The highest impact of the bromine chemistry is seen at Halley and Neumayer, and to a lesser extent at Syowa. These three sites are only weakly impacted by the NOx chemistry and the net ozone production occurring on the high Antarctic plateau. The differences in late winter/spring are attributed to the abundance of sea ice offshore from the sites, whereas those in summer are related to the topography of East Antarctica that promotes

  2. Temporal Characterisation of Ground-level Ozone Concentration in Klang Valley

    Science.gov (United States)

    Izzah Mohamad Hashim, Nur; Noor, Norazian Mohamed; Yasina Yusof, Sara

    2018-03-01

    In Malaysia, ground-level ozone (O3) is one of the most significant air pollutants due to the increasing sources of ozone precursors. Hence, the surface O3 concentration should have received substantial attention because of its negative effects to human health, vegetation and the environment. In this study, hourly air pollutants dataset (i.e O3, Carbon monoxide (CO), Nitrogen dioxide (NO2), Particulate matter (PM10), Non-methane hydrocarbon (NmHC), Sulphur dioxide (SO2)) and weather parameters (i.e. wind speed (WS), wind direction (WD), temperature (T), ultraviolet B (UVB)) for ten years period (2003-2012) in Klang Valley were selected for analysis in this study. Two monitoring stations were selected that are Petaling Jaya and Shah Alam. The aim of the study is to determine the diurnal variations of O3 concentrations according to the seasonal monsoon and the correlation between the ground-level O3 concentration and others parameter. A high concentration of ground-level O3 was observed during the first transition (April to May) for both of the stations. While at a low surface, O3 concentration was found out during the southwest monsoon within June to September. Pearson correlation was used to find the correlation between the O3 concentration and all other pollutants and weather parameters. Most of the relationship between O3concentrationswas positively correlated with NO2 and negative relationship was found out with NMHC. These results were expected since these pollutants are known as the O3 precursors. Besides that, O3 concentration and its precursors show a positive significant correlation with all meteorological factors except for relative humidity.

  3. Surface recombination of oxygen atoms in O2 plasma at increased pressure: II. Vibrational temperature and surface production of ozone

    Science.gov (United States)

    Lopaev, D. V.; Malykhin, E. M.; Zyryanov, S. M.

    2011-01-01

    Ozone production in an oxygen glow discharge in a quartz tube was studied in the pressure range of 10-50 Torr. The O3 density distribution along the tube diameter was measured by UV absorption spectroscopy, and ozone vibrational temperature TV was found comparing the calculated ab initio absorption spectra with the experimental ones. It has been shown that the O3 production mainly occurs on a tube surface whereas ozone is lost in the tube centre where in contrast the electron and oxygen atom densities are maximal. Two models were used to analyse the obtained results. The first one is a kinetic 1D model for the processes occurring near the tube walls with the participation of the main particles: O(3P), O2, O2(1Δg) and O3 molecules in different vibrational states. The agreement of O3 and O(3P) density profiles and TV calculated in the model with observed ones was reached by varying the single model parameter—ozone production probability (\\gamma_{O_{3}}) on the quartz tube surface on the assumption that O3 production occurs mainly in the surface recombination of physisorbed O(3P) and O2. The phenomenological model of the surface processes with the participation of oxygen atoms and molecules including singlet oxygen molecules was also considered to analyse \\gamma_{O_{3}} data obtained in the kinetic model. A good agreement between the experimental data and the data of both models—the kinetic 1D model and the phenomenological surface model—was obtained in the full range of the studied conditions that allowed consideration of the ozone surface production mechanism in more detail. The important role of singlet oxygen in ozone surface production was shown. The O3 surface production rate directly depends on the density of physisorbed oxygen atoms and molecules and can be high with increasing pressure and energy inputted into plasma while simultaneously keeping the surface temperature low enough. Using the special discharge cell design, such an approach opens up the

  4. Surface recombination of oxygen atoms in O2 plasma at increased pressure: II. Vibrational temperature and surface production of ozone

    International Nuclear Information System (INIS)

    Lopaev, D V; Malykhin, E M; Zyryanov, S M

    2011-01-01

    Ozone production in an oxygen glow discharge in a quartz tube was studied in the pressure range of 10-50 Torr. The O 3 density distribution along the tube diameter was measured by UV absorption spectroscopy, and ozone vibrational temperature T V was found comparing the calculated ab initio absorption spectra with the experimental ones. It has been shown that the O 3 production mainly occurs on a tube surface whereas ozone is lost in the tube centre where in contrast the electron and oxygen atom densities are maximal. Two models were used to analyse the obtained results. The first one is a kinetic 1D model for the processes occurring near the tube walls with the participation of the main particles: O( 3 P), O 2 , O 2 ( 1 Δ g ) and O 3 molecules in different vibrational states. The agreement of O 3 and O( 3 P) density profiles and T V calculated in the model with observed ones was reached by varying the single model parameter-ozone production probability (γ O 3 ) on the quartz tube surface on the assumption that O 3 production occurs mainly in the surface recombination of physisorbed O( 3 P) and O 2 . The phenomenological model of the surface processes with the participation of oxygen atoms and molecules including singlet oxygen molecules was also considered to analyse γ O 3 data obtained in the kinetic model. A good agreement between the experimental data and the data of both models-the kinetic 1D model and the phenomenological surface model-was obtained in the full range of the studied conditions that allowed consideration of the ozone surface production mechanism in more detail. The important role of singlet oxygen in ozone surface production was shown. The O 3 surface production rate directly depends on the density of physisorbed oxygen atoms and molecules and can be high with increasing pressure and energy inputted into plasma while simultaneously keeping the surface temperature low enough. Using the special discharge cell design, such an approach opens up

  5. Characterization of surface dielectric barrier discharge influenced by intermediate frequency for ozone production

    International Nuclear Information System (INIS)

    Abdelaziz, Ayman A; Ishijima, Tatsuo; Seto, Takafumi; Otani, Yoshio; Osawa, Naoki; Wedaa, Hassan

    2016-01-01

    The aim of this study is to investigate the effect of the intermediate frequency (1–10 kHz) of the sinusoidal driving voltage on the characteristics of a developed surface dielectric barrier discharge (SDBD)-based reactor having spikes on its discharge electrode. Moreover, its influence on the production of ozone and nitrogen oxide byproducts is evaluated. The results show that SDBD is operated in the filamentary mode at all the frequencies. Nevertheless, the pulses of the discharge current at high frequencies are much denser and have higher amplitudes than those at low frequencies. The analysis of the power consumed in the reactor shows that a small portion of the input power is dissipated in the dielectric material of SDBD source, whereas the major part of the power is consumed in the plasma discharge. The results of the ozone production show that higher frequencies have a slightly adverse effect on the ozone production at relatively high energy density values, where the ozone concentration is slightly decreased when the frequency is increased at the same energy density. The temperature of the discharge channels and gas is not a crucial factor for the decomposition of ozone in this reactor, while the results of the measurements of nitrogen oxides characteristics indicate that the formation of NO and NO 2 has a significant adverse effect on the production efficiency of ozone due to their oxidation to another nitrogen oxides and their catalytic effect. (paper)

  6. Why are models unable to reproduce multi-decadal trends in lower tropospheric baseline ozone levels?

    Science.gov (United States)

    Hu, L.; Liu, J.; Mickley, L. J.; Strahan, S. E.; Steenrod, S.

    2017-12-01

    Assessments of tropospheric ozone radiative forcing rely on accurate model simulations. Parrish et al (2014) found that three chemistry-climate models (CCMs) overestimate present-day O3 mixing ratios and capture only 50% of the observed O3 increase over the last five decades at 12 baseline sites in the northern mid-latitudes, indicating large uncertainties in our understanding of the ozone trends and their implications for radiative forcing. Here we present comparisons of outputs from two chemical transport models (CTMs) - GEOS-Chem and the Global Modeling Initiative model - with O3 observations from the same sites and from the global ozonesonde network. Both CTMs are driven by reanalysis meteorological data (MERRA or MERRA2) and thus are expected to be different in atmospheric transport processes relative to those freely running CCMs. We test whether recent model developments leading to more active ozone chemistry affect the computed ozone sensitivity to perturbations in emissions. Preliminary results suggest these CTMs can reproduce present-day ozone levels but fail to capture the multi-decadal trend since 1980. Both models yield widespread overpredictions of free tropospheric ozone in the 1980s. Sensitivity studies in GEOS-Chem suggest that the model estimate of natural background ozone is too high. We discuss factors that contribute to the variability and trends of tropospheric ozone over the last 30 years, with a focus on intermodel differences in spatial resolution and in the representation of stratospheric chemistry, stratosphere-troposphere exchange, halogen chemistry, and biogenic VOC emissions and chemistry. We also discuss uncertainty in the historical emission inventories used in models, and how these affect the simulated ozone trends.

  7. Ground-level ozone pollution and its health impacts in China

    Science.gov (United States)

    Liu, Huan; Liu, Shuai; Xue, Boru; Lv, Zhaofeng; Meng, Zhihang; Yang, Xiaofan; Xue, Tao; Yu, Qiao; He, Kebin

    2018-01-01

    In recent years, ground-level ozone pollution in China has become an increasingly prominent problem. This study simulated and analyzed spatiotemporal distribution of ozone and exposure level by the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) models and monitoring data from 1516 national air quality monitoring stations in China during 2015. The simulation results show that the Sichuan Basin, Shandong, Shanxi, Henan, Anhui, Qinghai-Tibetan Plateau, Yangtze River Delta (YRD), Pearl River Delta (PRD) and Beijing-Tianjin-Hebei (BTH) region had relatively high average annual concentrations of ozone. The regions with more than 10% nonattainment days of 160 μg/m3 (daily maximum 8-h) are mainly concentrated in BTH, Shandong Peninsula and YRD, where large seasonal variations were also found. Exposure levels were calculated based on population data and simulated ozone concentrations. The cumulative population exposed to daily maximum 8-h concentration greater than or equal to 100 μg/m3 was 816.04 million, 61.17% of the total. Three methods were used to estimate the mortality of chronic obstructive pulmonary disease (COPD) attributable to ozone. A comparative study using different exposure concentrations and threshold concentrations found large variations among these methods, although they were all peer-reviewed methods. The estimated mortality of COPD caused by ozone in China in 2015 ranged from 55341 to 80280, which mainly distributed in Beijing, Shandong, Henan, Hubei and Sichuan Province, the YRD and PRD region.

  8. An assessment of ozone levels, UV radiation and their occupational health hazard estimation during photocopying operation

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Bhupendra Pratap, E-mail: bpsingh0783@gmail.com; Kumar, Amit; Singh, Deepak; Punia, Monika; Kumar, Krishan; Jain, Vinod Kumar

    2014-06-30

    Highlights: • First quantitative report of ozone level and UV radiation emission from photocopier. • Ozone production is directly proportional with intensity of photocopy operation. • Ozone level from ground floor is significantly higher than basement photocopier. • Ozone production and UV radiation studied has less correlation during photocopy. • Health hazard issue has been evaluated for effect of UV radiation in terms of SED. - Abstract: This study investigates the levels of ozone concentration along with an ultraviolet (UV) and visible spectral radiation at eight photocopy centers in an academic institute, Delhi. Sampling was done in two types of locations, i.e., basement photocopy centers (BPC) and ground floor photocopy centers (GPC) for 8 h. Measurements of levels of ozone, UV and visible radiation were done by ozone analyzer, UV radiometer and Field spectra instrument, respectively. Results show that the hourly mean concentration of ozone was observed to be in the range of 1.8–10.0 ppb and 5.3–45.8 ppb for BPC and GPC, respectively. In terms UV radiations, energy lies between 5.0 × 10{sup −3} and 7.0 × 10{sup −3} mW/cm{sup 2} for ultraviolet A (UVA), 1.0 × 10{sup −3} and 2.0 × 10{sup −3} mW/cm{sup 2} for ultraviolet B (UVB) and 6.0 × 10{sup −3} and 8.0 × 10{sup −3} mW/cm{sup 2} for ultraviolet C (UVC). Correlation between the UV radiations and ozone production observed was statistically insignificant. To know the health hazard occurred to the workers, the standard erythema dose (SED) value was calculated for emitting UV radiation. The SED was estimated to be in the range of 0.02–0.04 and 0.02–0.32 for direct and indirect methods which is less than the guideline prescribed by Commission Internationale del’ Eclairage (CIE). In nutshell, person involved in photocopy operation for their livelihood must be trained and should have knowledge for the long term gradual build up health problems due to ozone and UV production from

  9. How to most effectively expand the global surface ozone observing network

    Science.gov (United States)

    Sofen, E. D.; Bowdalo, D.; Evans, M. J.

    2016-02-01

    Surface ozone observations with modern instrumentation have been made around the world for more than 40 years. Some of these observations have been made as one-off activities with short-term, specific science objectives and some have been made as part of wider networks which have provided a foundational infrastructure of data collection, calibration, quality control, and dissemination. These observations provide a fundamental underpinning to our understanding of tropospheric chemistry, air quality policy, atmosphere-biosphere interactions, etc. brought together eight of these networks to provide a single data set of surface ozone observations. We investigate how representative this combined data set is of global surface ozone using the output from a global atmospheric chemistry model. We estimate that on an area basis, 25 % of the globe is observed (34 % land, 21 % ocean). Whereas Europe and North America have almost complete coverage, other continents, Africa, South America, Australia, and Asia (12-17 %) show significant gaps. Antarctica is surprisingly well observed (78 %). Little monitoring occurs over the oceans, with the tropical and southern oceans particularly poorly represented. The surface ozone over key biomes such as tropical forests and savanna is almost completely unmonitored. A chemical cluster analysis suggests that a significant number of observations are made of polluted air masses, but cleaner air masses whether over the land or ocean (especially again in the tropics) are significantly under-observed. The current network is unlikely to see the impact of the El Niño-Southern Oscillation (ENSO) but may be capable of detecting other planetary-scale signals. Model assessment and validation activities are hampered by a lack of observations in regions where the models differ substantially, as is the ability to monitor likely changes in surface ozone over the next century. Using our methodology we are able to suggest new sites which would help to close

  10. How to most effectively expand the global surface ozone observing network

    Directory of Open Access Journals (Sweden)

    E. D. Sofen

    2016-02-01

    Full Text Available Surface ozone observations with modern instrumentation have been made around the world for more than 40 years. Some of these observations have been made as one-off activities with short-term, specific science objectives and some have been made as part of wider networks which have provided a foundational infrastructure of data collection, calibration, quality control, and dissemination. These observations provide a fundamental underpinning to our understanding of tropospheric chemistry, air quality policy, atmosphere–biosphere interactions, etc. brought together eight of these networks to provide a single data set of surface ozone observations. We investigate how representative this combined data set is of global surface ozone using the output from a global atmospheric chemistry model. We estimate that on an area basis, 25 % of the globe is observed (34 % land, 21 % ocean. Whereas Europe and North America have almost complete coverage, other continents, Africa, South America, Australia, and Asia (12–17 % show significant gaps. Antarctica is surprisingly well observed (78 %. Little monitoring occurs over the oceans, with the tropical and southern oceans particularly poorly represented. The surface ozone over key biomes such as tropical forests and savanna is almost completely unmonitored. A chemical cluster analysis suggests that a significant number of observations are made of polluted air masses, but cleaner air masses whether over the land or ocean (especially again in the tropics are significantly under-observed. The current network is unlikely to see the impact of the El Niño–Southern Oscillation (ENSO but may be capable of detecting other planetary-scale signals. Model assessment and validation activities are hampered by a lack of observations in regions where the models differ substantially, as is the ability to monitor likely changes in surface ozone over the next century. Using our methodology we are able to suggest new

  11. Impact of Future Emissions and Climate Change on Surface Ozone over China

    Science.gov (United States)

    Ma, C. T.; Westervelt, D. M.; Fiore, A. M.; Rieder, H. E.; Kinney, P.; Wang, S.; Correa, G. J. P.

    2017-12-01

    China's immense ambient air pollution problem and world-leading greenhouse gas emissions place it at the forefront of global efforts to address these related environmental concerns. Here, we analyze the impact of ECLIPSE (Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants) future emissions scenarios representative of current legislation (CLE) and maximum technically feasible emissions reductions (MFR) on surface ozone (O3) concentrations over China in the 2030s and 2050s, in the context of a changing climate. We use a suite of simulations performed with the NOAA Geophysical Fluid Dynamics Laboratory's AM3 global chemistry-climate model. To estimate the impact of climate change in isolation on Chinese air quality, we hold emissions of air pollutants including O3 precursors fixed at 2015 levels but allow climate (global sea surface temperatures and sea ice cover) to change according to decadal averages for the years 2026-2035 and 2046-2055 from a three-member ensemble of GFDL-CM3 simulations under the RCP8.5 high warming scenario. Evaluation of the present-day simulation (2015 CLE) with observations from 1497 chiefly urban air quality monitoring stations shows that simulated surface O3 is positively biased by 26 ppb on average over the domain of China. Previous studies, however, have shown that the modeled ozone response to changes in NOx emissions over the Eastern United States mirrors the magnitude and structure of observed changes in maximum daily average 8-hour (MDA8) O3 distributions. Therefore, we use the model's simulated changes for the 2030s and 2050s to project changes in policy-relevant MDA8 O3 concentrations. We find an overall increase in MDA8 O3 for CLE scenarios in which emissions of NOx precursors are projected to increase, and under MFR scenarios, an overall decrease, with the highest changes occurring in summertime for both 2030 and 2050 MFR. Under climate change alone, the model simulates a mean summertime decrease of 1.3 ppb

  12. Contribution of long-range transport to the ozone levels recorded in the Northeast of Portugal

    Science.gov (United States)

    Gama, C.; Nunes, T.; Marques, M. C.; Ferreira, F.

    2009-04-01

    In the past four years (2004-2007), measurements carried out at Lamas de Olo, the only air quality monitoring background station in the Northeast of Portugal, showed high ozone concentrations (97,7±29,7 g.m-3). This remote site, located in the middle of Alvão Natural Park, in Portugal, 1086 m asl, plays a significant role on the total amount of exceedances registered in the national air quality network. The analysis of the data recorded at this monitoring station revealed an annual cycle of ozone concentrations similar to the ones observed in other background sites of the Northern Hemisphere (Monks, 2000; Vingarzan and Taylor, 2003). This common feature comprises a distinct maximum during spring (peaking during the month of April). Nevertheless it is during the summer that the hourly concentrations are higher, due to the typical atmospheric and meteorological conditions that promote photochemical pollution episodes. Photochemical pollution episodes can be related with production of ozone in a local scale or in a global scale due to the transportation of polluted air masses. For this reason analysing these events is crucial to fully understand the behaviour of ozone in the Northeast of Portugal, in order to adopt the correct long-term policies. With the purpose of studying the influence of long-range transport on the ozone levels recorded at Lamas de Olo, a cluster analysis was performed on 96-hour back trajectories air masses. Different trajectory clusters represent air masses with different source regions of atmospheric pollutants and the influence of these regions on the atmospheric composition at the arrival point (receptor) of the trajectories can therefore be assessed (EMPA, 2008). The back trajectories were simulated 4 times per day, using HYSPLIT model. A "bottom-up" cluster methodology was used to group trajectories into clusters according to their characteristics, for several time periods with similar ozone levels and/or distributions. Ozone average

  13. [Responses of rice growth and development to elevated near-surface layer ozone (O3) concentration: a review].

    Science.gov (United States)

    Yang, Lian-xin; Wang, Yu-long; Shi, Guang-yao; Wang, Yun-xia; Zhu, Jian-guo

    2008-04-01

    Ozone (O3) is recognized as one of the most important air pollutants. At present, the worldwide average tropospheric O3 concentration has been increased from an estimated pre-industrial level of 38 nl L(-1) (25-45 nl L(-1), 8-h summer seasonal average) to approximately 50 nl L(-1) in 2000, and to 80 nl L(-1) by 2100 based on most pessimistic projections. Oryza sativa L. (rice) is the most important grain crop in the world, and thus, to correctly evaluate how the elevated near-surface layer O3 concentration will affect the growth and development of rice is of great significance. This paper reviewed the chamber (including closed and open top chamber)-based studies about the effects of atmospheric ozone enrichment on the rice visible injury symptoms, photosynthesis, water relationship, phenology, dry matter production and allocation, leaf membrane protective system, and grain yield and its components. Further research directions in this field were discussed.

  14. Characteristics of surface ozone and nitrogen oxides at urban, suburban and rural sites in Ningbo, China

    Science.gov (United States)

    Tong, Lei; Zhang, Huiling; Yu, Jie; He, Mengmeng; Xu, Nengbin; Zhang, Jingjing; Qian, Feizhong; Feng, Jiayong; Xiao, Hang

    2017-05-01

    Surface ozone (O3) is a harmful air pollutant that has attracted growing concern in China. In this study, the mixing ratios of O3 and nitrogen oxides (NOx) at three different sites (urban, suburban and rural) of Ningbo were continuously measured to investigate the spatiotemporal characteristics of O3 and its relationships with environmental variables. The diurnal O3 variations were characterized by afternoon maxima (38.7-53.1 ppb on annual average) and early morning minima (11.7-26.2 ppb) at all the three sites. Two seasonal peaks of O3 were observed in spring (April or May) and autumn (October) with minima being observed in winter (December). NOx levels showed generally opposite variations to that of O3 with diurnal and seasonal maxima occurring in morning/evening rush-hours and in winter, respectively. As to the inter-annual variations of air pollutants, generally decreasing and increasing trends were observed in NO and O3 levels, respectively, from 2012 to 2015 at both urban and suburban sites. O3 levels were positively correlated with temperature but negatively correlated with relative humidity and NOx levels. Significant differences in O3 levels were observed for different wind speeds and wind directions (p population and plant growth.

  15. An Evaluation of the GLOBE Surface Ozone Protocol After Five Years of Implementation

    Science.gov (United States)

    Pippin, M.; Ladd, I.; Fishman, J.

    2003-12-01

    The Surface Ozone Protocol has been a part of the GLOBE Program since 1998. Our goal has been to introduce the student to the subject of atmospheric chemistry and the relationship between air quality and other parameters such as temperature and cloud cover by providing teachers and students with a relatively accurate and inexpensive method to measure ozone. During the past five years, our group can point to both successes and disappointments. Vital elements for the successes include teacher training in data collection and analysis with integration into the core curriculum, a support structure within the schools and community to facilitate continuous data collection and reporting, quality assurance of the reported data and an open channel of communication between teachers and scientists. Once the protocol is implemented, we recognize that our GLOBE teachers require additional structure and support beyond the initial GLOBE training. Out of 57 GLOBE schools reporting ozone data, 47 schools have reported fewer than 100 data points, with 38 of those schools reporting fewer than 30 data points. However, four schools located in the Czech Republic are successfully implementing the surface ozone protocol and have reported over 500 ozone measurements with meta data providing continuous data sets over several years. We are currently developing the infrastructure for educator/community teams to facilitate year-round surface ozone measurements, and providing on-site training, follow up visits, and electronic based interactions to support the educator/community teams and students as they gather data. We present the successful strategies from the Czech Republic schools and provide suggestions for improving the involvement and retention for the U.S. schools.

  16. Shuttle SBUV (SSBUV) Ozone Profile, Ozone Total Column, Aerosol Index, and UV-Reflectivity, Level-2 50x50 km V008

    Data.gov (United States)

    National Aeronautics and Space Administration — The Shuttle Solar Backscatter Ultraviolet (SSBUV) Level-2 Ozone data are available for eight space shuttle missions flown between 1989 and 1996. SSBUV, a successor...

  17. Impact of near-surface atmospheric composition on ozone formation in Russia

    Science.gov (United States)

    Berezina, Elena; Moiseenko, Konstantin; Skorokhod, Andrey; Belikov, Igor; Pankratova, Natalia; Elansky, Nikolai

    2017-04-01

    One of the consequences of the human impact on the atmosphere is increasing in tropospheric ozone concentration, with the highest ozone level being observed in industrially developed and highly populated regions of the world. In these regions, main anthropogenic sources of carbon monoxide (CO), methane (CH4) and volatile organic compounds (VOCs) are concentrated. The oxidation of these compounds, when interacting with hydroxyl and nitrogen oxides at rather high temperature and sunlight, leads to ozone formation. CO and CH4 are slowly oxidized in the atmosphere and cause an increase in global and regional background ozone. However, the oxidation of some VOCs occurs during daylight hours and is accompanied by an increase in ozone concentration near VOCs sources, particularly in urban and industrial areas. The contribution of biogenic VOCs to ozone generation is estimated to be from 40 to 70% of the total contribution of all chemical ozone precursors in the troposphere [1], with isoprene playing the main role in ozone formation [2]. The impact of aromatic hydrocarbons to ozone formation is reported to be about 40% of the total ozone generation from the oxidation of anthropogenic VOCs [3]. In this study, the results of VOCs measurements (isoprene, benzene, toluene, phenol, styrene, xylene and propilbenzene) by proton mass spectrometry in different regions of Russia along the Trans-Siberian railway from Moscow to Vladivostok from TROICA-12 campaign on a mobile laboratory in summer 2008 are analyzed. It is shown that the TROICA-12 measurements were carried out mostly in moderately polluted (2≤NOx20 ppb) conditions ( 20 and 2% of measurements, correspondingly). The lower troposphere chemical regime in the campaign is found to be mainly NOx sensitive, both in rural and urban environments, with typical morning NMHC/NOx ratios being well above 20. Hence, ozone production rates are expected to be controlled by regional NOx emissions and their complex interplay with both

  18. Global impacts of surface ozone changes on crop yields and land use

    Science.gov (United States)

    Chuwah, Clifford; van Noije, Twan; van Vuuren, Detlef P.; Stehfest, Elke; Hazeleger, Wilco

    2015-04-01

    Exposure to surface ozone has detrimental impacts on vegetation and crop yields. In this study, we estimate ozone impacts on crop production and subsequent impacts on land use in the 2005-2050 period using results of the TM5 atmospheric chemistry and IMAGE integrated assessment model. For the crops represented in IMAGE, we compute relative yield losses based on published exposure-response functions. We examine scenarios with either constant or declining emission factors in a weak climate policy future (radiative forcing target of 6.0 W/m2 at the end of the century), as well as co-benefits of stringent climate policy (targeted at 2.6 W/m2). Without a large decrease in air pollutant emissions, higher ozone concentrations could lead to an increase in crop damage of up to 20% locally in 2050 compared to the situation in which the changes in ozone are not accounted for. This may lead to a 2.5% global increase in crop area, and a regional increase of 8.9% in Asia. Implementation of air pollution policies could limit crop yield losses due to ozone to maximally 10% in 2050 in the most affected regions. Similar effects can be obtained as a result of co-benefits from climate policy (reducing ozone precursor emissions). We also evaluated the impact of the corresponding land-use changes on the carbon cycle. Under the worst-case scenario analysed in this study, future ozone increases are estimated to increase the cumulative net CO2 emissions between 2005 and 2050 by about 3.7 Pg C, which corresponds to about 10% of baseline land use emissions over the same period.

  19. The impact of anthropogenic and biogenic emissions on surface ozone concentrations in Istanbul.

    Science.gov (United States)

    Im, Ulas; Poupkou, Anastasia; Incecik, Selahattin; Markakis, Konstantinos; Kindap, Tayfun; Unal, Alper; Melas, Dimitros; Yenigun, Orhan; Topcu, Sema; Odman, M Talat; Tayanc, Mete; Guler, Meltem

    2011-03-01

    Surface ozone concentrations at Istanbul during a summer episode in June 2008 were simulated using a high resolution and urban scale modeling system coupling MM5 and CMAQ models with a recently developed anthropogenic emission inventory for the region. Two sets of base runs were performed in order to investigate for the first time the impact of biogenic emissions on ozone concentrations in the Greater Istanbul Area (GIA). The first simulation was performed using only the anthropogenic emissions whereas the second simulation was performed using both anthropogenic and biogenic emissions. Biogenic NMVOC emissions were comparable with anthropogenic NMVOC emissions in terms of magnitude. The inclusion of biogenic emissions significantly improved the performance of the model, particularly in reproducing the low night time values as well as the temporal variation of ozone concentrations. Terpene emissions contributed significantly to the destruction of the ozone during nighttime. Biogenic NMVOCs emissions enhanced ozone concentrations in the downwind regions of GIA up to 25ppb. The VOC/NO(x) ratio almost doubled due to the addition of biogenic NMVOCs. Anthropogenic NO(x) and NMVOCs were perturbed by ±30% in another set of simulations to quantify the sensitivity of ozone concentrations to the precursor emissions in the region. The sensitivity runs, as along with the model-calculated ozone-to-reactive nitrogen ratios, pointed NO(x)-sensitive chemistry, particularly in the downwind areas. On the other hand, urban parts of the city responded more to changes in NO(x) due to very high anthropogenic emissions. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Using satellite data to guide emission control strategies for surface ozone pollution

    Science.gov (United States)

    Jin, X.; Fiore, A. M.

    2017-12-01

    Surface ozone (O3) has adverse effects on public health, agriculture and ecosystems. As a secondary pollutant, ozone is not emitted directly. Ozone forms from two classes of precursors: NOx and VOCs. We use satellite observations of formaldehyde (a marker of VOCs) and NO2 (a marker of NOx) to identify areas which would benefit more from reducing NOx emissions (NOx-limited) versus areas where reducing VOC emissions would lead to lower ozone (VOC-limited). We use a global chemical transport model (GEOS-Chem) to develop a set of threshold values that separate the NOx-limited and VOC-limited conditions. Combining these threshold values with a decadal record of satellite observations, we find that U.S. cities (e.g. New York, Chicago) have shifted from VOC-limited to NOx-limited ozone production regimes in the warm season. This transition reflects the NOx emission controls implemented over the past decade. Increasing NOx sensitivity implies that regional NOx emission control programs will improve O3 air quality more now than it would have a decade ago.

  1. Surface ozone background in the United States: Canadian and Mexican pollution influences

    Science.gov (United States)

    Wang, Huiqun; Jacob, Daniel J.; Le Sager, Philippe; Streets, David G.; Park, Rokjin J.; Gilliland, Alice B.; van Donkelaar, A.

    We use a global chemical transport model (GEOS-Chem) with 1° × 1° horizontal resolution to quantify the effects of anthropogenic emissions from Canada, Mexico, and outside North America on daily maximum 8-hour average ozone concentrations in US surface air. Simulations for summer 2001 indicate mean North American and US background concentrations of 26 ± 8 ppb and 30 ± 8 ppb, as obtained by eliminating anthropogenic emissions in North America vs. in the US only. The US background never exceeds 60 ppb in the model. The Canadian and Mexican pollution enhancement averages 3 ± 4 ppb in the US in summer but can be occasionally much higher in downwind regions of the northeast and southwest, peaking at 33 ppb in upstate New York (on a day with 75 ppb total ozone) and 18 ppb in southern California (on a day with 68 ppb total ozone). The model is successful in reproducing the observed variability of ozone in these regions, including the occurrence and magnitude of high-ozone episodes influenced by transboundary pollution. We find that exceedances of the 75 ppb US air quality standard in eastern Michigan, western New York, New Jersey, and southern California are often associated with Canadian and Mexican pollution enhancements in excess of 10 ppb. Sensitivity simulations with 2020 emission projections suggest that Canadian pollution influence in the Northeast US will become comparable in magnitude to that from domestic power plants.

  2. Impact of chemical lateral boundary conditions in a regional air quality forecast model on surface ozone predictions during stratospheric intrusions

    Science.gov (United States)

    Pendlebury, Diane; Gravel, Sylvie; Moran, Michael D.; Lupu, Alexandru

    2018-02-01

    A regional air quality forecast model, GEM-MACH, is used to examine the conditions under which a limited-area air quality model can accurately forecast near-surface ozone concentrations during stratospheric intrusions. Periods in 2010 and 2014 with known stratospheric intrusions over North America were modelled using four different ozone lateral boundary conditions obtained from a seasonal climatology, a dynamically-interpolated monthly climatology, global air quality forecasts, and global air quality reanalyses. It is shown that the mean bias and correlation in surface ozone over the course of a season can be improved by using time-varying ozone lateral boundary conditions, particularly through the correct assignment of stratospheric vs. tropospheric ozone along the western lateral boundary (for North America). Part of the improvement in surface ozone forecasts results from improvements in the characterization of near-surface ozone along the lateral boundaries that then directly impact surface locations near the boundaries. However, there is an additional benefit from the correct characterization of the location of the tropopause along the western lateral boundary such that the model can correctly simulate stratospheric intrusions and their associated exchange of ozone from stratosphere to troposphere. Over a three-month period in spring 2010, the mean bias was seen to improve by as much as 5 ppbv and the correlation by 0.1 depending on location, and on the form of the chemical lateral boundary condition.

  3. A network of autonomous surface ozone monitors in Antarctica: technical description and first results

    Directory of Open Access Journals (Sweden)

    S. J.-B. Bauguitte

    2011-04-01

    Full Text Available A suite of 10 autonomous ozone monitoring units, each powered using renewable energy, was developed and built to study surface ozone in Antarctica during the International Polar Year (2007–2009. The monitoring systems were deployed in a network around the Weddell Sea sector of coastal Antarctica with a transect up onto the Antarctic Plateau. The aim was to measure for a full year, thus gaining a much-improved broader view of boundary layer ozone seasonality at different locations as well as of factors affecting the budget of surface ozone in Antarctica. Ozone mixing ratios were measured based on UV photometry using a modified version of the commercial 2B Technologies Inc. Model 202 instrument. All but one of the autonomous units measured successfully within its predefined duty cycle throughout the year, with some differences in performance dependent on power availability and ambient temperature. Mean data recovery after removal of outliers was on average 70% (range 44–83% and precision varied between 1.5 and 8 ppbv, thus was sufficiently good to resolve year-round the main ozone features of scientific interest. We conclude that, with adequate power, and noting a minor communication problem, our units would be able to operate successfully at ambient temperatures down to −60 °C. Systems such as the one described in this paper, or derivatives of it, could therefore be deployed either as local or regional networks elsewhere in the Arctic or Antarctic. Here we present technical information and first results from the experiment.

  4. THE IMPACT OF OZONE ON THE LOWER FLAMMABLE LIMIT OF HYDROGEN IN VESSELS CONTAINING SAVANNAH RIVER SITE HIGH LEVEL WASTE

    Energy Technology Data Exchange (ETDEWEB)

    Sherburne, Carol [Savannah River Site (SRS), Aiken, SC (United States). Savannah River Remediation, LLC; Osterberg, Paul [Fauske and Associates, LLC, Burr Ridge, IL (United States); Johnson, Tom [Fauske and Associates, LLC, Burr Ridge, IL (United States); Frawely, Thomas [Fauske and Associates, LLC, Burr Ridge, IL (United States)

    2013-01-23

    The Savannah River Site, in conjunction with AREVA Federal services, has designed a process to treat dissolved radioactive waste solids with ozone. It is known that in this radioactive waste process, radionuclides radiolytically break down water into gaseous hydrogen and oxygen, which presents a well defined flammability hazard. Flammability limits have been established for both ozone and hydrogen separately; however, there is little information on mixtures of hydrogen and ozone. Therefore, testing was designed to provide critical flammability information necessary to support safety related considerations for the development of ozone treatment and potential scale-up to the commercial level. Since information was lacking on flammability issues at low levels of hydrogen and ozone, a testing program was developed to focus on filling this portion of the information gap. A 2-L vessel was used to conduct flammability tests at atmospheric pressure and temperature using a fuse wire ignition source at 1 percent ozone intervals spanning from no ozone to the Lower Flammable Limit (LFL) of ozone in the vessel, determined as 8.4%(v/v) ozone. An ozone generator and ozone detector were used to generate and measure the ozone concentration within the vessel in situ, since ozone decomposes rapidly on standing. The lower flammability limit of hydrogen in an ozone-oxygen mixture was found to decrease from the LFL of hydrogen in air, determined as 4.2 % (v/v) in this vessel. From the results of this testing, Savannah River was able to develop safety procedures and operating parameters to effectively minimize the formation of a flammable atmosphere.

  5. Projected global ground-level ozone impacts on vegetation under different emission and climate scenarios

    Directory of Open Access Journals (Sweden)

    P. Sicard

    2017-10-01

    Full Text Available The impact of ground-level ozone (O3 on vegetation is largely under-investigated at the global scale despite large areas worldwide that are exposed to high surface O3 levels. To explore future potential impacts of O3 on vegetation, we compared historical and projected surface O3 concentrations simulated by six global atmospheric chemistry transport models on the basis of three representative concentration pathways emission scenarios (i.e. RCP2.6, 4.5, 8.5. To assess changes in the potential surface O3 threat to vegetation at the global scale, we used the AOT40 metric. Results point out a significant exceedance of AOT40 in comparison with the recommendations of UNECE for the protection of vegetation. In fact, many areas of the Northern Hemisphere show that AOT40-based critical levels will be exceeded by a factor of at least 10 under RCP8.5. Changes in surface O3 by 2100 worldwide range from about +4–5 ppb in the RCP8.5 scenario to reductions of about 2–10 ppb in the most optimistic scenario, RCP2.6. The risk of O3 injury for vegetation, through the potential O3 impact on photosynthetic assimilation, decreased by 61 and 47 % under RCP2.6 and RCP4.5, respectively, and increased by 70 % under RCP8.5. Key biodiversity areas in southern and northern Asia, central Africa and North America were identified as being at risk from high O3 concentrations.

  6. Responses of evergreen and deciduous Quercus species to enhanced ozone levels

    International Nuclear Information System (INIS)

    Calatayud, Vicent; Cervero, Julia; Calvo, Esperanza; Garcia-Breijo, Francisco-Jose; Reig-Arminana, Jose; Sanz, Maria Jose

    2011-01-01

    Plants of one evergreen oak (Quercus ilex) and three deciduous oaks (Q. faginea, with small leaves; Q. pyrenaica and Q. robur, with large leaves) were exposed both to filtered air and to enhanced ozone levels in Open-Top Chambers. Q. faginea and Q. pyrenaica were studied for the first time. Based on visible injury, gas exchange, chlorophyll content and biomass responses, Q. pyrenaica was the most sensitive species, and Q. ilex was the most tolerant, followed by Q. faginea. Functional leaf traits of the species were related to differences in sensitivity, while accumulated ozone flux via stomata (POD 1.6 ) partly contributed to the observed differences. For risk assessment of Mediterranean vegetation, the diversity of responses detected in this study should be taken into account, applying appropriate critical levels. - Ozone tolerance overlapped with leaf traits in four Quercus species.

  7. Responses of evergreen and deciduous Quercus species to enhanced ozone levels

    Energy Technology Data Exchange (ETDEWEB)

    Calatayud, Vicent, E-mail: calatayud_viclor@gva.e [Instituto Universitario CEAM-UMH, Charles R. Darwin 14, Parc Tecnologic, 46980 Paterna, Valencia (Spain); Cervero, Julia; Calvo, Esperanza [Instituto Universitario CEAM-UMH, Charles R. Darwin 14, Parc Tecnologic, 46980 Paterna, Valencia (Spain); Garcia-Breijo, Francisco-Jose [Laboratorio de Anatomia e Histologia Vegetal ' Julio Iranzo' , Jardin Botanico, Universitat de Valencia, c/Quart 80, 46008 Valencia (Spain); Departamento de Ecosistemas Agroforestales, Escuela Tecnica Superior del Medio Rural y Enologia, Universidad Politecnica de Valencia, Avda. Blasco Ibanez 21, 46010 Valencia (Spain); Reig-Arminana, Jose [Departamento de Ecosistemas Agroforestales, Escuela Tecnica Superior del Medio Rural y Enologia, Universidad Politecnica de Valencia, Avda. Blasco Ibanez 21, 46010 Valencia (Spain); Sanz, Maria Jose [Instituto Universitario CEAM-UMH, Charles R. Darwin 14, Parc Tecnologic, 46980 Paterna, Valencia (Spain)

    2011-01-15

    Plants of one evergreen oak (Quercus ilex) and three deciduous oaks (Q. faginea, with small leaves; Q. pyrenaica and Q. robur, with large leaves) were exposed both to filtered air and to enhanced ozone levels in Open-Top Chambers. Q. faginea and Q. pyrenaica were studied for the first time. Based on visible injury, gas exchange, chlorophyll content and biomass responses, Q. pyrenaica was the most sensitive species, and Q. ilex was the most tolerant, followed by Q. faginea. Functional leaf traits of the species were related to differences in sensitivity, while accumulated ozone flux via stomata (POD{sub 1.6}) partly contributed to the observed differences. For risk assessment of Mediterranean vegetation, the diversity of responses detected in this study should be taken into account, applying appropriate critical levels. - Ozone tolerance overlapped with leaf traits in four Quercus species.

  8. Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

    Science.gov (United States)

    Yi, Kan; Liu, Junfeng; Ban-Weiss, George; Zhang, Jiachen; Tao, Wei; Cheng, Yanli; Tao, Shu

    2017-07-01

    The response of surface ozone (O3) concentrations to basin-scale warming and cooling of Northern Hemisphere oceans is investigated using the Community Earth System Model (CESM). Idealized, spatially uniform sea surface temperature (SST) anomalies of ±1 °C are individually superimposed onto the North Pacific, North Atlantic, and North Indian oceans. Our simulations suggest large seasonal and regional variability in surface O3 in response to SST anomalies, especially in the boreal summer. The responses of surface O3 associated with basin-scale SST warming and cooling have similar magnitude but are opposite in sign. Increasing the SST by 1 °C in one of the oceans generally decreases the surface O3 concentrations from 1 to 5 ppbv. With fixed emissions, SST increases in a specific ocean basin in the Northern Hemisphere tend to increase the summertime surface O3 concentrations over upwind regions, accompanied by a widespread reduction over downwind continents. We implement the integrated process rate (IPR) analysis in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During the boreal summer, basin-scale SST warming facilitates the vertical transport of O3 to the surface over upwind regions while significantly reducing the vertical transport over downwind continents. This process, as confirmed by tagged CO-like tracers, indicates a considerable suppression of intercontinental O3 transport due to increased tropospheric stability at lower midlatitudes induced by SST changes. Conversely, the responses of chemical O3 production to regional SST warming can exert positive effects on surface O3 levels over highly polluted continents, except South Asia, where intensified cloud loading in response to North Indian SST warming depresses both the surface air temperature and solar radiation, and thus photochemical O3 production. Our findings indicate a robust linkage between basin-scale SST

  9. Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: implications for long-range transport

    Directory of Open Access Journals (Sweden)

    K. Yi

    2017-07-01

    Full Text Available The response of surface ozone (O3 concentrations to basin-scale warming and cooling of Northern Hemisphere oceans is investigated using the Community Earth System Model (CESM. Idealized, spatially uniform sea surface temperature (SST anomalies of ±1 °C are individually superimposed onto the North Pacific, North Atlantic, and North Indian oceans. Our simulations suggest large seasonal and regional variability in surface O3 in response to SST anomalies, especially in the boreal summer. The responses of surface O3 associated with basin-scale SST warming and cooling have similar magnitude but are opposite in sign. Increasing the SST by 1 °C in one of the oceans generally decreases the surface O3 concentrations from 1 to 5 ppbv. With fixed emissions, SST increases in a specific ocean basin in the Northern Hemisphere tend to increase the summertime surface O3 concentrations over upwind regions, accompanied by a widespread reduction over downwind continents. We implement the integrated process rate (IPR analysis in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During the boreal summer, basin-scale SST warming facilitates the vertical transport of O3 to the surface over upwind regions while significantly reducing the vertical transport over downwind continents. This process, as confirmed by tagged CO-like tracers, indicates a considerable suppression of intercontinental O3 transport due to increased tropospheric stability at lower midlatitudes induced by SST changes. Conversely, the responses of chemical O3 production to regional SST warming can exert positive effects on surface O3 levels over highly polluted continents, except South Asia, where intensified cloud loading in response to North Indian SST warming depresses both the surface air temperature and solar radiation, and thus photochemical O3 production. Our findings indicate a robust linkage

  10. Sensitivity analysis of surface ozone to emission controls in Beijing and its neighboring area during the 2008 Olympic Games.

    Science.gov (United States)

    Gao, Yi; Zhang, Meigen

    2012-01-01

    The regional air quality modeling system RAMS (regional atmospheric modeling system)-CMAQ (community multi-scale air quality modeling system) is applied to analyze temporal and spatial variations in surface ozone concentration over Beijing and its surrounding region from July to October 2008. Comparison of simulated and observed meteorological elements and concentration of nitrogen oxides (NOx) and ozone at one urban site and three rural sites during Olympic Games show that model can generally reproduce the main observed feature of wind, temperature and ozone, but NOx concentration is overestimated. Although ozone concentration decreased during Olympics, high ozone episodes occurred on 24 July and 24 August with concentration of 360 and 245 microg/m3 at Aoyuncun site, respectively. The analysis of sensitive test, with and without emission controls, shows that emission controls could reduce ozone concentration in the afternoon when ozone concentration was highest but increase it at night and in the morning. The evolution of the weather system during the ozone episodes (24 July and 24 August) indicates that hot and dry air and a stable weak pressure field intensified the production of ozone and allowed it to accumulate. Process analysis at the urban site and rural site shows that under favorable weather condition on 24 August, horizontal transport was the main contributor of the rural place and the pollution from the higher layer would be transported to the surface layer. On 24 July, as the wind velocity was smaller, the impact of transport on the rural place was not obvious.

  11. Impact of shipping emissions on ozone levels over Europe: assessing the relative importance of the Standard Nomenclature for Air Pollution (SNAP) categories.

    Science.gov (United States)

    Tagaris, Efthimios; Stergiou, Ioannis; Sotiropoulou, Rafaella-Eleni P

    2017-06-01

    The impact of shipping emissions on ozone mixing ratio over Europe is assessed for July 2006 using the Community Multiscale Air Quality modeling system and the Netherlands Organization for Applied Scientific Research anthropogenic emission inventory. Results suggest that ship-induced ozone contribution to the total surface ozone exceeds 5% over the sea and near the coastline, while an increase up to 5% is simulated over a large portion of the European land. The largest impact (i.e., an increase up to 30%) is simulated over the Mediterranean Sea. In addition, shipping emissions are simulated to increase NO 2 mixing ratio more than 90%, locally, and to modify the oxidizing capacity of the atmosphere through hydroxyl radical formation (increase by 20-60% over the sea along the European coasts and near the coastal zone). Therefore, emissions from ships may counteract the benefits derived from the anthropogenic emissions reduction strategies over the continent. Simulations suggest regions where shipping emissions have a major impact on ozone mixing ratio compared to individual anthropogenic emission sector categories. Shipping emissions are estimated to play an important role on ozone levels compared to road transport sector near the coastal zone. The impact of shipping emissions on ozone formation is also profound over a great part of the European land compared to the rest of anthropogenic emission categories.

  12. Effect of Nearby Forest Fires on Ground Level Ozone Concentrations in Santiago, Chile

    Directory of Open Access Journals (Sweden)

    María A. Rubio

    2015-12-01

    Full Text Available On 4 and 8 January 2014, at the height of the austral summer, intense wildfires in forests and dry pastures occurred in the Melipilla sector, located about 70 km to the southwest of Santiago, the Chilean capital, affecting more than 6 million inhabitants. Low level winds transported the forest fire plume towards Santiago causing a striking decrease in visibility and a marked increase in the concentration of both primary (PM10 and CO and secondary (Ozone pollutants in the urban atmosphere. In particular, ozone maximum concentrations in the Santiago basin reached hourly averages well above 80 ppb, the national air quality standard. This ozone increase took place at the three sampling sites considered in the present study. These large values can be explained in terms of high NOx concentrations and NO2/NO ratios in biomass burning emissions.

  13. Response of Antarctic sea surface temperature and sea ice to ozone depletion

    Science.gov (United States)

    Ferreira, D.; Gnanadesikan, A.; Kostov, Y.; Marshall, J.; Seviour, W.; Waugh, D.

    2017-12-01

    The influence of the Antarctic ozone hole extends all the way from the stratosphere through the troposphere down to the surface, with clear signatures on surface winds, and SST during summer. In this talk we discuss the impact of these changes on the ocean circulation and sea ice state. We are notably motivated by the observed cooling of the surface Southern Ocean and associated increase in Antarctic sea ice extent since the 1970s. These trends are not reproduced by CMIP5 climate models, and the underlying mechanism at work in nature and the models remain unexplained. Did the ozone hole contribute to the observed trends?Here, we review recent advances toward answering these issues using "abrupt ozone depletion" experiments. The ocean and sea ice response is rather complex, comprising two timescales: a fast ( 1-2y) cooling of the surface ocean and sea ice cover increase, followed by a slower warming trend, which, depending on models, flip the sign of the SST and sea ice responses on decadal timescale. Although the basic mechanism seems robust, comparison across climate models reveal large uncertainties in the timescales and amplitude of the response to the extent that even the sign of the ocean and sea ice response to ozone hole and recovery remains unconstrained. After briefly describing the dynamics and thermodynamics behind the two-timescale response, we will discuss the main sources of uncertainties in the modeled response, namely cloud effects and air-sea heat exchanges, surface wind stress response and ocean eddy transports. Finally, we will consider the implications of our results on the ability of coupled climate models to reproduce observed Southern Ocean changes.

  14. A Simple Method for Measuring Ground-Level Ozone in the Atmosphere

    Science.gov (United States)

    Seeley, John V.; Seeley, Stacy K.; Bull, Arthur W.; Fehir, Richard J., Jr.; Cornwall, Susan; Knudsen, Gabriel A.

    2005-01-01

    An iodometric assay that allows the ground-level ozone concentration to be determined with an inexpensive sampling apparatus and a homemade photometer is described. This laboratory experiment applies a variety of different fundamental concepts including oxidation-reduction chemistry, the ideal gas law, and spectroscopic analysis and also provides…

  15. Decadal changes in summertime reactive oxidized nitrogen and surface ozone over the Southeast United States

    Science.gov (United States)

    Li, Jingyi; Mao, Jingqiu; Fiore, Arlene M.; Cohen, Ronald C.; Crounse, John D.; Teng, Alex P.; Wennberg, Paul O.; Lee, Ben H.; Lopez-Hilfiker, Felipe D.; Thornton, Joel A.; Peischl, Jeff; Pollack, Ilana B.; Ryerson, Thomas B.; Veres, Patrick; Roberts, James M.; Neuman, J. Andrew; Nowak, John B.; Wolfe, Glenn M.; Hanisco, Thomas F.; Fried, Alan; Singh, Hanwant B.; Dibb, Jack; Paulot, Fabien; Horowitz, Larry W.

    2018-02-01

    Widespread efforts to abate ozone (O3) smog have significantly reduced emissions of nitrogen oxides (NOx) over the past 2 decades in the Southeast US, a place heavily influenced by both anthropogenic and biogenic emissions. How reactive nitrogen speciation responds to the reduction in NOx emissions in this region remains to be elucidated. Here we exploit aircraft measurements from ICARTT (July-August 2004), SENEX (June-July 2013), and SEAC4RS (August-September 2013) and long-term ground measurement networks alongside a global chemistry-climate model to examine decadal changes in summertime reactive oxidized nitrogen (RON) and ozone over the Southeast US. We show that our model can reproduce the mean vertical profiles of major RON species and the total (NOy) in both 2004 and 2013. Among the major RON species, nitric acid (HNO3) is dominant (˜ 42-45 %), followed by NOx (31 %), total peroxy nitrates (ΣPNs; 14 %), and total alkyl nitrates (ΣANs; 9-12 %) on a regional scale. We find that most RON species, including NOx, ΣPNs, and HNO3, decline proportionally with decreasing NOx emissions in this region, leading to a similar decline in NOy. This linear response might be in part due to the nearly constant summertime supply of biogenic VOC emissions in this region. Our model captures the observed relative change in RON and surface ozone from 2004 to 2013. Model sensitivity tests indicate that further reductions of NOx emissions will lead to a continued decline in surface ozone and less frequent high-ozone events.

  16. The dynamics of ozone generation and mode transition in air surface micro-discharge plasma at atmospheric pressure

    International Nuclear Information System (INIS)

    Shimizu, Tetsuji; Zimmermann, Julia L; Morfill, Gregor E; Sakiyama, Yukinori; Graves, David B

    2012-01-01

    We present the transient, dynamic behavior of ozone production in surface micro-discharge (SMD) plasma in ambient air. Ultraviolet absorption spectroscopy at 254 nm was used to measure the time development of ozone density in a confined volume. We observed that ozone density increases monotonically over 1000 ppm for at least a few minutes when the input power is lower than ∼0.1 W/cm 2 . Interestingly, when input power is higher than ∼0.1 W/cm 2 , ozone density starts to decrease in a few tens of seconds at a constant power density, showing a peak ozone density. A model calculation suggests that the ozone depletion at higher power density is caused by quenching reactions with nitrogen oxides that are in turn created by vibrationally excited nitrogen molecules reacting with O atoms. The observed mode transition is significantly different from classical ozone reactors in that the transition takes place over time at a constant power. In addition, we observed a positive correlation between time-averaged ozone density and the inactivation rate of Escherichia coli on adjacent agar plates, suggesting that ozone plays a key role in inactivating bacteria under the conditions considered here. (paper)

  17. Factors Controlling Summertime Surface Ozone In The Western U.S

    Science.gov (United States)

    Gao, Mei

    In this dissertation we investigate different factors controlling summertime surface ozone (O3) in the western U.S., including the impacts from increased wildfire emissions, the modulation by North American summer monsoon as well as long-range transport of O3 and its precursors from outside of North America. We first analyze the surface ozone observations from the Clean Air Status and Trend Network (CASTNet) using a global chemical transport model (GEOS-Chem) to investigate the impact of biomass burning on surface O3 in the western U.S. (WUS) mountain ranges during the June--October fire season of 2007, one of the stronger fire years in the WUS in the past decade. GEOS-Chem O3 captures the observed seasonal, synoptic and daily variations. Model daily afternoon average surface O3 concentrations at the CASTNet sites are within 2 ppb of the observations, with correlation coefficients of 0.51--0.83 and Taylor scores of 0.64--0.92. Observed maximum daily 8-hour (MAD8) surface O3 concentrations are 37--8 ppb at the sites, while the corresponding model results are higher by 6 ppb on average. Model results show July--September maximum surface O3 enhancement of ~9 ppb on average because of biomass burning. Peaks in fire-contributed surface O3 correspond broadly with high levels of potassium (K), reaffirming a strong fire influence. We find a policy relevant background (PRB) O3 of 45.6 ppb on average during July--September. Fire-contributed O3 accounts for up to 30% of the PRB O3, highest in the intense fire region (Montana, Idaho, and Wyoming) with maxima in August and September. We also examine an unexpected summertime surface O3 minimum (~30--5 ppb) in July--August 2007 observed throughout the Southwestern U.S. (SWUS) by interpreting observations of O3 and rainfall from the Clean Air Status and Trends Network (CASTNet) with a global chemical transport model. The O3 minimum reflects competing chemical and dynamic factors as well as anthropogenic and natural influences. Its

  18. Ozone production using a power modulated surface dielectric barrier discharge in dry synthetic air

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Pekárek, S.; Prukner, Václav

    2012-01-01

    Roč. 32, č. 4 (2012), s. 743-754 ISSN 0272-4324 R&D Projects: GA ČR(CZ) GA202/09/0176 Institutional research plan: CEZ:AV0Z20430508 Keywords : ozone * surface DBD * synthetic air * nitrogen oxides * production efficiency Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.728, year: 2012 http://www.springerlink.com/content/h7p1j46381150510/fulltext. pdf

  19. Influence of Power Modulation on Ozone Production Using an AC Surface Dielectric Barrier Discharge in Oxygen

    Czech Academy of Sciences Publication Activity Database

    Šimek, Milan; Pekárek, S.; Prukner, Václav

    2010-01-01

    Roč. 30, č. 5 (2010), s. 607-617 ISSN 0272-4324 R&D Projects: GA ČR(CZ) GA202/09/0176 Institutional research plan: CEZ:AV0Z20430508 Keywords : Ozone * Surface DBD * Oxygen * Production efficiency Subject RIV: BL - Plasma and Gas Disc harge Physics Impact factor: 1.798, year: 2010 http://www.springerlink.com/content/28539775w5243513/

  20. Cadmium biosorption by ozonized activated sludge: The role of bacterial flocs surface properties and mixed liquor composition

    International Nuclear Information System (INIS)

    Laurent, Julien; Casellas, Magali; Pons, Marie-Noelle; Dagot, Christophe

    2010-01-01

    Cadmium uptake by activated sludge was studied following modifications of sludge composition and surface properties induced by ozone treatment. Ozone leads to the solubilization of sludge compounds as well as their mineralization, especially humic like substances. Small particles were formed following floc disintegration, leading to a decrease of average floc size. The study of surface properties underlined the mineralization as the number of surface binding sites decreased with the increase of ozone dose. Depending on ozone dose, cadmium uptake by activated sludge flocs was either increased or decreased. Different mechanisms were involved: below 10 mg O 3 /g TS, the increase of floc specific surface area following floc size decrease as well as the release of phosphate ions yielded an increase by 75% of cadmium uptake, due to the better availability of biosorption sites and the increase of precipitation. Inversely, at higher ozone doses, the number of biosorption sites decreased due to oxidation by ozone. Moreover, dissolved organic matter concentration increased and provided ligands for metal complexation. Cadmium uptake was therefore limited for ozone doses ranging from 10 to 16.8 mg O 3 /g TS.

  1. Impacts of ozone on trees and crops

    International Nuclear Information System (INIS)

    Felzer, B.S.; Cronina, T.; Melillo, J.M.; Reilly, J.M.; Xiaodong, Wang

    2007-01-01

    In this review article, we explore how surface-level ozone affects trees and crops with special emphasis on consequences for productivity and carbon sequestration. Vegetation exposure to ozone reduces photosynthesis, growth, and other plant functions. Ozone formation in the atmosphere is a product of NO x , which are also a source of nitrogen deposition. Reduced carbon sequestration of temperate forests resulting from ozone is likely offset by increased carbon sequestration from nitrogen fertilization. However, since fertilized crop-lands are generally not nitrogen-limited, capping ozone-polluting substances in the USA, Europe, and China can reduce future crop yield loss substantially. (authors)

  2. Evaluation of the flux gradient technique for measurement of ozone surface fluxes over snowpack at Summit, Greenland

    Directory of Open Access Journals (Sweden)

    F. Bocquet

    2011-10-01

    Full Text Available A multi-step procedure for investigating ozone surface fluxes over polar snow by the tower gradient method was developed and evaluated. These measurements were then used to obtain five months (April–August 2004 of turbulent ozone flux data at the Summit research camp located in the center of the Greenland ice shield. Turbulent fluxes were determined by the gradient method incorporating tower measurements of (a ozone gradients measured by commercial ultraviolet absorption analyzers, (b ambient temperature gradients using aspirated thermocouple sensors, and (c wind speed gradients determined by cup anemometers. All gradient instruments were regularly inter-compared by bringing sensors or inlets to the same measurement height. The developed protocol resulted in an uncertainty on the order of 0.1 ppbv for 30-min averaged ozone gradients that were used for the ozone flux calculations. This protocol facilitated a lower sensitivity threshold for the ozone flux determination of ∼8 × 10−3μg m−2 s−1, respectively ∼0.01 cm s−1 for the ozone deposition velocity for typical environmental conditions encountered at Summit. Uncertainty in the 30-min ozone exchange measurements (evaluated by the Monte Carlo statistical approach was on the order of 10−2 cm s−1. This uncertainty typically accounted to ~20–100% of the ozone exchange velocities that were determined. These measurements are among the most sensitive ozone deposition determinations reported to date. This flux experiment allowed for measurements of the relatively low ozone uptake rates encountered for polar snow, and thereby the study of their environmental and spring-versus-summer dependencies.

  3. Springtime high surface ozone events over the western United States: Quantifying the role of stratospheric intrusions

    Science.gov (United States)

    Fiore, A. M.; Lin, M.; Cooper, O. R.; Horowitz, L. W.; Naik, V.; Levy, H.; Langford, A. O.; Johnson, B. J.; Oltmans, S. J.; Senff, C. J.

    2011-12-01

    As the National Ambient Air Quality (NAAQS) standard for ozone (O_{3}) is lowered, it pushes closer to policy-relevant background levels (O_{3} concentrations that would exist in the absence of North American anthropogenic emissions), making attainment more difficult with local controls. We quantify the Asian and stratospheric components of this North American background, with a primary focus on the western United States. Prior work has identified this region as a hotspot for deep stratospheric intrusions in spring. We conduct global simulations at 200 km and 50 km horizontal resolution with the GFDL AM3 model, including a stratospheric O_{3} tracer and two sensitivity simulations with anthropogenic emissions from Asia and North America turned off. The model is evaluated with a suite of in situ and satellite measurements during the NOAA CalNex campaign (May-June 2010). The model reproduces the principle features in the observed surface to near tropopause distribution of O_{3} along the California coast, including its latitudinal variation and the development of regional high-O_{3} episodes. Four deep tropopause folds are diagnosed and we find that the remnants of these stratospheric intrusions are transported to the surface of Southern California and Western U.S. Rocky Mountains, contributing 10-30 ppbv positive anomalies relative to the simulated campaign mean stratospheric component in the model surface layer. We further examine the contribution of North American background, including its stratospheric and Asian components, to the entire distribution of observed MDA8 O_{3} at 12 high-elevation CASTNet sites in the Mountain West. We find that the stratospheric O_{3} tracer constitutes 50% of the North American background, and can enhance surface maximum daily 8-hour average (MDA8) O_{3} by 20 ppb when observed surface O_{3} is in the range of 60-80 ppbv. Our analysis highlights the potential for natural sources such as deep stratospheric intrusions to contribute

  4. Influences of the variation in inflow to East Asia on surface ozone over Japan during 1996–2005

    Directory of Open Access Journals (Sweden)

    S. Chatani

    2011-08-01

    Full Text Available Air quality simulations in which the global chemical transport model CHASER and the regional chemical transport model WRF/chem are coupled have been developed to consider the dynamic transport of chemical species across the boundaries of the domain of the regional chemical transport model. The simulation captures the overall seasonal variations of surface ozone, but overestimates its concentration over Japanese populated areas by approximately 20 ppb from summer to early winter. It is deduced that ozone formation around Northeast China and Japan in summer is overestimated in the simulation. On the other hand, the simulation well reproduces the interannual variability and the long-term trend of observed surface ozone over Japan. Sensitivity experiments have been performed to investigate the influence of the variation in inflow to East Asia on the interannual variability and the long-term trend of surface ozone over Japan during 1996–2005. The inflow defined in this paper includes the recirculation of species with sources within the East Asian region as well as the transport of species with sources out of the East Asian region. Results of sensitivity experiments suggest that inflow to East Asia accounts for approximately 30 % of the increasing trend of surface ozone, whereas it has much less influence on the interannual variability of observed surface ozone compared to meteorological processes within East Asia.

  5. Higher measured than modeled ozone production at increased NOx levels in the Colorado Front Range

    Directory of Open Access Journals (Sweden)

    B. C. Baier

    2017-09-01

    Full Text Available Chemical models must correctly calculate the ozone formation rate, P(O3, to accurately predict ozone levels and to test mitigation strategies. However, air quality models can have large uncertainties in P(O3 calculations, which can create uncertainties in ozone forecasts, especially during the summertime when P(O3 is high. One way to test mechanisms is to compare modeled P(O3 to direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS directly measured net P(O3 in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O3 was compared to rates calculated by a photochemical box model that was constrained by measurements of other chemical species and that used a lumped chemical mechanism and a more explicit one. Median observed P(O3 was up to a factor of 2 higher than that modeled during early morning hours when nitric oxide (NO levels were high and was similar to modeled P(O3 for the rest of the day. While all interferences and offsets in this new method are not fully understood, simulations of these possible uncertainties cannot explain the observed P(O3 behavior. Modeled and measured P(O3 and peroxy radical (HO2 and RO2 discrepancies observed here are similar to those presented in prior studies. While a missing atmospheric organic peroxy radical source from volatile organic compounds co-emitted with NO could be one plausible solution to the P(O3 discrepancy, such a source has not been identified and does not fully explain the peroxy radical model–data mismatch. If the MOPS accurately depicts atmospheric P(O3, then these results would imply that P(O3 in Golden, CO, would be NOx-sensitive for more of the day than what is calculated by models, extending the NOx-sensitive P(O3 regime from the afternoon further into the morning. These results could affect ozone reduction strategies for the region surrounding Golden and possibly other areas that do not comply with national ozone

  6. Higher measured than modeled ozone production at increased NOx levels in the Colorado Front Range

    Science.gov (United States)

    Baier, Bianca C.; Brune, William H.; Miller, David O.; Blake, Donald; Long, Russell; Wisthaler, Armin; Cantrell, Christopher; Fried, Alan; Heikes, Brian; Brown, Steven; McDuffie, Erin; Flocke, Frank; Apel, Eric; Kaser, Lisa; Weinheimer, Andrew

    2017-09-01

    Chemical models must correctly calculate the ozone formation rate, P(O3), to accurately predict ozone levels and to test mitigation strategies. However, air quality models can have large uncertainties in P(O3) calculations, which can create uncertainties in ozone forecasts, especially during the summertime when P(O3) is high. One way to test mechanisms is to compare modeled P(O3) to direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS) directly measured net P(O3) in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O3) was compared to rates calculated by a photochemical box model that was constrained by measurements of other chemical species and that used a lumped chemical mechanism and a more explicit one. Median observed P(O3) was up to a factor of 2 higher than that modeled during early morning hours when nitric oxide (NO) levels were high and was similar to modeled P(O3) for the rest of the day. While all interferences and offsets in this new method are not fully understood, simulations of these possible uncertainties cannot explain the observed P(O3) behavior. Modeled and measured P(O3) and peroxy radical (HO2 and RO2) discrepancies observed here are similar to those presented in prior studies. While a missing atmospheric organic peroxy radical source from volatile organic compounds co-emitted with NO could be one plausible solution to the P(O3) discrepancy, such a source has not been identified and does not fully explain the peroxy radical model-data mismatch. If the MOPS accurately depicts atmospheric P(O3), then these results would imply that P(O3) in Golden, CO, would be NOx-sensitive for more of the day than what is calculated by models, extending the NOx-sensitive P(O3) regime from the afternoon further into the morning. These results could affect ozone reduction strategies for the region surrounding Golden and possibly other areas that do not comply with national ozone regulations

  7. Study of Ozone Tropospheric Levels At The Castellon Area (spain) By Means of Passive Samplers

    Science.gov (United States)

    Delgado, J. M.; Esteve, V.

    Tropospheric ozone is produced by means of pollutants (mainly NOx and VOC's ) emitted by mobile sources like traffic or heating engines. In the case of La Plana de Castellon area, the cities, the industrial area called El Serrallo ( with its oil refinery and power plant), the tile factories and the main roads (A7-E15 and N-340), all they are the main pollutant focus of precursors contaminants. Nevertheless, areas far from these points suffer the harmful effects of oxidants as ozone. The aim of this work is the study of tropospheric ozone levels in far areas from Castellon, mainly in La Plana de Castellon area, by means of a new lower-cost sampling technology:passive sam- plers. The measurement campaign is made during the higher photochemical activity period (from May to September) in order to obtain the necessary data to make an ozone isoconcentration map. It has been divided into sampling periods of one week. Twenty samples are collected each sampling period to cover an interest area of 1400 Km2. Two of these samples are laboratory blanks, four are situated at reference points with two co-located points (beside an automatic ozone sampler) and the rest twelve samples are located around the sampling area of interest, in radial peripheral points around Castellon city an the main precursors pollutants points. Two different kind of passive samplers has been employed: Radielloo samplers developed by Dr. Cocheo at Fondazione Salvatore Maugeri and ozone passive samplers Ogawao developed by Dr. Koutrakis at Harvard University. Samples located by the coast show the lowest levels, 40 ug/m3, about 37% lower than the other measuring points. Levels in the city of Castellon are 50 ug/m3, 25% higher to coast levels. Nevertheless, highest levels are measured in the North area with values raising to 60 ug/m3, about 47% higher than coast values. At the inner area values are about 55 ug/m3 and at the south area values are about 50 ug/m3. We would like to thank Dr. M. Wolfosn

  8. Study of an Ozone Composing Mechanism derived from the Third Element on Surface of Electrode using Oxygen Gas: Part 2

    Science.gov (United States)

    Murai, Akira; Nakajima, Tsuyoshi

    In our third experiment, we changed the density of nitrogen through the addition of heat energy to the anode. A computer simulation confirmed the same phenomenon. Then the copper anode was replaced with an antimony anode. We found that antimony worked better than nitrogen as a third element. Finally, in the fourth experiment, we used an industrial ozone generator including ceramic dielectrics and a titanium expanded metal electrode. A decrease in the temperature of the cooling water led to a proportional increase in ozone. It follows the formula of van't Hoff. After spattering the surface of the electrodes with argon gas and supplying the ozone generator with 99% oxygen, we were able to produce ozone which was more than 20% higher in concentration than primary state ozone under the same conditions. The ozone generator produced ozone in high yield efficiency due to the optimum density of a third element like nitrogen on the surface of the electrodes. Antimony works better than nitrogen does as a third element.

  9. Surface Ozone Enrichment Downwind of Manaus City, in Central Amazonia

    Science.gov (United States)

    Carbone, S.; Rizzo, L. V.; Rodrigues, N. P.; Brito, J.; Cirino, G. G.; Souza, R. A. F. D.; Barbosa, H. M.; Artaxo, P.; Martin, S. T.

    2015-12-01

    Amazonia is a unique place to study the impact of anthropogenic emissions on atmospheric photochemistry, fueled by large inputs of solar radiation, humidity, biogenic emissions and turbulent mixing. In the wet season, thousands of km2 of Amazonian forest areas can be considered pristine, whereas in the dry season biomass burning emissions in regional scale add to picture. The Amazon region is also going through localized urban development, in particular, the Manaus city, with 2 million inhabitants. The GoAmazon2014/5 experiment seeks to understand the interactions between urban and biogenic emissions in Amazonia. The combination of biogenic volatile organic compounds and urban NOx emissions is expected to increase tropospheric O3 production, with impacts to the ecosystem and human health. To investigate this issue, surface O3 measurements were taken between Feb and Dec 2014 at two sites in Amazonia: T2, located in the outflow of the Manaus urban plume, and T3, sitting 60 km downwind of the city. The influence of the urban plume at T3 site was detected by a combination of typical ΔCN/ΔCO ratios, Hysplit backtrajectories and threshold concentrations of tracers such as particle number and black carbon. The transport from T2 to T3 typically lasted 7 hours. At T2, the O3 diurnal cycle showed a diurnal peak of 20 ppb in the wet season and of 35 ppb in the dry season, suggesting the contribution of regional biomass burning to O3 photochemical production. In the absence of urban or biomass burning emissions, O3 diurnal cycle at T3 showed a peak of 15 ppb, similar to observations taken in pristine forest areas in Amazonia. When the Manaus plume reached the T3 site in the afternoon, the diurnal O3 peak increased to 40 ppb, indicating a net O3 production rate of 3.6 ppb h-1 along this diurnal transport. When the Manaus plume reached the T3 site before sunrise, i.e., a transport during the night, the diurnal peak was anticipated and reached 25 ppb.

  10. Photocatalytic ozonation of urban wastewater and surface water using immobilized TiO2 with LEDs: Micropollutants, antibiotic resistance genes and estrogenic activity.

    Science.gov (United States)

    Moreira, Nuno F F; Sousa, José M; Macedo, Gonçalo; Ribeiro, Ana R; Barreiros, Luisa; Pedrosa, Marta; Faria, Joaquim L; Pereira, M Fernando R; Castro-Silva, Sérgio; Segundo, Marcela A; Manaia, Célia M; Nunes, Olga C; Silva, Adrián M T

    2016-05-01

    Photocatalytic ozonation was employed for the first time in continuous mode with TiO2-coated glass Raschig rings and light emitting diodes (LEDs) to treat urban wastewater as well as surface water collected from the supply area of a drinking water treatment plant (DWTP). Different levels of contamination and types of contaminants were considered in this work, including chemical priority substances (PSs) and contaminants of emerging concern (CECs), as well as potential human opportunistic antibiotic resistant bacteria and their genes (ARB&ARG). Photocatalytic ozonation was more effective than single ozonation (or even than TiO2 catalytic ozonation) in the degradation of typical reaction by-products (such as oxalic acid), and more effective than photocatalysis to remove the parent micropollutants determined in urban wastewater. In fact, only fluoxetine, clarithromycin, erythromycin and 17-alpha-ethinylestradiol (EE2) were detected after photocatalytic ozonation, by using solid-phase extraction (SPE) pre-concentration and LC-MS/MS analysis. In surface water, this treatment allowed the removal of all determined micropollutants to levels below the limit of detection (0.01-0.20 ng L(-1)). The efficiency of this process was then assessed based on the capacity to remove different groups of cultivable microorganisms and housekeeping (16S rRNA) and antibiotic resistance or related genes (intI1, blaTEM, qnrS, sul1). Photocatalytic ozonation was observed to efficiently remove microorganisms and ARGs. Although after storage total heterotrophic and ARB (to ciprofloxacin, gentamicin, meropenem), fungi, and the genes 16S rRNA and intI1, increased to values close to the pre-treatment levels, the ARGs (blaTEM, qnrS and sul1) were reduced to levels below/close to the quantification limit even after 3-days storage of treated surface water or wastewater. Yeast estrogen screen (YES), thiazolyl blue tetrazolium reduction (MTT) and lactate dehydrogenase (LDH) assays were also performed

  11. In search for evidence: combining ad hoc survey, monitoring, and modeling to estimate the potential and actual impact of ground level ozone on forests in Trentino (Northern Italy).

    Science.gov (United States)

    Gottardini, Elena; Cristofolini, Fabiana; Cristofori, Antonella; Ferretti, Marco

    2017-09-27

    A 5-year project was carried out over the period 2007-2011 to estimate the potential and actual ozone effect on forests in Trentino, Northern Italy (6207 km 2 ) (Ozone EFFORT). The objective was to provide explicit answers to three main questions: (i) is there a potential risk placed by ozone to vegetation? (ii) are there specific ozone symptoms on vegetation, and are they related to ozone levels? (iii) are there ozone-related effects on forest health and growth? Different methods and techniques were adopted as follows: monitoring ozone levels, ad hoc field survey for symptoms on vegetation and chlorophyll-related measurements, modeling to upscale ozone measurements, ozone flux estimation, statistical analysis, and modeling to detect whether a significant effect attributable to ozone exists. Ozone effects were assessed on an ad hoc-introduced bioindicator, on spontaneous woody species, and on forest trees. As for question (i), the different ozone-risk critical levels for both exposure and stomatal flux were largely exceeded in Trentino, evidencing a potentially critical situation for vegetation. As for question (ii), specific ozone foliar symptoms related to ozone exposure levels were observed on the introduced supersensitive Nicotiana tabacum L. cv Bel-W3 and on the spontaneous, ozone-sensitive Viburnum lantana L., but not on other 33 species surveyed in the field studies. Regarding question (iii), statistical analyses on forest health (in terms of defoliation) and growth (in terms of basal area increment) measured at 15 forest monitoring plots and tree rings (at one site) revealed no significant relationship with ozone exposure and flux. Instead, a set of factors related to biotic and abiotic causes, foliar nutrients, age, and site were identified as the main drivers of forest health and growth. In conclusion, while ozone levels and fluxes in the investigated region were much higher than current critical levels, evidence of impact on vegetation-and on forest

  12. Statistical Models to Assess the Health Effects and to Forecast Ground Level Ozone

    Czech Academy of Sciences Publication Activity Database

    Schlink, U.; Herbath, O.; Richter, M.; Dorling, S.; Nunnari, G.; Cawley, G.; Pelikán, Emil

    2006-01-01

    Roč. 21, č. 4 (2006), s. 547-558 ISSN 1364-8152 R&D Projects: GA AV ČR 1ET400300414 Institutional research plan: CEZ:AV0Z10300504 Keywords : statistical models * ground level ozone * health effects * logistic model * forecasting * prediction performance * neural network * generalised additive model * integrated assessment Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 1.992, year: 2006

  13. BUV/Nimbus-4 Level 2 High-Density Ozone Data V005 (BUVN4L2HDBUV) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Nimbus-4 BUV Level 2 High-Density Ozone Data collection contains the vertical distribtuion and total column amount of ozone, as well as the full set of ancillary...

  14. ACUTE OZONE-INDUCED INFLAMMATORY GENE EXPRESSION IN THE RAT LUNG IS NOT RELATED TO LEVELS OF ANTIOXIDANTS IN THE LAVAGE FLUID

    Science.gov (United States)

    ABSTRACT BODY: Ozone causes oxidative stress and lung inflammation. We hypothesized that rat strains with or without genetic susceptibility to cardiovascular disease will have different antioxidant levels in alveolar lining, and that ozone induced inflammatory gene expression wil...

  15. Global Surface Ozone Variability and Trends - The TOAR database and metrics products

    Science.gov (United States)

    Schultz, Martin

    2017-04-01

    In the context of the first Tropospheric Ozone Assessment Report (TOAR) the world's largest collection of surface ozone data has been assembled in a database at Forschungszentrum Juelich, Germany. Data span the period from 1970 to 2014. Station metadata have been harmonized and extended with information from several global high-resolution datasets. This allows for a first, globally uniform station characterisation as "urban" or "rural". Extensive quality control of the metadata and data was performed and feedback provided to original data providers. This harmonized database was then used to generate hundreds of aggregated aggregate statistics and ozone metrics for use in the analysis of trends in human health, vegetation, and climate impact assessments. These data products form the core data of the TOAR publications which shall become available as a special journal issue in October 2017. The presentation will provide an overview about the TOAR database and the TOAR data files, and demonstrate how they can be accessed and used. The potential for future developments will be discussed.

  16. Impact of forest fires, biogenic emissions and high temperatures on the elevated Eastern Mediterranean ozone levels during the hot summer of 2007

    Science.gov (United States)

    Hodnebrog, Ø.; Solberg, S.; Stordal, F.; Svendby, T. M.; Simpson, D.; Gauss, M.; Hilboll, A.; Pfister, G. G.; Turquety, S.; Richter, A.; Burrows, J. P.; Denier van der Gon, H. A. C.

    2012-09-01

    The hot summer of 2007 in southeast Europe has been studied using two regional atmospheric chemistry models; WRF-Chem and EMEP MSC-W. The region was struck by three heat waves and a number of forest fire episodes, greatly affecting air pollution levels. We have focused on ozone and its precursors using state-of-the-art inventories for anthropogenic, biogenic and forest fire emissions. The models have been evaluated against measurement data, and processes leading to ozone formation have been quantified. Heat wave episodes are projected to occur more frequently in a future climate, and therefore this study also makes a contribution to climate change impact research. The plume from the Greek forest fires in August 2007 is clearly seen in satellite observations of CO and NO2 columns, showing extreme levels of CO in and downwind of the fires. Model simulations reflect the location and influence of the fires relatively well, but the modelled magnitude of CO in the plume core is too low. Most likely, this is caused by underestimation of CO in the emission inventories, suggesting that the CO/NOx ratios of fire emissions should be re-assessed. Moreover, higher maximum values are seen in WRF-Chem than in EMEP MSC-W, presumably due to differences in plume rise altitudes as the first model emits a larger fraction of the fire emissions in the lowermost model layer. The model results are also in fairly good agreement with surface ozone measurements. Biogenic VOC emissions reacting with anthropogenic NOx emissions are calculated to contribute significantly to the levels of ozone in the region, but the magnitude and geographical distribution depend strongly on the model and biogenic emission module used. During the July and August heat waves, ozone levels increased substantially due to a combination of forest fire emissions and the effect of high temperatures. We found that the largest temperature impact on ozone was through the temperature dependence of the biogenic emissions

  17. Impact of forest fires, biogenic emissions and high temperatures on the elevated Eastern Mediterranean ozone levels during the hot summer of 2007

    Directory of Open Access Journals (Sweden)

    Ø. Hodnebrog

    2012-09-01

    Full Text Available The hot summer of 2007 in southeast Europe has been studied using two regional atmospheric chemistry models; WRF-Chem and EMEP MSC-W. The region was struck by three heat waves and a number of forest fire episodes, greatly affecting air pollution levels. We have focused on ozone and its precursors using state-of-the-art inventories for anthropogenic, biogenic and forest fire emissions. The models have been evaluated against measurement data, and processes leading to ozone formation have been quantified. Heat wave episodes are projected to occur more frequently in a future climate, and therefore this study also makes a contribution to climate change impact research.

    The plume from the Greek forest fires in August 2007 is clearly seen in satellite observations of CO and NO2 columns, showing extreme levels of CO in and downwind of the fires. Model simulations reflect the location and influence of the fires relatively well, but the modelled magnitude of CO in the plume core is too low. Most likely, this is caused by underestimation of CO in the emission inventories, suggesting that the CO/NOx ratios of fire emissions should be re-assessed. Moreover, higher maximum values are seen in WRF-Chem than in EMEP MSC-W, presumably due to differences in plume rise altitudes as the first model emits a larger fraction of the fire emissions in the lowermost model layer. The model results are also in fairly good agreement with surface ozone measurements.

    Biogenic VOC emissions reacting with anthropogenic NOx emissions are calculated to contribute significantly to the levels of ozone in the region, but the magnitude and geographical distribution depend strongly on the model and biogenic emission module used. During the July and August heat waves, ozone levels increased substantially due to a combination of forest fire emissions and the effect of high temperatures. We found that the largest temperature impact on

  18. Surface ozone scenario and air quality in the north-central part of India.

    Science.gov (United States)

    Saini, Renuka; Taneja, Ajay; Singh, Pradyumn

    2017-09-01

    Tropospheric pollutants including surface ozone (O 3 ), nitrogen dioxide (NO 2 ), carbon monoxide (CO) and meteorological parameters were measured at a traffic junction (78°2' E and 27°11' N) in Agra, India from January 2012 to December 2012. Temporal analysis of pollutants suggests that annual average mixing ratios of tropospheric pollutants were: O 3 - 22.97±23.36ppbV, NO 2 - 19.84±16.71ppbV and CO - 0.91±0.86ppmV, with seasonal variations of O 3 having maximum mixing ratio during summer season (32.41±19.31ppbV), whereas lowest was found in post-monsoon season (8.74±3.8ppbV). O 3 precursors: NO 2 and CO, showed inverse relationship with O 3 . Seasonal variation and high O 3 episodes during summer are associated with meteorological parameters such as high solar radiation, atmospheric temperature and transboundary transport. The interdependence of these variables showed a link between the daytime mixing ratios of O 3 with the nighttime level of NO 2 . The mixing ratios of CO and NO 2 showed tight correlations, which confirms the influence of vehicular emissions combined with other anthropogenic activities due to office/working hours, shallowing, and widening of boundary layer. FLEXTRA backward trajectories for the O 3 episode days clearly indicate the transport from the NW and W to S/SE and SW direction at Agra in different seasons. Copyright © 2017. Published by Elsevier B.V.

  19. Ground level ozone effects in individual growth phases of central european submountain beech forests

    Directory of Open Access Journals (Sweden)

    Kellerová Daniela

    2014-03-01

    Full Text Available We observed ground level ozone concentrations on a series of five beech experimental plots, one representing the original stand and the other four generated and modified by cuts of graduated intensity. The study was carried out in a beech ecosystem in the Kremnické vrchy Mts, the Western Carpathian region, in years 1999-2008. The plots, established in 1989, were evaluated and compared statistically before and after the cutting modification in 2004. The level of significance of the effect of this intervention was 99% on the plot representing small-area clear-cut and on the plot treated with medium cut. Differences, though not significant, were also found in the other plots. Apart from the effects due to the stocking reduction, the whole post-intervention period was characterised with the influence of progressively increasing average air temperatures and similarly increasing ozone concentrations. Globally, the ozone concentrations on all plots were lower (average value 39 μg m-3 during the period 1999-2003 than in the following years 2004-2008 (average value 55 μg m-3. Maximum values measured in the growing season ranged from 36 to 140 μg m-3. The allowable limit exceeded 10 times in years 1999-2003 but 17 times in years 2004-2008, implying worsening conditions in Central European beech forest stands.

  20. Impact of high-resolution sea surface temperature, emission spikes and wind on simulated surface ozone in Houston, Texas during a high ozone episode

    Science.gov (United States)

    Pan, Shuai; Choi, Yunsoo; Jeon, Wonbae; Roy, Anirban; Westenbarger, David A.; Kim, Hyun Cheol

    2017-03-01

    Model-measurement comparisons for surface ozone often show significant error, which could be attributed to problems in meteorology and emissions fields. A WRF-SMOKE-CMAQ air quality modeling system was used to investigate the contributions of these inputs. In this space, a base WRF run (BASE) and a WRF run initializing with NOAA GOES satellite sea surface temperature (SST) (SENS) were performed to clarify the impact of high-resolution SST on simulated surface ozone (O3) over the Greater Houston area during 25 September 2013, corresponding to the high O3 episode during the NASA DISCOVER-AQ Texas campaign. The SENS case showed reduced land-sea thermal contrast during early morning hours due to 1-2 °C lower SST over water bodies. The lowered SST reduced the model wind speed and slowed the dilution rate. These changes led to a simulated downwind O3 change of ∼5 ppb near the area over land with peak simulated afternoon O3. However, the SENS case still under-predicted surface O3 in urban and industrial areas. Episodic flare emissions, dry sunny postfrontal stagnated conditions, and land-bay/sea breeze transitions could be the potential causes of the high O3. In order to investigate the additional sources of error, three sensitivity simulations were performed for the high ozone time period. These involved adjusted emissions, adjusted wind fields, and both adjusted emissions and winds. These scenarios were superimposed on the updated SST (SENS) case. Adjusting NOx and VOC emissions using simulated/observed ratios improved correlation and index of agreement (IOA) for NOx from 0.48 and 0.55 to 0.81 and 0.88 respectively, but still reported spatial misalignment of afternoon O3 hotspots. Adjusting wind fields to represent morning weak westerly winds and afternoon converging zone significantly mitigated under-estimation of the observed O3 peak. For example, simulations with adjusted wind fields and adjusted (emissions + wind fields) reduced under-estimation of the peak

  1. Ozone threat

    International Nuclear Information System (INIS)

    Rajput, M.A.

    1995-01-01

    Ozone hole was first discovered in 1980. Thus 15 years even after the first warming, the world is no where near to the elimination of man made gases that threaten to destroy the ozone layer. Ozone depletion has become a matter of enormous threat which remains to be solved by the Scientists and intelligentia of the world. Ozone (O3) is a pungent poisonous gas. It forms a layer at a distance of about 15 miles above the earth's surface which helps shield living things from the sun shearing ultra violet light. If ozone is lost, more ultra violet light reaches the earth, which can lead to increasing rate of skin cancer, the death of micro organisms and the failure of crops and plants. It was in 1974 when it was discovered that Chlorofluorocarbons (CFCs) cold rise slowly to the upper atmosphere and destroy the earth's fragile ozone shield. Chlorofluorocarbons are commonly used as coolants (such as Freon) for home and automobile air conditioners and in the making of fast food containers. CFCs take about 100 years or more to reach he stratosphere to damage the ozone layers. In 1988, Scientists confirmed that upto 3% of the ozone layer over the more populated Northern Hemisphere has been destroyed. it is believed that for every 1% decrease in ozone, skin cancers are expected to rise 5 to 6 per cent due to the increase of ultraviolet light. Cases of cataracts and certain human immune system diseases are also expected to rise. (author)

  2. Wildfire influences on the variability and trend of summer surface ozone in the mountainous western United States

    Directory of Open Access Journals (Sweden)

    X. Lu

    2016-11-01

    Full Text Available Increasing wildfire activities in the mountainous western US may present a challenge for the region to attain a recently revised ozone air quality standard in summer. Using current Eulerian chemical transport models to examine the wildfire ozone influences is difficult due to uncertainties in fire emissions, inadequate model chemistry, and resolution. Here we quantify the wildfire influence on the ozone variability, trends, and number of high MDA8 (daily maximum 8 h average ozone days over this region in summers (June, July, and August 1989–2010 using a new approach. We define a fire index using retroplumes (plumes of back-trajectory particles computed by a Lagrangian dispersion model (FLEXPART and develop statistical models based on the fire index and meteorological parameters to interpret MDA8 ozone concentrations measured at 13 Intermountain West surface sites. We show that the statistical models are able to capture the ozone enhancements by wildfires and give results with some features different from the GEOS-Chem Eulerian chemical transport model. Wildfires enhance the Intermountain West regional summer mean MDA8 ozone by 0.3–1.5 ppbv (daily episodic enhancements reach 10–20 ppbv at individual sites with large interannual variability, which are strongly correlated with the total MDA8 ozone. We find large fire impacts on the number of exceedance days; for the 13 CASTNet sites, 31 % of the summer days with MDA8 ozone exceeding 70 ppbv would not occur in the absence of wildfires.

  3. Ground-level ozone in four Chinese cities: precursors, regional transport and heterogeneous processes

    Science.gov (United States)

    Xue, L. K.; Wang, T.; Gao, J.; Ding, A. J.; Zhou, X. H.; Blake, D. R.; Wang, X. F.; Saunders, S. M.; Fan, S. J.; Zuo, H. C.; Zhang, Q. Z.; Wang, W. X.

    2014-12-01

    We analyzed the measurements of ozone (O3) and its precursors made at rural/suburban sites downwind of four large Chinese cities - Beijing, Shanghai, Guangzhou and Lanzhou, to elucidate their pollution characteristics, regional transport, in situ production, and impacts of heterogeneous processes. The same measurement techniques and observation-based model were used to minimize uncertainties in comparison of the results due to difference in methodologies. All four cities suffered from serious O3 pollution but showed different precursor distributions. The model-calculated in situ O3 production rates were compared with the observed change rates to infer the relative contributions of on-site photochemistry and transport. At the rural site downwind of Beijing, export of the well-processed urban plumes contributed to the extremely high O3 levels (up to an hourly value of 286 ppbv), while the O3 pollution observed at suburban sites of Shanghai, Guangzhou and Lanzhou was dominated by intense in situ production. The O3 production was in a volatile organic compound (VOC)-limited regime in both Shanghai and Guangzhou, and a NOx-limited regime in Lanzhou. The key VOC precursors are aromatics and alkenes in Shanghai, and aromatics in Guangzhou. The potential impacts on O3 production of several heterogeneous processes, namely, hydrolysis of dinitrogen pentoxide (N2O5), uptake of hydro peroxy radical (HO2) on particles and surface reactions of NO2 forming nitrous acid (HONO), were assessed. The analyses indicate the varying and considerable impacts of these processes in different areas of China depending on the atmospheric abundances of aerosol and NOx, and suggest the urgent need to better understand these processes and represent them in photochemical models.

  4. Trends in total column ozone over Australia and New Zealand and its influence on clear-sky surface erythemal irradiance

    International Nuclear Information System (INIS)

    Bodeker, G. E.

    1995-01-01

    Australia and New Zealand are two of the countries closest to the Antarctic ozone depletion and may therefore be 'at risk' as a result of the associated increases in surface ultraviolet (UV) radiation. To investigate the possible impact of mid-latitude ozone decreases on surface erythemal irradiances, monthly mean total ozone has been calculated from daily total ozone mapping spectrometer data for 5 Australian cities (Canberra, Hobart, Melbourne, Perth and Sydney) and 3 New Zealand cities (Auckland, Christchurch and Wellington) from 1979 to 1992. These values have then been used as inputs to a single layer model to calculate noon clear-sky global UV irradiances and associated erythemal irradiances. In addition, the monthly mean ozone data have been modelled statistically for each location to reveal a long-term linear trend, an annual variation, a Quasi-Biennial Oscillation (QBO), a solar cycle component and a semi-annual (6 month) signal. Coefficients from these statistical models have been used to estimate monthly mean ozone and noon clear-sky erythemal irradiances to the year 2000 for each city. It is assumed that the rate of increase of stratospheric chlorine over the remainder of the century will remain constant. Given that there is some evidence that the rate of increase is decreasing, the results present here should be regarded as an upper limit. 33 refs., 7 tabs., 4 figs

  5. Understanding Long-Term Variations in Surface Ozone in United States (U.S. National Parks

    Directory of Open Access Journals (Sweden)

    Deborah McGlynn

    2018-03-01

    Full Text Available Long-term surface ozone observations at 25 National Park Service sites across the United States were analyzed for processes on varying time scales using a time scale decomposition technique, the Ensemble Empirical Mode Decomposition (EEMD. Time scales of interest include the seasonal cycle, large-scale climate oscillations, and long-term (>10 years trends. Emission reductions were found to have a greater impact on sites that are nearest major urban areas. Multidecadal trends in surface ozone were increasing at a rate of 0.07 to 0.37 ppbv year−1 before 2004 and decreasing at a rate of −0.08 to −0.60 ppbv year−1 after 2004 for sites in the East, Southern California, and Northwestern Washington. Sites in the Intermountain West did not experience a reversal of trends from positive to negative until the mid- to late 2000s. The magnitude of the annual amplitude (=annual maximum–minimum decreased at eight sites, two in the West, two in the Intermountain West, and four in the East, by 5–20 ppbv and significantly increased at three sites; one in Alaska, one in the West, and one in the Intermountain West, by 3–4 ppbv. Stronger decreases in the annual amplitude occurred at a greater proportion of sites in the East (4/6 sites than in the West/Intermountain West (4/19 sites. The date of annual maximums and/or minimums has changed at 12 sites, occurring 10–60 days earlier in the year. There appeared to be a link between the timing of the annual maximum and the decrease in the annual amplitude, which was hypothesized to be related to a decrease in ozone titration resulting from NOx emission reductions. Furthermore, it was found that a phase shift of the Pacific Decadal Oscillation (PDO, from positive to negative, in 1998–1999 resulted in increased occurrences of La Niña-like conditions. This shift had the effect of directing more polluted air masses from East Asia to higher latitudes over the North American continent. The change in the

  6. An epidemiological assessment of stomatal ozone flux-based critical levels for visible ozone injury in Southern European forests.

    Science.gov (United States)

    Sicard, Pierre; De Marco, Alessandra; Dalstein-Richier, Laurence; Tagliaferro, Francesco; Renou, Camille; Paoletti, Elena

    2016-01-15

    Southern forests are at the highest ozone (O3) risk in Europe where ground-level O3 is a pressing sanitary problem for ecosystem health. Exposure-based standards for protecting vegetation are not representative of actual field conditions. A biologically-sound stomatal flux-based standard has been proposed, although critical levels for protection still need to be validated. This innovative epidemiological assessment of forest responses to O3 was carried out in 54 plots in Southeastern France and Northwestern Italy in 2012 and 2013. Three O3 indices, namely the accumulated exposure AOT40, and the accumulated stomatal flux with and without an hourly threshold of uptake (POD1 and POD0) were compared. Stomatal O3 fluxes were modeled (DO3SE) and correlated to measured forest-response indicators, i.e. crown defoliation, crown discoloration and visible foliar O3 injury. Soil water content, a key variable affecting the severity of visible foliar O3 injury, was included in DO3SE. Based on flux-effect relationships, we developed species-specific flux-based critical levels (CLef) for forest protection against visible O3 injury. For O3 sensitive conifers, CLef of 19 mmol m(-2) for Pinus cembra (high O3 sensitivity) and 32 mmol m(-2) for Pinus halepensis (moderate O3 sensitivity) were calculated. For broadleaved species, we obtained a CLef of 25 mmol m(-2) for Fagus sylvatica (moderate O3 sensitivity) and of 19 mmol m(-2) for Fraxinus excelsior (high O3 sensitivity). We showed that an assessment based on PODY and on real plant symptoms is more appropriated than the concentration-based method. Indeed, POD0 was better correlated with visible foliar O3 injury than AOT40, whereas AOT40 was better correlated with crown discoloration and defoliation (aspecific indicators). To avoid an underestimation of the real O3 uptake, we recommend the use of POD0 calculated for hours with a non-null global radiation over the 24-h O3 accumulation window. Copyright © 2015 Elsevier B.V. All rights

  7. Impact of climate change on surface ozone and deposition of sulphur and nitrogen in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Langner, J.; Bergstroem, R.; Foltescu, V. [Swedish Meteorological and Hydrological Institute, Norrkoeping (Sweden)

    2005-02-01

    The potential impact of regional climate change on the distribution and deposition of air pollutants in Europe has been studied using a regional chemistry/transport/deposition model, MATCH. MATCH was set up using meteorological output from two 10-year climate change experiments made with the Rossby Centre regional Atmospheric climate model version 1 (RCA1). RCA1 was forced by boundary conditions from two different global climate models using the IPCC IS92a (business as usual) emission scenario. The global mean warming in both the GCMs was 2.6 K and was reached in the period 2050-2070. Simulations with MATCH indicate substantial potential impact of regional climate change on both deposition of oxidised nitrogen and concentrations of surface ozone. The simulations show a strong increase in surface ozone expressed as AOT40 and mean of daily maximum over southern and central Europe and a decrease in northern Europe. The simulated changes in April-September AOT40 are significant in relation to inter-annual variability over extended areas. Changes in deposition of oxidised nitrogen are much smaller and also less coherent due to the strong inter-annual variability in precipitation in the RCA1 simulations and differences in the regional climate change simulated with RCA1 in the two regional scenarios. Changes in simulated annual deposition are significant in relation to inter-annual variability only over small areas. This indicates that longer simulation periods are necessary to establish changes in deposition. (author)

  8. Impact of climate change on surface ozone and deposition of sulphur and nitrogen in Europe

    Science.gov (United States)

    Langner, Joakim; Bergström, Robert; Foltescu, Valentin

    The potential impact of regional climate change on the distribution and deposition of air pollutants in Europe has been studied using a regional chemistry/transport/deposition model, MATCH. MATCH was set up using meteorological output from two 10-year climate change experiments made with the Rossby Centre regional Atmospheric climate model version 1 (RCA1). RCA1 was forced by boundary conditions from two different global climate models using the IPCC IS92a (business as usual) emission scenario. The global mean warming in both the GCMs was 2.6 K and was reached in the period 2050-2070. Simulations with MATCH indicate substantial potential impact of regional climate change on both deposition of oxidised nitrogen and concentrations of surface ozone. The simulations show a strong increase in surface ozone expressed as AOT40 and mean of daily maximum over southern and central Europe and a decrease in northern Europe. The simulated changes in April-September AOT40 are significant in relation to inter-annual variability over extended areas. Changes in deposition of oxidised nitrogen are much smaller and also less coherent due to the strong inter-annual variability in precipitation in the RCA1 simulations and differences in the regional climate change simulated with RCA1 in the two regional scenarios. Changes in simulated annual deposition are significant in relation to inter-annual variability only over small areas. This indicates that longer simulation periods are necessary to establish changes in deposition.

  9. Ozone Oxidation of Self-Assembled Monolayers on SiOx-Coated Zinc Selenide Surfaces

    Science.gov (United States)

    McIntire, T. M.; Ryder, O. S.; Finlayson-Pitts, B. J.

    2008-12-01

    Airborne particles are important for visibility, human health, climate, and atmospheric reactions. Atmospheric particles contain a significant fraction of organics and such compounds present on airborne particles are susceptible to oxidation by atmospheric oxidants, such as OH, ozone, halogen atoms, and nitrogen trioxide. Oxidized organics associated with airborne particles are thought to be polar, hygroscopic species with enhanced cloud-nucleating properties. Oxide layers on silicon, or SiO2-coated substrates, act as models of environmentally relevant surfaces such as dust particles upon which organics adsorb. We have shown previously that ozone oxidation of unsaturated self-assembled monolayers (SAMs) on silicon attenuated total reflectance (ATR) crystals leads to the formation of carbonyl groups and micron-sized, hydrophobic organic aggregates surrounded by carbon depleted substrate that do not have increased water uptake as previously assumed. Reported here are further ATR-FTIR studies of the oxidation of alkene SAMs on ZnSe and SiO2-coated ZnSe. These substrates have the advantage that they transmit below 1500 cm-1, allowing detection of additional product species. These experiments show that the loss of C=C and formation of carbonyl groups is also accompanied by formation of a peak at 1110 cm-1, attributed to the secondary ozonide. Details concerning the products and mechanism of ozonolysis of alkene SAMs on surfaces based on these new data are presented and the implications for the oxidation of alkenes on airborne dust particles are discussed.

  10. Assessing the effects of oil sands related ozone precursor emissions on ambient ozone levels in the Alberta oil sands region, Canada

    Science.gov (United States)

    Cho, Sunny; Vijayaraghavan, Krish; Spink, David; Cosic, Biljana; Davies, Mervyn; Jung, Jaegun

    2017-11-01

    A study was undertaken to determine whether, and the extent to which, increased ground-level ozone (O3) precursor emissions from oil sands development have impacted ambient air quality in the north-eastern Alberta, Canada, over the period 1998 to 2012. Temporal trends in emissions of O3 precursors (NOx and VOC) and ambient air concentrations of O3 precursors, and O3 were examined using the Theil-Sen statistical analysis method. Statistically significant correlations between NOx emissions and ambient NOx concentrations were found mainly near surface (open-pit) mining areas where mine fleets are a large source of NOx emissions. No statistically significant trends in the 4th highest daily maximum 8-hr average O3 at any of the continuous and passive ambient air monitoring stations were found. A significant long-term decrease in monthly averaged O3 is observed at some ambient monitoring sites in summer. A visual examination of long-term variations in annual NOx and VOC emissions and annual 4th highest daily maximum 8-hr O3 concentrations does not reveal any indication of a correlation between O3 concentrations and O3 precursor emissions or ambient levels in the study area. Despite a significant increase in oil sands NOx emissions (8%/yr), there is no statistically significant increase in long-term O3 concentrations at any of monitoring stations considered. This suggests that there is surplus NOx available in the environment which results in a titration of ambient O3 in the areas that have ambient monitoring. The limited ambient O3 monitoring data distant from NOx emission sources makes it impossible to assess the impact of these increased O3 precursor levels on O3 levels on a regional scale. As a precautionary measure, the increasing oil sands development O3 precursor emissions would require that priority be given to the management of these emissions to prevent possible future O3 ambient air quality issues.

  11. Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990-2013

    Science.gov (United States)

    Andersson, Camilla; Alpfjord, Heléne; Robertson, Lennart; Karlsson, Per Erik; Engardt, Magnuz

    2017-11-01

    We have constructed two data sets of hourly resolution reanalyzed near-surface ozone (O3) concentrations for the period 1990-2013 for Sweden. Long-term simulations from a chemistry-transport model (CTM) covering Europe were combined with hourly ozone concentration observations at Swedish and Norwegian background measurement sites using retrospective variational data analysis. The reanalysis data sets show improved performance over the original CTM when compared to independent observations. In one of the reanalyses, we included all available hourly near-surface O3 observations, whilst in the other we carefully selected time-consistent observations. Based on the second reanalysis we investigated statistical aspects of the distribution of the near-surface O3 concentrations, focusing on the linear trend over the 24-year period. We show that high near-surface O3 concentrations are decreasing and low O3 concentrations are increasing, which is reflected in observed improvement of many health and vegetation indices (apart from those with a low threshold). Using the CTM we also conducted sensitivity simulations to quantify the causes of the observed change, focusing on three factors: change in hemispheric background concentrations, meteorology and anthropogenic emissions. The rising low concentrations of near-surface O3 in Sweden are caused by a combination of all three factors, whilst the decrease in the highest O3 concentrations is caused by European O3 precursor emissions reductions. While studying the impact of anthropogenic emissions changes, we identified systematic differences in the modeled trend compared to observations that must be caused by incorrect trends in the utilized emissions inventory or by too high sensitivity of our model to emissions changes.

  12. Identifying ozone-sensitive communities of (semi-)natural vegetation suitable for mapping exceedance of critical levels

    International Nuclear Information System (INIS)

    Mills, G.; Hayes, F.; Jones, M.L.M.; Cinderby, S.

    2007-01-01

    Using published data on the responses of individual species to ozone, 54 EUNIS (European Nature Information System) level 4 communities with six or more ozone-sensitive species (%OS) and c. 20% or more species tested for ozone sensitivity, were identified as potentially ozone-sensitive. The largest number of these communities (23) was associated with Grasslands, with Heathland, scrub and tundra, and Mires, bogs and fens having the next highest representation at 11 and 8 level 4 communities each respectively. Within the grasslands classification, E4 (Alpine and sub-alpine grasslands), E5 (Woodland fringes and clearings) and E1 (Dry grasslands) were the most sensitive with 68.1, 51.6 and 48.6%OS respectively. It is feasible to map the land-cover for these and other communities at level 2, but it may not be currently possible to map the land-cover for all communities identified to be ozone-sensitive at levels 3 and 4. - Grassland communities such as alpine and sub-alpine grasslands have the highest potential sensitivity ozone, based on the responses of their component species

  13. Ozone: Good Up High, Bad Nearby

    Science.gov (United States)

    ... occurs in two layers of the atmosphere. The layer closest to the Earth’s surface is the troposphere. Here, ground- level or “ ... or use. Over time, these chemicals damage the earth’s protective ozone layer. What is Happening to the “Good” Ozone Layer? ...

  14. Ozone Reductions Using Residential Building Envelopes

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Iain S.; Sherman, Max; Nazaroff, William W.

    2009-02-01

    Ozone is an air pollutant with that can have significant health effects and a significant source of ozone in some regions of California is outdoor air. Because people spend the vast majority of their time indoors, reduction in indoor levels of ozone could lead to improved health for many California residents. Ozone is removed from indoor air by surface reactions and can also be filtered by building envelopes. The magnitude of the envelope impact depends on the specific building materials that the air flows over and the geometry of the air flow paths through the envelope that can be changes by mechanical ventilation operation. The 2008 Residential Building Standards in California include minimum requirements for mechanical ventilation by referencing ASHRAE Standard 62.2. This study examines the changes in indoor ozone depending on the mechanical ventilation system selected to meet these requirements. This study used detailed simulations of ventilation in a house to examine the impacts of different ventilation systems on indoor ozone concentrations. The simulation results showed that staying indoors reduces exposure to ozone by 80percent to 90percent, that exhaust ventilation systems lead to lower indoor ozone concentrations, that opening of windows should be avoided at times of high outdoor ozone, and that changing the time at which mechanical ventilation occurs has the ability to halve exposure to ozone. Future work should focus on the products of ozone reactions in the building envelope and the fate of these products with respect to indoor exposures.

  15. Exposure to environmentally-relevant levels of ozone negatively influence pollen and fruit development

    International Nuclear Information System (INIS)

    Gillespie, Colin; Stabler, Daniel; Tallentire, Eva; Goumenaki, Eleni; Barnes, Jeremy

    2015-01-01

    A combination of in vitro and in vivo studies on tomato (Lycopersicon esculentum Mill. cv. Triton) revealed that environmentally-relevant levels of ozone (O 3 ) pollution adversely affected pollen germination, germ tube growth and pollen-stigma interactions – pollen originating from plants raised in charcoal-Purafil ® filtered air (CFA) exhibited reduced germ tube development on the stigma of plants exposed to environmentally-relevant levels of O 3 . The O 3 -induced decline in in vivo pollen viability was reflected in increased numbers of non-fertilized and fertilized non-viable ovules in immature fruit. Negative effects of O 3 on fertilization occurred regardless of the timing of exposure, with reductions in ovule viability evident in O 3  × CFA and CFA × O 3 crossed plants. This suggests O 3 -induced reductions in fertilization were associated with reduced pollen viability and/or ovule development. Fruit born on trusses independently exposed to 100 nmol mol −1 O 3 (10 h d −1 ) from flowering exhibited a decline in seed number and this was reflected in a marked decline in the weight and size of individual fruit – a clear demonstration of the direct consequence of the effects of the pollutant on reproductive processes. Ozone exposure also resulted in shifts in the starch and ascorbic acid (Vitamin C) content of fruit that were consistent with accelerated ripening. The findings of this study draw attention to the need for greater consideration of, and possibly the adoption of weightings for the direct impacts of O 3 , and potentially other gaseous pollutants, on reproductive biology during ‘risk assessment’ exercises. - Highlights: • Environmentally-relevant levels of ozone exert negative effects on pollen viability that translate into direct impacts on fruit yield. • Negative impacts of O 3 pollution on reproductive processes were evident regardless of the stage of plant development. • Exposure to environmentally-relevant levels of

  16. Ultraviolet light and ozone surface modification of poly-alpha α-methylstyrene using electroless nickel plating

    International Nuclear Information System (INIS)

    Chi Fangting; Sichuan Univ., Chengdu; Li Bo; Liu Yiyang; Chen Sufen; Jiang Bo

    2009-01-01

    The deposition capability of nickel on the surface of poly-α-methylstyrene microspheres was improved by combined treatment of ozone aeration and UV irradiation in aqueous ammonia. Surface properties of the treated film were investigated by X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared(FT-TR) measurements. The samples were characterized by SEM. The results indicate that after ultraviolet joint ozone treatment, the surfaces of microspheres were oxidized, and the amine and amide groups are introduced on their surface. The images of SEM show the adhesion between microspheres and nickel-phosphorus films was improved after surface modification. This was attributed to amide which could chemisorb palladium ions to catalyze electroless nickel plating on the pretreated surface of microspheres. (authors)

  17. An epidemiological assessment of stomatal ozone flux-based critical levels for visible ozone injury in Southern European forests

    Energy Technology Data Exchange (ETDEWEB)

    Sicard, Pierre, E-mail: pierre.sicard@acri-he.fr [ACRI-HE, 260 route du Pin Montard, BP 234, 06904 Sophia Antipolis cedex (France); De Marco, Alessandra [ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development), 76, Lungotevere Thaon de Revel, Rome (Italy); Dalstein-Richier, Laurence [GIEFS (Groupe International d' Etudes des Forêts Sud-européennes), 60, Avenue des Hespérides, 06300 Nice (France); Tagliaferro, Francesco [IPLA (Istituto per le Piante da Legno e l‘Ambiente), Corso Casale 476, 10132 Turin (Italy); Renou, Camille [ACRI-HE, 260 route du Pin Montard, BP 234, 06904 Sophia Antipolis cedex (France); Paoletti, Elena [IPSP-CNR (Consiglio Nazionale delle Ricerche — Istituto per la Protezione Sostenibile delle Piante), Via Madonna del Piano 10, 50019 Sesto Fiorentino (Florence) (Italy)

    2016-01-15

    Southern forests are at the highest ozone (O{sub 3}) risk in Europe where ground-level O{sub 3} is a pressing sanitary problem for ecosystem health. Exposure-based standards for protecting vegetation are not representative of actual field conditions. A biologically-sound stomatal flux-based standard has been proposed, although critical levels for protection still need to be validated. This innovative epidemiological assessment of forest responses to O{sub 3} was carried out in 54 plots in Southeastern France and Northwestern Italy in 2012 and 2013. Three O{sub 3} indices, namely the accumulated exposure AOT40, and the accumulated stomatal flux with and without an hourly threshold of uptake (POD1 and POD0) were compared. Stomatal O{sub 3} fluxes were modeled (DO3SE) and correlated to measured forest-response indicators, i.e. crown defoliation, crown discoloration and visible foliar O{sub 3} injury. Soil water content, a key variable affecting the severity of visible foliar O{sub 3} injury, was included in DO3SE. Based on flux–effect relationships, we developed species-specific flux-based critical levels (CLef) for forest protection against visible O{sub 3} injury. For O{sub 3} sensitive conifers, CLef of 19 mmol m{sup −2} for Pinus cembra (high O{sub 3} sensitivity) and 32 mmol m{sup −2} for Pinus halepensis (moderate O{sub 3} sensitivity) were calculated. For broadleaved species, we obtained a CLef of 25 mmol m{sup −2} for Fagus sylvatica (moderate O{sub 3} sensitivity) and of 19 mmol m{sup −2} for Fraxinus excelsior (high O{sub 3} sensitivity). We showed that an assessment based on PODY and on real plant symptoms is more appropriated than the concentration-based method. Indeed, POD0 was better correlated with visible foliar O{sub 3} injury than AOT40, whereas AOT40 was better correlated with crown discoloration and defoliation (aspecific indicators). To avoid an underestimation of the real O{sub 3} uptake, we recommend the use of POD0 calculated for

  18. No consistent effects of ozone exposure for one growth season on levels of polyamines in Picea abies

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, J.E.; Jensen, E. [Tromsoe Univ. (Norway). Dept. of Plant Physiology and Microbiology

    1998-07-01

    It is well known that ozone is detrimental to plants, due to its action as a strong oxidant. Polyamines have been suggested as protecting against oxidative stress, and have been reported as being induced by ozone in plants. However, there is a paucity of data on tree species exposed to ozone for an extended period under field-like conditions. In the present investigation, mature spruce clones were exposed to ozone (200 or 400 {mu}g m{sup -3} air) in open-top chambers for an entire growth season at two localities in Norway, and levels of the polyamines putrescine, spermidine and spermine were measured. No consistent effects of ozone fumigation were found on levels of any of the polyamines; not for two clones showing visible injury (yellow needles), and not for four apparently healthy clones. Thus, there was no correlation between sensitivity or tolerance to ozone and polyamine content. However, there were significant differences in polyamine contents between clones and the two localities of exposure 18 refs, 3 figs

  19. Coating and dispersion of ceramic nanoparticles by UV-ozone etching assisted surface-initiated living radical polymerization.

    Science.gov (United States)

    Arita, Toshihiko

    2010-10-01

    Commercially available unmodified ceramic nanoparticles (NPs) in dry powder state were surface-modified and dispersed in almost single-crystal size. The surface-initiated living radical polymerization after just UV-ozone soft etching enables one to graft polymers onto the surface of ceramic NPs and disperse them in solvents. Furthermore, a number of NPs were dispersed with single-crystal sizes. The technique developed here could be applied to almost all ceramic NPs including metal nitrides.

  20. Field-analysis of potable water quality and ozone efficiency in ozone-assisted biological filtration systems for surface water treatment.

    Science.gov (United States)

    Zanacic, Enisa; Stavrinides, John; McMartin, Dena W

    2016-11-01

    Potable water treatment in small communities is challenging due to a complexity of factors starting with generally poor raw water sources, a smaller tax and consumption base that limit capital and operating funds, and culminating in what is typically a less sophisticated and robust water treatment plant for production and delivery of safe, high quality potable water. The design and optimization of modular ozone-assisted biological filtration systems can address some of these challenges. In surface water treatment, the removal of organic matter (e.g., dissolved organic carbon - DOC), inorganic nutrients and other exposure-related contaminants (e.g., turbidity and dissolved solids) from the raw water source is essential. Thus, a combination of chemical and biological oxidation processes can produce an effective and efficient water treatment plant design that is also affordable and robust. To that end, the ozone-assisted biological filtration water treatment plants in two communities were evaluated to determine the efficacy of oxidation and contaminant removal processes. The results of testing for in-field system performance indicate that plant performance is particularly negatively impacted by high alkalinity, high organics loading, and turbidity. Both bicarbonate and carbonate alkalinity were observed to impede ozone contact and interaction with DOC, resulting in lower than anticipated DOC oxidation efficiency and bioavailability. The ozone dosage at both water treatment plants must be calculated on a more routine basis to better reflect both the raw water DOC concentration and presence of alkalinities to ensure maximized organics oxidation and minimization of trihalomethanes production. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. LPS levels in root canals after the use of ozone gas and high frequency electrical pulses

    Directory of Open Access Journals (Sweden)

    Tiago André Fontoura de MELO

    2016-01-01

    Full Text Available Abstract The present study aims to verify the effect of ozone gas (OZY® System and high frequency electric pulse (Endox® System systems on human root canals previously contaminated with Escherichia colilipopolysaccharide (LPS. Fifty single-rooted teeth had their dental crowns removed and root lengths standardized to 16 mm. The root canals were prepared up to #60 hand K-files and sterilized using gamma radiation with cobalt 60. The specimens were divided into the following five groups (n = 10 based on the disinfection protocol used: OZY® System, one 120-second-pulse (OZY 1p; OZY® System, four 24-second-pulses (OZY 4p; and Endox® System (ENDOX. Contaminated and non-contaminated canals were exposed only to apyrogenic water and used as positive (C+ and negative (C- controls, respectively. LPS (O55:B55 was administered in all root canals except those belonging to group C-. After performing disinfection, LPS samples were collected from the canals using apyrogenic paper tips. Limulus Amoebocyte Lysate (LAL was used to quantify the LPS levels, and the data obtained was analyzed using one-way ANOVA. The disinfection protocols used were unable to reduce the LPS levels significantly (p = 0.019. The use of ozone gas and high frequency electric pulses was not effective in eliminating LPS from the root canals.

  2. Surface ozone at the Devils Postpile National Monument receptor site during low and high wildland fire years

    Science.gov (United States)

    Andrzej Bytnerowicz; Joel D. Burley; Ricardo Cisneros; Haiganoush K. Preisler; Susan Schilling; Donald Schweizer; John Ray; Deanna Dulen; Christopher Beck; Bianca Auble

    2013-01-01

    Surface ozone (O3) was measured at the Devils Postpile National Monument (DEPO), eastern Sierra Nevada Mountains, California, during the 2007 (low-fire) and 2008 (high-fire) summer seasons. While mean and median values of O3 concentrations for the 2007 and 2008 summer seasons were similar, maximum O3...

  3. Influence of the North American monsoon on Southern California tropospheric ozone levels during summer in 2013 and 2014

    Science.gov (United States)

    Granados-Muñoz, Maria Jose; Johnson, Matthew S.; Leblanc, Thierry

    2017-06-01

    The impact of the North American (NA) monsoon on tropospheric ozone variability in Southern California is investigated using lidar measurements at Jet Propulsion Laboratory-Table Mountain Facility, California, and the chemical-transport model GEOS-Chem. Routine lidar observations obtained in July-August 2013-2014 reveal a consistent ozone enhancement of 23 ppbv in the free troposphere (6-9 km), when ozone-rich air is transported along the western edge of the upper level anticyclone associated with the NA monsoon from regions where maximum lightning-induced NOx production occurs. When the high-pressure system shifts to the southeast, a zonal westerly flow of the air parcels reaching the Table Mountain Facility (TMF) occurs, prohibiting the lightning-induced ozone enhanced air to reach TMF. This modulation of tropospheric ozone by the position of the NA monsoon anticyclone could have implications on long-term ozone trends associated with our changing climate, due to the expected widening of the tropical belt affecting the strength and position of the anticyclone.

  4. Identification of heptanal and nonanal in bronchoalveolar lavage from rats exposed to low levels of ozone

    Energy Technology Data Exchange (ETDEWEB)

    Cueto, R.; Squadrito, G.L.; Bermudez, E.; Pryor, W.A. (Biodynamics Institute, Louisiana State University, Baton Rouge (United States))

    1992-10-15

    Heptanal and nonanal are identified from in vitro studies as potential biomarkers of exposure to ozone, the former resulting from ozonation of palmitoleic acid and the latter from oleic acid. An analytical method is developed based on derivatization using O-pentafluorobenzylhydroxylamine HCl and gas chromatography. These molecules also are present in the lung lavage of Sprague-Dawley rats exposed to 1.3 ppm ozone for 10 hr. These results suggest aldehydes may be useful dosimeters for ozone and indicate that unsaturated fatty acids in the lung lining fluid layer undergo ozonation in vivo.

  5. Radiation Level Changes at RAM Package Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Opperman, Erich [Washington Savannah River Company; Hawk, Mark B [ORNL; Kapoor, Ashok [U.S. Department of Energy, Office of Packaging and Transportation; Natali, Ronald [R. B. Natali Consulting, Inc.

    2010-01-01

    This paper will explore design considerations required to meet the regulations that limit radiation level variations at external surfaces of radioactive material (RAM) packages. The radiation level requirements at package surfaces (e.g. TS-R-1 paragraphs 531 and 646) invoke not only maximum radiation levels, but also strict limits on the allowable increase in the radiation level during transport. This paper will explore the regulatory requirements by quantifying the amount of near surface movement and/or payload shifting that results in a 20% increase in the radiation level at the package surface. Typical IP-2, IP-3, Type A and Type B packaging and source geometries will be illustrated. Variations in surface radiation levels are typically the result of changes in the geometry of the surface due to an impact, puncture or crush event, or shifting and settling of radioactive contents.

  6. Ozone Pollution

    Science.gov (United States)

    Known as tropospheric or ground-level ozone, this gas is harmful to human heath and the environment. Since it forms from emissions of volatile organic compounds (VOCs) and nitrogen oxides (NOx), these pollutants are regulated under air quality standards.

  7. MISR Level 2 Surface parameters V002

    Data.gov (United States)

    National Aeronautics and Space Administration — This Level 2 Land Surface product contains information on land directional reflectance properties,albedos(spectral & PAR integrated),FPAR,asssociated radiation...

  8. Volatile organic compounds measured in summer in Beijing and their role in ground-level ozone formation

    Science.gov (United States)

    Shao, Min; Lu, Sihua; Liu, Ying; Xie, Xin; Chang, Chichung; Huang, Shan; Chen, Zhongmin

    2009-01-01

    Beijing has long suffered from serious ground-level ozone pollution, and volatile organic compounds (VOCs) play a key role in ozone formation. To understand the chemical speciation of VOCs in Beijing, nonmethane hydrocarbons (NMHCs) and oxygenated VOCs (OVOCs) were measured in summer in Beijing and nearby provinces (VOCs in this work means NMHCs+OVOCs). A variation of VOC mixing ratios and chemical speciation from 2004 to 2006 was observed at an urban site in Beijing. The typical VOC species, e.g., propane, propene, and toluene, had comparable or lower mixing ratios than levels found in other cities that previously hosted the Olympic Games, while the mixing ratios for isoprene were higher. The chemical compositions of VOCs within Beijing were heavily influenced by vehicular emissions and differed from those obtained in Tianjin and Hebei Province. OVOCs were an important component, accounting for 54% and 37% in the VOC mixing ratio in 2005 and 2006, respectively, and about 40% of the OH loss rates. The main reactive VOC compounds were aldehydes and alkenes. By using isoprene chemistry and the ratio of ethylbenzene to mp-xylene, the initial mixing ratios of VOCs were estimated. The VOCs had similar variation patterns to ambient ozone and peroxyacetyl nitrate (PAN) concentrations. The correlation between daily maximum ozone concentrations and initial VOCs revealed that ozone formation was sensitive to VOCs for both urban (Peking University, PKU) and rural (Yufa) sites. A reduction in NOx would lead to a decrease in ozone at Yufa, but would cause increased ozone at the PKU site.

  9. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: The influence of zeolite chemical surface characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Alejandro, Serguei [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Núcleo de Energías Renovables (F. Ingeniería), Universidad Católica de Temuco, Rudecindo Ortega 02950, Temuco (Chile); Valdés, Héctor, E-mail: hvaldes@ucsc.cl [Laboratorio de Tecnologías Limpias (F. Ingeniería), Universidad Católica de la Santísima Concepción, Alonso de Ribera 2850, Concepción (Chile); Manéro, Marie-Hélène [Université de Toulouse (France); INPT, UPS (France); Laboratoire de Génie Chimique, 4, Allée Emile Monso, F–31030 Toulouse (France); CNRS (France); Laboratoire de Génie Chimique, F–31030 Toulouse (France); Zaror, Claudio A. [Departamento de Ingeniería Química (F. Ingeniería), Universidad de Concepción, Concepción, Correo 3, Casilla 160–C (Chile)

    2014-06-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity.

  10. Oxidative regeneration of toluene-saturated natural zeolite by gaseous ozone: The influence of zeolite chemical surface characteristics

    International Nuclear Information System (INIS)

    Alejandro, Serguei; Valdés, Héctor; Manéro, Marie-Hélène; Zaror, Claudio A.

    2014-01-01

    Highlights: • Surface acidity of modified natural zeolite is related to its chemical reactivity. • Brønsted acid sites are associated to toluene adsorption. • Lewis acid sites could decompose ozone generating surface active oxygen species. • Infrared spectra evidence active atomic oxygen and oxidation by-product formation. • 2NH4Z1 sample shows the highest reactivity toward adsorbed toluene. - Abstract: In this study, the effect of zeolite chemical surface characteristics on the oxidative regeneration of toluene saturated-zeolite samples is investigated. A Chilean natural zeolite (53% clinoptilolite, 40% mordenite and 7% quartz) was chemically modified by acid treatment with hydrochloric acid and by ion-exchange with ammonium sulphate. Thermal pre-treatments at 623 and 823 K were applied and six zeolite samples with different chemical surface characteristics were generated. Chemical modification of natural zeolite followed by thermal out-gassing allows distinguishing the role of acidic surface sites on the regeneration of exhausted zeolites. An increase in Brønsted acid sites on zeolite surface is observed as a result of ammonium-exchange treatment followed by thermal treatment at 623 K, thus increasing the adsorption capacity toward toluene. High ozone consumption could be associated to a high content of Lewis acid sites, since these could decompose ozone into atomic active oxygen species. Then, surface oxidation reactions could take part among adsorbed toluene at Brønsted acid sites and surface atomic oxygen species, reducing the amount of adsorbed toluene after the regenerative oxidation with ozone. Experimental results show that the presence of adsorbed oxidation by-products has a negative impact on the recovery of zeolite adsorption capacity

  11. A simple UV-ozone surface treatment to enhance photocatalytic performance of TiO 2 loaded polymer nanofiber membranes

    KAUST Repository

    Dilpazir, S.

    2016-01-29

    Homogeneously dispersed titanium dioxide loaded polyacrylonitrile nanofiber membranes with increased active mass loading, Ti3+ surface defects and hydrophilicity were fabricated by combining electrospinning and UV-ozone surface treatment. The photocatalytic activity improved by a factor of ∼2 and the kinetics of photodegradation switched from pseudo-first order to pseudo-second order with increasing TiO2 content with a maximum rate constant of 20.7 h-1. © The Royal Society of Chemistry 2016.

  12. Oxygen termination of homoepitaxial diamond surface by ozone and chemical methods: An experimental and theoretical perspective

    Science.gov (United States)

    Navas, Javier; Araujo, Daniel; Piñero, José Carlos; Sánchez-Coronilla, Antonio; Blanco, Eduardo; Villar, Pilar; Alcántara, Rodrigo; Montserrat, Josep; Florentin, Matthieu; Eon, David; Pernot, Julien

    2018-03-01

    Phenomena related with the diamond surface of both power electronic and biosensor devices govern their global behaviour. In particular H- or O-terminations lead to wide variations in their characteristics. To study the origins of such aspects in greater depth, different methods to achieve oxygen terminated diamond were investigated following a multi-technique approach. DFT calculations were then performed to understand the different configurations between the C and O atoms. Three methods for O-terminating the diamond surface were performed: two physical methods with ozone at different pressures, and an acid chemical treatment. X-ray photoelectron spectroscopy, spectroscopic ellipsometry, HRTEM, and EELS were used to characterize the oxygenated surface. Periodic-DFT calculations were undertaken to understand the effect of the different ways in which the oxygen atoms are bonded to carbon atoms on the diamond surface. XPS results showed the presence of hydroxyl or ether groups, composed of simple Csbnd O bonds, and the acid treatment resulted in the highest amount of O on the diamond surface. In turn, ellipsometry showed that the different treatments led to the surface having different optical properties, such as a greater refraction index and extinction coefficient in the case of the sample subjected to acid treatment. TEM analysis showed that applying temperature treatment improved the distribution of the oxygen atoms at the interface and that this generates a thinner amount of oxygen at each position and higher interfacial coverage. Finally, DFT calculations showed both an increase in the number of preferential electron transport pathways when π bonds and ether groups appear in the system, and also the presence of states in the middle of the band gap when there are π bonds, Cdbnd C or Cdbnd O.

  13. Observations of atmospheric ozone - 38 to 76 deg north latitude at altitudes from 8 km to the surface

    Science.gov (United States)

    Gregory, G. L.; Beck, S. M.; Hudgins, C. H.

    1984-01-01

    Ozone data were obtained from 8 km to the surface and at latitudes from 38 to 76 deg N during January and February 1983. Flight lines covered northeastern U.S., Canada, and Greenland. The results of the latitudinal survey at 5- to 8-km altitude showed O3 mixing ratios to be about 40 ppbv with little variation in latitude. One region of elevated O3 was observed and extended from 54 N to 57 deg N latitude. Ozone reached 150 ppbv at 6.4-km altitude. This sampling was stratospheric air as the tropopause height was 5.6-km altitude. Profiles at 76, 67, and 53 deg N showed O3 to be be well mixed from about 5 km to the surface. In some cases, profiles identified a layer of 1 km to 100 m vertical dimension at the surface, in which O3 destruction had occurred.

  14. Spatio-temporal trends of surface ozone and its related factors in Shanghai

    Science.gov (United States)

    Lin, Y.; Duan, Y.; Fu, Q.; Wang, Q.; Hu, M.

    2017-12-01

    The monitoring data in Shanghai during 2006-2016 demonstrated that the ozone concentration is increasing annually, however, the interannual changing trend of the relevant meteorological factors is not significant except horizontal wind speed. The diurnal variation of O3 hourly concentration indicated that the duration of O3 pollution has been increased. The spatial analysis of ozone pollution found that the ozone exceedances in the southwest suburbs is more prominent than other areas, while the potential of increasing ozone exceedances can not be ignored in the downtown of Shanghai. Ozone pollution wind roses of multiple sites demostrated that the southern part of Shanghai is the key area that affects the ozone pollution in Shanghai. The analysis of the impact of NO2 emission reduction shows that although the annual concencentration of O3 at Shanghai is increasing, however, the inner ring area and North suburbs, where the NO2 emission reduction are the most obvious, the rising rate of ozone is much lower than the area between inner and outer ring and western suburbs. Therefore, the ozone pollution control in Shanghai should stick to the reduction of NOx, and simultaneously promote the reduction of VOCs.

  15. Development and Implementation of a Near-Real-Time Web Reporting System on Ground-Level Ozone in Europe

    DEFF Research Database (Denmark)

    Normander, Bo; Haigh, Tim; Christiansen, Jesper S.

    2008-01-01

    in exchanging data and knowledge. Near-real-time information systems on the Web seem to be a valuable complement to future environmental reporting, and the European Environment Agency is currently investigating the requirements needed to extend the use of near-real-time data, including reporting on air......This article presents the development and results of Ozone Web-a near-real-time Web-based approach to communicate environmental information to policy makers, researchers, and the general public. In Ozone Web, ground-level ozone information from 750 air quality measurement stations across Europe...... is collected on an hourly basis, filtered, interpolated, and presented on zoomable maps and graphs. Compared with other environmental information initiatives, the main aspects of this Website is the allowance for user interactivity, free access to data, and high timeliness. Data are published 2 to 3 h after...

  16. The response of surface ozone to climate change over the Eastern United States

    Directory of Open Access Journals (Sweden)

    P. N. Racherla

    2008-02-01

    Full Text Available We investigate the response of surface ozone (O3 to future climate change in the eastern United States by performing simulations corresponding to present (1990s and future (2050s climates using an integrated model of global climate, tropospheric gas-phase chemistry, and aerosols. A future climate has been imposed using ocean boundary conditions corresponding to the IPCC SRES A2 scenario for the 2050s decade. Present-day anthropogenic emissions and CO2/CH4 mixing ratios have been used in both simulations while climate-sensitive emissions were allowed to vary with the simulated climate. The severity and frequency of O3 episodes in the eastern U.S. increased due to future climate change, primarily as a result of increased O3 chemical production. The 95th percentile O3 mixing ratio increased by 5 ppbv and the largest frequency increase occured in the 80–90 ppbv range; the US EPA's current 8-h ozone primary standard is 80 ppbv. The increased O3 chemical production is due to increases in: 1 natural isoprene emissions; 2 hydroperoxy radical concentrations resulting from increased water vapor concentrations; and, 3 NOx concentrations resulting from reduced PAN. The most substantial and statistically significant (p<0.05 increases in episode frequency occurred over the southeast and midatlantic U.S., largely as a result of 20% higher annual-average natural isoprene emissions. These results suggest a lengthening of the O3 season over the eastern U.S. in a future climate to include late spring and early fall months. Increased chemical production and shorter average lifetime are two consistent features of the seasonal response of surface O3, with increased dry deposition loss rates contributing most to the reduced lifetime in all seasons except summer. Significant interannual variability is observed in the frequency of O3

  17. The effect of entrainment through atmospheric boundary layer growth on observed and modeled surface ozone in the Colorado Front Range

    Science.gov (United States)

    Kaser, L.; Patton, E. G.; Pfister, G. G.; Weinheimer, A. J.; Montzka, D. D.; Flocke, F.; Thompson, A. M.; Stauffer, R. M.; Halliday, H. S.

    2017-06-01

    Ozone concentrations at the Earth's surface are controlled by meteorological and chemical processes and are a function of advection, entrainment, deposition, and net chemical production/loss. The relative contributions of these processes vary in time and space. Understanding the relative importance of these processes controlling surface ozone concentrations is an essential component for designing effective regulatory strategies. Here we focus on the diurnal cycle of entrainment through atmospheric boundary layer (ABL) growth in the Colorado Front Range. Aircraft soundings and surface observations collected in July/August 2014 during the DISCOVER-AQ/FRAPPÉ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality/Front Range Air Pollution and Photochemistry Éxperiment) campaigns and equivalent data simulated by a regional chemical transport model are analyzed. Entrainment through ABL growth is most important in the early morning, fumigating the surface at a rate of 5 ppbv/h. The fumigation effect weakens near noon and changes sign to become a small dilution effect in the afternoon on the order of -1 ppbv/h. The chemical transport model WRF-Chem (Weather Research and Forecasting Model with chemistry) underestimates ozone at all altitudes during this study on the order of 10-15 ppbv. The entrainment through ABL growth is overestimated by the model in the order of 0.6-0.8 ppbv/h. This results from differences in boundary layer growth in the morning and ozone concentration jump across the ABL top in the afternoon. This implicates stronger modeled fumigation in the morning and weaker modeled dilution after 11:00 LT.

  18. Ozone layer - climate change interactions. Influence on UV levels and UV related effects

    NARCIS (Netherlands)

    Kelfkens G; Bregman A; de Gruijl FR; van der Leun JC; Piquet A; van Oijen T; Gieskes WWC; van Loveren H; Velders GJM; Martens P; Slaper H; NOP; LPI; LLO

    2002-01-01

    Ozone in the atmosphere serves as a partially protective filter against the most harmful part of the solar UV-spectrum. Decreases in ozone lead to increases in ambient UV with a wide variety of adverse effects on human health, aquatic and terrestrial ecosystems and food chains. Human health

  19. Reformulated and alternative fuels: modeled impacts on regional air quality with special emphasis on surface ozone concentration.

    Science.gov (United States)

    Schell, Benedikt; Ackermann, Ingmar J; Hass, Heinz

    2002-07-15

    The comprehensive European Air Pollution and Dispersion model system was used to estimate the impacts of the usage of reformulated and alternative fuels on regional air quality with special emphasis on surface ozone concentrations. A severe western European summer smog episode in July 1994 has been used as a reference, and the model predictions have been evaluated for this episode. A forecast simulation for the year 2005 (TREND) has been performed, including the future emission development based on the current legislation and technologies available. The results of the scenario TREND are used as a baseline for the other 2005 fuel scenarios, including fuel reformulation, fuel sulfur content, and compressed natural gas (CNG) as an alternative fuel. Compared to the year 1994, significant reductions in episode peak ozone concentrations and ozone grid hours are predicted for the TREND scenario. These reductions are even more pronounced within the investigated alternative and reformulated fuel scenarios. Especially, low sulfur fuels are appropriate for an immediate improvement in air quality, because they effect the emissions of the whole fleet. Furthermore, the simulation results indicate that the introduction of CNG vehicles would also enhance air quality with respect to ozone.

  20. Platelet adhesion and protein adsorption on silicone rubber surface by ozone-induced grafted polymerization with carboxybetaine monomer.

    Science.gov (United States)

    Zhou, Jun; Yuan, Jiang; Zang, Xiaopeng; Shen, Jian; Lin, Sicong

    2005-03-10

    Platelet adhesion and protein adsorption on the silicone rubber film grafted with N,N'-dimethyl-N-methacryloyloxyethyl-N-(2-carboxyethyl) ammonium (DMMCA) was studied. The grafting was carried out by means of ozone-induced method and was confirmed by ATR-FTIR and XPS investigations. The grafted films possessed relatively hydrophilic surface revealed by contact angle measurement. The blood compatibility of the grafted film was evaluated in vitro by platelet adhesion in platelet-rich plasma (PRP) and protein absorption in bovine fibrinogen (BFG) using silicone film as the reference. No substantial platelet adhesion was observed for the grafted films incubated in PRP for 60 and 180 min. The protein absorption was also significantly reduced after incubated in bovine fibrinogen for 60 min. Both the results indicated that the blood compatibility of silicone rubber was greatly improved by ozone-induced grafting of carboxybetaine zwitterionic polymer onto its surface.

  1. Impact of natural gas development in the Marcellus and Utica shales on regional ozone and fine particulate matter levels

    Science.gov (United States)

    Roohani, Yusuf H.; Roy, Anirban A.; Heo, Jinhyok; Robinson, Allen L.; Adams, Peter J.

    2017-04-01

    The Marcellus and Utica shale formations have recently been the focus of intense natural gas development and production, increasing regional air pollutant emissions. Here we examine the effects of these emissions on regional ozone and fine particulate matter (PM2.5) levels using the chemical transport model, CAMx, and estimate the public health costs with BenMAP. Simulations were performed for three emissions scenarios for the year 2020 that span a range potential development storylines. In areas with the most gas development, the 'Medium Emissions' scenario, which corresponds to an intermediate level of development and widespread adoption of new equipment with lower emissions, is predicted to increase 8-hourly ozone design values by up to 2.5 ppbv and average annual PM2.5 concentrations by as much as 0.27 μg/m3. These impacts could range from as much as a factor of two higher to a factor of three lower depending on the level of development and the adoption of emission controls. Smaller impacts (e.g. 0.1-0.5 ppbv of ozone, depending on the emissions scenario) are predicted for non-attainment areas located downwind of the Marcellus region such as New York City, Philadelphia and Washington, DC. Premature deaths for the 'Medium Emissions' scenario are predicted to increase by 200-460 annually. The health impacts as well as the changes in ozone and PM2.5 were all driven primarily by NOx emissions.

  2. Long-term change in the source contribution to surface ozone over Japan

    Science.gov (United States)

    Nagashima, Tatsuya; Sudo, Kengo; Akimoto, Hajime; Kurokawa, Junichi; Ohara, Toshimasa

    2017-07-01

    The relative contributions of various source regions to the long-term (1980-2005) increasing trend in surface ozone (O3) over Japan were estimated by a series of tracer-tagging simulations using a global chemical transport model. The model simulated the observed increasing trend in surface O3, including its seasonal variation and geographical features, in Japan well and demonstrated the relative roles of different source regions in forming this trend. Most of the increasing trend in surface O3 over Japan ( ˜ 97 %) that was simulated was explained as the sum of trends in contributions of different regions to photochemical O3 production. The increasing trend in O3 produced in China accounted for 36 % of the total increasing trend and those in the other northeast Asian regions (the Korean Peninsula, coastal regions in East Asia, and Japan) each accounted for about 12-15 %. Furthermore, the contributions of O3 created in the entire free troposphere and in western, southern, and southeastern Asian regions also increased, and their increasing trends accounted for 16 and 7 % of the total trend, respectively. The impact of interannual variations in climate, in methane concentration, and in emission of O3 precursors from different source regions on the relative contributions of O3 created in each region estimated above was also investigated. The variation of climate and the increase in methane concentration together caused the increase of photochemical O3 production in several regions, and represented about 19 % of the total increasing trend in surface O3 over Japan. The increase in emission of O3 precursors in China caused an increase of photochemical O3 production not only in China itself but also in the other northeast Asian regions and accounted for about 46 % of the total increase in surface O3 over Japan. Similarly, the relative impact of O3 precursor emission changes in the Korean Peninsula and Japan were estimated as about 16 and 4 % of the total increasing trend

  3. Optimization of artificial neural network models through genetic algorithms for surface ozone concentration forecasting.

    Science.gov (United States)

    Pires, J C M; Gonçalves, B; Azevedo, F G; Carneiro, A P; Rego, N; Assembleia, A J B; Lima, J F B; Silva, P A; Alves, C; Martins, F G

    2012-09-01

    This study proposes three methodologies to define artificial neural network models through genetic algorithms (GAs) to predict the next-day hourly average surface ozone (O(3)) concentrations. GAs were applied to define the activation function in hidden layer and the number of hidden neurons. Two of the methodologies define threshold models, which assume that the behaviour of the dependent variable (O(3) concentrations) changes when it enters in a different regime (two and four regimes were considered in this study). The change from one regime to another depends on a specific value (threshold value) of an explanatory variable (threshold variable), which is also defined by GAs. The predictor variables were the hourly average concentrations of carbon monoxide (CO), nitrogen oxide, nitrogen dioxide (NO(2)), and O(3) (recorded in the previous day at an urban site with traffic influence) and also meteorological data (hourly averages of temperature, solar radiation, relative humidity and wind speed). The study was performed for the period from May to August 2004. Several models were achieved and only the best model of each methodology was analysed. In threshold models, the variables selected by GAs to define the O(3) regimes were temperature, CO and NO(2) concentrations, due to their importance in O(3) chemistry in an urban atmosphere. In the prediction of O(3) concentrations, the threshold model that considers two regimes was the one that fitted the data most efficiently.

  4. The impact of climate change and emissions control on future ozone levels: Implications for human health.

    Science.gov (United States)

    Stowell, Jennifer D; Kim, Young-Min; Gao, Yang; Fu, Joshua S; Chang, Howard H; Liu, Yang

    2017-11-01

    Overwhelming evidence has shown that, from the Industrial Revolution to the present, human activities influence ground-level ozone (O 3 ) concentrations. Past studies demonstrate links between O 3 exposure and health. However, knowledge gaps remain in our understanding concerning the impacts of climate change mitigation policies on O 3 concentrations and health. Using a hybrid downscaling approach, we evaluated the separate impact of climate change and emission control policies on O 3 levels and associated excess mortality in the US in the 2050s under two Representative Concentration Pathways (RCPs). We show that, by the 2050s, under RCP4.5, increased O 3 levels due to combined climate change and emission control policies, could contribute to an increase of approximately 50 premature deaths annually nationwide in the US. The biggest impact, however, is seen under RCP8.5, where rises in O 3 concentrations are expected to result in over 2,200 additional premature deaths annually. The largest increases in O 3 are seen in RCP8.5 in the Northeast, the Southeast, the Central, and the West regions of the US. Additionally, when O 3 increases are examined by climate change and emissions contributions separately, the benefits of emissions mitigation efforts may significantly outweigh the effects of climate change mitigation policies on O 3 -related mortality. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Influence of local meteorology and NO2conditions on ground-level ozone concentrations in the eastern part of Texas, USA.

    Science.gov (United States)

    Gorai, A K; Tuluri, F; Tchounwou, P B; Ambinakudige, S

    2015-02-01

    The influence of local climatic factors on ground-level ozone concentrations is an area of increasing interest to air quality management in regards to future climate change. This study presents an analysis on the role of temperature, wind speed, wind direction, and NO 2 level on ground-level ozone concentrations over the region of Eastern Texas, USA. Ozone concentrations at the ground level depend on the formation and dispersion processes. Formation process mainly depends on the precursor sources, whereas, the dispersion of ozone depends on meteorological factors. Study results showed that the spatial mean of ground-level ozone concentrations was highly dependent on the spatial mean of NO 2 concentrations. However, spatial distributions of NO 2 and ozone concentrations were not uniformed throughout the study period due to uneven wind speeds and wind directions. Wind speed and wind direction also played a significant role in the dispersion of ozone. Temperature profile in the area rarely had any effects on the ozone concentrations due to low spatial variations.

  6. Influence of ozone precursors and particulate matter on the variation of surface ozone at an urban site of Delhi, India

    Directory of Open Access Journals (Sweden)

    Ashima Sharma

    2016-03-01

    Full Text Available Continuous measurements of surface O3 and its precursors (NO, NO2, CO, CH4 and NMHCs at an urban site of Delhi, India during January 2012 to December 2013 are presented. In the present study, the annual average mixing ratios of surface O3, NO, NO2, CO, CH4 and NMHC were 30 ± 6 ppb, 24 ± 6 ppb, 15 ± 4 ppb, 1.5 ± 0.4 ppm, 2.4 ± 0.4 ppm and 0.4 ± 0.1 ppm, respectively. The maximum average mixing ratios of surface O3, NO and NO2 were observed during the summer, whereas, the minimum average mixing ratios of ambient NO and NO2 were during monsoon seasons. The surface O3, NO and NO2 have shown the prominent diurnal variations during all the seasons at the observational site of Delhi. The result reveals that the surface O3 was negatively correlated with NOx and CO during the study. The linear scatter plot analysis shows that the PM2.5 and PM10 present in the ambient air of Delhi influence the production of surface O3 at observational site.

  7. Areal Measurements of Ozone, Water, and Heat Fluxes Over Land With Different Surface Complexity, Using Aircraft

    International Nuclear Information System (INIS)

    Hicks, Bruce B.

    2001-01-01

    Contemporary models addressing issues of air quality and/or atmospheric deposition continue to exploit air-surface exchange formulations originating from single-tower studies. In reality,these expressions describe situations that are rare in the real world - nearly flat and spatially homogeneous. There have been several theoretical suggestions about how to extend from single-point understanding to areal descriptions, but so far the capability to address the problem experimentally has been limited. In recent years, however, developments in sensing technology have permitted adaptation of eddy-correlation methods to low-flying aircraft in a far more cost-effective manner than previously. A series of field experiments has been conducted, ranging from flat farmland to rolling countryside, employing a recently modified research aircraft operated by the US NationalOceanic and Atmospheric Administration (NOAA). The results demonstrate the complexity of the spatial heterogeneity question,especially for pollutants (ozone in particular). In general, the uncertainty associated with the adoption of any single-point formulation when describing areal averages is likely to be in the range 10% to 40%. In the case of sensible and latent heat fluxes, the overall behavior is controlled by the amount of energy available. For pollutant deposition, there is no constraint equivalent to the net radiation limitation on convective heat exchange. Consequently, dry deposition rates and air-surface exchange of trace gases in general are especially vulnerable to errors in spatial extrapolation. The results indicate that the susceptibility of dry deposition formulations to terrain complexity depends on the deposition velocity itself. For readily transferred pollutants (such as HNO 3 ), a factor of two error could be involved

  8. Projected carbon dioxide to increase grass pollen and allergen exposure despite higher ozone levels.

    Directory of Open Access Journals (Sweden)

    Jennifer M Albertine

    Full Text Available One expected effect of climate change on human health is increasing allergic and asthmatic symptoms through changes in pollen biology. Allergic diseases have a large impact on human health globally, with 10-30% of the population affected by allergic rhinitis and more than 300 million affected by asthma. Pollen from grass species, which are highly allergenic and occur worldwide, elicits allergic responses in 20% of the general population and 40% of atopic individuals. Here we examine the effects of elevated levels of two greenhouse gases, carbon dioxide (CO2, a growth and reproductive stimulator of plants, and ozone (O3, a repressor, on pollen and allergen production in Timothy grass (Phleum pratense L.. We conducted a fully factorial experiment in which plants were grown at ambient and/or elevated levels of O3 and CO2, to simulate present and projected levels of both gases and their potential interactive effects. We captured and counted pollen from flowers in each treatment and assayed for concentrations of the allergen protein, Phl p 5. We found that elevated levels of CO2 increased the amount of grass pollen produced by ∼50% per flower, regardless of O3 levels. Elevated O3 significantly reduced the Phl p 5 content of the pollen but the net effect of rising pollen numbers with elevated CO2 indicate increased allergen exposure under elevated levels of both greenhouse gases. Using quantitative estimates of increased pollen production and number of flowering plants per treatment, we estimated that airborne grass pollen concentrations will increase in the future up to ∼200%. Due to the widespread existence of grasses and the particular importance of P. pratense in eliciting allergic responses, our findings provide evidence for significant impacts on human health worldwide as a result of future climate change.

  9. Surface-to-surface registration using level sets

    DEFF Research Database (Denmark)

    Hansen, Mads Fogtmann; Erbou, Søren G.; Vester-Christensen, Martin

    2007-01-01

    problem can be approximated by the image registration (IR) problem of the signed distance maps (SDMs) of the surfaces confined to some narrow band. By shrinking the narrow bands around the zero level sets the solution to the IR problem converges towards the S2SR problem. It is our hypothesis...... that this approach is more robust and less prone to fall into local minima than ordinary surface-to-surface registration. The IR problem is solved using the inverse compositional algorithm. In this paper, a set of 40 pelvic bones of Duroc pigs are registered to each other w.r.t. the Euclidean transformation...

  10. ANTIOXIDANT SUPPLEMENTATION AND NASAL INFLAMMATORY RESPONSES AMONG YOUNG ASTHMATICS EXPOSED TO HIGH LEVELS OF OZONE

    Science.gov (United States)

    Background: Recent studies examining the inflammatory response in atopic asthma to ozone suggest a release of soluble mediators of inflammation factors that might be related to reactive oxygen species (ROS). Antioxidant could prove useful in subjects exposed to additional oxidati...

  11. MLS/Aura Level 2 Ozone (O3) Mixing Ratio V004

    Data.gov (United States)

    National Aeronautics and Space Administration — ML2O3 is the EOS Aura Microwave Limb Sounder (MLS) standard product for ozone derived from radiances measured by the 240 GHz radiometer. The current version is 4.2....

  12. WRF-Chem simulated surface ozone over south Asia during the pre-monsoon: effects of emission inventories and chemical mechanisms

    Directory of Open Access Journals (Sweden)

    A. Sharma

    2017-12-01

    Full Text Available We evaluate numerical simulations of surface ozone mixing ratios over the south Asian region during the pre-monsoon season, employing three different emission inventories in the Weather Research and Forecasting model with Chemistry (WRF-Chem with the second-generation Regional Acid Deposition Model (RADM2 chemical mechanism: the Emissions Database for Global Atmospheric Research – Hemispheric Transport of Air Pollution (EDGAR-HTAP, the Intercontinental Chemical Transport Experiment phase B (INTEX-B and the Southeast Asia Composition, Cloud, Climate Coupling Regional Study (SEAC4RS. Evaluation of diurnal variability in modelled ozone compared to observational data from 15 monitoring stations across south Asia shows the model ability to reproduce the clean, rural and polluted urban conditions over this region. In contrast to the diurnal average, the modelled ozone mixing ratios during noontime, i.e. hours of intense photochemistry (11:30–16:30 IST – Indian Standard Time – UTC +5:30, are found to differ among the three inventories. This suggests that evaluations of the modelled ozone limited to 24 h average are insufficient to assess uncertainties associated with ozone buildup. HTAP generally shows 10–30 ppbv higher noontime ozone mixing ratios than SEAC4RS and INTEX-B, especially over the north-west Indo-Gangetic Plain (IGP, central India and southern India. The HTAP simulation repeated with the alternative Model for Ozone and Related Chemical Tracers (MOZART chemical mechanism showed even more strongly enhanced surface ozone mixing ratios due to vertical mixing of enhanced ozone that has been produced aloft. Our study indicates the need to also evaluate the O3 precursors across a network of stations and the development of high-resolution regional inventories for the anthropogenic emissions over south Asia accounting for year-to-year changes to further reduce uncertainties in modelled ozone over this region.

  13. WRF-Chem simulated surface ozone over south Asia during the pre-monsoon: effects of emission inventories and chemical mechanisms

    Science.gov (United States)

    Sharma, Amit; Ojha, Narendra; Pozzer, Andrea; Mar, Kathleen A.; Beig, Gufran; Lelieveld, Jos; Gunthe, Sachin S.

    2017-12-01

    We evaluate numerical simulations of surface ozone mixing ratios over the south Asian region during the pre-monsoon season, employing three different emission inventories in the Weather Research and Forecasting model with Chemistry (WRF-Chem) with the second-generation Regional Acid Deposition Model (RADM2) chemical mechanism: the Emissions Database for Global Atmospheric Research - Hemispheric Transport of Air Pollution (EDGAR-HTAP), the Intercontinental Chemical Transport Experiment phase B (INTEX-B) and the Southeast Asia Composition, Cloud, Climate Coupling Regional Study (SEAC4RS). Evaluation of diurnal variability in modelled ozone compared to observational data from 15 monitoring stations across south Asia shows the model ability to reproduce the clean, rural and polluted urban conditions over this region. In contrast to the diurnal average, the modelled ozone mixing ratios during noontime, i.e. hours of intense photochemistry (11:30-16:30 IST - Indian Standard Time - UTC +5:30), are found to differ among the three inventories. This suggests that evaluations of the modelled ozone limited to 24 h average are insufficient to assess uncertainties associated with ozone buildup. HTAP generally shows 10-30 ppbv higher noontime ozone mixing ratios than SEAC4RS and INTEX-B, especially over the north-west Indo-Gangetic Plain (IGP), central India and southern India. The HTAP simulation repeated with the alternative Model for Ozone and Related Chemical Tracers (MOZART) chemical mechanism showed even more strongly enhanced surface ozone mixing ratios due to vertical mixing of enhanced ozone that has been produced aloft. Our study indicates the need to also evaluate the O3 precursors across a network of stations and the development of high-resolution regional inventories for the anthropogenic emissions over south Asia accounting for year-to-year changes to further reduce uncertainties in modelled ozone over this region.

  14. Unraveling the sources of ground level ozone in the Intermountain Western United States using Pb isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, John N. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Weiss-Penzias, Peter [University of California at Santa Cruz, Santa Cruz, CA (United States); Fine, Rebekka [University of Nevada, Reno, NV (United States); McDade, Charles E.; Trzepla, Krystyna [University of California at Davis, Crocker Nuclear Laboratory, Davis, CA (United States); Brown, Shaun T. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Gustin, Mae Sexauer [University of Nevada, Reno, NV (United States)

    2015-10-15

    Ozone as an atmospheric pollutant is largely produced by anthropogenic precursors and can significantly impact human and ecosystem health, and climate. The U.S. Environmental Protection Agency has recently proposed lowering the ozone standard from 75 ppbv (MDA8 = Maximum Daily 8-Hour Average) to between 65 and 70 ppbv. This will result in remote areas of the Intermountain West that includes many U.S. National Parks being out of compliance, despite a lack of significant local sources. We used Pb isotope fingerprinting and back-trajectory analysis to distinguish sources of imported ozone to Great Basin National Park in eastern Nevada. During discrete Chinese Pb events (> 1.1 ng/m{sup 3} & > 80% Asian Pb) trans-Pacific transported ozone was 5 ± 5.5 ppbv above 19 year averages for those dates. In contrast, concentrations during regional transport from the Los Angeles and Las Vegas areas were 15 ± 2 ppbv above the long-term averages, and those characterized by high-altitude transport 3 days prior to sampling were 19 ± 4 ppbv above. However, over the study period the contribution of trans-Pacific transported ozone increased at a rate of 0.8 ± 0.3 ppbv/year, suggesting that Asian inputs will exceed regional and high altitude sources by 2015–2020. All of these sources will impact regulatory compliance with a new ozone standard, given increasing global background. - Highlights: • Ozone can significantly impact human and ecosystem health and climate. • Pb isotopes and back-trajectory analysis were used to distinguish sources of O{sub 3}. • Baseline concentrations in the Western US are ~ 54 ppbv. • During discrete Asia events O{sub 3} increased by 5 ± 5.5 ppbv and during S CA events by 15 ± 2 ppbv. • Data indicate that Asian ozone inputs will exceed other sources by 2015–2020.

  15. Attempts to probe the ozone layer and the ultraviolet-B levels of the past.

    Science.gov (United States)

    Björn, Lars Olof; McKenzie, Richard L

    2007-07-01

    To get a proper perspective on the current status of atmospheric ozone, which protects the biosphere from ultraviolet-B (UV-B; 280-315 nm) radiation, it would be of value to know how ozone and UV-B radiation have varied in the past. The record of worldwide ozone monitoring goes back only a few decades, and the record of reliable UV-B measurements is even shorter. Here we review indirect methods to assess their status further back in time. These include variations in the Sun's emission and how these affect the atmosphere, changes in the Earth's orbit, geologic imprints of atmospheric ozone, effects of catastrophic events such as volcanic eruptions, biological proxies of UV-B radiation, the spectral signature of terrestrial ozone in old recordings of star spectra, and the modeling of UV-B irradiance from ozone data and meteorological recordings. Although reliable reconstructions do not yet extend far into the past, there is some hope for future progress.

  16. Setting ozone critical levels for protecting horticultural Mediterranean crops: Case study of tomato

    International Nuclear Information System (INIS)

    González-Fernández, I.; Calvo, E.; Gerosa, G.; Bermejo, V.; Marzuoli, R.; Calatayud, V.; Alonso, R.

    2014-01-01

    Seven experiments carried out in Italy and Spain have been used to parameterising a stomatal conductance model and establishing exposure– and dose–response relationships for yield and quality of tomato with the main goal of setting O 3 critical levels (CLe). CLe with confidence intervals, between brackets, were set at an accumulated hourly O 3 exposure over 40 nl l −1 , AOT40 = 8.4 (1.2, 15.6) ppm h and a phytotoxic ozone dose above a threshold of 6 nmol m −2 s −1 , POD6 = 2.7 (0.8, 4.6) mmol m −2 for yield and AOT40 = 18.7 (8.5, 28.8) ppm h and POD6 = 4.1 (2.0, 6.2) mmol m −2 for quality, both indices performing equally well. CLe confidence intervals provide information on the quality of the dataset and should be included in future calculations of O 3 CLe for improving current methodologies. These CLe, derived for sensitive tomato cultivars, should not be applied for quantifying O 3 -induced losses at the risk of making important overestimations of the economical losses associated with O 3 pollution. -- Highlights: • Seven independent experiments from Italy and Spain were analysed. • O 3 critical levels are proposed for the protection of summer horticultural crops. • Exposure- and flux-based O 3 indices performed equally well. • Confidence intervals of the new O 3 critical levels are calculated. • A new method to estimate the degree risk of O 3 damage is proposed. -- Critical levels for tomato yield were set at AOT40 = 8.4 ppm h and POD6 = 2.7 mmol m −2 and confidence intervals should be used for improving O 3 risk assessment

  17. Spatiotemporal prediction of daily ambient ozone levels across China using random forest for human exposure assessment.

    Science.gov (United States)

    Zhan, Yu; Luo, Yuzhou; Deng, Xunfei; Grieneisen, Michael L; Zhang, Minghua; Di, Baofeng

    2018-02-01

    In China, ozone pollution shows an increasing trend and becomes the primary air pollutant in warm seasons. Leveraging the air quality monitoring network, a random forest model is developed to predict the daily maximum 8-h average ozone concentrations ([O 3 ] MDA8 ) across China in 2015 for human exposure assessment. This model captures the observed spatiotemporal variations of [O 3 ] MDA8 by using the data of meteorology, elevation, and recent-year emission inventories (cross-validation R 2  = 0.69 and RMSE = 26 μg/m 3 ). Compared with chemical transport models that require a plenty of variables and expensive computation, the random forest model shows comparable or higher predictive performance based on only a handful of readily-available variables at much lower computational cost. The nationwide population-weighted [O 3 ] MDA8 is predicted to be 84 ± 23 μg/m 3 annually, with the highest seasonal mean in the summer (103 ± 8 μg/m 3 ). The summer [O 3 ] MDA8 is predicted to be the highest in North China (125 ± 17 μg/m 3 ). Approximately 58% of the population lives in areas with more than 100 nonattainment days ([O 3 ] MDA8 >100 μg/m 3 ), and 12% of the population are exposed to [O 3 ] MDA8 >160 μg/m 3 (WHO Interim Target 1) for more than 30 days. As the most populous zones in China, the Beijing-Tianjin Metro, Yangtze River Delta, Pearl River Delta, and Sichuan Basin are predicted to be at 154, 141, 124, and 98 nonattainment days, respectively. Effective controls of O 3 pollution are urgently needed for the highly-populated zones, especially the Beijing-Tianjin Metro with seasonal [O 3 ] MDA8 of 140 ± 29 μg/m 3 in summer. To the best of the authors' knowledge, this study is the first statistical modeling work of ambient O 3 for China at the national level. This timely and extensively validated [O 3 ] MDA8 dataset is valuable for refining epidemiological analyses on O 3 pollution in China. Copyright © 2017 Elsevier Ltd. All rights

  18. Forecasting of ozone level in time series using MLP model with a novel hybrid training algorithm

    Science.gov (United States)

    Wang, Dong; Lu, Wei-Zhen

    As far as the impact of tropospheric ozone (O 3) on human heath and plant life are concerned, forecasting its daily maximum level is of great importance in Hong Kong as well as other metropolises in the world. This paper proposed a multi-layer perceptron (MLP) model with a novel hybrid training method to perform the forecasting task. The training method synergistically couples a stochastic particle swarm optimization (PSO) algorithm and a deterministic Levenberg-Marquardt (LM) algorithm, which aims at exploiting the advantage of both. The performance of such a hybrid model is further compared with ones obtained by the MLP model trained individually by these two training methods mentioned above. Based on original data collected from two typical monitoring sites with different O 3 formation and transportation mechanism, the simulation results show that the hybrid model is more robust and efficient than the other two models by not only producing good results during non-episodes but also providing better consistency with the original data during episodes.

  19. Responses to ozone pollution of alfalfa exposed to increasing salinity levels

    International Nuclear Information System (INIS)

    Maggio, Albino; Chiaranda, Fabrizio Quaglietta; Cefariello, Roberto; Fagnano, Massimo

    2009-01-01

    Stomatal closure and biosynthesis of antioxidant molecules are two fundamental components of the physiological machinery that lead to stress adaptation during plant's exposure to salinity. Since high stomatal resistance may also contribute in counteracting O 3 damages, we hypothesized that soil salinization may increase O 3 tolerance of crops. An experiment was performed with alfalfa grown in filtered (AOT40 = 0 in both years) and non-filtered (AOT40 = 9.7 in 2005 and 6.9 ppm h in 2006) open-top chambers. Alfalfa yield was reduced by O 3 (-33%) only in plants irrigated with salt-free water, while the increasing levels of soil salinity until 1.06 dS m -1 reduced both stomatal conductance and plant O 3 uptake, thus linearly reducing O 3 effects on yield. Therefore a reliable flux-based model for assessing the effects of O 3 on crop yield should take into account soil salinity. - Moderate saline stress can reduce ozone uptake and yield losses in alfalfa plants.

  20. Responses to ozone pollution of alfalfa exposed to increasing salinity levels

    Energy Technology Data Exchange (ETDEWEB)

    Maggio, Albino; Chiaranda, Fabrizio Quaglietta; Cefariello, Roberto [DIAAT, Naples University Federico II, via Universita 100, 80055 Portici (Italy); Fagnano, Massimo, E-mail: fagnano@unina.i [DIAAT, Naples University Federico II, via Universita 100, 80055 Portici (Italy)

    2009-05-15

    Stomatal closure and biosynthesis of antioxidant molecules are two fundamental components of the physiological machinery that lead to stress adaptation during plant's exposure to salinity. Since high stomatal resistance may also contribute in counteracting O{sub 3} damages, we hypothesized that soil salinization may increase O{sub 3} tolerance of crops. An experiment was performed with alfalfa grown in filtered (AOT40 = 0 in both years) and non-filtered (AOT40 = 9.7 in 2005 and 6.9 ppm h in 2006) open-top chambers. Alfalfa yield was reduced by O{sub 3} (-33%) only in plants irrigated with salt-free water, while the increasing levels of soil salinity until 1.06 dS m{sup -1} reduced both stomatal conductance and plant O{sub 3} uptake, thus linearly reducing O{sub 3} effects on yield. Therefore a reliable flux-based model for assessing the effects of O{sub 3} on crop yield should take into account soil salinity. - Moderate saline stress can reduce ozone uptake and yield losses in alfalfa plants.

  1. Analysis of Summer Ozone Concentration in the Salt Lake Valley

    Science.gov (United States)

    Long, Katherine Ansley

    Observations and analyses of ozone concentrations and near-surface wind are examined during the latter half of June 2015 when the highest ozone levels of the 2015 summer were observed in the urban areas of northern Utah referred to locally as the Wasatch Front. A novel mix of ozone observations from sensors at fixed sites as well as mobile platforms (vehicles, light rail car, and news helicopter) help to define the spatiotemporal distribution of ozone along the Wasatch Front and the nearby Great Salt Lake. The ozone and wind observations are assimilated separately using a two-dimensional variational analysis system to obtain ozone and 10-m wind analyses at 1-km horizontal resolution every hour to determine the best representation of ozone distribution throughout the region. Two case studies are used to illustrate the diurnal evolution and transportation of ozone concentrations relative to local wind circulations driven primarily by lake-land and mountain-valley thermal contrasts. Ozone pollution roses at the fixed sensor locations for day and night periods and composites of the 1-km resolution analyses during the 15-day period as a function of time of day help to define common diurnal patterns. This study provides information on how ozone is distributed throughout the region and indicates that areas of high ozone concentrations are a function of the complex interaction of thermal flows in urban, rural, and lake boundary layers.

  2. Impacts of Ozone-vegetation Interactions and Biogeochemical Feedbacks on Atmospheric Composition and Air Quality Under Climate Change

    Science.gov (United States)

    Sadeke, M.; Tai, A. P. K.; Lombardozzi, D.; Val Martin, M.

    2015-12-01

    Surface ozone pollution is one of the major environmental concerns due to its damaging effects on human and vegetation. One of the largest uncertainties of future surface ozone prediction comes from its interaction with vegetation under a changing climate. Ozone can be modulated by vegetation through, e.g., biogenic emissions, dry deposition and transpiration. These processes are in turn affected by chronic exposure to ozone via lowered photosynthesis rate and stomatal conductance. Both ozone and vegetation growth are expected to be altered by climate change. To better understand these climate-ozone-vegetation interactions and possible feedbacks on ozone itself via vegetation, we implement an online ozone-vegetation scheme [Lombardozzi et al., 2015] into the Community Earth System Model (CESM) with active atmospheric chemistry, climate and land surface components. Previous overestimation of surface ozone in eastern US, Canada and Europe is shown to be reduced by >8 ppb, reflecting improved model-observation comparison. Simulated surface ozone is lower by 3.7 ppb on average globally. Such reductions (and improvements) in simulated ozone are caused mainly by lower isoprene emission arising from reduced leaf area index in response to chronic ozone exposure. Effects via transpiration are also potentially significant but require better characterization. Such findings suggest that ozone-vegetation interaction may substantially alter future ozone simulations, especially under changing climate and ambient CO2 levels, which would further modulate ozone-vegetation interactions. Inclusion of such interactions in Earth system models is thus necessary to give more realistic estimation and prediction of surface ozone. This is crucial for better policy formulation regarding air quality, land use and climate change mitigation. Reference list: Lombardozzi, D., et al. "The Influence of Chronic Ozone Exposure on Global Carbon and Water Cycles." Journal of Climate 28.1 (2015): 292-305.

  3. Eurasian continental background and regionally polluted levels of ozone and CO observed in northeast Asia

    Science.gov (United States)

    Pochanart, Pakpong; Kato, Shungo; Katsuno, Takao; Akimoto, Hajime

    The roles of Eurasian/Siberian continental air masses transport and the impact of large-scale East Asian anthropogenic emissions on tropospheric ozone and carbon monoxide levels in northeast Asia were investigated. Seasonal behaviors of O 3 and CO mixing ratios in background continental (BC) air masses and regionally polluted continental (RPC) air masses were identified using trajectory analyses of Eurasian continental air masses and multi-year O 3 and CO data observed at Happo, a mountain site in Japan. RPC air masses show significantly higher O 3 and CO mixing ratios (annual average of 53.9±6.0 and 200±41 ppb, respectively) than BC air masses (44.4±3.6 and 167±17 ppb, respectively). Large scale anthropogenic emissions in East Asia are suggested to contribute about 10 ppb of photochemical O 3 and 32 ppb of CO at Happo. A comparative study of O 3 and CO observed at other sites, i.e., Oki Islands and Mondy in northeast Asia, showed similarities suggesting that O 3 mixing ratios in BC air masses at Happo could be representative for remote northeast Asia. However, CO mixing ratios in BC air masses at Happo are higher than the background level in Siberia. The overestimate is probably related to an increase in the CO baseline gradient between Siberia and the East Asia Pacific rim, and perturbations by sub-grid scale pollution transport and regional-scale boreal forest fires in Siberia when the background continental air masses are transported to Japan.

  4. Ozone Layer Observations

    Science.gov (United States)

    McPeters, Richard; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    The US National Aeronautics and Space Administration (NASA) has been monitoring the ozone layer from space using optical remote sensing techniques since 1970. With concern over catalytic destruction of ozone (mid-1970s) and the development of the Antarctic ozone hole (mid-1980s), long term ozone monitoring has become the primary focus of NASA's series of ozone measuring instruments. A series of TOMS (Total Ozone Mapping Spectrometer) and SBUV (Solar Backscatter Ultraviolet) instruments has produced a nearly continuous record of global ozone from 1979 to the present. These instruments infer ozone by measuring sunlight backscattered from the atmosphere in the ultraviolet through differential absorption. These measurements have documented a 15 Dobson Unit drop in global average ozone since 1980, and the declines in ozone in the antarctic each October have been far more dramatic. Instruments that measure the ozone vertical distribution, the SBUV and SAGE (Stratospheric Aerosol and Gas Experiment) instruments for example, show that the largest changes are occurring in the lower stratosphere and upper troposphere. The goal of ozone measurement in the next decades will be to document the predicted recovery of the ozone layer as CFC (chlorofluorocarbon) levels decline. This will require a continuation of global measurements of total column ozone on a global basis, but using data from successor instruments to TOMS. Hyperspectral instruments capable of measuring in the UV will be needed for this purpose. Establishing the relative roles of chemistry and dynamics will require instruments to measure ozone in the troposphere and in the stratosphere with good vertical resolution. Instruments that can measure other chemicals important to ozone formation and destruction will also be needed.

  5. Impacts of stratospheric sulfate geoengineering on tropospheric ozone

    Directory of Open Access Journals (Sweden)

    L. Xia

    2017-10-01

    Full Text Available A range of solar radiation management (SRM techniques has been proposed to counter anthropogenic climate change. Here, we examine the potential effects of stratospheric sulfate aerosols and solar insolation reduction on tropospheric ozone and ozone at Earth's surface. Ozone is a key air pollutant, which can produce respiratory diseases and crop damage. Using a version of the Community Earth System Model from the National Center for Atmospheric Research that includes comprehensive tropospheric and stratospheric chemistry, we model both stratospheric sulfur injection and solar irradiance reduction schemes, with the aim of achieving equal levels of surface cooling relative to the Representative Concentration Pathway 6.0 scenario. This allows us to compare the impacts of sulfate aerosols and solar dimming on atmospheric ozone concentrations. Despite nearly identical global mean surface temperatures for the two SRM approaches, solar insolation reduction increases global average surface ozone concentrations, while sulfate injection decreases it. A fundamental difference between the two geoengineering schemes is the importance of heterogeneous reactions in the photochemical ozone balance with larger stratospheric sulfate abundance, resulting in increased ozone depletion in mid- and high latitudes. This reduces the net transport of stratospheric ozone into the troposphere and thus is a key driver of the overall decrease in surface ozone. At the same time, the change in stratospheric ozone alters the tropospheric photochemical environment due to enhanced ultraviolet radiation. A shared factor among both SRM scenarios is decreased chemical ozone loss due to reduced tropospheric humidity. Under insolation reduction, this is the dominant factor giving rise to the global surface ozone increase. Regionally, both surface ozone increases and decreases are found for both scenarios; that is, SRM would affect regions of the world differently in terms of air

  6. Impacts of stratospheric sulfate geoengineering on tropospheric ozone

    Science.gov (United States)

    Xia, Lili; Nowack, Peer J.; Tilmes, Simone; Robock, Alan

    2017-10-01

    A range of solar radiation management (SRM) techniques has been proposed to counter anthropogenic climate change. Here, we examine the potential effects of stratospheric sulfate aerosols and solar insolation reduction on tropospheric ozone and ozone at Earth's surface. Ozone is a key air pollutant, which can produce respiratory diseases and crop damage. Using a version of the Community Earth System Model from the National Center for Atmospheric Research that includes comprehensive tropospheric and stratospheric chemistry, we model both stratospheric sulfur injection and solar irradiance reduction schemes, with the aim of achieving equal levels of surface cooling relative to the Representative Concentration Pathway 6.0 scenario. This allows us to compare the impacts of sulfate aerosols and solar dimming on atmospheric ozone concentrations. Despite nearly identical global mean surface temperatures for the two SRM approaches, solar insolation reduction increases global average surface ozone concentrations, while sulfate injection decreases it. A fundamental difference between the two geoengineering schemes is the importance of heterogeneous reactions in the photochemical ozone balance with larger stratospheric sulfate abundance, resulting in increased ozone depletion in mid- and high latitudes. This reduces the net transport of stratospheric ozone into the troposphere and thus is a key driver of the overall decrease in surface ozone. At the same time, the change in stratospheric ozone alters the tropospheric photochemical environment due to enhanced ultraviolet radiation. A shared factor among both SRM scenarios is decreased chemical ozone loss due to reduced tropospheric humidity. Under insolation reduction, this is the dominant factor giving rise to the global surface ozone increase. Regionally, both surface ozone increases and decreases are found for both scenarios; that is, SRM would affect regions of the world differently in terms of air pollution. In conclusion

  7. Shuttle SBUV (SSBUV) Level 2 Ozone Profile and Total Column, Aerosol Index, and UV-Reflectivity V008 (SSBUVO3) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The Shuttle Solar Backscatter Ultraviolet (SSBUV) Level-2 Ozone data are available for eight space shuttle missions flown between 1989 and 1996. SSBUV, a successor...

  8. HIRDLS/Aura Level 3 Ozone (O3) 1deg Lat Zonal Fourier Coefficients V007 (H3ZFCO3) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The "HIRDLS/Aura Level 3 Ozone (O3) Zonal Fourier Coefficients" version 7 data product (H3ZFCO3) contains the entire mission (~3 years) of HIRDLS data expressed as...

  9. Exploring the direct impacts of particulate matter and surface ozone on global crop production

    Science.gov (United States)

    Schiferl, L. D.; Heald, C. L.

    2016-12-01

    The current era of rising food demand to feed an increasing population along with expansion of industrialization throughout the globe has been accompanied by deteriorating air quality and an enhancement in agricultural activity. Both air quality and the food supply are vitally important to sustaining human enterprise, and understanding the effects air quality may have on agricultural production is critical. Particulate matter (PM) in the atmosphere decreases the total photosynthetically available radiation (PAR) available to crops through the scattering and absorption of radiation while also increasing the diffuse fraction (DF) of this PAR. Since plants respond positively to a higher DF through the more even distribution of photons to all leaves, the net effect of PM on crop production depends on the magnitudes of these values and the response mechanisms of a specific crop. In contrast, atmospheric ozone always acts to decrease crop production through its phytotoxic properties. While the relationships between ozone and crop production have been readily studied, the effects of PM on crop production and their relative importance compared to ozone is much more uncertain. This study uses the GEOS-Chem chemical transport model linked to the RRTMG radiative transfer model and the DSSAT crop model to explore the impacts of PM and ozone on the globally distributed production of maize, rice, wheat and soybeans. First, we examine how air quality differentially affects total seasonal production by crop and region. Second, we investigate the dependence of simulated production on air quality over different timescales and under varying cloud conditions.

  10. Characteristics of Surface Ozone in Agra, a Sub-urban site in Indo ...

    Indian Academy of Sciences (India)

    65

    (2003) conducted their study at the high altitude site of Mt. ..... 247 other sites in India, ozone followed different diurnal and seasonal variations. At the high altitude. 248 site in Nainital (Sarangi et al., 2014), highest monthly mean (62 ..... meteorology on temporal evolution of O3 at a tropical location in northeast India; Environ.

  11. Characteristics of Surface Ozone in Agra, a Sub-urban site in Indo ...

    Indian Academy of Sciences (India)

    65

    Ozone (O3) is a secondary pollutant which has an important effect on air quality, climate. 49 change and atmospheric chemistry (Solomon et al., 2000; Sitch et al., 2007). Depending on its. 50 location in the atmosphere, O3 can influence human health and climate; in the stratosphere, O3. 51 filters out detrimental ultraviolet ...

  12. Vertical ozone characteristics in urban boundary layer in Beijing.

    Science.gov (United States)

    Ma, Zhiqiang; Xu, Honghui; Meng, Wei; Zhang, Xiaoling; Xu, Jing; Liu, Quan; Wang, Yuesi

    2013-07-01

    Vertical ozone and meteorological parameters were measured by tethered balloon in the boundary layer in the summer of 2009 in Beijing, China. A total of 77 tethersonde soundings were taken during the 27-day campaign. The surface ozone concentrations measured by ozonesondes and TEI 49C showed good agreement, albeit with temporal difference between the two instruments. Two case studies of nocturnal secondary ozone maxima are discussed in detail. The development of the low-level jet played a critical role leading to the observed ozone peak concentrations in nocturnal boundary layer (NBL). The maximum of surface ozone was 161.7 ppbv during the campaign, which could be attributed to abundant precursors storage near surface layer at nighttime. Vertical distribution of ozone was also measured utilizing conventional continuous analyzers on 325-m meteorological observation tower. The results showed the NBL height was between 47 and 280 m, which were consistent with the balloon data. Southerly air flow could bring ozone-rich air to Beijing, and the ozone concentrations exceeded the China's hourly ozone standard (approximately 100 ppb) above 600 m for more than 12 h.

  13. Chronic exposure to ozone and nitric acid vapor results in increased levels of rat pulmonary putrescine

    Energy Technology Data Exchange (ETDEWEB)

    Sindhu, R.K.; Kikkawa, Yutaka [Department of Pathology, College of Medicine, University of California at Irvine, Irvine (United States); Mautz, W.J. [Department of Community and Environmental Medicine, University of California at Irvine, Irvine, CA (United States)

    1998-06-01

    In the past decade, there has been growing public concern for the human health effects of exposure to environmental pollutants. Ozone (O{sub 3}) is one of the most reactive components of photochemical air pollution. Despite extensive investigations by many laboratories on the functional, biochemical, and cellular effects of O{sub 3} exposure in humans, animals, and in vitro systems, questions remain concerning the potential adverse effects to human health represented by chronic near-ambient exposure to this environmental pollutant. In the present investigation, the influence of inhalation of O{sub 3} and nitric acid (HNO{sub 3}) vapor on polyamine levels was examined in rat lungs. Male F344/N rats were exposed nose-only to 0.15 ppm O{sub 3} and 50 {mu}g/m{sup 3} HNO{sub 3} vapor alone and in combination for 4 hours/day, 3 days/week for a total of 40 weeks. At this time the animals were sacrificed and their lungs were examined for polyamine contents. Exposure to O{sub 3} and O{sub 3} plus HNO{sub 3} vapor caused a significant increase in the putrescine content of the lung compared to the air-exposed controls (P < 0.05). The concentrations of pulmonary spermidine and spermine were not significantly increased by exposure to either O{sub 3} or HNO{sub 3} vapor alone or in combination compared to the air-exposed controls. The role of polyamines in repair and anti-inflammatory processes has been discussed. (orig.) (orig.) With 1 fig., 1 tab., 30 refs.

  14. Developing ozone critical levels for multi-species canopies of Mediterranean annual pastures.

    Science.gov (United States)

    Calvete-Sogo, H; González-Fernández, I; García-Gómez, H; Alonso, R; Elvira, S; Sanz, J; Bermejo-Bermejo, V

    2017-01-01

    Ozone (O 3 ) critical levels (CLe) are still poorly developed for herbaceous vegetation. They are currently based on single species responses which do not reflect the multi-species nature of semi-natural vegetation communities. Also, the potential effects of other factors like the nitrogen (N) input are not considered in their derivation, making their use uncertain under natural conditions. Exposure- and dose-response relationships were derived from two open-top chamber experiments exposing a mixture of 6 representative annual Mediterranean pasture species growing in natural soil to 4 O 3 fumigation levels and 3 N inputs. The Deposition of O 3 and Stomatal Exchange model (DO 3 SE) was modified to account for the multi-species nature of the canopy following a big-leaf approach. This new approach was used for estimating a multi-species phytotoxic O 3 dose (POD y-MS ). Response relationships were derived based on O 3 exposure (AOT40) and flux (POD y-MS ) indices. The treatment effects were similar in the two seasons: O 3 reduced the aboveground biomass growth and N modulated this response. Gas exchange rates presented a high inter-specific variability and important inter-annual fluctuations as a result of varying growing conditions during the two years. The AOT40-based relationships were not statistically significant except when the highest N input was considered alone. In contrast, POD y-MS relationships were all significant but for the lowest N input level. The influence of the N input on the exposure- and dose-response relationships implies that N can modify the O 3 CLe. However, this is an aspect that has not been considered so far in the methodologies for establishing O 3 CLe. Averaging across N input levels, a multi-species O 3 CLe (CLe f-MS ) is proposed POD 1-MS  = 7.9 mmol m -2 , accumulated over 1.5 month with a 95% confidence interval of (5.9, 9.8). Further efforts will be needed for comparing the CLe f-MS with current O 3 CLe f based on single species

  15. Association of short-term exposure to ground-level ozone and respiratory outpatient clinic visits in a rural location – Sublette County, Wyoming, 2008–2011

    Energy Technology Data Exchange (ETDEWEB)

    Pride, Kerry R., E-mail: hgp3@cdc.gov [Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA (United States); Wyoming Department of Health, 6101 Yellowstone Road, Suite 510, Cheyenne, WY 82002 (United States); Peel, Jennifer L. [Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523 (United States); Robinson, Byron F. [Scientific Education and Professional Development Program Office, Office of Surveillance, Epidemiology and Laboratory Services, Centers for Disease Control and Prevention, 1600 Clifton Rd, NE, E-92, Atlanta, GA 30333 (United States); Busacker, Ashley [Field Support Branch, Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Wyoming Department of Health, 6101 Yellowstone Road, Suite 510, Cheyenne, WY 82002 (United States); Grandpre, Joseph [Chronic Disease Epidemiologist, Wyoming Department of Health, 6101 Yellowstone Road, Suite 510, Cheyenne, WY 82002 (United States); Bisgard, Kristine M. [Scientific Education and Professional Development Program Office, Office of Surveillance, Epidemiology and Laboratory Services, Centers for Disease Control and Prevention, 600 Clifton Road, NE, E-92, Atlanta, GA 30333 (United States); Yip, Fuyuen Y. [Air Pollution and Respiratory Disease Branch, Centers for Disease Control and Prevention, 600 Clifton Rd, NE, E-92, Atlanta, GA 30333 (United States); Murphy, Tracy D. [Wyoming Department of Health, 101 Yellowstone Road, Suite 510, Cheyenne, WY 82002 (United States)

    2015-02-15

    Objective: Short-term exposure to ground-level ozone has been linked to adverse respiratory and other health effects; previous studies typically have focused on summer ground-level ozone in urban areas. During 2008–2011, Sublette County, Wyoming (population: ~10,000 persons), experienced periods of elevated ground-level ozone concentrations during the winter. This study sought to evaluate the association of daily ground-level ozone concentrations and health clinic visits for respiratory disease in this rural county. Methods: Clinic visits for respiratory disease were ascertained from electronic billing records of the two clinics in Sublette County for January 1, 2008–December 31, 2011. A time-stratified case-crossover design, adjusted for temperature and humidity, was used to investigate associations between ground-level ozone concentrations measured at one station and clinic visits for a respiratory health concern by using an unconstrained distributed lag of 0–3 days and single-day lags of 0 day, 1 day, 2 days, and 3 days. Results: The data set included 12,742 case-days and 43,285 selected control-days. The mean ground-level ozone observed was 47±8 ppb. The unconstrained distributed lag of 0–3 days was consistent with a null association (adjusted odds ratio [aOR]: 1.001; 95% confidence interval [CI]: 0.990–1.012); results for lags 0, 2, and 3 days were consistent with the null. However, the results for lag 1 were indicative of a positive association; for every 10-ppb increase in the 8-h maximum average ground-level ozone, a 3.0% increase in respiratory clinic visits the following day was observed (aOR: 1.031; 95% CI: 0.994–1.069). Season modified the adverse respiratory effects: ground-level ozone was significantly associated with respiratory clinic visits during the winter months. The patterns of results from all sensitivity analyzes were consistent with the a priori model. Conclusions: The results demonstrate an association of increasing ground-level

  16. Changes in the surface ozone after the windstorm in 2004, in the High Tatras

    Directory of Open Access Journals (Sweden)

    Bičárová Svetlana

    2015-06-01

    Full Text Available Extreme wind event in November 2004 caused spacious destruction of slope forests in the Tatra National Park, Slovakia. Relevant changes of land cover motivated researchers to investigate damaged forest ecosystem and its response to different environmental conditions. Surface ozone (O3 is a minor but not negligible compound of the ambient air. Control strategies for the reduction of O3 precursor emissions have been applied in Europe during the last two decades. In spite of these reductions, air quality indices for O3 suggest that highland sites are more vulnerable to health and environmental risk than lowlands where mostly emissions from road transport and industry are produced. Both anthropogenic sources and biogenic precursors (BVOC from forest vegetation play a relevant role in the tropospheric photochemistry, especially at mountainous and rural locations. The parameters of air quality are measured at background station Stará Lesná in the High Tatras region since 1992 in frame of an European project EMEP. Long-term data series (1992-2013 of O3 concentrations obtained for site Stará Lesná provide specific opportunity to investigate the response of BVOC reduction on O3 variability after windstorm 2004. Evaluation of these data indicates moderate increase of annual, monthly and hourly O3 means for the period from 2005 to 2013 in comparison with the previous period 1992-2004. Temporal interpolation shows evident changes of O3 concentrations, especially ~30% increase for night hours in spring season and on the contrary ~15% decrease for daylight afternoon hours in summer season. Statistically significant changes were identified for spring months (April and May, 0-6 hours and summer months (July, 12-20 hours. Increasing O3 values in the night may be associated with the absence of BVOC for ozonolysis reaction that is one of the mechanism for O3 depletion. On the other hand, the decline of daylight O3 values in summer suggests lower O3 production

  17. Spatial Variation of Ground Level Ozone Concentrations and its Health Impacts in an Urban Area in India.

    Science.gov (United States)

    Gorai, Amit Kumar; Tchounwou, Paul B; Mitra, Gargi

    2017-01-01

    The present study was designed to analyze the spatial distributions of ground-level ozone (GLO) concentrations in Ranchi (Jharkhand, India) using geostatistical approaches. From September 2014 to August 2015, monthly GLO concentrations were monitored in 40-identified locations distributed in the region of study. In every month, the monitoring was done at three different time periods of the day; 5.30 AM to 7.30 AM, 11.30 AM to 1.30 PM, and 5.30 PM to 8 PM). The time duration was assigned based on the temporal variations of GLO concentrations. The descriptive statistics indicate that the spatial mean ozone concentrations ranged from 23.45 μg m -3 to 53.91 μg m -3 in morning hours, from 82.50 μg m -3 to 126.66 μg m -3 in the day time and from 40.04 μg m -3 to 71.25 μg m -3 in the evening hours. The higher level of spatial variance observed in the months of December (standard deviation: 24.21), July (standard deviation: 29.59) and November (standard deviation: 19.60) for the morning, noon, and evening time, respectively. The effects of meteorological factors (wind speed and wind direction) on the ozone concentrations were also analysed. The study confirmed that wind speed is not the dominant factor for influencing the GLO concentrations. The study also analysed the ozone air quality index (OZAQI) for assessing the health impacts in the study area. The result suggests that most of the area had the moderate category of OZAQI (101-200) and that leads to breathing discomfort for people with lung and heart disease.

  18. Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China - Part 2: The roles of anthropogenic emissions and climate variability

    Science.gov (United States)

    Xu, Wanyun; Xu, Xiaobin; Lin, Meiyun; Lin, Weili; Tarasick, David; Tang, Jie; Ma, Jianzhong; Zheng, Xiangdong

    2018-01-01

    despite ozone increases in eastern China. Analysis of the Trajectory-mapped Ozonesonde data set for the Stratosphere and Troposphere (TOST) and trajectory residence time reveals increases in direct ozone transport from the eastern sector during autumn, which adds to the autumnal ozone increase. We further examine the links of ozone variability at WLG to the quasi-biennial oscillation (QBO), the East Asian summer monsoon (EASM), and the sunspot cycle. Our results suggest that the 2-3-, 3-7-, and 11-year periodicities are linked to the QBO, EASM index, and sunspot cycle, respectively. A multivariate regression analysis is performed to quantify the relative contributions of various factors to surface ozone concentrations at WLG. Through an observational and modelling analysis, this study demonstrates the complex relationships between surface ozone at remote locations and its dynamical and chemical influencing factors.

  19. Trends of tropospheric ozone over Europe

    Energy Technology Data Exchange (ETDEWEB)

    Roemer, M.

    1996-12-31

    The purpose of the study on the title subject is to investigate the phenomena which have contributed to the observed trends of surface concentrations of ozone (O{sub 3}) and related species in The Netherlands and nearby countries. The presence in the European troposphere of relatively high concentrations of so-called ozone precursors establish a net chemical production of ozone. Since the atmospheric residence time of methane (CH{sub 4}) is much longer than that of all other VOC-species the rest is often referred to as non-methane volatile organic compounds (NMVOCs). The photo-stationary state relations are a set of three chemical reactions which rapidly converts ozone and nitrogen monoxide (NO) into nitrogen dioxide and oxygen (O{sub 2}) and vice versa. In NO{sub x}-rich environments such as in The Netherlands, this set of reactions transforms much of the ozone into NO{sub 2} which therefore can be regarded as potential ozone. Under such conditions it is convenient to use oxidant which is a conserved quantity for the photo-stationary state relations. The combination of NO{sub x} and VOCs produces ozone, but also other secondary species such as peroxyacetylnitrate (PAN). There are, however, a few differences between the formation of ozone and PAN and there are differences in their background levels as well. PAN concentrations in Europe are strongly determined by local (European) production, much more than the ozone concentrations in Europe. Therefore, studying trends of PAN concentrations is useful in distinguishing the contributions of different processes to the trends of ozone. Important aspects which possibly have contributed to trends of ozone concentrations are mentioned and discussed. Several aspects concerning the quantitative analysis of trends of surface concentrations of ozone, oxidant, PAN, NOX and NMVOS were investigated. The emphasis in this study is on the contribution of European emission changes since 1980 to the trends of ozone and oxidant

  20. Lidar Measurements of Tropospheric Ozone in the Arctic

    Directory of Open Access Journals (Sweden)

    Seabrook Jeffrey

    2016-01-01

    Full Text Available This paper reports on differential absorption lidar (DIAL measurements of tropospheric ozone in the Canadian Arctic during springtime. Measurements at Eureka Weather Station revealed that mountains have a significant effect on the vertical structure of ozone above Ellesmere Island. Ozone depletion events were observed when air that had spent significant time near to the frozen surface of the Arctic Ocean reached Eureka. This air arrived at Eureka by flowing over the surrounding mountains. Surface level ozone depletions were not observed during periods when the flow of air from over the sea ice was blocked by mountains. In the case of blocking there was an enhancement in the amount of ozone near the surface as air from the mid troposphere descended in the lee of the mountains. Three case studies will be shown in the presentation, while one is described in this paper.

  1. A statistical model for forecasting hourly ozone levels during fire season

    Science.gov (United States)

    Haiganoush K. Preisler; Shiyuan (Sharon) Zhong; Annie Esperanza; Leland Tarnay; Julide Kahyaoglu-Koracin

    2009-01-01

    Concerns about smoke from large high-intensity and managed low intensity fires have been increasing during the past decade. Because smoke from large high-intensity fires are known to contain and generate secondary fine particles (PM2.5) and ozone precursors, the effect of fires on air quality in the southern Sierra Nevada is a serious management...

  2. Ozone bleaching of South African Eucalyptus grandis kraft pulps containing high levels of hexenuronic acids

    CSIR Research Space (South Africa)

    Andrew, JE

    2013-08-01

    Full Text Available was a preliminary investigation into the use of ozone in bleaching sequences for kraft pulps produced from South African Eucalyptus grandis wood chips, which typically contained high amounts of hexenuronic acids (HexA). The objective of the study...

  3. Low level of stratospheric ozone near the Jharia coal field in India

    Indian Academy of Sciences (India)

    Although air pollution due to oxides and dioxides of carbon, nitrogen and sulphur is reported to have increased in this area due to large-scale opencast mining and coal fires, no significant study on the possible impact of coal fires on the stratospheric ozone concentration has been reported so far. The possible impact of coal ...

  4. Low level of stratospheric ozone near the Jharia coal field in India

    Indian Academy of Sciences (India)

    Although air pollution due to oxides and dioxides of carbon, nitrogen and sulphur is reported to have increased in this area due to large-scale opencast mining and ... data obtained from Upper Atmospheric Research Satellite (UARS MLS), Earth Observing System Microwave Limb Sounder (EOS MLS) and Ozone Monitoring ...

  5. Method for Reduction of Pesticide Residue Levels in Raspberry and Blackcurrant Based on Utilization of Ozone

    Directory of Open Access Journals (Sweden)

    Balawejder Maciej

    2014-12-01

    Full Text Available The method for the reduction of pesticide residues in soft fruits based on utilization of ozone was proposed. The procedure allows for effective reduction of boscalid residues by 38% in raspberries, and about 58% thiram in blackcurrants. Furthermore, it can be used on an industrial scale.

  6. Quantifying ozone uptake at the canopy level of spruce, pine and larch trees at the alpine timberline: an approach based on sap flow measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wieser, G.; Matyssek, R.; Koestner, B.; Oberhuber, W

    2003-11-01

    Sap-flow based measurements can be used to estimate ozone uptake at whole-tree and stand levels. - Micro-climatic and ambient ozone data were combined with measurements of sap flow through tree trunks in order to estimate whole-tree ozone uptake of adult Norway spruce (Picea abies), cembran pine (Pinus cembra), and European larch (Larix decidua) trees. Sap flow was monitored by means of the heat balance approach in two trees of each species during the growing season of 1998. In trees making up the stand canopy, the ozone uptake by evergreen foliages was significantly higher than by deciduous ones, when scaled to the ground area. However, if expressed per unit of whole-tree foliage area, ozone flux through the stomata into the needle mesophyll was 1.09, 1.18 and 1.40 nmol m{sup -2} s{sup -1} in Picea abies, Pinus cembra and Larix decidua, respectively. These fluxes are consistent with findings from measurements of needle gas exchange, published from the same species at the study site. It is concluded that the sap flow-based approach offers an inexpensive, spatially and temporally integrating way for estimating ozone uptake at the whole-tree and stand level, intrinsically covering the effect of boundary layers on ozone flux.

  7. Application of Response Surface Methodology for characterization of ozone production from Multi-Cylinder Reactor in non-thermal plasma device

    Science.gov (United States)

    Lian See, Tan; Zulazlan Shah Zulkifli, Ahmad; Mook Tzeng, Lim

    2018-04-01

    Ozone is a reactant which can be applied for various environmental treatment processes. It can be generated via atmospheric air non-thermal plasmas when sufficient voltages are applied through a combination of electrodes and dielectric materials. In this study, the concentration of ozone generated via two different configurations of multi-cylinder dielectric barrier discharge (DBD) reactor (3 x 40 mm and 10 x 10 mm) was investigated. The influence of the voltage and the duty cycle to the concentration of ozone generated by each configuration was analysed using response surface methodology. Voltage was identified as significant factor to the ozone production process. However, the regressed model was biased towards one of the configuration, leaving the predicted results of another configuration to be out of range.

  8. Foreign and Domestic Contributions to Springtime Ozone Pollution over China

    Science.gov (United States)

    Ni, R.; Lin, J.; Yan, Y.; Lin, W.; Chen, H.

    2017-12-01

    Ozone is a critical air pollutant that damages human health and vegetation. Previous studies for the United States and Europe have shown large influences of foreign emissions on domestic ozone levels, whereas the relative contributions of foreign versus domestic emissions are much less clear for China. Here, we use a global-regional two-way coupled model system based on GEOS-Chem to quantify the contributions to springtime ozone over China from anthropogenic emissions in major source regions across the globe. Our results indicate considerable influences of foreign anthropogenic pollution on China's ozone pollution. Together, foreign anthropogenic emissions enhance springtime surface ozone over China by 3 12 ppb. Of all ozone over China produced by global anthropogenic emissions, foreign emissions contribute 40% near the surface, and the contribution increases with altitude until a value of 80% in the upper troposphere. Impact from Japan and Korea is 1 2 ppb over east coastal regions, and negligible in inland. Anthropogenic emissions of South and South-East Asia increase ozone over Tibet and the Yunnan-Guizhou Plateau by up to 5 ppb, and their contribution increases with height due to strong vertical transport. Pollution from North America and Europe mainly accompanies strong westerly winds and frequent cyclonic activities that are favorable to long-range transport. European anthropogenic pollution enhances surface ozone by 1 3 ppb over West and North China. Despite a much longer transport distance, the contribution from North America is greater than European contribution due to the nearly doubled amount of anthropogenic NMVOC emissions. The high percentage contribution of foreign anthropogenic emissions to China's ozone pollution can be partly explained by excessive domestic NOx emissions that suppress ozone production efficiency and even destroy ozone. Our study is relevant to Chinese ozone pollution control and global environmental protection collaboration.

  9. Spatiotemporal trends in ground-level ozone concentrations and metrics in France over the time period 1999-2012.

    Science.gov (United States)

    Sicard, Pierre; Serra, Romain; Rossello, Philippe

    2016-08-01

    The hourly ozone (O3) data from 332 background monitoring stations, spread in France, were analyzed over the period 1999-2012 and short-term trends were calculated. In the current climate change context, the calculation of human health- and vegetation-relevant metrics, and of associated trends, provides a consistent method to establish proper and effective policies to reduce the adverse O3 effects. The generation of optimal O3 maps, for risk and exposure assessment, is challenging. To overcome this issue, starting from a set of stations, a hybrid regression-interpolation approach was proposed. Annual surface O3 metrics, O3 human health metrics (number of exceedances of daily maximum 8-h values greater than 60 ppb and SOMO35) and O3 vegetation impact metrics (AOT40 for vegetation and forests) were investigated at individual sites. Citizens are more exposed to high O3 levels in rural areas than people living in the cities. The annual mean concentrations decreased by -0.12ppbyear(-1) at rural stations, and the significant reduction at 67% of stations, particularly during the warm season, in the number of episodic high O3 concentrations (e.g. 98th percentile, -0.19ppbyear(-1)) can be associated with the substantial reductions in NOx and VOCs emissions in the EU-28 countries since the early 1990s Inversely, the O3 background level is rising at 76% of urban sites (+0.14ppbyear(-1)), particularly during the cold period. This rise can be attributed to increases in imported O3 by long-range transport and to a low O3 titration by NO due to the reduction in local NOx emissions. The decrease in health-related and vegetation-relevant O3 metrics, at almost all stations, is driven by decreases in regional photochemical O3 formation and in peak O3 concentrations. The short-term trends highlight that the threat to population and vegetation declined between 1999 and 2012 in France, demonstrating the success of European control strategies over the last 20 years. However, for all

  10. The role of bay breezes and regional transport on a high surface ozone episode during the Houston, Texas DISCOVER-AQ field campaign

    Science.gov (United States)

    Loughner, C.; Follette-Cook, M. B.; Pickering, K. E.; Estes, M. J.

    2014-12-01

    The highest observed surface ozone concentrations in the Houston metropolitan area in 2013 occurred on September 25, which coincided with the Texas DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field campaign. Surface ozone was elevated throughout the Houston metropolitan area. Maximum 8-hour average ozone peaked along the western shore of Galveston Bay, reaching 124 ppbv, almost 50 ppbv above the current EPA standard of 75 ppbv, at La Porte Sylvan Beach. Continental air pollution from the north and northeast was transported into the Houston metropolitan area where it mixed with locally generated emissions. A bay breeze circulation formed causing pollutants that were transported out over the water in the morning to recirculate back inland where they mixed with freshly emitted pollution near the bay breeze convergence zone. The highest surface ozone concentrations were reported near the bay breeze front at La Porte Sylvan Beach. This ozone episode will be presented using measurements made during the DISCOVER-AQ field campaign and WRF and CMAQ model simulations.

  11. Identification of ozonation by-products of 4- and 5-methyl-1H-benzotriazole during the treatment of surface water to drinking water.

    Science.gov (United States)

    Müller, Alexander; Weiss, Stefan C; Beisswenger, Judith; Leukhardt, H Georg; Schulz, Wolfgang; Seitz, Wolfram; Ruck, Wolfgang K L; Weber, Walter H

    2012-03-01

    During the treatment of surface water to drinking water, ozonation is often used for disinfection and to remove organic trace substances, whereby oxidation by-products can be formed. Here we use the example of tolyltriazole to describe an approach for identifying relevant oxidation by-products in the laboratory and subsequently detecting them in an industrial-scale process. The identification process involves ozonation experiments with pure substances at laboratory level (concentration range mg L(-1)). The reaction solutions from different ozone contact times were analyzed by high performance liquid chromatography - quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) in full scan mode. Various approaches were used to detect the oxidation by-products: (i) target searches of postulated oxidation by-products, (ii) comparisons of chromatograms (e.g., UV/VIS) of the different samples, and (iii) color-coded abundance time courses (kinetic) of all detected compounds were illustrated in a kind of a heat map. MS/MS, H/D exchange, and derivatization experiments were used for structure elucidation for the detected by-product. Due to the low contaminant concentrations (ng L(-1)-range) of contaminants in the untreated water, the conversion of results from laboratory experiments to an industrial-scale required the use of HPLC-MS/MS with sample enrichment (e.g., solid phase extraction.) In cases where reference substances were not available or oxidation by-products without clear structures were detected, reaction solutions from laboratory experiments were used to optimize the analytical method to detect ng L(-1) in the samples of the industrial processes. We exemplarily demonstrated the effectiveness of the methodology with the industrial chemicals 4- and 5-methyl-1H-benzotriazole (4- and 5-MBT) as an example. Moreover, not only did we identify several oxidation by-products in the laboratory experiments tentatively, but also detected three of the eleven reaction

  12. Effect of a Combination of Low Level Ozone and Metal Ions on Reducing Escherichia coli O157:H7 and Listeria monocytogenes

    Directory of Open Access Journals (Sweden)

    Ok-Hwan Lee

    2013-04-01

    Full Text Available Ozonated water has been used as a strong antimicrobial agent against foodborne pathogens. In this study, the combined effect of low level ozonated water and different added components, including 0.2% starch and metal ions (1 mM CuCl2·2H2O and 0.1 mM AgNO3, on inactivation of Escherichia coli O157:H7 and Listeria monocytogenes was investigated. Treatment with 0.4 ppm ozonated water for 30 min resulted in a maximum log reduction in E. coli O157:H7 and L. monocytogenes compared to initial bacterial counts. The log reductions of bacteria in a starch solution containing ozonated water were slightly higher than those in ozonated water alone. Furthermore, the log reductions of E. coli O157:H7 (2.59 and 4.71 log cfu/mL and L. monocytogenes (2.53 and 4.28 log cfu/mL in a metal ion solution containing 0.2 and 0.4 ppm ozone for 30 min were significantly higher than those of the water and starch added groups (p < 0.05. These results indicate that a combination of ozonated water and metal ions may be useful as a antimicrobial agent.

  13. Impacts of a large boreal wildfire on ground level atmospheric concentrations of PAHs, VOCs and ozone

    Science.gov (United States)

    Wentworth, Gregory R.; Aklilu, Yayne-abeba; Landis, Matthew S.; Hsu, Yu-Mei

    2018-04-01

    During May 2016 a very large boreal wildfire burned throughout the Athabasca Oil Sands Region (AOSR) in central Canada, and in close proximity to an extensive air quality monitoring network. This study examines speciated 24-h integrated polycyclic aromatic hydrocarbon (PAH) and volatile organic compound (VOC) measurements collected every sixth day at four and seven sites, respectively, from May to August 2016. The sum of PAHs (ΣPAH) was on average 17 times higher in fire-influenced samples (852 ng m-3, n = 8), relative to non-fire influenced samples (50 ng m-3, n = 64). Diagnostic PAH ratios in fire-influenced samples were indicative of a biomass burning source, whereas ratios in June to August samples showed additional influence from petrogenic and fossil fuel combustion. The average increase in the sum of VOCs (ΣVOC) was minor by comparison: 63 ppbv for fire-influenced samples (n = 16) versus 46 ppbv for non-fire samples (n = 90). The samples collected on August 16th and 22nd had large ΣVOC concentrations at all sites (average of 123 ppbv) that were unrelated to wildfire emissions, and composed primarily of acetaldehyde and methanol suggesting a photochemically aged air mass. Normalized excess enhancement ratios (ERs) were calculated for 20 VOCs and 23 PAHs for three fire influenced samples, and the former were generally consistent with previous observations. To our knowledge, this is the first study to report ER measurements for a number of VOCs and PAHs in fresh North American boreal wildfire plumes. During May the aged wildfire plume intercepted the cities of Edmonton (∼380 km south) or Lethbridge (∼790 km south) on four separate occasions. No enhancement in ground-level ozone (O3) was observed in these aged plumes despite an assumed increase in O3 precursors. In the AOSR, the only daily-averaged VOCs which approached or exceeded the hourly Alberta Ambient Air Quality Objectives (AAAQOs) were benzene (during the fire) and acetaldehyde (on August 16th

  14. Impact of parameterization choices on the restitution of ozone deposition over vegetation

    Science.gov (United States)

    Le Morvan-Quéméner, Aurélie; Coll, Isabelle; Kammer, Julien; Lamaud, Eric; Loubet, Benjamin; Personne, Erwan; Stella, Patrick

    2018-04-01

    Ozone is a potentially phyto-toxic air pollutant, which can cause leaf damage and drastically alter crop yields, causing serious economic losses around the world. The VULNOZ (VULNerability to OZone in Anthropised Ecosystems) project is a biology and modeling project that aims to understand how plants respond to the stress of high ozone concentrations, then use a set of models to (i) predict the impact of ozone on plant growth, (ii) represent ozone deposition fluxes to vegetation, and finally (iii) estimate the economic consequences of an increasing ozone background the future. In this work, as part of the VULNOZ project, an innovative representation of ozone deposition to vegetation was developed and implemented in the CHIMERE regional chemistry-transport model. This type of model calculates the average amount of ozone deposited on a parcel each hour, as well as the integrated amount of ozone deposited to the surface at the regional or country level. Our new approach was based on a refinement of the representation of crop types in the model and the use of empirical parameters specific to each crop category. The results obtained were compared with a conventional ozone deposition modeling approach, and evaluated against observations from several agricultural areas in France. They showed that a better representation of the distribution between stomatal and non-stomatal ozone fluxes was obtained in the empirical approach, and they allowed us to produce a new estimate of the total amount of ozone deposited on the subtypes of vegetation at the national level.

  15. Ozone-induced foliar damage and release of stress volatiles is highly dependent on stomatal openness and priming by low-level ozone exposure in Phaseolus vulgaris.

    Science.gov (United States)

    Li, Shuai; Harley, Peter C; Niinemets, Ülo

    2017-09-01

    Acute ozone exposure triggers major emissions of volatile organic compounds (VOCs), but quantitatively, it is unclear how different ozone doses alter the start and the total amount of these emissions, and the induction rate of different stress volatiles. It is also unclear whether priming (i.e. pre-exposure to lower O 3 concentrations) can modify the magnitude and kinetics of volatile emissions. We investigated photosynthetic characteristics and VOC emissions in Phaseolus vulgaris following acute ozone exposure (600 nmol mol -1 for 30 min) under illumination and in darkness and after priming with 200 nmol mol -1 O 3 for 30 min. Methanol and lipoxygenase (LOX) pathway product emissions were induced rapidly, followed by moderate emissions of methyl salicylate (MeSA). Stomatal conductance prior to acute exposure was lower in darkness and after low O 3 priming than in light and without priming. After low O 3 priming, no MeSA and lower LOX emissions were detected under acute exposure. Overall, maximum emission rates and the total amount of emitted LOX products and methanol were quantitatively correlated with total stomatal ozone uptake. These results indicate that different stress volatiles scale differently with ozone dose and highlight the key role of stomatal conductance in controlling ozone uptake, leaf injury and volatile release. © 2017 John Wiley & Sons Ltd.

  16. Ozone-induced foliar damage and release of stress volatiles is highly dependent on stomatal openness and priming by low-level ozone exposure in Phaseolus vulgaris

    Science.gov (United States)

    Li, Shuai; Harley, Peter C.; Niinemets, Ülo

    2018-01-01

    Acute ozone exposure triggers major emissions of volatile organic compounds (VOC), but quantitatively, it is unclear how different ozone doses alter the start and the total amount of these emissions, and the induction rate of different stress volatiles. It is also unclear whether priming (i.e., pre-exposure to lower O3 concentrations) can modify the magnitude and kinetics of volatile emissions. We investigated photosynthetic characteristics and VOC emissions in Phaseolus vulgaris following acute ozone exposure (600 nmol mol-1 for 30 min) under illumination and in darkness and after priming with 200 nmol mol-1 O3 for 30 min. Methanol and lipoxygenase (LOX) pathway product emissions were induced rapidly, followed by moderate emissions of methyl salicylate (MeSA). Stomatal conductance prior to acute exposure was lower in darkness and after low O3 priming than in light and without priming. After low O3 priming, no MeSA and lower LOX emissions were detected under acute exposure. Overall, maximum emission rates and the total amount of emitted LOX products and methanol were quantitatively correlated with total stomatal ozone uptake. These results indicate that different stress volatiles scale differently with ozone dose and highlight the key role of stomatal conductance in controlling ozone uptake, leaf injury and volatile release. PMID:28623868

  17. Ground Level Ozone Peak Forecast using Neural Networks and Kalman Filter

    Czech Academy of Sciences Publication Activity Database

    Pelikán, Emil; Eben, Kryštof; Vondráček, Jiří; Krejčíř, Pavel; Keder, J.

    2000-01-01

    Roč. 3, č. 2 (2000), s. 3-8 ISSN 1335-339X Grant - others:APPETISE(XE) IST-99-11764; MŽP ČR(CZ) ZZ520/2/97; MŠMT ČR(CZ) VS96008 Institutional research plan: AV0Z1030915 Keywords : ozone forecast * neural classifications * Kalman filter * genetic algorithms * Kohonen maps * Czech Republic Subject RIV: BB - Applied Statistics, Operational Research

  18. Case study of stratospheric ozone affecting ground-level oxidant concentrations

    International Nuclear Information System (INIS)

    Lamb, R.G.

    1977-01-01

    During the predawn hours of 19 November 1972, the air pollution monitoring station at Santa Rosa, Calif., recorded five consecutive hours of oxidant concentrations in excess of the present National Ambient Air Quality Standard. The highest of the hourly averages was 0.23 ppm. From a detailed analysis of the meteorological conditions surrounding this incident, it is shown that the ozone responsible for the anomalous concentrations originated in the stratosphere and not from anthropogenic sources

  19. Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in apple juice at different pH levels by gaseous ozone treatment.

    Science.gov (United States)

    Song, W-J; Shin, J-Y; Ryu, S; Kang, D-H

    2015-08-01

    We investigated the effect of ozone treatment of apple juice at different pH levels for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes. Apple juice (pH 3.0, 4.0 and 5.0) inoculated with the three pathogens were treated with gaseous ozone (3.0 l min(-1) flow rate and 2.0-3.0 g m(-3) ) for up to 4 min. Ozone treatment (4 min) of pH 3.0 apple juice resulted in >5.36 log CFU ml(-1) reduction of E. coli O157:H7. Ozone treatment of pH 4.0 and 5.0 apple juice for 4 min reduced this pathogen by 5.12 log CFU ml(-1) and 1.86 log CFU ml(-1) respectively. The combination of low pH and ozone showed a great antimicrobial effect in apple juice. Salm. Typhimurium and L. monocytogenes showed a reduction trend similar to E. coli O157:H7. There were no significant changes of colour values when apple juice was treated with ozone, except for b values. Among all ozone treated samples, the browning index was lower than that of nontreated samples and there were no significant differences in total phenolic contents. In conclusion, ozone treatment of low pH apple juice was significantly effective in inactivation of foodborne pathogens while maintaining acceptable apple juice quality. The antimicrobial effect of ozone treatment on foodborne pathogens in apple juice can be reinforced by lowering the pH of apple juice. © 2015 The Society for Applied Microbiology.

  20. Spatial Variation of Ground Level Ozone Concentrations and its Health Impacts in an Urban Area in India

    OpenAIRE

    Gorai, Amit Kumar; Tchounwou, Paul B.; Mitra, Gargi

    2017-01-01

    The present study was designed to analyze the spatial distributions of ground-level ozone (GLO) concentrations in Ranchi (Jharkhand, India) using geostatistical approaches. From September 2014 to August 2015, monthly GLO concentrations were monitored in 40-identified locations distributed in the region of study. In every month, the monitoring was done at three different time periods of the day; 5.30 AM to 7.30 AM, 11.30 AM to 1.30 PM, and 5.30 PM to 8 PM). The time duration was assigned based...

  1. Ambient ozone effects on gas exchange and total non-structural carbohydrate levels in cutleaf coneflower (Rudbeckia laciniata L.) growing in Great Smoky Mountains National Park.

    Science.gov (United States)

    Neufeld, Howard S; Peoples, Seth J; Davison, Alan W; Chappelka, Arthur H; Somers, Greg L; Thomley, Jill E; Booker, Fitzgerald L

    2012-01-01

    Ozone-sensitive and -tolerant individuals of cutleaf coneflower (Rudbeckia laciniata L.) were compared for their gas exchange characteristics and total non-structural carbohydrates at Purchase Knob, a high elevation site in Great Smoky Mountains National Park, USA. Photosynthesis and stomatal conductance decreased with increased foliar stipple. Sensitive plants had lower photosynthetic rates for all leaves, except the very youngest and oldest when compared to tolerant plants. Stomatal conductance decreased with increasing leaf age, but no ozone-sensitivity differences were found. Lower leaves had less starch than upper ones, while leaves on sensitive plants had less than those on tolerant plants. These results show that ambient levels of ozone in Great Smoky Mountains National Park can adversely affect gas exchange, water use efficiency and leaf starch content in sensitive coneflower plants. Persistence of sensitive genotypes in the Park may be due to physiological recovery in low ozone years. Copyright © 2011 Elsevier Ltd. All rights reserved.

  2. Links between extreme UV-radiation, total ozone, surface albedo and cloudiness: An analysis of 30 years of data from Switzerland and Austria

    Science.gov (United States)

    Rieder, H. E.; Staehelin, J.; Weihs, P.; Vuilleumier, L.; Blumthaler, M.; Holawe, F.; Lindfors, A.; Maeder, J. A.; Simic, S.; Wagner, J. E.; Walker, D.; Ribatet, M.

    2009-04-01

    Since the discovery of anthropogenic ozone depletion in the early 1970s (e.g. Molina and Rowland, 1974; Farman et al., 1985) the interest in stratospheric ozone trends and solar UV-B increased within the scientific community and the general public because of the link between reduced total column ozone and increased UV-radiation doses. Stratospheric ozone (e.g. Koch et al., 2005) and erythemal UV-radiation (e.g. Rieder et al., 2008) in the northern mid-latitudes are characterized by strong temporal variability. Long-term measurements of UV-B radiation are rare and datasets are only available for few locations and most of these measurements do not provide spectral information on the UV part of the spectra. During strong efforts in the reconstruction of erythemal UV, datasets of past UV-radiation doses became available for several measurement sites all over the globe. For Switzerland and Austria reconstructed UV datasets are available for 3 measurement sites (Davos, Sonnblick and Vienna) (Lindfors and Vuilleumier, 2005; Rieder et al., 2008). The world's longest ozone time series dating back to 1926 is available from Arosa, Switzerland, and is discussed in detail by Staehelin et al. (1998a,b). Recently new tools from extreme value theory have been applied to the Arosa time series to describe extreme events in low and high total ozone (Rieder et al., 2009). In our study we address the question of how much of the extremes in UV-radiation can be attributed to extremes in total ozone, high surface albedo and cloudiness. An analysis of the frequency distributions of such extreme events for the last decades is presented to gain a better understanding of the links between extreme erythemal UV-radiation, total ozone, surface albedo and clouds. References: Farman, J. C., Gardiner, B. G., and Shanklin, J. D.: Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction, Nature, 315, 207-210, 1985. Koch, G., Wernli, H., Schwierz, C., Staehelin, J., and Peter, T

  3. Two Years of Ozone Vertical Profiles Collected from Aircraft over California and the Pacific Ocean

    Science.gov (United States)

    Austerberry, D.; Yates, E. L.; Roby, M.; Chatfield, R. B.; Iraci, L. T.; Pierce, B.; Fairlie, T. D.; Johnson, B. J.; Ives, M.

    2012-12-01

    Tropospheric ozone transported across the Pacific Ocean has been strongly suggested to contribute substantially to surface ozone levels at several sites within Northern California's Sacramento Valley. Because this contribution can affect a city's ability to meet regulatory ozone limits, the influence of Pacific ozone transport has implications for air quality control strategies in the San Joaquin Valley (SJV). The Alpha Jet Atmospheric Experiment is designed to collect a multi-year data set of tropospheric ozone vertical profiles. Forty-four flights with ozone profiles were conducted between February 2nd, 2011 and August 9th, 2012, and approximately ten more flights are expected in the remainder of 2012. Twenty marine air profiles have been collected at sites including Trinidad Head and two locations tens of kilometers offshore at 37° N latitude. Good agreement is seen with ozonesondes launched from Trinidad Head. Additional profiles over Merced, California were obtained on many of these flight days. These in-situ measurements were conducted during spiral descents of H211's Alpha Jet at mid-day local times using a 2B Technologies Dual Beam Ozone Monitor. Hourly surface ambient ozone data were obtained from the California Air Resources Board's SJV monitoring sites. For each site, the Pearson linear correlation coefficient was calculated between ozone in a 300m vertical layer of an offshore profile and the surface site at varying time offsets from the time of the profile. Each site's local and regional ozone production component was estimated and removed. The resulting correlations suggest instances of Pacific ozone transport following some of the offshore observations. Real-Time Air Quality Modeling System (RAQMS) products constrained by assimilated satellite data model the transport of ozone enhancements and guide flight planning. RAQMS hindcasts also suggest that ozone transport to the surface of the SJV basin occurred following some of these offshore profiles

  4. Air Quality Guide for Ozone

    Science.gov (United States)

    GO! Local Air Quality Conditions Zip Code: State : My Current Location Air Quality Guide for Ozone Ground-level ozone is one of our nation’s most common air pollutants. Use the chart below to help reduce ...

  5. Ozone precursor levels and responses to emissions reductions: Analysis of regional oxidant model results

    Science.gov (United States)

    Milford, Jana B.; Gao, Dongfen; Zafirakou, Antigoni; Pierce, Thomas E.

    An analysis of results from the Regional Oxidant Modeling for Northeast Transport (ROMNET) study ( U.S. EPA, 1991, EPA-450/4-91-002a) has investigated the chemical conditions under which air quality was predicted to improve with reductions in ROG and/or NO ξ emissions, or with changes in the composition of ROG emissions. The ROMNET simulations used emissions projected to the year 2005, with meteorological conditions from July 1988. Predicted concentrations of PAN, HNO 3, H 2O 2 and HCHO are shown along with O 3 for the 2005 base case, allowing limited comparisons to be made with field observations and results from other modeling studies. Predicted secondary pollutant concentrations indicate an unusual degree of photochemical activity over much of the model domain, directionally consistent with the extreme nature of the July 1988 episode. Reducing NO ξ emissions was predicted to reduce O 3 in grid cells in which reactive nitrogen (NO y) concentrations were below about 25 ppb, but to be counterproductive for some cells with higher NO y. The New York City area where NO ξ control was predicted to be counterproductive was characterized by very high NO ξ to NO y ratios. Ozone was relatively insensitive to ROG controls in grid cells with NO y concentrations below 5-10 ppb. Comparison of unweighted ROG concentrations with concentrations weighted by HO rate constants (i.e. reactivity) showed that the latter varied less across locations. Predicted spatial gradients of NO y were generally sharper than those of reactivity-weighted ROG, supporting a dominant role for variations in NO y in controlling the sensitivity of ozone to its precursors. Reductions in reactivity-weighted ROG achieved with composition changes were similar to reductions achieved with ROG emissions cuts, explaining the similar response of ozone to these two control strategies.

  6. Tropospheric ozone seasonal and long-term variability as seen by lidar and surface measurements at the JPL-Table Mountain Facility, California

    Directory of Open Access Journals (Sweden)

    M. J. Granados-Muñoz

    2016-07-01

    Full Text Available A combined surface and tropospheric ozone climatology and interannual variability study was performed for the first time using co-located ozone photometer measurements (2013–2015 and tropospheric ozone differential absorption lidar measurements (2000–2015 at the Jet Propulsion Laboratory Table Mountain Facility (TMF; elev. 2285 m, in California. The surface time series were investigated both in terms of seasonal and diurnal variability. The observed surface ozone is typical of high-elevation remote sites, with small amplitude of the seasonal and diurnal cycles, and high ozone values, compared to neighboring lower altitude stations representative of urban boundary layer conditions. The ozone mixing ratio ranges from 45 ppbv in the winter morning hours to 65 ppbv in the spring and summer afternoon hours. At the time of the lidar measurements (early night, the seasonal cycle observed at the surface is similar to that observed by lidar between 3.5 and 9 km. Above 9 km, the local tropopause height variation with time and season impacts significantly the ozone lidar observations. The frequent tropopause folds found in the vicinity of TMF (27 % of the time, mostly in winter and spring produce a dual-peak vertical structure in ozone within the fold layer, characterized by higher-than-average values in the bottom half of the fold (12–14 km, and lower-than-averaged values in the top half of the fold (14–18 km. This structure is consistent with the expected origin of the air parcels within the fold, i.e., mid-latitude stratospheric air folding down below the upper tropospheric sub-tropical air. The influence of the tropopause folds extends down to 5 km, increasing the ozone content in the troposphere. No significant signature of interannual variability could be observed on the 2000–2015 de-seasonalized lidar time series, with only a statistically non-significant positive anomaly during the years 2003–2007. Our trend analysis

  7. Ozone-vegetation interaction in the Earth system: implications for air quality, ecosystems and agriculture

    Science.gov (United States)

    Tai, A. P. K.; Lombardozzi, D.; Val Martin, M.; Heald, C. L.

    2015-12-01

    Surface ozone is one of the most significant air pollutants due to its damaging effects not only on human health, but also on vegetation and crop productivity. Chronic ozone exposure has been shown to reduce photosynthesis and interfere with gas exchange in plants, which in turn affect the surface energy balance, carbon sink and other biogeochemical fluxes. Ozone damage on vegetation can thus have major ramifications on climate and atmospheric composition, including possible feedbacks onto ozone itself (see figure) that are not well understood. The damage of ozone on crops has been well documented, but a mechanistic understanding is not well established. Here we present several results pertaining to ozone-vegetation interaction. Using the Community Earth System Model, we find that inclusion of ozone damage on plants reduces the global land carbon sink by up to 5%, while simulated ozone is modified by -20 to +4 ppbv depending on the relative importance of competing mechanisms in different regions. We also perform a statistical analysis of multidecadal global datasets of crop yields, agroclimatic variables and ozone exposures to characterize the spatial variability of crop sensitivity to ozone and temperature extremes, specifically accounting for the confounding effect of ozone-temperature covariation. We find that several crops exhibit stronger sensitivity to ozone than found by previous field studies, with a strong anticorrelation between the sensitivity and average ozone levels that reflects biological adaptive ozone resistance. Our results show that a more complete understanding of ozone-vegetation interaction is necessary to derive more realistic future projections of climate, air quality and agricultural production, and thereby to formulate optimal strategies to safeguard public health and food security.

  8. Ozone Levels in the North and South of Jordan: Effects of Transboundary Air Pollution

    Science.gov (United States)

    Alsawair, Jihad Khalaf

    The first phase of this work sought to assess the causes of air quality deterioration in the south of the region over the Red Sea near the resort areas of Eilat and Aqaba. Accordingly, a coordinated Jordanian-Israeli study was performed during the month of November 2007 along the boarder of the two countries. The Jordanian measurements were made at a fixed monitoring location in the city of Aqaba, while the Israeli measurements were made using a mobile laboratory at kibbutz Eilot some 3 km north of the coastal city of Eilat. The results indicated that pollution episodes are highly dependent on wind direction, where southerly winds carry local transportation (i.e., ship, trucks) and possibly some industrial emissions towards the north end of the Red Sea, while northerly winds are associated with the transport of regional O 3. The results revealed that under the prevailing (˜90% of the time) northerly wind flows, the quality of the air is relatively good for all primary pollutants but O3 was elevated, indicative of the downwind regional transport of this secondary species from the Mediterranean coast. However, during days with southerly air flow the air quality was significantly deteriorated with elevated levels of sulfur dioxide (SO2) and nitrogen oxides (NOx). The second phase of this work, which also involved Jordanian and Israeli scientists, was undertaken in the northern part of the region for a two-week period in May/June 2009. This part of the research was aimed at examining previous modeling results that indicated that elevated O3 levels should occur in Northern Jordan from emissions in Northern Israel that are transported a distance of more than 100 km. Ozone and other pollutants were monitored at five sites in Israel (Haifa, Neve Shanan, Kiryat Tivon, Afula, and Maoz Haim) and two in Jordan (Taiba and Irbid). The sites were located along the prevailing wind direction that presumably moves air-masses eastward from the Mediterranean coast, over the Israel

  9. Quantifying ozone uptake at the canopy level of spruce, pine and larch trees at the alpine timberline: an approach based on sap flow measurement.

    Science.gov (United States)

    Wieser, G; Matyssek, R; Köstner, B; Oberhuber, W

    2003-01-01

    Micro-climatic and ambient ozone data were combined with measurements of sap flow through tree trunks in order to estimate whole-tree ozone uptake of adult Norway spruce (Picea abies), cembran pine (Pinus cembra), and European larch (Larix decidua) trees. Sap flow was monitored by means of the heat balance approach in two trees of each species during the growing season of 1998. In trees making up the stand canopy, the ozone uptake by evergreen foliages was significantly higher than by deciduous ones, when scaled to the ground area. However, if expressed per unit of whole-tree foliage area, ozone flux through the stomata into the needle mesophyll was 1.09, 1.18 and 1.40 nmol m(-2) s(-1) in Picea abies, Pinus cembra and Larix decidua, respectively. These fluxes are consistent with findings from measurements of needle gas exchange, published from the same species at the study site. It is concluded that the sap flow-based approach offers an inexpensive, spatially and temporally integrating way for estimating ozone uptake at the whole-tree and stand level, intrinsicly covering the effect of boundary layers on ozone flux.

  10. Exposure-Relevant Ozone Chemistry in Occupied Spaces

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Beverly Kaye [Univ. of California, Berkeley, CA (United States)

    2009-04-01

    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

  11. Observed and predicted sensitivities of extreme surface ozone to meteorological drivers in three US cities

    Science.gov (United States)

    Fix, Miranda J.; Cooley, Daniel; Hodzic, Alma; Gilleland, Eric; Russell, Brook T.; Porter, William C.; Pfister, Gabriele G.

    2018-03-01

    We conduct a case study of observed and simulated maximum daily 8-h average (MDA8) ozone (O3) in three US cities for summers during 1996-2005. The purpose of this study is to evaluate the ability of a high resolution atmospheric chemistry model to reproduce observed relationships between meteorology and high or extreme O3. We employ regional coupled chemistry-transport model simulations to make three types of comparisons between simulated and observational data, comparing (1) tails of the O3 response variable, (2) distributions of meteorological predictor variables, and (3) sensitivities of high and extreme O3 to meteorological predictors. This last comparison is made using two methods: quantile regression, for the 0.95 quantile of O3, and tail dependence optimization, which is used to investigate even higher O3 extremes. Across all three locations, we find substantial differences between simulations and observational data in both meteorology and meteorological sensitivities of high and extreme O3.

  12. Ozone risk for crops and pastures in present and future climates.

    Science.gov (United States)

    Fuhrer, Jürg

    2009-02-01

    Ozone is the most important regional-scale air pollutant causing risks for vegetation and human health in many parts of the world. Ozone impacts on yield and quality of crops and pastures depend on precursor emissions, atmospheric transport and leaf uptake and on the plant's biochemical defence capacity, all of which are influenced by changing climatic conditions, increasing atmospheric CO(2) and altered emission patterns. In this article, recent findings about ozone effects under current conditions and trends in regional ozone levels and in climatic factors affecting the plant's sensitivity to ozone are reviewed in order to assess implications of these developments for future regional ozone risks. Based on pessimistic IPCC emission scenarios for many cropland regions elevated mean ozone levels in surface air are projected for 2050 and beyond as a result of both increasing emissions and positive effects of climate change on ozone formation and higher cumulative ozone exposure during an extended growing season resulting from increasing length and frequency of ozone episodes. At the same time, crop sensitivity may decline in areas where warming is accompanied by drying, such as southern and central Europe, in contrast to areas at higher latitudes where rapid warming is projected to occur in the absence of declining air and soil moisture. In regions with rapid industrialisation and population growth and with little regulatory action, ozone risks are projected to increase most dramatically, thus causing negative impacts major staple crops such as rice and wheat and, consequently, on food security. Crop improvement may be a way to increase crop cross-tolerance to co-occurring stresses from heat, drought and ozone. However, the review reveals that besides uncertainties in climate projections, parameters in models for ozone risk assessment are also uncertain and model improvements are necessary to better define specific targets for crop improvements, to identify regions

  13. Ozone levels in the Empty Quarter of Saudi Arabia--application of adaptive neuro-fuzzy model.

    Science.gov (United States)

    Rahman, Syed Masiur; Khondaker, A N; Khan, Rouf Ahmad

    2013-05-01

    In arid regions, primary pollutants may contribute to the increase of ozone levels and cause negative effects on biotic health. This study investigates the use of adaptive neuro-fuzzy inference system (ANFIS) for ozone prediction. The initial fuzzy inference system is developed by using fuzzy C-means (FCM) and subtractive clustering (SC) algorithms, which determines the important rules, increases generalization capability of the fuzzy inference system, reduces computational needs, and ensures speedy model development. The study area is located in the Empty Quarter of Saudi Arabia, which is considered as a source of huge potential for oil and gas field development. The developed clustering algorithm-based ANFIS model used meteorological data and derived meteorological data, along with NO and NO₂ concentrations and their transformations, as inputs. The root mean square error and Willmott's index of agreement of the FCM- and SC-based ANFIS models are 3.5 ppbv and 0.99, and 8.9 ppbv and 0.95, respectively. Based on the analysis of the performance measures and regression error characteristic curves, it is concluded that the FCM-based ANFIS model outperforms the SC-based ANFIS model.

  14. Ozone modeling within plasmas for ozone sensor applications

    OpenAIRE

    Arshak, Khalil; Forde, Edward; Guiney, Ivor

    2007-01-01

    peer-reviewed Ozone (03) is potentially hazardous to human health and accurate prediction and measurement of this gas is essential in addressing its associated health risks. This paper presents theory to predict the levels of ozone concentration emittedfrom a dielectric barrier discharge (DBD) plasma for ozone sensing applications. This is done by postulating the kinetic model for ozone generation, with a DBD plasma at atmospheric pressure in air, in the form of a set of rate equations....

  15. Modifiers of short-term effects of ozone on mortality in eastern Massachusetts - A case-crossover analysis at individual level

    Directory of Open Access Journals (Sweden)

    Schwartz Joel

    2010-01-01

    Full Text Available Abstract Background Substantial epidemiological studies demonstrate associations between exposure to ambient ozone and mortality. A few studies simply examine the modification of this ozone effect by individual characteristics and socioeconomic status, but socioeconomic status was usually coded at the city level. Methods This study used a case-crossover design to examine whether impacts of ozone on mortality were modified by socioeconomic status coded at the tract or characteristics at an individual level in eastern Massachusetts, US for a period May-September, 1995-2002, with a total of 157,197 non-accident deaths aging 35 years or older. We used moving averages of maximal 8-hour concentrations of ozone monitored at 8 stationary stations as personal exposure. Results A 10 ppb increase in the four-day moving average of maximal 8-hour ozone was associated with 1.68% (95% confidence interval (CI: 0.51%, 2.87%, 1.96% (95% CI: -1.83%, 5.90%, 8.28% (95% CI: 0.66%, 16.48%, 0.44% (95% CI: -1.45%, 2.37%, -0.83% (95% CI: -2.94%, 1.32%, -1.09% (95% CI: -4.27%, 2.19% and 6.5% (95% CI: 1.74%, 11.49% changes in all natural deaths, respiratory disorders, diabetes, cardiovascular diseases, heart diseases, acute myocardial infarction and stroke, respectively. We did not find any evidence that the associations were significantly modified by socioeconomic status or individual characteristics although small differences of estimates across subpopulations were demonstrated. Conclusions Exposure to ozone was associated with specific cause mortality in Eastern Massachusetts during May-September, 1995-2002. There was no evidence that effects of ozone on mortality were significantly modified by socioeconomic status and individual characteristics.

  16. Ozone bioindicator sampling and estimation

    Science.gov (United States)

    Gretchen C, Smith; William D. Smith; John W. Coulston

    2007-01-01

    Ozone is an important forest stressor that has been measured at known phytotoxic levels at forest locations across the United States. The percent forest exhibiting negative impacts from ozone air pollution is one of the Montreal Process indicators of forest health and vitality. The ozone bioindicator data of the U.S. Forest Service Forest Inventory and Analysis Program...

  17. Surface chemistry of a pine-oil cleaner and other terpene mixtures with ozone on vinyl flooring tiles.

    Science.gov (United States)

    Ham, Jason E; Wells, J Raymond

    2011-04-01

    Indoor environments are dynamic reactors where consumer products (such as cleaning agents, deodorants, and air fresheners) emit volatile organic compounds (VOCs) that can subsequently interact with indoor oxidants such as ozone (O(3)), hydroxyl radicals, and nitrate radicals. Typically, consumer products consist of mixtures of VOCs and semi-VOCs which can react in the gas-phase or on surfaces with these oxidants to generate a variety of oxygenated products. In this study, the reaction of a pine-oil cleaner (POC) with O(3) (100ppb) on a urethane-coated vinyl flooring tile was investigated at 5% and 50% relative humidity. These results were compared to previous α-terpineol+O(3) reactions on glass and vinyl surfaces. Additionally, other terpene and terpene alcohol mixtures were formulated to understand the emission profiles as seen in the POC data. Results showed that the α-terpineol+O(3) reaction products were the prominent species that were also observed in the POC/O(3) surface experiments. Furthermore, α-terpineol+O(3) reactions generate the largest fraction of oxygenated products even in equal mixtures of other terpene alcohols. This finding suggests that the judicial choice of terpene alcohols for inclusion in product formulations may be useful in reducing oxidation product emissions. Published by Elsevier Ltd.

  18. Improved meteorology and ozone air quality simulations using MODIS land surface parameters in the Yangtze River Delta urban cluster, China

    Science.gov (United States)

    Li, Mengmeng; Wang, Tijian; Xie, Min; Zhuang, Bingliang; Li, Shu; Han, Yong; Song, Yu; Cheng, Nianliang

    2017-03-01

    Land surface parameters play an important role in the land-atmosphere coupling and thus are critical to the weather and dispersion of pollutants in the atmosphere. This work aims at improving the meteorology and air quality simulations for a high-ozone (O3) event in the Yangtze River Delta urban cluster of China, through incorporation of satellite-derived land surface parameters. Using Moderate Resolution Imaging Spectroradiometer (MODIS) input to specify the land cover type, green vegetation fraction, leaf area index, albedo, emissivity, and deep soil temperature provides a more realistic representation of surface characteristics. Preliminary evaluations reveal clearly improved meteorological simulation with MODIS input compared with that using default parameters, particularly for temperature (from -2.5 to -1.7°C for mean bias) and humidity (from 9.7% to 4.3% for mean bias). The improved meteorology propagates through the air quality system, which results in better estimates for surface NO2 (from 11.5 to 8.0 ppb for mean bias) and nocturnal O3 low-end concentration values (from -18.8 to -13.6 ppb for mean bias). Modifications of the urban land surface parameters are the main reason for model improvement. The deeper urban boundary layer and intense updraft induced by the urban heat island are favorable for pollutant dilution, thus contributing to lower NO2 and elevated nocturnal O3. Furthermore, the intensified sea-land breeze circulation may exacerbate O3 pollution at coastal cities through pollutant recirculation. Improvement of mesoscale meteorology and air quality simulations with satellite-derived land surface parameters will be useful for air pollution monitoring and forecasting in urban areas.

  19. Threat to food security under current levels of ground level ozone: A case study for Indian cultivars of rice

    Science.gov (United States)

    Rai, Richa; Agrawal, Madhoolika; Agrawal, S. B.

    2010-11-01

    A higher ozone concentration in rural agricultural region poses threat to food production in developing countries. The present study was conducted to evaluate the growth, biomass accumulation and allocation pattern, quantitative and qualitative characteristics of grains for two tropical rice cultivars ( Oryza sativa L. cv NDR 97 and Saurabh 950) at ambient O 3 concentrations at a rural site in the Indo Gangetic plains of India. Percent inhibition in number of leaves was higher for NDR 97, but in leaf area for Saurabh 950 grown in non filtered chambers (NFCs) compared to filtered chambers (FCs). Higher inhibition in root biomass was recorded in Saurabh 950 and in leaf and standing dead biomass for NDR 97. During vegetative phase, relative growth rate showed more percent inhibition in Saurabh 950, but at reproductive phase in NDR 97. Net assimilation rate showed higher values for Saurabh 950 than NDR 97 in NFCs but percent inhibition in leaf area ratio was higher for former than latter cultivar in NFCs. The ozone resistance was higher in NDR 97 during vegetative phase, but in Saurabh 950 at reproductive phase. Number of grains was higher in NDR 97 than Saurabh 950, but test weight and weight of grains m -2 showed reverse trends. Concentrations of starch, protein, P, N, Ca, Mg and K decreased, while reducing and total soluble sugar increased in grains of both the cultivars in NFCs compared to FCs. The study concluded that under ambient condition of O 3 exposure, the two cultivars responded differently. Saurabh 950 favoured biomass translocation priority towards ear in reproductive phase and hence showed higher resistivity due to maintenance of higher test weight. NDR 97, however, showed better growth during vegetative period, but could not allocate efficiently to developing ears, hence higher number of unfilled grains in NFCs led lower test weight.

  20. Improvement of the prediction of surface ozone concentration over conterminous U.S. by a computationally efficient second-order Rosenbrock solver in CAM4-Chem

    Science.gov (United States)

    Sun, Jian; Fu, Joshua S.; Drake, John; Lamarque, Jean-Francois; Tilmes, Simone; Vitt, Francis

    2017-03-01

    The global chemistry-climate model (CAM4-Chem) overestimates the surface ozone concentration over the conterminous U.S. (CONUS). Reasons for this positive bias include emission, meteorology, chemical mechanism, and solver. In this study, we explore the last possibility by examining the sensitivity to the numerical methods for solving the chemistry equations. A second-order Rosenbrock (ROS-2) solver is implemented in CAM4-Chem to examine its influence on the surface ozone concentration and the computational performance of the chemistry program. Results show that under the same time step size (1800 s), statistically significant reduction of positive bias is achieved by the ROS-2 solver. The improvement is as large as 5.2 ppb in Eastern U.S. during summer season. The ROS-2 solver is shown to reduce the positive bias in Europe and Asia as well, indicating the lower surface ozone concentration over the CONUS predicted by the ROS-2 solver is not a trade-off consequence with increasing the ozone concentration at other global regions. In addition, by refining the time step size to 180 s, the first-order implicit solver does not provide statistically significant improvement of surface ozone concentration. It reveals that the better prediction from the ROS-2 solver is not only due to its accuracy but also due to its suitability for stiff chemistry equations. As an added benefit, the computation cost of the ROS-2 solver is almost half of first-order implicit solver. The improved computational efficiency of the ROS-2 solver is due to the reuse of the Jacobian matrix and lower upper (LU) factorization during its multistage calculation.

  1. Evaluation of broadband surface solar irradiance derived from the Ozone Monitoring Instrument

    NARCIS (Netherlands)

    Wang, P.; Sneep, M.; Veefkind, J.P.; Stammes, P.; Levelt, P.F.

    2014-01-01

    Surface solar irradiance (SSI) data are important for planning and estimating the production of solar power plants. Long-term high quality surface solar radiation data are needed for monitoring climate change. This paper presents a new surface solar irradiance dataset, the broadband (0.2–4 ?m)

  2. A cloud-ozone data product from Aura OMI and MLS satellite measurements

    Directory of Open Access Journals (Sweden)

    J. R. Ziemke

    2017-11-01

    Full Text Available Ozone within deep convective clouds is controlled by several factors involving photochemical reactions and transport. Gas-phase photochemical reactions and heterogeneous surface chemical reactions involving ice, water particles, and aerosols inside the clouds all contribute to the distribution and net production and loss of ozone. Ozone in clouds is also dependent on convective transport that carries low-troposphere/boundary-layer ozone and ozone precursors upward into the clouds. Characterizing ozone in thick clouds is an important step for quantifying relationships of ozone with tropospheric H2O, OH production, and cloud microphysics/transport properties. Although measuring ozone in deep convective clouds from either aircraft or balloon ozonesondes is largely impossible due to extreme meteorological conditions associated with these clouds, it is possible to estimate ozone in thick clouds using backscattered solar UV radiation measured by satellite instruments. Our study combines Aura Ozone Monitoring Instrument (OMI and Microwave Limb Sounder (MLS satellite measurements to generate a new research product of monthly-mean ozone concentrations in deep convective clouds between 30° S and 30° N for October 2004–April 2016. These measurements represent mean ozone concentration primarily in the upper levels of thick clouds and reveal key features of cloud ozone including: persistent low ozone concentrations in the tropical Pacific of  ∼ 10 ppbv or less; concentrations of up to 60 pphv or greater over landmass regions of South America, southern Africa, Australia, and India/east Asia; connections with tropical ENSO events; and intraseasonal/Madden–Julian oscillation variability. Analysis of OMI aerosol measurements suggests a cause and effect relation between boundary-layer pollution and elevated ozone inside thick clouds over landmass regions including southern Africa and India/east Asia.

  3. A cloud-ozone data product from Aura OMI and MLS satellite measurements

    Science.gov (United States)

    Ziemke, Jerald R.; Strode, Sarah A.; Douglass, Anne R.; Joiner, Joanna; Vasilkov, Alexander; Oman, Luke D.; Liu, Junhua; Strahan, Susan E.; Bhartia, Pawan K.; Haffner, David P.

    2017-11-01

    Ozone within deep convective clouds is controlled by several factors involving photochemical reactions and transport. Gas-phase photochemical reactions and heterogeneous surface chemical reactions involving ice, water particles, and aerosols inside the clouds all contribute to the distribution and net production and loss of ozone. Ozone in clouds is also dependent on convective transport that carries low-troposphere/boundary-layer ozone and ozone precursors upward into the clouds. Characterizing ozone in thick clouds is an important step for quantifying relationships of ozone with tropospheric H2O, OH production, and cloud microphysics/transport properties. Although measuring ozone in deep convective clouds from either aircraft or balloon ozonesondes is largely impossible due to extreme meteorological conditions associated with these clouds, it is possible to estimate ozone in thick clouds using backscattered solar UV radiation measured by satellite instruments. Our study combines Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) satellite measurements to generate a new research product of monthly-mean ozone concentrations in deep convective clouds between 30° S and 30° N for October 2004-April 2016. These measurements represent mean ozone concentration primarily in the upper levels of thick clouds and reveal key features of cloud ozone including: persistent low ozone concentrations in the tropical Pacific of ˜ 10 ppbv or less; concentrations of up to 60 pphv or greater over landmass regions of South America, southern Africa, Australia, and India/east Asia; connections with tropical ENSO events; and intraseasonal/Madden-Julian oscillation variability. Analysis of OMI aerosol measurements suggests a cause and effect relation between boundary-layer pollution and elevated ozone inside thick clouds over landmass regions including southern Africa and India/east Asia.

  4. Impact of interactive chemistry of stratospheric ozone on Southern Hemisphere paleoclimate simulation

    Science.gov (United States)

    Noda, Satoshi; Kodera, Kunihiko; Adachi, Yukimasa; Deushi, Makoto; Kitoh, Akio; Mizuta, Ryo; Murakami, Shigenori; Yoshida, Kohei; Yoden, Shigeo

    2017-01-01

    A series of numerical simulations of the mid-Holocene (6 kyr B.P.) climate are performed by using an Earth System Model of the Meteorological Research Institute of the Japan Meteorological Agency to investigate the impact of stratospheric ozone distribution, which is modulated by the change in orbital elements of the Earth, on the surface climate. The results of interactive ozone chemistry calculations for the mid-Holocene and preindustrial periods are compared with those of the corresponding experiments in the fifth Coupled Model Intercomparison Project (CMIP5), in which the ozone distribution was prescribed to the 1850 Common Era level. The contribution of the interactive ozone chemistry in a quasi-equilibrium state reveals a significant anomaly of up to +1.7 K in the Antarctic region for the annual mean zonal mean surface air temperature. This impact on the surface climate is explained by a similar mechanism to the cooling influence of the Antarctic ozone hole but opposite in sign: Weakening of the westerly jet associated with the Southern Annular Mode provides weakening of equatorward ocean surface current, sea ice retreat, and then warm sea surface temperature and surface air temperature. All the mid-Holocene runs by CMIP5 models with the prescribed ozone had cold bias in sea surface temperature when compared with geological proxy data, whereas the bias is reduced in our simulations by using interactive ozone chemistry. We recommend that climate models include interactive sea ice and ozone distribution that are consistent with paleosolar insolation.

  5. Adaptive-network-based fuzzy inference system (ANFIS modelbased prediction of the surface ozone concentration

    Directory of Open Access Journals (Sweden)

    Savić Marija

    2014-01-01

    Full Text Available This paper presents the results of the tropospheric ozone concentration modeling as the dependence on volatile organic compounds - VOCs (Benzene, Toluene, m,p-Xylene, o-Xylene, Ethylbenzene; nonorganic compounds - NOx (NO, NO2, NOx, CO, H2S, SO2 and PM10 in the ambient air in parallel with the meteorological parameters: temperature, solar radiation, relative humidity, wind speed and direction. Modeling is based on measured results obtained during the year 2009. The measurements were performed at the measuring station located within an agricultural area, in vicinity of city of Zrenjanin (Serbian Banat, Serbia. Statistical analysis of obtained data, based on bivariate correlation analysis indicated that accurate modeling cannot be performed using linear statistics approach. Also, considering that almost all input variables have wide range of relative change (ratio of variance compared to range, nonlinear statistic analysis method based on only one rule describing the behavior of input variable, most certainly wouldn’t present accurate enough results. From that reason, modeling approach was based on Adaptive-Network-Based Fuzzy Inference System (ANFIS. Model obtained using ANFIS methodology resulted with high accuracy, with prediction potential of above 80%, considering that obtained determination coefficient for the final model was R2=0.802.

  6. Bay breeze climatology at two sites along the Chesapeake bay from 1986-2010: Implications for surface ozone.

    Science.gov (United States)

    Stauffer, Ryan M; Thompson, Anne M

    Hourly surface meteorological measurements were coupled with surface ozone (O 3 ) mixing ratio measurements at Hampton, Virginia and Baltimore, Maryland, two sites along the Chesapeake Bay in the Mid-Atlantic United States, to examine the behavior of surface O 3 during bay breeze events and quantify the impact of the bay breeze on local O 3 pollution. Analyses were performed for the months of May through September for the years 1986 to 2010. The years were split into three groups to account for increasingly stringent environmental regulations that reduced regional emissions of nitrogen oxides (NO x ): 1986-1994, 1995-2002, and 2003-2010. Each day in the 25-year record was marked either as a bay breeze day, a non-bay breeze day, or a rainy/cloudy day based on the meteorological data. Mean eight hour (8-h) averaged surface O 3 values during bay breeze events were 3 to 5 parts per billion by volume (ppbv) higher at Hampton and Baltimore than on non-bay breeze days in all year periods. Anomalies from mean surface O 3 were highest in the afternoon at both sites during bay breeze days in the 2003-2010 study period. In conjunction with an overall lowering of baseline O 3 after the 1995-2002 period, the percentage of total exceedances of the Environmental Protection Agency (EPA) 75 ppbv 8-h O 3 standard that occurred on bay breeze days increased at Hampton for 2003-2010, while remaining steady at Baltimore. These results suggest that bay breeze circulations are becoming more important to causing exceedance events at particular sites in the region, and support the hypothesis of Martins et al. (2012) that highly localized meteorology increasingly drives air quality events at Hampton.

  7. Variations of Ground-level Ozone Concentration in Malaysia: A Case Study in West Coast of Peninsular Malaysia

    Directory of Open Access Journals (Sweden)

    Hashim Nur Izzah Mohamad

    2017-01-01

    Full Text Available Hourly ground ozone concentration, measured from the monitoring stations in the West Coast of Peninsular Malaysia for the period of 10 years (2003-2012 were used to analyse the ozone characteristic in Nilai, Melaka and Petaling Jaya. The prediction of tropospheric ozone concentrations is very important due to the negative impacts of ozone on human health, climate and vegetation. The mean concentration of ozone at the studied areas had not exceeded the recommended value of Malaysia Ambient Air Quality Guideline (MAAQG for 8-hour average (0.06 ppm, however some of the measurements exceeded the hourly permitted concentration by MAAQG that is 0.1 ppm. Higher concentration of ozone can be observed during the daytime since ozone needs sunlight for the photochemical reactions. The diurnal cycle of ozone concentration has a mid-day peak (14:00-15:00 and lower night-time concentrations. The ozone concentration slowly rises after the sun rises (08:00, reaching a maximum during daytime and then decreases until the next morning.

  8. Impacts of brown carbon from biomass burning on surface UV and ozone photochemistry in the Amazon Basin

    KAUST Repository

    Mok, Jungbin

    2016-11-11

    The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or “brown” carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305–368 nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18% and lead to reduced concentrations of radicals OH, HO2, and RO2 by up to 17%, 15%, and 14%, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

  9. Impacts of Brown Carbon from Biomass Burning on Surface UV and Ozone Photochemistry in the Amazon Basin

    Science.gov (United States)

    Mok, Jungbin; Krotkov, Nickolay A.; Arola, Antti; Torres, Omar; Jethva, Hiren; Andrade, Marcos; Labow, Gordon; Eck, Thomas F.; Li, Zhangqing; Dickerson, Russell R.; hide

    2016-01-01

    The spectral dependence of light absorption by atmospheric particulate matter has major implications for air quality and climate forcing, but remains uncertain especially in tropical areas with extensive biomass burning. In the September-October 2007 biomass-burning season in Santa Cruz, Bolivia, we studied light absorbing (chromophoric) organic or brown carbon (BrC) with surface and space-based remote sensing. We found that BrC has negligible absorption at visible wavelengths, but significant absorption and strong spectral dependence at UV wavelengths. Using the ground-based inversion of column effective imaginary refractive index in the range 305368nm, we quantified a strong spectral dependence of absorption by BrC in the UV and diminished ultraviolet B (UV-B) radiation reaching the surface. Reduced UV-B means less erythema, plant damage, and slower photolysis rates. We use a photochemical box model to show that relative to black carbon (BC) alone, the combined optical properties of BrC and BC slow the net rate of production of ozone by up to 18 and lead to reduced concentrations of radicals OH, HO2, and RO2 by up to 17, 15, and 14, respectively. The optical properties of BrC aerosol change in subtle ways the generally adverse effects of smoke from biomass burning.

  10. Mass tracking for chemical analysis: the causes of ozone formation in southern Ontario during BAQS-Met 2007

    Directory of Open Access Journals (Sweden)

    P. A. Makar

    2010-11-01

    Full Text Available A three-level nested regional air pollution model has been used to study the processes leading to high ozone concentrations in the southern Great Lakes region of North America. The highest resolution simulations show that complex interactions between the lake-breeze circulation and the synoptic flow lead to significant enhancements in the photochemical production and transport of ozone at the local scale. Mass tracking of individual model processes show that Lakes Erie and St. Clair frequently act as photochemical ozone production regions, with average mid-day production rates of up to 3 ppbv per hour. Enhanced ozone levels are evident over these two lakes in 23-day-average surface ozone fields. Analysis of other model fields and aircraft measurements suggests that vertical circulation enhances ozone levels at altitudes up to 1500 m over Lake St. Clair, whereas subsidence enhances ozone over Lake Erie in a shallow layer only 250 m deep. Mass tracking of model transport shows that lake-breeze surface convergence zones combined with the synoptic flow can then carry ozone and its precursors hundreds of kilometers from these source areas, in narrow, elongated features. Comparison with surface mesonet ozone observations confirm the presence, magnitude, and timing of these features, which can create local ozone enhancements on the order of 30 ppbv above the regional ozone levels. Sensitivity analyses of model-predicted ozone and HOx concentrations show that most of the region is VOC-limited, and that the secondary oxidation pathways of aromatic hydrocarbons have a key role in setting the region's ozone and HOx levels.

  11. The relationship between typhoons' peripheral circulation and ground-level ozone concentrations in central Taiwan.

    Science.gov (United States)

    Cheng, Wan-Li; Lai, Li-Wei; Den, Walter; Wu, Meng-Ting; Hsueh, Chao-An; Lin, Pay-Liam; Pai, Chueh-Ling; Yan, Yeou-Lih

    2014-02-01

    Surface data of meteorological parameters (wind speed, wind direction, and mixing height) and air pollutant concentrations (O3, NO, and NO2) were collected for a 92-day period associated with typhoon formation in 2005. The influence of typhoons on O3 concentration were defined by azimuth and distance from Taiwan, and Types A, B, and C correspond to typhoons less than 1,500 km from Taiwan and located between azimuths 45° and 135°, 135° and 225°, and 225° and 45°, respectively. Type D corresponds to typhoons more than 1,500 km from Taiwan. Titration reactions were conducted at three temporal phases: 2000-0700, 0800-1100, and 1200-1400 LST (Local Standard Time). The air pollution model (TAPM) was used to simulate wind fields and trajectories of air masses. It was determined that typhoon position affected O3 concentration, temporal and spatial patterns of O3 titration and vertical meteorological characteristics, which were not all at the statistically significant level.

  12. Multi-year objective analyses of warm season ground-level ozone and PM2.5 over North America using real-time observations and Canadian operational air quality models

    Science.gov (United States)

    Robichaud, A.; Ménard, R.

    2014-02-01

    Multi-year objective analyses (OA) on a high spatiotemporal resolution for the warm season period (1 May to 31 October) for ground-level ozone and for fine particulate matter (diameter less than 2.5 microns (PM2.5)) are presented. The OA used in this study combines model outputs from the Canadian air quality forecast suite with US and Canadian observations from various air quality surface monitoring networks. The analyses are based on an optimal interpolation (OI) with capabilities for adaptive error statistics for ozone and PM2.5 and an explicit bias correction scheme for the PM2.5 analyses. The estimation of error statistics has been computed using a modified version of the Hollingsworth-Lönnberg (H-L) method. The error statistics are "tuned" using a χ2 (chi-square) diagnostic, a semi-empirical procedure that provides significantly better verification than without tuning. Successful cross-validation experiments were performed with an OA setup using 90% of data observations to build the objective analyses and with the remainder left out as an independent set of data for verification purposes. Furthermore, comparisons with other external sources of information (global models and PM2.5 satellite surface-derived or ground-based measurements) show reasonable agreement. The multi-year analyses obtained provide relatively high precision with an absolute yearly averaged systematic error of less than 0.6 ppbv (parts per billion by volume) and 0.7 μg m-3 (micrograms per cubic meter) for ozone and PM2.5, respectively, and a random error generally less than 9 ppbv for ozone and under 12 μg m-3 for PM2.5. This paper focuses on two applications: (1) presenting long-term averages of OA and analysis increments as a form of summer climatology; and (2) analyzing long-term (decadal) trends and inter-annual fluctuations using OA outputs. The results show that high percentiles of ozone and PM2.5 were both following a general decreasing trend in North America, with the eastern

  13. Multi-year objective analyses of warm season ground-level ozone and PM2.5 over North America using real-time observations and Canadian operational air quality models

    Science.gov (United States)

    Robichaud, A.; Ménard, R.

    2013-05-01

    We present multi-year objective analyses (OA) on a high spatio-temporal resolution (15 or 21 km, every hour) for the warm season period (1 May-31 October) for ground-level ozone (2002-2012) and for fine particulate matter (diameter less than 2.5 microns (PM2.5)) (2004-2012). The OA used here combines the Canadian Air Quality forecast suite with US and Canadian surface air quality monitoring sites. The analysis is based on an optimal interpolation with capabilities for adaptive error statistics for ozone and PM2.5 and an explicit bias correction scheme for the PM2.5 analyses. The estimation of error statistics has been computed using a modified version of the Hollingsworth-Lönnberg's (H-L) method. Various quality controls (gross error check, sudden jump test and background check) have been applied to the observations to remove outliers. An additional quality control is applied to check the consistency of the error statistics estimation model at each observing station and for each hour. The error statistics are further tuned "on the fly" using a χ2 (chi-square) diagnostic, a procedure which verifies significantly better than without tuning. Successful cross-validation experiments were performed with an OA set-up using 90% of observations to build the objective analysis and with the remainder left out as an independent set of data for verification purposes. Furthermore, comparisons with other external sources of information (global models and PM2.5 satellite surface derived measurements) show reasonable agreement. The multi-year analyses obtained provide relatively high precision with an absolute yearly averaged systematic error of less than 0.6 ppbv (parts per billion by volume) and 0.7 μg m-3 (micrograms per cubic meter) for ozone and PM2.5 respectively and a random error generally less than 9 ppbv for ozone and under 12 μg m-3 for PM2.5. In this paper, we focus on two applications: (1) presenting long term averages of objective analysis and analysis increments

  14. Spectral analysis of atmospheric composition: application to surface ozone model–measurement comparisons

    Directory of Open Access Journals (Sweden)

    D. R. Bowdalo

    2016-07-01

    Full Text Available Models of atmospheric composition play an essential role in our scientific understanding of atmospheric processes and in providing policy strategies to deal with societally relevant problems such as climate change, air quality, and ecosystem degradation. The fidelity of these models needs to be assessed against observations to ensure that errors in model formulations are found and that model limitations are understood. A range of approaches are necessary for these comparisons. Here, we apply a spectral analysis methodology for this comparison. We use the Lomb–Scargle periodogram, a method similar to a Fourier transform, but better suited to deal with the gapped data sets typical of observational data. We apply this methodology to long-term hourly ozone observations and the equivalent model (GEOS-Chem output. We show that the spectrally transformed observational data show a distinct power spectrum with regimes indicative of meteorological processes (weather, macroweather and specific peaks observed at the daily and annual timescales together with corresponding harmonic peaks at one-half, one-third, etc., of these frequencies. Model output shows corresponding features. A comparison between the amplitude and phase of these peaks introduces a new comparison methodology between model and measurements. We focus on the amplitude and phase of diurnal and seasonal cycles and present observational/model comparisons and discuss model performance. We find large biases notably for the seasonal cycle in the mid-latitude Northern Hemisphere where the amplitudes are generally overestimated by up to 16 ppbv, and phases are too late on the order of 1–5 months. This spectral methodology can be applied to a range of model–measurement applications and is highly suitable for Multimodel Intercomparison Projects (MIPs.

  15. Impact of forest fires, biogenic emissions and high temperatures on the elevated Eastern Mediterranean ozone levels during the hot summer of 2007

    NARCIS (Netherlands)

    Hodnebrog, Ø.; Solberg, S.; Stordal, F.; Svendby, T.M.; Simpson, D.; Gauss, M.; Hilboll, A.; Pfister, G.G.; Turquety, S.; Richter, A.; Burrows, J.P.; Denier Van Der Gon, H.A.C.

    2012-01-01

    The hot summer of 2007 in southeast Europe has been studied using two regional atmospheric chemistry models; WRF-Chem and EMEP MSC-W. The region was struck by three heat waves and a number of forest fire episodes, greatly affecting air pollution levels. We have focused on ozone and its precursors

  16. An estimation of COPD cases and respiratory mortality related to Ground-Level Ozone in the metropolitan Ahvaz during 2011

    Directory of Open Access Journals (Sweden)

    Sahar Geravandi

    2016-02-01

    Full Text Available Background & Aims of the Study :  Ground-Level Ozone (GLO is the component of one of greatest concern that threatened human health in both developing as well as developed countries. The GLO mainly enters the body through the respiration and can cause decrements in pulmonary complications, eye burning, shortness of breath, coughing, failure of immune defense, decreases forced vital capacity, reduce lung function of the lungs and increase rate of mortality. Ahwaz with high emission air pollutants because of numerous industries is one of the metropolitan Iranian polluted. The aim of this study is evaluate to Chronic Obstructive Pulmonary Disease (COPD and respiratory mortality related to GLO in the air of metropolitan Ahvaz during 2011. Materials & Methods: We used the generalized additive Air Q model for estimation of COPD and respiratory mortality attributed to GLO pollutant. Data of GLO were collected in four monitoring stations Ahvaz Department of Environment. Raw data processing by Excel software and at final step they were converted as input file to the Air Q model for estimate number of COPD Cases and respiratory mortality. Results: According to result this study, The Naderi and Havashenasi had the highest and the lowest GLO concentrations. The results of this study showed that cumulative cases of COPD and respiratory mortality which related to GLO were 34 and 30 persons, respectively. Also, Findings showed that approximately 11 % COPD and respiratory mortality happened when the GLO concentrations was more than 20 μg/m 3 . Conclusions: exposure to GLO pollution has stronger effects on human health in Ahvaz. Findings showed that there were a significant relationship between concentration of GLO and COPD and respiratory mortality. Therefore; the higher ozone pollutant value can depict mismanagement in urban air quality.  

  17. Reforestation as a novel abatement and compliance measure for ground-level ozone.

    Science.gov (United States)

    Kroeger, Timm; Escobedo, Francisco J; Hernandez, José L; Varela, Sebastián; Delphin, Sonia; Fisher, Jonathan R B; Waldron, Janice

    2014-10-07

    High ambient ozone (O3) concentrations are a widespread and persistent problem globally. Although studies have documented the role of forests in removing O3 and one of its precursors, nitrogen dioxide (NO2), the cost effectiveness of using peri-urban reforestation for O3 abatement purposes has not been examined. We develop a methodology that uses available air quality and meteorological data and simplified forest structure growth-mortality and dry deposition models to assess the performance of reforestation for O3 precursor abatement. We apply this methodology to identify the cost-effective design for a hypothetical 405-ha, peri-urban reforestation project in the Houston-Galveston-Brazoria O3 nonattainment area in Texas. The project would remove an estimated 310 tons of (t) O3 and 58 t NO2 total over 30 y. Given its location in a nitrogen oxide (NOx)-limited area, and using the range of Houston area O3 production efficiencies to convert forest O3 removal to its NOx equivalent, this is equivalent to 127-209 t of the regulated NOx. The cost of reforestation per ton of NOx abated compares favorably to that of additional conventional controls if no land costs are incurred, especially if carbon offsets are generated. Purchasing agricultural lands for reforestation removes this cost advantage, but this problem could be overcome through cost-share opportunities that exist due to the public and conservation benefits of reforestation. Our findings suggest that peri-urban reforestation should be considered in O3 control efforts in Houston, other US nonattainment areas, and areas with O3 pollution problems in other countries, wherever O3 formation is predominantly NOx limited.

  18. Reforestation as a novel abatement and compliance measure for ground-level ozone

    Science.gov (United States)

    Kroeger, Timm; Escobedo, Francisco J.; Hernandez, José L.; Varela, Sebastián; Delphin, Sonia; Fisher, Jonathan R. B.; Waldron, Janice

    2014-01-01

    High ambient ozone (O3) concentrations are a widespread and persistent problem globally. Although studies have documented the role of forests in removing O3 and one of its precursors, nitrogen dioxide (NO2), the cost effectiveness of using peri-urban reforestation for O3 abatement purposes has not been examined. We develop a methodology that uses available air quality and meteorological data and simplified forest structure growth-mortality and dry deposition models to assess the performance of reforestation for O3 precursor abatement. We apply this methodology to identify the cost-effective design for a hypothetical 405-ha, peri-urban reforestation project in the Houston–Galveston–Brazoria O3 nonattainment area in Texas. The project would remove an estimated 310 tons of (t) O3 and 58 t NO2 total over 30 y. Given its location in a nitrogen oxide (NOx)-limited area, and using the range of Houston area O3 production efficiencies to convert forest O3 removal to its NOx equivalent, this is equivalent to 127–209 t of the regulated NOx. The cost of reforestation per ton of NOx abated compares favorably to that of additional conventional controls if no land costs are incurred, especially if carbon offsets are generated. Purchasing agricultural lands for reforestation removes this cost advantage, but this problem could be overcome through cost-share opportunities that exist due to the public and conservation benefits of reforestation. Our findings suggest that peri-urban reforestation should be considered in O3 control efforts in Houston, other US nonattainment areas, and areas with O3 pollution problems in other countries, wherever O3 formation is predominantly NOx limited. PMID:25201970

  19. Impacts of ozone-vegetation coupling and feedbacks on global air quality, ecosystems and food security

    Science.gov (United States)

    Tai, A. P. K.

    2016-12-01

    Surface ozone is an air pollutant of significant concerns due to its harmful effects on human health, vegetation and crop productivity. Chronic ozone exposure is shown to reduce photosynthesis and interfere with gas exchange in plants, thereby influencing surface energy balance and biogeochemical fluxes with important ramifications for climate and atmospheric composition, including possible feedbacks onto ozone itself that are not well understood. Ozone damage on crops has been well documented, but a mechanistic understanding is not well established. Here we present several results pertaining to the effects of ozone-vegetation coupling on air quality, ecosystems and agriculture. Using the Community Earth System Model (CESM), we find that inclusion of ozone damage on plants reduces the global land carbon sink by up to 5%, while simulated ozone is enhanced by up to 6 ppbv North America, Europe and East Asia. This strong positive feedback on ozone air quality via ozone-vegetation coupling arises mainly from reduced stomatal conductance, which induces two feedback pathways: 1) reduced dry deposition and ozone uptake; and 2) reduced evapotranspiration that enhances vegetation temperature and thus isoprene emission. Using the same ozone-vegetation scheme in a crop model within CESM, we further examine the impacts of historical ozone exposure on global crop production. We contrast our model results with a separate statistical analysis designed to characterize the spatial variability of crop-ozone-temperature relationships and account for the confounding effect of ozone-temperature covariation, using multidecadal global datasets of crop yields, agroclimatic variables and ozone exposures. We find that several crops (especially C4 crops such as maize) exhibit stronger sensitivities to ozone than found by field studies or in CESM simulations. We also find a strong anticorrelation between crop sensitivities and average ozone levels, reflecting biological adaptive ozone

  20. Factors dominating 3-dimensional ozone distribution during high tropospheric ozone period.

    Science.gov (United States)

    Chen, Xiaoyang; Liu, Yiming; Lai, Anqi; Han, Shuangshuang; Fan, Qi; Wang, Xuemei; Ling, Zhenhao; Huang, Fuxiang; Fan, Shaojia

    2018-01-01

    Data from an in situ monitoring network and five ozone sondes are analysed during August of 2012, and a high tropospheric ozone episode is observed around the 8th of AUG. The Community Multi-scale Air Quality (CMAQ) model and its process analysis tool were used to study factors and mechanisms for high ozone mixing ratio at different levels of ozone vertical profiles. A sensitive scenario without chemical initial and boundary conditions (ICBCs) from MOZART4-GEOS5 was applied to study the impact of stratosphere-troposphere exchange (STE) on vertical ozone. The simulation results indicated that the first high ozone peak near the tropopause was dominated by STE. Results from process analysis showed that: in the urban area, the second peak at approximately 2 km above ground height was mainly caused by local photochemical production. The third peak (near surface) was mainly caused by the upwind transportation from the suburban/rural areas; in the suburban/rural areas, local photochemical production of ozone dominated the high ozone mixing ratio from the surface to approximately 3 km height. Furthermore, the capability of indicators to distinguish O 3 -precursor sensitivity along the vertical O 3 profiles was investigated. Two sensitive scenarios, which had cut 30% anthropogenic NO X or VOC emissions, showed that O 3 -precursor indicators, specifically the ratios of O 3 /NOy, H 2 O 2 /HNO 3 or H 2 O 2 /NO Z , could partly distinguish the O 3 -precursor sensitivity between VOCs-sensitive and NOx-sensitive along the vertical profiles. In urban area, the O 3 -precursor relationship transferred from VOCs-sensitive within the boundary layer to NOx-sensitive at approximately 1-3 km above ground height, further confirming the dominant roles of transportation and photochemical production in high O 3 peaks at the near-ground layer and 2 km above ground height, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The Use of Critical Levels for Determining Plant Response to Ozone in Europe and in North America

    Directory of Open Access Journals (Sweden)

    Robert C. Musselman

    2007-01-01

    Full Text Available Critical levels to determine plant response to ozone (O3 have been used in Europe since the 1980s, utilizing the concentration-based AOT40 to relate plant response to ambient O3 exposure. More recently, there has been progress in Europe toward utilizing flux-based critical levels, because plant response is more closely related to O3 uptake than to the amount of O3 in ambient air. Flux-based critical levels are plant species specific; data for parameterization of flux-based critical levels models are lacking for most plant species. Although flux-based critical levels are now being used for a limited number of agricultural crops and tree species where data are available, the use of flux-based critical levels is limited by the lack of adequate consideration and incorporation of plant internal detoxification mechanisms in flux modeling. Critical levels have not been used in North America; however, recent interest in the U.S. and Canada for using critical loads for nitrogen and sulfur has generated interest in using critical levels for O3. A major obstacle for utilization of critical levels in North America is that ambient air quality standards for O3 in the U.S. and Canada are concentration based. It appears that cumulative exposure-based metrics, particularly when implemented with a quantification of peak concentrations and environmental variables, such as a drought index, are currently the most useful to relate O3 to vegetation response. Because data are unavailable to quantify detoxification potential of vegetation, effective flux models are not available to determine plant response to O3.

  2. Fermi level on hydrogen terminated diamond surfaces

    Czech Academy of Sciences Publication Activity Database

    Rezek, Bohuslav; Saurer, C.; Nebel, C. E.; Stutzmann, M.; Ristein, J.; Ley, L.; Snidero, E.; Bergonzo, P.

    2003-01-01

    Roč. 82, č. 14 (2003), s. 2266-2268 ISSN 0003-6951 EU Projects: European Commission(XE) HPRN-CT-1999-00139 Grant - others:DFC(DE) NE524-2 Institutional research plan: CEZ:AV0Z1010914 Keywords : atomic force microscope(AFM) * Kelvin probe experiments * diamond surface Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.049, year: 2003

  3. Coupling aerosol surface and bulk chemistry with a kinetic double layer model (K2-SUB: oxidation of oleic acid by ozone

    Directory of Open Access Journals (Sweden)

    C. Pfrang

    2010-05-01

    Full Text Available We present a kinetic double layer model coupling aerosol surface and bulk chemistry (K2-SUB based on the PRA framework of gas-particle interactions (Pöschl-Rudich-Ammann, 2007. K2-SUB is applied to a popular model system of atmospheric heterogeneous chemistry: the interaction of ozone with oleic acid. We show that our modelling approach allows de-convoluting surface and bulk processes, which has been a controversial topic and remains an important challenge for the understanding and description of atmospheric aerosol transformation. In particular, we demonstrate how a detailed treatment of adsorption and reaction at the surface can be coupled to a description of bulk reaction and transport that is consistent with traditional resistor model formulations.

    From literature data we have derived a consistent set of kinetic parameters that characterise mass transport and chemical reaction of ozone at the surface and in the bulk of oleic acid droplets. Due to the wide range of rate coefficients reported from different experimental studies, the exact proportions between surface and bulk reaction rates remain uncertain. Nevertheless, the model results suggest an important role of chemical reaction in the bulk and an approximate upper limit of ~10−11 cm2 s−1 for the surface reaction rate coefficient. Sensitivity studies show that the surface accommodation coefficient of the gas-phase reactant has a strong non-linear influence on both surface and bulk chemical reactions. We suggest that K2-SUB may be used to design, interpret and analyse future experiments for better discrimination between surface and bulk processes in the oleic acid-ozone system as well as in other heterogeneous reaction systems of atmospheric relevance.

  4. Impact of Biofuel Poplar Cultivation on Ground-Level Ozone and Premature Human Mortality Depends on Cultivar Selection and Planting Location.

    Science.gov (United States)

    Ashworth, Kirsti; Wild, Oliver; Eller, Allyson S D; Hewitt, C Nick

    2015-07-21

    Isoprene and other volatile organic compounds emitted from vegetation play a key role in governing the formation of ground-level ozone. Emission rates of such compounds depend critically on the plant species. The cultivation of biofuel feedstocks will contribute to future land use change, altering the distribution of plant species and hence the magnitude and distribution of emissions. Here we use relationships between biomass yield and isoprene emissions derived from experimental data for 29 commercially available poplar hybrids to assess the impact that the large-scale cultivation of poplar for use as a biofuel feedstock will have on air quality, specifically ground-level ozone concentrations, in Europe. We show that the increases in ground-level ozone across Europe will increase the number of premature deaths attributable to ozone pollution each year by up to 6%. Substantial crop losses (up to ∼9 Mt y(-1) of wheat and maize) are also projected. We further demonstrate that these impacts are strongly dependent on the location of the poplar plantations, due to the prevailing meteorology, the population density, and the dominant crop type of the region. Our findings indicate the need for a concerted and centralized decision-making process that considers all aspects of future land use change in Europe, and not just the effect on greenhouse gas emissions.

  5. Comment on ``Theory of the photodissociation of ozone in the Hartley continuum: Potential energy surfaces, conical intersections, and photodissociation dynamics'' [J. Chem. Phys. 123, 014306 (2005)

    Science.gov (United States)

    Grebenshchikov, S. Yu.; Schinke, R.

    2007-06-01

    We demonstrate in this Comment that the quantum mechanical absorption spectrum of the Hartley band of ozone, calculated using the diabatic B state potential energy surface constructed from the ab initio data of the title paper, is strongly structured. This result, which is in agreement with previous theoretical studies of the Hartley band, contradicts the findings of Baloïtcha and Balint-Kurti and questions the accuracy of their calculations.

  6. Formaldehyde Column Density Measurements as a Suitable Pathway to Estimate Near-Surface Ozone Tendencies from Space

    Science.gov (United States)

    Schroeder, Jason R.; Crawford, James H.; Fried, Alan; Walega, James; Weinheimer, Andrew; Wisthaler, Armin; Mueller, Markus; Mikoviny, Tomas; Chen, Gao; Shook, Michael; hide

    2016-01-01

    In support of future satellite missions that aim to address the current shortcomings in measuring air quality from space, NASA's Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaign was designed to enable exploration of relationships between column measurements of trace species relevant to air quality at high spatial and temporal resolution. In the DISCOVER-AQ data set, a modest correlation (r2 = 0.45) between ozone (O3) and formaldehyde (CH2O) column densities was observed. Further analysis revealed regional variability in the O3-CH2O relationship, with Maryland having a strong relationship when data were viewed temporally and Houston having a strong relationship when data were viewed spatially. These differences in regional behavior are attributed to differences in volatile organic compound (VOC) emissions. In Maryland, biogenic VOCs were responsible for approx.28% of CH2O formation within the boundary layer column, causing CH2O to, in general, increase monotonically throughout the day. In Houston, persistent anthropogenic emissions dominated the local hydrocarbon environment, and no discernable diurnal trend in CH2O was observed. Box model simulations suggested that ambient CH2O mixing ratios have a weak diurnal trend (+/-20% throughout the day) due to photochemical effects, and that larger diurnal trends are associated with changes in hydrocarbon precursors. Finally, mathematical relationships were developed from first principles and were able to replicate the different behaviors seen in Maryland and Houston. While studies would be necessary to validate these results and determine the regional applicability of the O3-CH2O relationship, the results presented here provide compelling insight into the ability of future satellite missions to aid in monitoring near-surface air quality.

  7. Changes in PEP Carboxylase, Rubisco and Rubisco activase mRNA levels from maize (Zea mays exposed to a chronic ozone stress

    Directory of Open Access Journals (Sweden)

    LOUIS LEITAO

    2007-01-01

    Full Text Available We quantified the ozone impact on levels of Zea mays L. cv. Chambord mRNAs encoding C4-phosphoenolpyruvate carboxylase (C4-PEPc, ribulose-l,5-bisphosphate carboxylase/oxygenase small and large subunits (Rubisco-SSU and Rubisco-LSU, respectively and Rubisco activase (RCA using real-time RT-PCR. Foliar pigment content, PEPc and Rubisco protein amounts were simultaneously determined. Two experiments were performed to study the ozone response of the 5th and the 10th leaf. For each experiment, three ozone concentrations were tested in open-top chambers: non-filtered air (NF, control and non-filtered air containing 40 (+40 and 80 nL L-1 (+80 ozone. Regarding the 5th leaf, +40 atmosphere induced a loss in pigmentation, PEPc and Rubisco activase mRNAs. However, it was unable to notably depress carboxylase protein amounts and mRNAs encoding Rubisco. Except for Rubisco mRNAs, all other measured parameters from 5th leaf were depressed by +80 atmosphere. Regarding the 10th leaf, +40 atmosphere increased photosynthetic pigments and transcripts encoding Rubisco and Rubisco activase. Rubisco and PEPc protein amounts were not drastically changed, even if they tended to be increased. Level of C4-PEPc mRNA remained almost stable. In response to +80 atmosphere, pigments and transcripts encoding PEPc were notably decreased. Rubisco and PEPc protein amounts also declined to a lesser extent. Conversely, the level of transcripts encoding both Rubisco subunits and Rubisco activase that were not consistently disturbed tended to be slightly augmented. So, the present study suggests that maize leaves can respond differentially to a similar ozone stress

  8. Surface reaction mechanisms during ozone and oxygen plasma assisted atomic layer deposition of aluminum oxide.

    Science.gov (United States)

    Rai, Vikrant R; Vandalon, Vincent; Agarwal, Sumit

    2010-09-07

    We have elucidated the reaction mechanism and the role of the reactive intermediates in the atomic layer deposition (ALD) of aluminum oxide from trimethyl aluminum in conjunction with O(3) and an O(2) plasma. In situ attenuated total reflection Fourier transform infrared spectroscopy data show that both -OH groups and carbonates are formed on the surface during the oxidation cycle. These carbonates, once formed on the surface, are stable to prolonged O(3) exposure in the same cycle. However, in the case of plasma-assisted ALD, the carbonates decompose upon prolonged O(2) plasma exposure via a series reaction kinetics of the type, A (CH(3)) --> B (carbonates) --> C (Al(2)O(3)). The ratio of -OH groups to carbonates on the surface strongly depends on the oxidizing agent, and also the duration of the oxidation cycle in plasma-assisted ALD. However, in both O(3) and O(2) plasma cycles, carbonates are a small fraction of the total number of reactive sites compared to the hydroxyl groups.

  9. Plant phenology, growth and nutritive quality of Briza maxima: Responses induced by enhanced ozone atmospheric levels and nitrogen enrichment

    International Nuclear Information System (INIS)

    Sanz, J.; Bermejo, V.; Muntifering, R.; Gonzalez-Fernandez, I.; Gimeno, B.S.; Elvira, S.; Alonso, R.

    2011-01-01

    An assessment of the effects of tropospheric ozone (O 3 ) levels and substrate nitrogen (N) supplementation, singly and in combination, on phenology, growth and nutritive quality of Briza maxima was carried out. Two serial experiments were developed in Open-Top Chambers (OTC) using three O 3 and three N levels. Increased O 3 exposure did not affect the biomass-related parameters, but enhanced senescence, increased fiber foliar content (especially lignin concentration) and reduced plant life span; these effects were related to senescence acceleration induced by the pollutant. Added N increased plant biomass production and improved nutritive quality by decreasing foliar fiber concentration. Interestingly, the effects of N supplementation depended on meteorological conditions and plant physiological activity. N supplementation counteracted the O 3 -induced senescence but did not modifiy the effects on nutritive quality. Nutritive quality and phenology should be considered in new definitions of the O 3 limits for the protection of herbaceous vegetation. - Research highlights: → Forage quality (foliar protein and fiber content) and phenology are more O 3 -sensitive than growth parameters in the Mediterranean annual grass Briza maxima. → The effects of N supplementation depended on meteorological conditions and plant physiological activity. → Increase in nitrogen supplementation counterbalanced the O 3 -induced increase in senescence biomass. → Nutritive quality and phenology should be considered in new definitions of the O 3 limits for the protection of natural herbaceous vegetation. - Forage quality and phenology are more O 3 -sensitive than growth parameters in the Mediterranean annual grass Briza maxima.

  10. Bromide Sources and Loads in Swiss Surface Waters and Their Relevance for Bromate Formation during Wastewater Ozonation.

    Science.gov (United States)

    Soltermann, Fabian; Abegglen, Christian; Götz, Christian; von Gunten, Urs

    2016-09-20

    Bromide measurements and mass balances in the catchments of major Swiss rivers revealed that chemical industry and municipal waste incinerators are the most important bromide sources and account for ∼50% and ∼20%, respectively, of the ∼2000 tons of bromide discharged in the Rhine river in 2014 in Switzerland. About 100 wastewater treatment plants (WWTPs) will upgrade their treatment for micropollutant abatement in the future to comply with Swiss regulations. An upgrade with ozonation may lead to unintended bromate formation in bromide-containing wastewaters. Measured bromide concentrations were industry). Wastewater ozonation formed little bromate at specific ozone doses of ≤0.4 mg O3/mg DOC, while the bromate yields were almost linearly correlated to the specific ozone dose for higher ozone doses. Molar bromate yields for typical specific ozone doses in wastewater treatment (0.4-0.6 mg O3/mg DOC) are ≤3%. In a modeled extreme scenario (in which all upgraded WWTPs release 10 μg L(-1) of bromate), bromate concentrations increased by major Swiss rivers and by several micrograms per liter in receiving water bodies with a high fraction of municipal wastewater.

  11. Low level of stratospheric ozone near the Jharia coal field in India

    Indian Academy of Sciences (India)

    that serve as channels for oxygen to the burning coal. One may also get to see smoke emitting vents, burnt/baked rocks, residual sulphur encrustation, dry soil and a local rise in the surface tempera- ture. Smoke plumes from these fires contain poi- sonous gases such as oxides and dioxides of carbon, nitrogen and sulphur.

  12. Yield and nutritive quality of sericea lespedeza (Lespedeza cuneata) and little bluestem (Schizachyrium scoparium) exposed to ground-level ozone

    International Nuclear Information System (INIS)

    Powell, M.C.; Muntifering, R.B.; Lin, J.C.; Chappelka, A.H.

    2003-01-01

    Ground-level ozone decreased the nutritive quality of select warm-season forages for ruminant herbivores. - Sericea lespedeza (Lespedeza cuneata cv. Interstate 76) and little bluestem (Schizachyrium scoparium cv. Aldous) were raised from seed in a glasshouse, transplanted into 5.7-l pots and placed into open-top chambers (OTC) on 6 June 1999. Following a 7-day adjustment period, each of six OTCs (duplicate OTCs per treatment) was ventilated with either air that had been carbon-filtered (CF) to remove ambient ozone (O 3 ); non-filtered (NF), representative of ambient air; or enriched to twice-ambient O 3 concentration (2X). Primary-growth forage was harvested on days 7, 32, 46, 59 and 72 following the start of fumigation, and regrowth forage from the first primary-growth harvest was harvested on days 36, 54 and 72 following the start of fumigation. Dry matter (DM) yield of either forage species did not differ among treatments except in the final regrowth period when yield of sericea lespedeza was greater for the NF than 2X O 3 treatment. In vitro DM digestibility (IVDMD) and concentrations of crude protein (CP), soluble phenolics (SP) and condensed tannins (CT) in primary-growth sericea lespedeza did not differ between treatments, but NF primary-growth forage had higher concentration of protein-precipitating tannins (PPT) than did 2X primary-growth forage. Concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in NF and 2X than in CF primary-growth sericea lespedeza. Similarly, concentrations of NDF and ADL were higher, and IVDMD was lower for NF and 2X than for CF regrowth sericea lespedeza. Concentrations of ADF and ADL were lower, whereas IVDMD, in vitro NDF digestibility (IVNDFD) and concentrations of CP and SP were greater, in CF than in NF and 2X primary-growth little bluestem. Percentages IVDMD and IVNDFD and concentrations of CP and SP in NF primary-growth little bluestem were greater than

  13. Inflammatory Cytokines and White Blood Cell Counts Response to Environmental Levels of Diesel Exhaust and Ozone Inhalation Exposures

    Science.gov (United States)

    Epidemiological observations of urban inhalation exposures to diesel exhaust (DE) and ozone (O3) have shown pre-clinical cardiopulmonary responses in humans. Identifying the key biological mechanisms that initiate these health bioindicators is difficult due to variability in envi...

  14. Modeling the regional impact of ship emissions on NOx and ozone levels over the Eastern Atlantic and Western Europe using ship plume parameterization

    Directory of Open Access Journals (Sweden)

    P. Pisoft

    2010-07-01

    Full Text Available In general, regional and global chemistry transport models apply instantaneous mixing of emissions into the model's finest resolved scale. In case of a concentrated source, this could result in erroneous calculation of the evolution of both primary and secondary chemical species. Several studies discussed this issue in connection with emissions from ships and aircraft. In this study, we present an approach to deal with the non-linear effects during dispersion of NOx emissions from ships. It represents an adaptation of the original approach developed for aircraft NOx emissions, which uses an exhaust tracer to trace the amount of the emitted species in the plume and applies an effective reaction rate for the ozone production/destruction during the plume's dilution into the background air. In accordance with previous studies examining the impact of international shipping on the composition of the troposphere, we found that the contribution of ship induced surface NOx to the total reaches 90% over remote ocean and makes 10–30% near coastal regions. Due to ship emissions, surface ozone increases by up to 4–6 ppbv making 10% contribution to the surface ozone budget. When applying the ship plume parameterization, we show that the large scale NOx decreases and the ship NOx contribution is reduced by up to 20–25%. A similar decrease was found in the case of O3. The plume parameterization suppressed the ship induced ozone production by 15–30% over large areas of the studied region. To evaluate the presented parameterization, nitrogen monoxide measurements over the English Channel were compared with modeled values and it was found that after activating the parameterization the model accuracy increases.

  15. Surface Crystallization of Cloud Droplets: Implications for Climate Change and Ozone Depletion

    Science.gov (United States)

    Tabazadeh, A.; Djikaev, Y. S.; Reiss, H.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    The process of supercooled liquid water crystallization into ice is still not well understood. Current experimental data on homogeneous freezing rates of ice nucleation in supercooled water droplets show considerable scatter. For example, at -33 C, the reported freezing nucleation rates vary by as much as 5 orders of magnitude, which is well outside the range of measurement uncertainties. Until now, experimental data on the freezing of supercooled water has been analyzed under the assumption that nucleation of ice took place in the interior volume of a water droplet. Here, the same data is reanalyzed assuming that the nucleation occurred "pseudoheterogeneously" at the air (or oil)-liquid water interface of the droplet. Our analysis suggest that the scatter in the nucleation data can be explained by two main factors. First, the current assumption that nucleation occurs solely inside the volume of a water droplet is incorrect. Second, because the nucleation process most likely occurs on the surface, the rates of nuclei formation could differ vastly when oil or air interfaces are involved. Our results suggest that ice freezing in clouds may initiate on droplet surfaces and such a process can allow for low amounts of liquid water (approx. 0.002 g per cubic meters) to remain supercooled down to -40 C as observed in the atmosphere.

  16. Phase space barriers and dividing surfaces in the absence of critical points of the potential energy: Application to roaming in ozone

    Energy Technology Data Exchange (ETDEWEB)

    Mauguière, Frédéric A. L., E-mail: frederic.mauguiere@bristol.ac.uk; Collins, Peter, E-mail: peter.collins@bristol.ac.uk; Wiggins, Stephen, E-mail: stephen.wiggins@mac.com [School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Kramer, Zeb C., E-mail: zebcolterkramer@gmail.com; Ezra, Gregory S., E-mail: gse1@cornell.edu [Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States); Carpenter, Barry K., E-mail: carpenterb1@cardiff.ac.uk [School of Chemistry, Cardiff University, Cardiff CF10 3AT (United Kingdom); Farantos, Stavros C., E-mail: farantos@iesl.forth.gr [Institute of Electronic Structure and Laser, Foundation for Research and Technology - Hellas, and Department of Chemistry, University of Crete, Iraklion 711 10, Crete (Greece)

    2016-02-07

    We examine the phase space structures that govern reaction dynamics in the absence of critical points on the potential energy surface. We show that in the vicinity of hyperbolic invariant tori, it is possible to define phase space dividing surfaces that are analogous to the dividing surfaces governing transition from reactants to products near a critical point of the potential energy surface. We investigate the problem of capture of an atom by a diatomic molecule and show that a normally hyperbolic invariant manifold exists at large atom-diatom distances, away from any critical points on the potential. This normally hyperbolic invariant manifold is the anchor for the construction of a dividing surface in phase space, which defines the outer or loose transition state governing capture dynamics. We present an algorithm for sampling an approximate capture dividing surface, and apply our methods to the recombination of the ozone molecule. We treat both 2 and 3 degrees of freedom models with zero total angular momentum. We have located the normally hyperbolic invariant manifold from which the orbiting (outer) transition state is constructed. This forms the basis for our analysis of trajectories for ozone in general, but with particular emphasis on the roaming trajectories.

  17. Experimental and modelling study of the effect of airflow orientation with respect to strip electrode on ozone production of surface dielectric barrier discharge

    Science.gov (United States)

    Mikeš, J.; Pekárek, S.; Soukup, I.

    2016-11-01

    This study examines the effect of airflow orientation with respect to the strip active electrode on concentration of ozone and nitrogen dioxide produced in a planar generator based on the surface dielectric barrier discharge. The orientation of the airflow was tested in parallel and perpendicular with respect to the strips. It was found that in the investigated range of average discharge power, the ozone concentration increases approximately by 25% when airflow was oriented in parallel with respect to the strips in comparison with perpendicular orientation of the airflow. Similarly the increase of nitrogen dioxide concentration was observed for parallel orientation of the airflow with respect to the strips in comparison with the perpendicular orientation of the airflow. Within the range of wavelengths from 250 to 1100 nm, the changes of intensities of spectral lines associated with airflow orientation have been observed. A 3D numerical model describing ion trajectories and airflow patterns have also been developed.

  18. Mapping critical levels of ozone, sulfur dioxide and nitrogen oxide for crops, forests and natural vegetation in the United States

    International Nuclear Information System (INIS)

    Rosenbaum, B.J.; Strickland, T.C.; McDowell, M.K.

    1994-01-01

    Air pollution abatement strategies for controlling nitrogen dioxide, sulfur dioxide, and ozone emissions in the United States focus on a 'standards-based' approach. This approach places limits on air pollution by maintaining a baseline value for air quality, no matter what the ecosystem can or cannot withstand. This paper, presents example critical levels maps for the conterminous U.S. developed using the 'effects-based' mapping approach as defined by the United Nations Economic Commission for Europe's Convention on Long-Range Transboundary Air Pollution, Task Force on Mapping. This approach emphasizes the pollution level or load capacity an ecosystem can accommodate before degradation occurs, and allows for analysis of cumulative effects. Presents the first stage of an analysis that reports the distribution of exceedances of critical levels for NO 2 , SO 2 , and O 3 in sensitive forest, crop, and natural vegetation ecosystems in the contiguous United States. It is concluded that extrapolation to surrounding geographic areas requires the analysis of diverse and compounding factors that preclude simple extrapolation methods. Pollutant data depicted in this analysis are limited to locationally specific data, and would be enhanced by utilizing spatial statistics, along with converging associated anthropogenic and climatological factors. Values used for critical levels were derived from current scientific knowledge. While not intended to be a definitive value, adjustments will occur as the scientific community gains new insight to pollutant/receptor relationships. We recommend future analysis to include a refinement of sensitive receptor data coverages and to report relative proportions of exceedances at varying grid scales. 27 refs., 4 figs., 1 tab

  19. UV radiation from the young sun and oxygen and ozone levels in the prebiological palaeoatmosphere

    Science.gov (United States)

    Canuto, V. M.; Levine, J. S.; Augustsson, T. R.; Imhoff, C. L.

    1982-01-01

    UV measurements of young T-Tauri stars, resembling the sun at an age of a few million years, have recently been made with the International Ultraviolet Explorer. They indicate that young stars emit up to 10,000 times more UV than the present sun. The implications for the origin and evolution of O2 and O3 in the prebiological palaeoatmosphere are presented here. The results of photochemical calculations indicate that the O2 surface mixing ratio was a factor 10,000-1,000,000 times greater than the standard value of 10 to the -15. This new value reconciles the simultaneous existence of oxidized iron and reduced uranium.

  20. Nitrogen management is essential to prevent tropical oil palm plantations from causing ground-level ozone pollution

    Science.gov (United States)

    Hewitt, Nick; Lee, James

    2010-05-01

    More than half the world's rainforest has been lost to agriculture since the Industrial Revolution. Among the most widespread tropical crops is oil palm (Elaeis guineensis): global production now exceeds 35 million tonnes per year. In Malaysia, for example, 13% of land area is now oil palm plantation, compared with 1% in 1974. There are enormous pressures to increase palm oil production for food, domestic products, and, especially, biofuels. Greater use of palm oil for biofuel production is predicated on the assumption that palm oil is an ‘‘environmentally friendly'' fuel feedstock. Here we show, using measurements and models, that oil palm plantations in Malaysia directly emit more oxides of nitrogen and volatile organic compounds than rainforest. These compounds lead to the production of ground-level ozone (O3), an air pollutant that damages human health, plants, and materials, reduces crop productivity, and has effects on the Earth's climate. Our measurements show that, at present, O3 concentrations do not differ significantly over rainforest and adjacent oil palm plantation landscapes. However, our model calculations predict that if concentrations of oxides of nitrogen in Borneo are allowed to reach those currently seen over rural North America and Europe, ground-level O3 concentrations will reach 100 parts per billion (109) volume (ppbv) and exceed levels known to be harmful to human health. Our study provides an early warning of the urgent need to develop policies that manage nitrogen emissions if the detrimental effects of palm oil production on air quality and climate are to be avoided.

  1. A diabatic circulation two-dimensional model with photochemistry - Simulations of ozone and long-lived tracers with surface sources

    Science.gov (United States)

    Stordal, F.; Isaksen, I. S. A.; Horntveth, K.

    1985-01-01

    Numerous studies have been concerned with the possibility of a reduction of the stratospheric ozone layer. Such a reduction could lead to an enhanced penetration of ultraviolet (UV) radiation to the ground, and, as a result, to damage in the case of several biological processes. It is pointed out that the distributions of many trace gases, such as ozone, are governed in part by transport processes. The present investigation presents a two-dimensional photochemistry-transport model using the residual circulation. The global distribution of both ozone and components with ground sources computed in this model is in good agreement with the observations even though slow diffusion is adopted. The agreement is particularly good in the Northern Hemisphere. The results provide additional support for the idea that tracer transport in the stratosphere is mainly of advective nature.

  2. The impact of biofuel poplar cultivation on ground-level ozone and premature human mortality depends on cultivar selection and planting location

    OpenAIRE

    Ashworth, Kirsti; Wild, Oliver; Eller, A.S.D.; Hewitt, C. N.

    2015-01-01

    Isoprene and other volatile organic compounds emitted from vegetation play a key role in governing the formation of ground-level ozone. Emission rates of such compounds depend critically on the plant species. Future land use change, driven by the cultivation of biofuel feedstocks, will change the distribution of plant species and hence the magnitude and distribution of emissions. Here we use relationships between biomass yield and isoprene emissions derived from experimental data for 29 comme...

  3. Empirical ozone isopleths as a tool to identify ozone production regimes

    Science.gov (United States)

    Thielmann, Axel; Prévôt, André S. H.; Grüebler, Franca C.; Staehelin, Johannes

    Ozone isopleths plotted with measured values of ozone, hydrocarbons and total reactive nitrogen (NOy) are proposed to visualize ozone production regimes at distinct locations. The applicability of the concept is confirmed with measurements at two distinct sites in the Italian Po Basin. Empirical ozone isopleths at the urban site clearly show ROG-sensitive ozone production, with ozone increasing with increasing ROG concentrations and decreasing with increasing ambient levels of NOx. At the rural site NOx-sensitive ozone production prevails, in accordance with previous results.

  4. Plant phenology, growth and nutritive quality of Briza maxima: Responses induced by enhanced ozone atmospheric levels and nitrogen enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Sanz, J., E-mail: j.sanz@ciemat.e [Ecotoxicity of Atmospheric Pollutants, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Bermejo, V., E-mail: victoria.bermejo@ciemat.e [Ecotoxicity of Atmospheric Pollutants, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Muntifering, R., E-mail: muntirb@auburn.ed [Department of Animal Sciences, Auburn University, Auburn, AL 36849 (United States); Gonzalez-Fernandez, I., E-mail: ignacio.gonzalez@ciemat.e [Ecotoxicity of Atmospheric Pollutants, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Gimeno, B.S., E-mail: benjamin.gimeno@ciemat.e [Ecotoxicity of Atmospheric Pollutants, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Elvira, S., E-mail: susana.elvira@ciemat.e [Ecotoxicity of Atmospheric Pollutants, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain); Alonso, R., E-mail: rocio.alonso@ciemat.e [Ecotoxicity of Atmospheric Pollutants, CIEMAT, Avda, Complutense 22, 28040 Madrid (Spain)

    2011-02-15

    An assessment of the effects of tropospheric ozone (O{sub 3}) levels and substrate nitrogen (N) supplementation, singly and in combination, on phenology, growth and nutritive quality of Briza maxima was carried out. Two serial experiments were developed in Open-Top Chambers (OTC) using three O{sub 3} and three N levels. Increased O{sub 3} exposure did not affect the biomass-related parameters, but enhanced senescence, increased fiber foliar content (especially lignin concentration) and reduced plant life span; these effects were related to senescence acceleration induced by the pollutant. Added N increased plant biomass production and improved nutritive quality by decreasing foliar fiber concentration. Interestingly, the effects of N supplementation depended on meteorological conditions and plant physiological activity. N supplementation counteracted the O{sub 3}-induced senescence but did not modifiy the effects on nutritive quality. Nutritive quality and phenology should be considered in new definitions of the O{sub 3} limits for the protection of herbaceous vegetation. - Research highlights: Forage quality (foliar protein and fiber content) and phenology are more O{sub 3}-sensitive than growth parameters in the Mediterranean annual grass Briza maxima. The effects of N supplementation depended on meteorological conditions and plant physiological activity. Increase in nitrogen supplementation counterbalanced the O{sub 3}-induced increase in senescence biomass. Nutritive quality and phenology should be considered in new definitions of the O{sub 3} limits for the protection of natural herbaceous vegetation. - Forage quality and phenology are more O{sub 3}-sensitive than growth parameters in the Mediterranean annual grass Briza maxima.

  5. Ozone depletion calculations

    International Nuclear Information System (INIS)

    Luther, F.M.; Chang, J.S.; Wuebbles, D.J.; Penner, J.E.

    1992-01-01

    Models of stratospheric chemistry have been primarily directed toward an understanding of the behavior of stratospheric ozone. Initially this interest reflected the diagnostic role of ozone in the understanding of atmospheric transport processes. More recently, interest in stratospheric ozone has arisen from concern that human activities might affect the amount of stratospheric ozone, thereby affecting the ultraviolet radiation reaching the earth's surface and perhaps also affecting the climate with various potentially severe consequences for human welfare. This concern has inspired a substantial effort to develop both diagnostic and prognostic models of stratospheric ozone. During the past decade, several chemical agents have been determined to have potentially significant impacts on stratospheric ozone if they are released to the atmosphere in large quantities. These include oxides of nitrogen, oxides of hydrogen, chlorofluorocarbons, bromine compounds, fluorine compounds and carbon dioxide. In order to assess the potential impact of the perturbations caused by these chemicals, mathematical models have been developed to handle the complex coupling between chemical, radiative, and dynamical processes. Basic concepts in stratospheric modeling are reviewed

  6. Surface ozone over southern Africa; synthesis of monitoring results during the cross border air pollution impact assessment project

    CSIR Research Space (South Africa)

    Zunckel, M

    2004-11-01

    Full Text Available - efstroom University for CHE. Diab, R.D., Thompson, A.M., Zunckel, M., Coetzee, G.J.R., Combrink, J., Bodeker, G.E., Fishman, J., Sokolic, F., McNamara, D.P., Archer, C.B., Nganga, D., 1996. Vertical ozone distribution over southern Africaand adjacent oceans....A., Johnson, B.J., Shadwick, D.S., Cuevas, E., Schmidlin, F.J., Tarasick, D.W., Claude, H., Kerr, J.B., Uchino, O., 1998. Trends of ozone in the troposphere. Geophysical Research Letters 25 (2), 139?142. Scheel, H.E., Sladkovic, R., Brunke, E-G., Seiler, W...

  7. The contrasting responses of soil microorganisms in two rice cultivars to elevated ground-level ozone

    International Nuclear Information System (INIS)

    Feng, Youzhi; Yu, Yongjie; Tang, Haoye; Zu, Qianhui; Zhu, Jianguo; Lin, Xiangui

    2015-01-01

    Although elevated ground-level O 3 has a species–specific impact on plant growth, the differences in soil biota responses to O 3 pollution among rice cultivars are rarely reported. Using O 3 Free-Air Concentration Enrichment, the responses of the rhizospheric bacterial communities in the O 3 -tolerant (YD6) and the O 3 -sensitive (IIY084) rice cultivars to O 3 pollution and their differences were assessed by pyrosequencing at rice tillering and anthesis stages. Elevated ground-level O 3 negatively influenced the bacterial community in cultivar YD6 at both rice growth stages by decreasing the bacterial phylogenetic diversities and response ratios. In contrast, in cultivar IIY084, the bacterial community responded positively at the rice tillering stage under O 3 pollution. However, several keystone bacterial guilds were consistently negatively affected by O 3 pollution in two rice cultivars. These findings indicate that continuously O 3 pollution would negatively influence rice agroecosystem and the crop cultivar is important in determining the soil biota responses to elevated O 3 . - Highlights: • We investigated the soil biota in two rice cultivars in presence of elevated O 3 . • The contrasting responses of soil biota were found between two rice cultivars. • Some keystone bacterial guilds were consistently negatively affected by O 3 pollution. • The crop cultivar is important in determining soil biota responses to elevated O 3 . - The crop cultivar is important in determining the soil biota responses to elevated O 3

  8. Transpacific transport of ozone pollution and the effect of recent Asian emission increases on air quality in North America: an integrated analysis using satellite, aircraft, ozonesonde, and surface observations

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2008-10-01

    Full Text Available We use an ensemble of aircraft, satellite, sonde, and surface observations for April–May 2006 (NASA/INTEX-B aircraft campaign to better understand the mechanisms for transpacific ozone pollution and its implications for North American air quality. The observations are interpreted with a global 3-D chemical transport model (GEOS-Chem. OMI NO2 satellite observations constrain Asian anthropogenic NOx emissions and indicate a factor of 2 increase from 2000 to 2006 in China. Satellite observations of CO from AIRS and TES indicate two major events of Asian transpacific pollution during INTEX-B. Correlation between TES CO and ozone observations shows evidence for transpacific ozone pollution. The semi-permanent Pacific High and Aleutian Low cause splitting of transpacific pollution plumes over the Northeast Pacific. The northern branch circulates around the Aleutian Low and has little impact on North America. The southern branch circulates around the Pacific High and some of that air impacts western North America. Both aircraft measurements and model results show sustained ozone production driven by peroxyacetylnitrate (PAN decomposition in the southern branch, roughly doubling the transpacific influence from ozone produced in the Asian boundary layer. Model simulation of ozone observations at Mt. Bachelor Observatory in Oregon (2.7 km altitude indicates a mean Asian ozone pollution contribution of 9±3 ppbv to the mean observed concentration of 54 ppbv, reflecting mostly an enhancement in background ozone rather than episodic Asian plumes. Asian pollution enhanced surface ozone concentrations by 5–7 ppbv over western North America in spring 2006. The 2000–2006 rise in Asian anthropogenic emissions increased this influence by 1–2 ppbv.

  9. Plant Species Sensitivity Distributions for ozone exposure

    International Nuclear Information System (INIS)

    Goethem, T.M.W.J. van; Azevedo, L.B.; Zelm, R. van; Hayes, F.; Ashmore, M.R.; Huijbregts, M.A.J.

    2013-01-01

    This study derived Species Sensitivity Distributions (SSD), representing a cumulative stressor-response distribution based on single-species sensitivity data, for ozone exposure on natural vegetation. SSDs were constructed for three species groups, i.e. trees, annual grassland and perennial grassland species, using species-specific exposure–response data. The SSDs were applied in two ways. First, critical levels were calculated for each species group and compared to current critical levels for ozone exposure. Second, spatially explicit estimates of the potentially affected fraction of plant species in Northwestern Europe were calculated, based on ambient ozone concentrations. We found that the SSD-based critical levels were lower than for the current critical levels for ozone exposure, with conventional critical levels for ozone relating to 8–20% affected plant species. Our study shows that the SSD concept can be successfully applied to both derive critical ozone levels and estimate the potentially affected species fraction of plant communities along specific ozone gradients. -- Highlights: ► Plant Species Sensitivity Distributions were derived for ozone exposure. ► Annual grassland species, as a species assemblage, tend to be most sensitive to ozone. ► Conventional critical levels for ozone relate to 8–20% affected plant species. ► The affected fraction of plant species for current ozone exposure in Northwestern Europe is estimated. -- Species Sensitivity Distributions offer opportunities in ozone risk assessment to both derive critical levels and estimate the affected fraction of a plant community

  10. Stomatal conductance of semi-natural Mediterranean grasslands: implications for the development of ozone critical levels.

    Science.gov (United States)

    Alonso, R; Bermejo, V; Sanz, J; Valls, B; Elvira, S; Gimeno, B S

    2007-04-01

    Intra-genus and intra-specific variation and the influence of nitrogen enrichment on net assimilation and stomatal conductance of some annual Trifolium species of Mediterranean dehesa grasslands were assessed under experimental conditions. Also gas exchange rates were compared between some Leguminosae and Poaceae species growing in the field in a dehesa ecosystem in central Spain. The results showed that the previously reported different O3 sensitivity of some Trifolium species growing in pots does not seem to be related to different maximum g(s) values. In addition, no clear differences on gas exchange rates could be attributed to Leguminosae and Poaceae families growing in the field, with intra-genus variation being more important than differences found between families. Further studies are needed to increase the database for developing a flux-based approach for setting O3 critical levels for semi-natural Mediterranean species.

  11. Ozone observations over the UAE and their analysis with GEM-AQ model

    Science.gov (United States)

    Majeed, Tariq; Kaminski, Jacek; Iqbal, Mazhar; Abbasi, Naveed; Lootah, Nadia; Struzewska, Joanna; Durka, Pawel

    A study of ozone climatology in the UAE began in 2006 with a couple of ozone sounding experiments to the measure the vertical profiles of ozone and their analysis by using the Global Environmental Multiscale - Air Quality (GEM-AQ) model. The purpose of this study was to gain insight into the chemical and dynamical structures in the atmosphere of this unique subtropical location (latitude 24.45N; longitude 54.22E). Ozone sounding with balloon-borne ECC ozonesonde has been continued since 2006. In this paper, we present ozone profiles throughout the troposphere and the stratosphere characterizing the wet (January - April) and dry (May - August) seasons of 2013 over the UAE. Preliminary results of wet season profiles indicate that the stratospheric ozone is quite stable while thick polluted layers confined to the lower tropospheric heights, showing enhancements in ozone contents. The amount of tropospheric ozone which is transported from the stratosphere by dynamical processes, although not well known, shows considerable variation both geographically and seasonally. Excessive values of ozone mixing ratios in the range 50 - 55 ppb near the ground are observed. These values are 20 to 30% larger than those observed at nearby sounding stations like New Delhi (India) and Esfahan (Iran) using the same technique. The surface ozone in the dry season is observed to be even larger compared to the wet season exceeding 100 ppb on occasions. The difference in these values probably reflects the elevated levels of air pollution due to petrochemicals and automobile emissions in the UAE. We will present ECC sounding data and GEM-AQ results including a discussion on the high levels of surface ozone responsible for contaminating the air quality in the UAE. This work is supported by National Research Foundation, UAE.

  12. Stomatal conductance of semi-natural Mediterranean grasslands: Implications for the development of ozone critical levels

    International Nuclear Information System (INIS)

    Alonso, R.; Bermejo, V.; Sanz, J.; Valls, B.; Elvira, S.; Gimeno, B.S.

    2007-01-01

    Intra-genus and intra-specific variation and the influence of nitrogen enrichment on net assimilation and stomatal conductance of some annual Trifolium species of Mediterranean dehesa grasslands were assessed under experimental conditions. Also gas exchange rates were compared between some Leguminosae and Poaceae species growing in the field in a dehesa ecosystem in central Spain. The results showed that the previously reported different O 3 sensitivity of some Trifolium species growing in pots does not seem to be related to different maximum g s values. In addition, no clear differences on gas exchange rates could be attributed to Leguminosae and Poaceae families growing in the field, with intra-genus variation being more important than differences found between families. Further studies are needed to increase the database for developing a flux-based approach for setting O 3 critical levels for semi-natural Mediterranean species. - The stomatal conductance model incorporated within the EMEP DO 3 SE deposition module needs to be re-parameterised for Mediterranean semi-natural vegetation

  13. Stomatal conductance of semi-natural Mediterranean grasslands: Implications for the development of ozone critical levels

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, R. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain)]. E-mail: rocio.alonso@ciemat.es; Bermejo, V. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Sanz, J. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Valls, B. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Elvira, S. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain); Gimeno, B.S. [Ecotoxicology of Air Pollution, CIEMAT (Ed. 70), Avda. Complutense 22, Madrid 28040 (Spain)

    2007-04-15

    Intra-genus and intra-specific variation and the influence of nitrogen enrichment on net assimilation and stomatal conductance of some annual Trifolium species of Mediterranean dehesa grasslands were assessed under experimental conditions. Also gas exchange rates were compared between some Leguminosae and Poaceae species growing in the field in a dehesa ecosystem in central Spain. The results showed that the previously reported different O{sub 3} sensitivity of some Trifolium species growing in pots does not seem to be related to different maximum g {sub s} values. In addition, no clear differences on gas exchange rates could be attributed to Leguminosae and Poaceae families growing in the field, with intra-genus variation being more important than differences found between families. Further studies are needed to increase the database for developing a flux-based approach for setting O{sub 3} critical levels for semi-natural Mediterranean species. - The stomatal conductance model incorporated within the EMEP DO{sub 3}SE deposition module needs to be re-parameterised for Mediterranean semi-natural vegetation.

  14. Chemical composition of pre-monsoon air in the Indo-Gangetic Plain measured using a new air quality facility and PTR-MS: high surface ozone and strong influence of biomass burning

    Science.gov (United States)

    Sinha, V.; Kumar, V.; Sarkar, C.

    2014-06-01

    One seventh of the world's population lives in the Indo-Gangetic Plain (IGP) and the fertile region sustains agricultural food crop production for much of South Asia, yet it remains one of the most under-studied regions of the world in terms of atmospheric composition and chemistry. In particular, the emissions and chemistry of volatile organic compounds (VOCs) that form surface ozone and secondary organic aerosol through photochemical reactions involving nitrogen oxides are not well understood. In this study, ambient levels of VOCs such as methanol, acetone, acetaldehyde, acetonitrile and isoprene were measured for the first time in the IGP. A new atmospheric chemistry facility that combines India's first high-sensitivity proton transfer reaction mass spectrometer, an ambient air quality station and a meteorological station, was used to quantify in situ levels of several VOCs and air pollutants in May 2012 at a suburban site in Mohali (northwest IGP). Westerly winds arriving at high wind speeds (5-20 m s-1) in the pre-monsoon season at the site were conducive for chemical characterization of regional emission signatures. Average levels of VOCs and air pollutants in May~2012 ranged from 1.2 to 2.7 nmol mol-1 for aromatic VOCs, 5.9 to 37.5 nmol mol-1 for the oxygenated VOCs, 1.4 nmol mol-1 for acetonitrile, 1.9 nmol mol-1 for isoprene, 567 nmol mol-1 for carbon monoxide, 57.8 nmol mol-1 for ozone, 11.5 nmol mol-1 for nitrogen oxides, 7.3 nmol mol-1 for sulfur dioxide, 104 μg m-3 for PM2.5 and 276 μg m-3 for PM10. By analyzing the one-minute in situ data with meteorological parameters and applying chemical tracers (e.g., acetonitrile for biomass burning) and inter-VOC correlations, we were able to constrain major emission source activities on both temporal and diel scales. Wheat residue burning caused massive increases (> 3 times the baseline values) for all the measured VOCs and primary pollutants. Other forms of biomass burning at night were also a significant

  15. Chemical composition of pre-monsoon air in the Indo-Gangetic Plain measured using a new PTR-MS and air quality facility: high surface ozone and strong influence of biomass burning

    Science.gov (United States)

    Sinha, V.; Kumar, V.; Sarkar, C.

    2013-12-01

    One seventh of the world population lives in the Indo-Gangetic Plain (IGP) and the fertile region sustains agricultural food crop production for much of South Asia. Yet it remains one of the most under-studied regions of the world in terms of atmospheric composition and chemistry. In particular, the emissions and chemistry of volatile organic compounds (VOCs) that form surface ozone and secondary organic aerosol through photochemical reactions involving nitrogen oxides is not well understood. In this study, ambient levels of VOCs such as methanol, acetone, acetaldehyde, acetonitrile and isoprene were measured for the first time in the IGP. A new atmospheric chemistry facility that combines India's first high sensitivity proton transfer reaction mass spectrometer, an ambient air quality station and meteorological station, was used to quantify in-situ levels of several VOCs and air pollutants in May 2012 at a suburban site in Mohali (N. W. IGP). Westerly winds arriving at high wind speeds (5-20 m s-1) in the pre-monsoon season at the site, were conducive for chemical characterization of regional emission signatures. Average levels of VOCs and air pollutants in May 2012 ranged from 1.2-1.7 nmol mol-1 for aromatic VOCs, 5.9-37.4 nmol mol-1 for the oxygenated VOCs, 1.4 nmol mol-1 for acetonitrile, 1.9 nmol mol-1 for isoprene, 567 nmol mol-1 for carbon monoxide, 57.8 nmol mol-1 for ozone, 11.5 nmol mol-1 for nitrogen oxides, 7.3 nmol mol-1 for sulphur dioxide, 104 μg m-3 for PM2.5 and 276 μg m-3 for PM10. By analyzing the one minute in-situ data with meteorological parameters and applying chemical tracers (e.g. acetonitrile for biomass burning) and inter-VOC correlations, we were able to constrain major emission source activities on both temporal and diel scales. Wheat residue burning activity caused massive increases (> 3 times of baseline values) for all the measured VOCs and primary pollutants. Other forms of biomass burning at night were also a significant source

  16. Temporal multiscaling characteristics of particulate matter PM 10 and ground-level ozone O3 concentrations in Caribbean region

    Science.gov (United States)

    Plocoste, Thomas; Calif, Rudy; Jacoby-Koaly, Sandra

    2017-11-01

    A good knowledge of the intermittency of atmospheric pollutants is crucial for air pollution management. We consider here particulate matter PM 10 and ground-level ozone O3 time series in Guadeloupe archipelago which experiments a tropical and humid climate in the Caribbean zone. The aim of this paper is to study their scaling statistics in the framework of fully developed turbulence and Kolmogorov's theory. Firstly, we estimate their Fourier power spectra and consider their scaling properties in the physical space. The power spectra computed follows a power law behavior for both considered pollutants. Thereafter we study the scaling behavior of PM 10 and O3 time series. Contrary to numerous studies where the multifractal detrended fluctuation analysis is frequently applied, here, the classical structure function analysis is used to extract the scaling exponent or multifractal spectrum ζ(q) ; this function provides a full characterization of a process at all intensities and all scales. The obtained results show that PM 10 and O3 possess intermittent and multifractal properties. The singularity spectrum MS(α) also confirms both pollutants multifractal features. The originality of this work comes from a statistical modeling performed on ζ(q) and MS(α) by a lognormal model to compute the intermittency parameter μ. By contrast with PM 10 which mainly depends on puffs of Saharan dust (synoptic-scale), O3 is more intermittent due to variability of its local precursors. The results presented in this paper can help to better understand the mechanisms governing the dynamics of PM 10 and O3 in Caribbean islands context.

  17. Setting ozone critical levels for annual Mediterranean pasture species: Combined analysis of open-top chamber experiments.

    Science.gov (United States)

    Sanz, J; González-Fernández, I; Elvira, S; Muntifering, R; Alonso, R; Bermejo-Bermejo, V

    2016-11-15

    Annual Dehesa-type pastures comprise semi-natural vegetation communities dominated by annual species characteristic of the Mediterranean basin areas of Southern Europe. This study analyses all the datasets available on the effects of ozone (O3) on annual pasture species in order to review and propose new exposure- and flux-based O3 critical levels (CLes) following the methodology of the Convention on Long-Range Transboundary Air Pollution (CLRTAP). Based on the potential effect on pastures main ecosystem services, the availability of data and the statistical significance of the regressions, three variables have been selected for establishing CLes: total above-ground biomass, consumable food value (CFV), as a nutritional quality index, and reproductive capacity based on flower and seed production. New CLes proposed for a 10% loss (with 95% confidence intervals between brackets) of above-ground biomass and reproductive capacity were, respectively, AOT40=3.1 (2.6, 3.8) and 2.0 (1.5, 2.8) ppmh and POD1=12.2 (8.9, 15.5) and 7.2 (1.1, 13.3) mmolm(-2). The provisional AOT40- and POD1-based CLes for CFV were 2.3 (1.6, 4.0) ppmh and 4.6 (2.7, 6.5) mmolm(-2) respectively. By using only O3-sensitive species for the exposure and dose-response functions, the proposed CLes should be used for risk assessments. Their use for quantifying O3 damage may lead to an overestimation of the effects. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Generation of ozone by pulsed corona discharge over water surface in hybrid gas-liquid electrical discharge reactor

    Czech Academy of Sciences Publication Activity Database

    Lukeš, Petr; Člupek, Martin; Babický, Václav; Šunka, Pavel; Janda, V.

    2005-01-01

    Roč. 38, č. 3 (2005), s. 409-416 ISSN 0022-3727 R&D Projects: GA ČR(CZ) GA202/02/1026 Institutional research plan: CEZ:AV0Z20430508 Keywords : Corona disc harge * hybrid reactor * ozone * water treatment Subject RIV: BL - Plasma and Gas Disc harge Physics Impact factor: 1.957, year: 2005

  19. Surface and boundary layer exchanges of volatile organic compounds, nitrogen oxides and ozone during the GABRIEL campaign

    NARCIS (Netherlands)

    Ganzeveld, L.; Eerdekens, G.; Feig, G.; Fischer, H.; Harder, H.; Konigstedt, R.; Kubistin, D.; Martinez, M.; Meixner, F. X.; Scheeren, H. A.; Sinha, V.; Taraborrelli, D.; Williams, J.; de Arellano, J. Vila-Guerau; Lelieveld, J.

    2008-01-01

    We present an evaluation of sources, sinks and turbulent transport of nitrogen oxides, ozone and volatile organic compounds (VOC) in the boundary layer over French Guyana and Suriname during the October 2005 GABRIEL campaign by simulating observations with a single-column chemistry and climate model

  20. Reductions in bacterial microorganisms by filtration and ozonation of the surface water supply at the USFWS Northeast Fishery Center

    Science.gov (United States)

    A water filtration and ozonation system was recently installed to treat creek water used to culture species of concern at the U.S. Fish and Wildlife Service's Northeast Fishery Center, Lamar National Fish Hatchery (NFH). Past experience with fish culture indicates that the following bacterial pathog...

  1. Intra-urban spatial variability of surface ozone in Riverside, CA: viability and validation of low-cost sensors

    Science.gov (United States)

    Sadighi, Kira; Coffey, Evan; Polidori, Andrea; Feenstra, Brandon; Lv, Qin; Henze, Daven K.; Hannigan, Michael

    2018-03-01

    Sensor networks are being more widely used to characterize and understand compounds in the atmosphere like ozone (O3). This study employs a measurement tool, called the U-Pod, constructed at the University of Colorado Boulder, to investigate spatial and temporal variability of O3 in a 200 km2 area of Riverside County near Los Angeles, California. This tool contains low-cost sensors to collect ambient data at non-permanent locations. The U-Pods were calibrated using a pre-deployment field calibration technique; all the U-Pods were collocated with regulatory monitors. After collocation, the U-Pods were deployed in the area mentioned. A subset of pods was deployed at two local regulatory air quality monitoring stations providing validation for the collocation calibration method. Field validation of sensor O3 measurements to minute-resolution reference observations resulted in R2 and root mean squared errors (RMSEs) of 0.95-0.97 and 4.4-5.9 ppbv, respectively. Using the deployment data, ozone concentrations were observed to vary on this small spatial scale. In the analysis based on hourly binned data, the median R2 values between all possible U-Pod pairs varied from 0.52 to 0.86 for ozone during the deployment. The medians of absolute differences were calculated between all possible pod pairs, 21 pairs total. The median values of those median absolute differences for each hour of the day varied between 2.2 and 9.3 ppbv for the ozone deployment. Since median differences between U-Pod concentrations during deployment are larger than the respective root mean square error values, we can conclude that there is spatial variability in this criteria pollutant across the study area. This is important because it means that citizens may be exposed to more, or less, ozone than they would assume based on current regulatory monitoring.

  2. Long-term trends of surface ozone and its influencing factors at the Mt Waliguan GAW station, China – Part 2: The roles of anthropogenic emissions and climate variability

    Directory of Open Access Journals (Sweden)

    W. Xu

    2018-01-01

    summertime ozone measured at WLG shows no significant trend despite ozone increases in eastern China. Analysis of the Trajectory-mapped Ozonesonde data set for the Stratosphere and Troposphere (TOST and trajectory residence time reveals increases in direct ozone transport from the eastern sector during autumn, which adds to the autumnal ozone increase. We further examine the links of ozone variability at WLG to the quasi-biennial oscillation (QBO, the East Asian summer monsoon (EASM, and the sunspot cycle. Our results suggest that the 2–3-, 3–7-, and 11-year periodicities are linked to the QBO, EASM index, and sunspot cycle, respectively. A multivariate regression analysis is performed to quantify the relative contributions of various factors to surface ozone concentrations at WLG. Through an observational and modelling analysis, this study demonstrates the complex relationships between surface ozone at remote locations and its dynamical and chemical influencing factors.

  3. Interaction between isoprene and ozone fluxes in a poplar plantation and its impact on air quality at the European level

    NARCIS (Netherlands)

    Zenone, T.; Hendriks, C.; Brilli, F.; Fransen, E.; Gioli, B.; Portillo-Estrada, M.; Schaap, M.; Ceulemans, R.

    2016-01-01

    The emission of isoprene and other biogenic volatile organic compounds from vegetation plays an important role in tropospheric ozone (O3) formation. The potentially large expansion of isoprene emitting species (e.g., poplars) for bioenergy production might, therefore, impact tropospheric O3

  4. Reduction in pesticide residue levels in olives by ozonated and tap water treatments and their transfer into olive oil.

    Science.gov (United States)

    Kırış, Sevilay; Velioglu, Yakup Sedat

    2016-01-01

    The effects of different wash times (2 and 5 min) with tap and ozonated water on the removal of nine pesticides from olives and the transfer ratios of these pesticides during olive oil production were determined. The reliability of the analytical methods was also tested. The applied methods of analysis were found to be suitable based on linearity, trueness, repeatability, selectivity and limit of quantification all the pesticides tested. All tap and ozonated water wash cycles removed a significant quantity of the pesticides from the olives, with a few exceptions. Generally, extending the wash time increased the pesticide reduction with ozonated water, but did not make significant differences with tap water. During olive oil processing, depending on the processing technique and physicochemical properties of the pesticides, eight of nine pesticides were concentrated into olive oil (processing factor > 1) with almost no significant difference between treatments. Imidacloprid did not pass into olive oil. Ozonated water wash for 5 min reduced chlorpyrifos, β-cyfluthrin, α-cypermethrin and imidacloprid contents by 38%, 50%, 55% and 61% respectively in olives.

  5. Stratospheric impact on tropospheric ozone variability and trends: 1990–2009

    Directory of Open Access Journals (Sweden)

    P. G. Hess

    2013-01-01

    Full Text Available The influence of stratospheric ozone on the interannual variability and trends in tropospheric ozone is evaluated between 30 and 90° N from 1990–2009 using ozone measurements and a global chemical transport model, the Community Atmospheric Model with chemistry (CAM-chem. Long-term measurements from ozonesondes, at 150 and 500 hPa, and the Measurements of OZone and water vapour by in-service Airbus aircraft programme (MOZAIC, at 500 hPa, are analyzed over Japan, Canada, the Eastern US and Northern and Central Europe. The measurements generally emphasize northern latitudes, although the simulation suggests that measurements over the Canadian, Northern and Central European regions are representative of the large-scale interannual ozone variability from 30 to 90° N at 500 hPa. CAM-chem is run with input meteorology from the National Center for Environmental Prediction; a tagging methodology is used to identify the stratospheric contribution to tropospheric ozone concentrations. A variant of the synthetic ozone tracer (synoz is used to represent stratospheric ozone. Both the model and measurements indicate that on large spatial scales stratospheric interannual ozone variability drives significant tropospheric variability at 500 hPa and the surface. In particular, the simulation and the measurements suggest large stratospheric influence at the surface sites of Mace Head (Ireland and Jungfraujoch (Switzerland as well as many 500 hPa measurement locations. Both the measurements and simulation suggest the stratosphere has contributed to tropospheric ozone trends. In many locations between 30–90° N 500 hPa ozone significantly increased from 1990–2000, but has leveled off since (from 2000–2009. The simulated global ozone budget suggests global stratosphere-troposphere exchange increased in 1998–1999 in association with a global ozone anomaly. Discrepancies between the simulated and measured ozone budget include a large underestimation of

  6. Photochemical model evaluation of the ground-level ozone impacts on ambient air quality and vegetation health in the Alberta oil sands region: Using present and future emission scenarios

    Science.gov (United States)

    Vijayaraghavan, Krish; Cho, Sunny; Morris, Ralph; Spink, David; Jung, Jaegun; Pauls, Ron; Duffett, Katherine

    2016-09-01

    One of the potential environmental issues associated with oil sands development is increased ozone formation resulting from NOX and volatile organic compound emissions from bitumen extraction, processing and upgrading. To manage this issue in the Athabasca Oil Sands Region (AOSR) in northeast Alberta, a regional multi-stakeholder group, the Cumulative Environmental Management Association (CEMA), developed an Ozone Management Framework that includes a modelling based assessment component. In this paper, we describe how the Community Multi-scale Air Quality (CMAQ) model was applied to assess potential ground-level ozone formation and impacts on ambient air quality and vegetation health for three different ozone precursor cases in the AOSR. Statistical analysis methods were applied, and the CMAQ performance results met the U.S. EPA model performance goal at all sites. The modelled 4th highest daily maximum 8-h average ozone concentrations in the base and two future year scenarios did not exceed the Canada-wide standard of 65 ppb or the newer Canadian Ambient Air Quality Standards of 63 ppb in 2015 and 62 ppb in 2020. Modelled maximum 1-h ozone concentrations in the study were well below the Alberta Ambient Air Quality Objective of 82 ppb in all three cases. Several ozone vegetation exposure metrics were also evaluated to investigate the potential impact of ground-level ozone on vegetation. The chronic 3-months SUM60 exposure metric is within the CEMA baseline range (0-2000 ppb-hr) everywhere in the AOSR. The AOT40 ozone exposure metric predicted by CMAQ did not exceed the United Nations Economic Commission for Europe (UN/ECE) threshold of concern of 3000 ppb-hr in any of the cases but is just below the threshold in high-end future emissions scenario. In all three emission scenarios, the CMAQ predicted W126 ozone exposure metric is within the CEMA baseline threshold of 4000 ppb-hr. This study outlines the use of photochemical modelling of the impact of an industry (oil

  7. Ozone modeling

    International Nuclear Information System (INIS)

    McIllvaine, C.M.

    1994-01-01

    Exhaust gases from power plants that burn fossil fuels contain concentrations of sulfur dioxide (SO 2 ), nitric oxide (NO), particulate matter, hydrocarbon compounds and trace metals. Estimated emissions from the operation of a hypothetical 500 MW coal-fired power plant are given. Ozone is considered a secondary pollutant, since it is not emitted directly into the atmosphere but is formed from other air pollutants, specifically, nitrogen oxides (NO), and non-methane organic compounds (NMOQ) in the presence of sunlight. (NMOC are sometimes referred to as hydrocarbons, HC, or volatile organic compounds, VOC, and they may or may not include methane). Additionally, ozone formation Alternative is a function of the ratio of NMOC concentrations to NO x concentrations. A typical ozone isopleth is shown, generated with the Empirical Kinetic Modeling Approach (EKMA) option of the Environmental Protection Agency's (EPA) Ozone Isopleth Plotting Mechanism (OZIPM-4) model. Ozone isopleth diagrams, originally generated with smog chamber data, are more commonly generated with photochemical reaction mechanisms and tested against smog chamber data. The shape of the isopleth curves is a function of the region (i.e. background conditions) where ozone concentrations are simulated. The location of an ozone concentration on the isopleth diagram is defined by the ratio of NMOC and NO x coordinates of the point, known as the NMOC/NO x ratio. Results obtained by the described model are presented

  8. Role of the boundary layer in the occurrence and termination of the tropospheric ozone depletion events in polar spring

    Science.gov (United States)

    Cao, Le; Platt, Ulrich; Gutheil, Eva

    2016-05-01

    Tropospheric ozone depletion events (ODEs) in the polar spring are frequently observed in a stable boundary layer condition, and the end of the events occurs when there is a breakup of the boundary layer. In order to improve the understanding of the role of the boundary layer in the ozone depletion event, a one-dimensional model is developed, focusing on the occurrence and the termination period of the ozone depletion episode. A module accounting for the vertical air transport is added to a previous box model, and a first-order parameterization is used for the estimation of the vertical distribution of the turbulent diffusivity. Simulations are performed for different strengths of temperature inversion as well as for different wind speeds. The simulation results suggest that the reactive bromine species released from the underlying surface into the lowest part of the troposphere initially stay in the boundary layer, leading to an increase of the bromine concentration. This bromine accumulation causes the ozone destruction below the top of the boundary layer. After the ozone is totally depleted, if the temperature inversion intensity decreases or the wind speed increases, the severe ozone depletion event tends to transit into a partial ozone depletion event or it recovers to the normal ozone background level of 30-40 ppb. This recovery process takes about 2 h. Due to the presence of high-level HBr left from the initial occurrence of ODEs, the complete removal of ozone in the boundary layer is achieved a few days after the first termination of ODE. The time required for the recurrence of the ozone depletion in a 1000 m boundary layer is approximately 5 days, while the initial occurrence of the complete ozone consumption takes 15 days. The present model is suitable to clarify the reason for both the start and the termination of the severe ozone depletion as well as the partial ozone depletion in the observations.

  9. Assessing the risk caused by ground level ozone to European forest trees: A case study in pine, beech and oak across different climate regions

    International Nuclear Information System (INIS)

    Emberson, Lisa D.; Bueker, Patrick; Ashmore, Mike R.

    2007-01-01

    Two different indices have been proposed for estimation of the risk caused to forest trees across Europe by ground-level ozone, (i) the concentration based AOT40 index (Accumulated Over a Threshold of 40 ppb) and (ii) the recently developed flux based AFstY index (Accumulated stomatal Flux above a flux threshold Y). This paper compares the AOT40 and AFstY indices for three forest trees species at different locations in Europe. The AFstY index is estimated using the DO 3 SE (Deposition of Ozone and Stomatal Exchange) model parameterized for Scots pine (Pinus sylvestris), beech (Fagus sylvatica) and holm oak (Quercus ilex). The results show a large difference in the perceived O 3 risk when using AOT40 and AFstY indices both between species and regions. The AOT40 index shows a strong north-south gradient across Europe, whereas there is little difference between regions in the modelled values of AFstY. There are significant differences in modelled AFstY between species, which are predominantly determined by differences in the timing and length of the growing season, the periods during which soil moisture deficit limits stomatal conductance, and adaptation to soil moisture stress. This emphasizes the importance of defining species-specific flux response variables to obtain a more accurate quantification of O 3 risk. - A new flux-based model provides a revised assessment of risks of ozone impacts to European forests

  10. Impacto del tratamiento con ozono sobre las propiedades superficiales del carbón activado Impact of ozone treatment on activated carbon surface properties

    Directory of Open Access Journals (Sweden)

    Héctor Valdés

    2011-08-01

    Full Text Available El uso conjunto de ozono y carbón activado para tratar efluentes tóxicos ha sido demostrado recientemente. Sin embargo, existen dudas acerca del efecto del ozono sobre las propiedades del carbón activado. En este artículo se presentan resultados sobre la modificación de las propiedades superficiales de un carbón activado comercial por la acción del ozono durante diferentes tiempos de exposición. Las propiedades químicas superficiales del carbón activado fueron evaluadas utilizando las técnicas de neutralización selectiva, desorción térmica programada (DTP y el pH del punto de carga cero. Las características texturales fueron evaluadas mediante microscopía electrónica de barrido. El área superficial aparente, el volumen de microporos y mesoporos fueron obtenidos a partir de las isotermas de adsorción de nitrógeno a 77 K. Las propiedades adsortivas fueron caracterizadas por el índice de adsorción de azul de metileno. Los resultados demuestran que los grupos superficiales oxigenados presentes en el carbón activado se modifican producto del tratamiento con el ozono. A mayores dosis de ozono, el carbón sufre mayor oxidación y se incrementan los grupos ácidos en especial los grupos carboxílicos, mientras que el pH de punto de carga cero disminuye. El área BET, así como el volumen de microporos disminuyen al igual que el poder de adsorción de azul de metileno.The combined use of ozone and activated carbon has recently started to be developed for the treatment of toxic effluents. However, the effect of ozone on the properties of activated carbon is not fully elucidated. A study was undertaken of modifications of the surface properties of a commercial activated carbon produced by its ozonation during different time periods. Surface chemistry of the activated carbon samples was characterized by of selective neutralization, temperature-programmed desorption, and pH of the point of zero charge. Surface area and volume of

  11. Towards the retrieval of tropospheric ozone with the ozone monitoring instrument (OMI)

    NARCIS (Netherlands)

    Mielonen, T.; De Haan, J.F.; Van Peet, J.C.A.; Eremenko, M.; Veefkind, J.P.

    2015-01-01

    We have assessed the sensitivity of the operational Ozone Monitoring Instrument (OMI) ozone profile retrieval algorithm to a number of a priori and radiative transfer assumptions. We studied the effect of stray light correction, surface albedo assumptions and a priori ozone profiles on the retrieved

  12. Understanding and improving global crop response to ozone pollution

    Science.gov (United States)

    Concentrations of ground-level ozone ([O3]) over much of the Earth’s land surface have more than doubled since pre-industrial times. The air pollutant is highly variable over time and space, which makes it difficult to assess the average agronomic and economic impacts of the pollutant as well as to ...

  13. 21 CFR 184.1563 - Ozone.

    Science.gov (United States)

    2010-04-01

    ...: Category of food Maximum treatment level in food Functional use Bottled water that prior to ozonation meets... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Ozone. 184.1563 Section 184.1563 Food and Drugs... Substances Affirmed as GRAS § 184.1563 Ozone. (a) Ozone (O3, CAS Reg. No. 10028-15-6) is an unstable blue gas...

  14. Evaluating a Space-Based Indicator of Surface Ozone-NOx-VOC Sensitivity Over Midlatitude Source Regions and Application to Decadal Trends

    Science.gov (United States)

    Jin, Xiaomeng; Fiore, Arlene M.; Murray, Lee T.; Valin, Lukas C.; Lamsal, Lok N.; Duncan, Bryan; Folkert Boersma, K.; De Smedt, Isabelle; Abad, Gonzalo Gonzalez; Chance, Kelly; Tonnesen, Gail S.

    2017-10-01

    Determining effective strategies for mitigating surface ozone (O3) pollution requires knowledge of the relative ambient concentrations of its precursors, NOx, and VOCs. The space-based tropospheric column ratio of formaldehyde to NO2 (FNR) has been used as an indicator to identify NOx-limited versus NOx-saturated O3 formation regimes. Quantitative use of this indicator ratio is subject to three major uncertainties: (1) the split between NOx-limited and NOx-saturated conditions may shift in space and time, (2) the ratio of the vertically integrated column may not represent the near-surface environment, and (3) satellite products contain errors. We use the GEOS-Chem global chemical transport model to evaluate the quantitative utility of FNR observed from the Ozone Monitoring Instrument over three northern midlatitude source regions. We find that FNR in the model surface layer is a robust predictor of the simulated near-surface O3 production regime. Extending this surface-based predictor to a column-based FNR requires accounting for differences in the HCHO and NO2 vertical profiles. We compare four combinations of two OMI HCHO and NO2 retrievals with modeled FNR. The spatial and temporal correlations between the modeled and satellite-derived FNR vary with the choice of NO2 product, while the mean offset depends on the choice of HCHO product. Space-based FNR indicates that the spring transition to NOx-limited regimes has shifted at least a month earlier over major cities (e.g., New York, London, and Seoul) between 2005 and 2015. This increase in NOx sensitivity implies that NOx emission controls will improve O3 air quality more now than it would have a decade ago.

  15. Fabrication and characterization of multi-level hierarchical surfaces.

    Science.gov (United States)

    Bhushan, Bharat; Lee, Hyungoo

    2012-01-01

    A nanostructured surface may exhibit low adhesion or high adhesion depending upon fibrillar density, and it presents the possibility of realizing eco-friendly surface structures with desirable adhesion by mimicking the mechanics of fibrillar adhesive surfaces of biological systems. The current research uses a patterning technique to fabricate smart adhesion surfaces: one-, two- and three-level hierarchical synthetic adhesive structure surfaces with various fibrillar densities and diameters. The contact angles and contact angle hysteresis were measured to characterize the wettability. A conventional and a glass ball attached to an atomic force microscope (AFM) tip were used to obtain the adhesive forces via force-distance curves and to study the buckling behavior of a single fiber on the hierarchical structures.

  16. Defense meteorological satellite measurements of total ozone

    International Nuclear Information System (INIS)

    Lovill, J.E.; Ellis, J.S.; Luther, F.M.; Sullivan, R.J.; Weichel, R.L.

    1992-01-01

    A multichannel filter radiometer (MFR) on Defense Meteorological Satellites (DMS) that measured total ozone on a global-scale from March 1977 - February 1980 is described. The total ozone data measured by the MFR were compared with total ozone data taken by surfaced-based Dobson spectrophotometers. When comparisons were made for five months, the Dobson spectrophotometer measured 2-5% more total ozone than the MFR. Comparisons between the Dobson spectrophotometer and the MFR showed a reduced RMS difference as the comparisons were made at closer proximity. A Northern Hemisphere total ozone distribution obtained from MFR data is presented

  17. Final report, ongoing key comparison BIPM.QM-K1, ozone at ambient level, comparison with ISCIII (December 2014)

    Science.gov (United States)

    Viallon, Joële; Moussay, Philippe; Idrees, Faraz; Wielgosz, Robert; Sanchez, Carmen; Morillo Gomez, Pilar

    2015-01-01

    As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone national standard of the Instituto de Salud Carlos III (ISCIII) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount-of-substance fraction range of 0 nmol/mol to 500 nmol/mol. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Ozone depletion update.

    Science.gov (United States)

    Coldiron, B M

    1996-03-01

    Stratospheric ozone depletion due to chlorofluorocarbons an d increased ultraviolet radiation penetration has long been predicted. To determine if predictions of ozone depletion are correct and, if so, the significance of this depletion. Review of the English literature regarding ozone depletion and solar ultraviolet radiation. The ozone layer is showing definite thinning. Recently, significantly increased ultraviolet radiation transmission has been detected at ground level at several metering stations. It appears that man-made aerosols (air pollution) block increased UVB transmission in urban areas. Recent satellite measurements of stratospheric fluorine levels more directly implicate chlorofluorocarbons as a major source of catalytic stratospheric chlorine, although natural sources may account for up to 40% of stratospheric chlorine. Stratospheric chlorine concentrations, and resultant increased ozone destruction, will be enhanced for at least the next 70 years. The potential for increased transmission of ultraviolet radiation will exist for the next several hundred years. While little damage due to increased ultraviolet radiation has occurred so far, the potential for long-term problems is great.

  19. Ground-Based Lidar for Atmospheric Boundary Layer Ozone Measurements

    Science.gov (United States)

    Kuang, Shi; Newchurch, Michael J.; Burris, John; Liu, Xiong

    2013-01-01

    Ground-based lidars are suitable for long-term ozone monitoring as a complement to satellite and ozonesonde measurements. However, current ground-based lidars are unable to consistently measure ozone below 500 m above ground level (AGL) due to both engineering issues and high retrieval sensitivity to various measurement errors. In this paper, we present our instrument design, retrieval techniques, and preliminary results that focus on the high-temporal profiling of ozone within the atmospheric boundary layer (ABL) achieved by the addition of an inexpensive and compact mini-receiver to the previous system. For the first time, to the best of our knowledge, the lowest, consistently achievable observation height has been extended down to 125 m AGL for a ground-based ozone lidar system. Both the analysis and preliminary measurements demonstrate that this lidar measures ozone with a precision generally better than 10% at a temporal resolution of 10 min and a vertical resolution from 150 m at the bottom of the ABL to 550 m at the top. A measurement example from summertime shows that inhomogeneous ozone aloft was affected by both surface emissions and the evolution of ABL structures.

  20. Temperature Trends in the Tropical Upper Troposphere and Lower Stratosphere: Connections with Sea Surface Temperatures and Implications for Water Vapor and Ozone

    Science.gov (United States)

    Garfinkel, C. I.; Waugh, D. W.; Oman, L. D.; Wang, L.; Hurwitz, M. M.

    2013-01-01

    Satellite observations and chemistry-climate model experiments are used to understand the zonal structure of tropical lower stratospheric temperature, water vapor, and ozone trends. The warming in the tropical upper troposphere over the past 30 years is strongest near the Indo-Pacific warm pool, while the warming trend in the western and central Pacific is much weaker. In the lower stratosphere, these trends are reversed: the historical cooling trend is strongest over the Indo-Pacific warm pool and is weakest in the western and central Pacific. These zonal variations are stronger than the zonal-mean response in boreal winter. Targeted experiments with a chemistry-climate model are used to demonstrate that sea surface temperature (hereafter SST) trends are driving the zonal asymmetry in upper tropospheric and lower stratospheric tropical temperature trends. Warming SSTs in the Indian Ocean and in the warm pool region have led to enhanced moist heating in the upper troposphere, and in turn to a Gill-like response that extends into the lower stratosphere. The anomalous circulation has led to zonal structure in the ozone and water vapor trends near the tropopause, and subsequently to less water vapor entering the stratosphere. The radiative impact of these changes in trace gases is smaller than the direct impact of the moist heating. Projected future SSTs appear to drive a temperature and water vapor response whose zonal structure is similar to the historical response. In the lower stratosphere, the changes in water vapor and temperature due to projected future SSTs are of similar strength to, though slightly weaker than, that due directly to projected future CO2, ozone, and methane.

  1. A siphon gage for monitoring surface-water levels

    Science.gov (United States)

    McCobb, T.D.; LeBlanc, D.R.; Socolow, R.S.

    1999-01-01

    A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standpipe and the water body equilibrate and provide a measurable static water surface in the standpipe. The siphon gage was designed to allow quick and accurate year-round measurements with minimal maintenance. Currently available devices for monitoring surface-water levels commonly involve time-consuming and costly installation and surveying, and the movement of reference points and the presence of ice cover in cold regions cause discontinuity and inaccuracy in the data collected. Installation and field testing of a siphon gage using 0.75-in-diameter polyethylene tubing at Ashumet Pond in Falmouth, Massachusetts, demonstrated that the siphon gage can provide long-term data with a field effort and accuracy equivalent to measurement of ground-water levels at an observation well.A device that uses a siphon tube to establish a hydraulic connection between the bottom of an onshore standpipe and a point at the bottom of a water body was designed and tested for monitoring surface-water levels. Water is added to the standpipe to a level sufficient to drive a complete slug of water through the siphoning tube and to flush all air out of the system. The water levels in the standpipe and the water body equilibrate and provide a measurable static water surface in the standpipe. The siphon gage was designed to allow quick and accurate year-round measurements with minimal maintenance. Currently available devices for monitoring surface-water levels commonly involve time-consuming and costly installation and surveying, and the movement of reference points and the presence of ice cover in cold

  2. The Effect of Major Meteor Streams on the Total Ozone in the Earth's Atmosphere

    Science.gov (United States)

    Gorbanev, Yu. M.; Stogneeva, I. A.; Shestopalov, V. A.; Knyazkova, E. F.; Kimakovskaya, I. I.; Kimakovskay, S. R.; Golubaev, A. V.

    The correlation between the total ozone and activity of major meteor streams, such as the Perseids, Geminids, Leonids and Orionids, has been found using the Total Ozone Mapping Spectrometer (TOMS) measurements of the global ozone distribution over the periods 1978 - 1993 and 1996 - 2001. The autocorrelation analysis of the total ozone time series for the period of about 20 years has confirmed the existence of regular changes in the ozone levels at the peaks of meteor shower activity. It has been established that TO decreases after the dates of peak activity of meteor streams (e.g. the Perseids) or during the whole periods of meteor shower activity (e.g. the Geminids, Orionids and Leonids). The analysis of the total ozone distribution (in the Southern and Northern Hemispheres), as well as the local distribution of ozone (over the selected surface area of several hundred square kilometres), was performed during the Leonid meteor shower in 1999. The atmospheric zones for which the ozone distribution pattern can be described as a result of interaction between the meteor shower material and the ozone layer were localised by applying the TOMS data. Such zones correspond to the regions where the highest Leonid activity has been observed. According to the radar observations (conducted in Kazan, Russian Federation), three activity maxima of the 1988 Geminid shower were reported: on the nights of 7th, 12th and 14th December, 1988. The TO decrease was observed on the same dates. Thus, the analysis of the TO changes during the periods of intense meteor shower's activity enables to preliminary assess the maximum overall decline in the total ozone concentration which makes about 5 DU over two weeks. From the results obtained it can be inferred that the ozone layer can be used as an indicator of the interaction between the meteoric material and the Earth's atmosphere.

  3. SBUV2/NOAA-11 Level 2 Daily Ozone Profile and Total Column from CD-ROM V008 (SBUV2N11O3) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The version 8 SBUV/2 NOAA-11 ozone data were first released at the 2004 Quadrennial Ozone Symposium on DVD. The DVD contained all of the SBUV/2 data from NOAA-9,...

  4. SBUV2/NOAA-16 Level 2 Daily Ozone Profile and Total Column from CD-ROM V008 (SBUV2N16O3) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The version 8 SBUV/2 NOAA-16 ozone data were first released at the 2004 Quadrennial Ozone Symposium on DVD. The DVD contained all of the SBUV/2 data from NOAA-9,...

  5. SBUV2/NOAA-9 Level 2 Daily Ozone Profile and Total Column from CD-ROM V008 (SBUV2N09O3) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The version 8 SBUV/2 NOAA-9 ozone data were first released at the 2004 Quadrennial Ozone Symposium on DVD. The DVD contained all of the SBUV/2 data from NOAA-9,...

  6. SBUV/Nimbus-7 Level 2 Daily Ozone Profile and Total Column from CD-ROM V008 (SBUVN7O3) at GES DISC

    Data.gov (United States)

    National Aeronautics and Space Administration — The version 8 SBUV Nimbus-7 ozone data were first released at the 2004 Quadrennial Ozone Symposium on DVD. The DVD contained all of the SBUV/2 data from NOAA-9,...

  7. Immobilized enzymes: understanding enzyme - surface interactions at the molecular level.

    Science.gov (United States)

    Hoarau, Marie; Badieyan, Somayesadat; Marsh, E Neil G

    2017-11-22

    Enzymes immobilized on solid supports have important and industrial and medical applications. However, their uses are limited by the significant reductions in activity and stability that often accompany the immobilization process. Here we review recent advances in our understanding of the molecular level interactions between proteins and supporting surfaces that contribute to changes in stability and activity. This understanding has been facilitated by the application of various surface-sensitive spectroscopic techniques that allow the structure and orientation of enzymes at the solid/liquid interface to be probed, often with monolayer sensitivity. An appreciation of the molecular interactions between enzyme and surface support has allowed the surface chemistry and method of enzyme attachement to be fine-tuned such that activity and stability can be greatly enhanced. These advances suggest that a much wider variety of enzymes may eventually be amenable to immobilization as green catalysts.

  8. Automatic Measurement of Low Level Contamination on Concrete Surfaces

    International Nuclear Information System (INIS)

    Tachibana, M.; Itoh, H.; Shimada, T.; Yanagihara, S.

    2002-01-01

    Automatic measurement of radioactivity is necessary for considering cost effectiveness in final radiological survey of building structures in decommissioning nuclear facilities. The RAPID (radiation measuring pilot device for surface contamination) was developed to be applied to automatic measurement of low level contamination on concrete surfaces. The RAPID has a capability to measure contamination with detection limit of 0.14 Bq/cm2 for 60Co in 30 seconds of measurement time and its efficiency is evaluated to be 5 m2/h in a normal measurement option. It was confirmed that low level contamination on concrete surfaces could be surveyed by the RAPID efficiently compared with direct measurement by workers through its actual application

  9. Origin of metallic surface core-level shifts

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Abrikosov, I. A.

    1995-01-01

    The unique property of the open 4f energy shell in the lanthanide metals is used to show that the initial-state energy shift gives an insufficient description of surface core-level shifts. Instead a treatment, which fully includes the final-state screening, account for the experimentally observed...

  10. Optimization of Catalytic Ozonation Process for Formaldehyde Mineralization from Synthetic Wastewater by Fe/MgO Nanoparticles Synthesis by Sol-Gel Method by Response Surface Model

    Directory of Open Access Journals (Sweden)

    Ghorban Asgari

    2014-09-01

    Full Text Available Background: Design experiment stages of formalin mineralization process by center composition design (CCD cause ease of work, reducing the number of samples, increasing the accuracy of optimized conditions and the interaction parameters determined during the process. The aim of this study was optimization of catalytic ozonation process for formaldehyde mineralization from synthetic wastewater by Fe/MgO nanoparticles synthesis by sol-gel method by response surface model. Methods: This experimental study was conducted in a semi-batch reactor, using a RSM by taking 3 factors in the final stage of pH (7-9, reaction time (10-20 min and catalyst dose (1.1-1.3 g/L was investigated. Synthesis of nanoparticles was done by sol-gel method. The results were analyzed by Design Expert 7.0.1 software. Results: The results showed that the process was dependent on the parameters studied and changing each parameter, affected the process efficiency and other parameters. The optimum conditions predicted for the process was 86.51% of mineralization efficiency. Optimum condition included pH=8.82, reaction time of 20 minute and catalyst dose of 1.3 g/L. The correlation coefficient for the process was determined 0.91. Conclusion: Using a statistical model could reduce the number of experiments, the accuracy and the prediction process. The catalytic ozonation process has the ability to remove formaldehyde with high efficiency and the process was environmental friendly.

  11. A multi-model analysis of vertical ozone profiles

    Science.gov (United States)

    Jonson, J. E.; Stohl, A.; Fiore, A. M.; Hess, P.; Szopa, S.; Wild, O.; Zeng, G.; Dentener, F. J.; Lupu, A.; Schultz, M. G.; Duncan, B. N.; Sudo, K.; Wind, P.; Schulz, M.; Marmer, E.; Cuvelier, C.; Keating, T.; Zuber, A.; Valdebenito, A.; Dorokhov, V.; de Backer, H.; Davies, J.; Chen, G. H.; Johnson, B.; Tarasick, D. W.; Stübi, R.; Newchurch, M. J.; von der Gathen, P.; Steinbrecht, W.; Claude, H.

    2010-06-01

    A multi-model study of the long-range transport of ozone and its precursors from major anthropogenic source regions was coordinated by the Task Force on Hemispheric Transport of Air Pollution (TF HTAP) under the Convention on Long-range Transboundary Air Pollution (LRTAP). Vertical profiles of ozone at 12-h intervals from 2001 are available from twelve of the models contributing to this study and are compared here with observed profiles from ozonesondes. The contributions from each major source region are analysed for selected sondes, and this analysis is supplemented by retroplume calculations using the FLEXPART Lagrangian particle dispersion model to provide insight into the origin of ozone transport events and the cause of differences between the models and observations. In the boundary layer ozone levels are in general strongly affected by regional sources and sinks. With a considerably longer lifetime in the free troposphere, ozone here is to a much larger extent affected by processes on a larger scale such as intercontinental transport and exchange with the stratosphere. Such individual events are difficult to trace over several days or weeks of transport. This may explain why statistical relationships between models and ozonesonde measurements are far less satisfactory than shown in previous studies for surface measurements at all seasons. The lowest bias between model-calculated ozone profiles and the ozonesonde measurements is seen in the winter and autumn months. Following the increase in photochemical activity in the spring and summer months, the spread in model results increases, and the agreement between ozonesonde measurements and the individual models deteriorates further. At selected sites calculated contributions to ozone levels in the free troposphere from intercontinental transport are shown. Intercontinental transport is identified based on differences in model calculations with unperturbed emissions and emissions reduced by 20% by region

  12. A multi-model analysis of vertical ozone profiles

    Directory of Open Access Journals (Sweden)

    J. E. Jonson

    2010-06-01

    Full Text Available A multi-model study of the long-range transport of ozone and its precursors from major anthropogenic source regions was coordinated by the Task Force on Hemispheric Transport of Air Pollution (TF HTAP under the Convention on Long-range Transboundary Air Pollution (LRTAP. Vertical profiles of ozone at 12-h intervals from 2001 are available from twelve of the models contributing to this study and are compared here with observed profiles from ozonesondes. The contributions from each major source region are analysed for selected sondes, and this analysis is supplemented by retroplume calculations using the FLEXPART Lagrangian particle dispersion model to provide insight into the origin of ozone transport events and the cause of differences between the models and observations.

    In the boundary layer ozone levels are in general strongly affected by regional sources and sinks. With a considerably longer lifetime in the free troposphere, ozone here is to a much larger extent affected by processes on a larger scale such as intercontinental transport and exchange with the stratosphere. Such individual events are difficult to trace over several days or weeks of transport. This may explain why statistical relationships between models and ozonesonde measurements are far less satisfactory than shown in previous studies for surface measurements at all seasons. The lowest bias between model-calculated ozone profiles and the ozonesonde measurements is seen in the winter and autumn months. Following the increase in photochemical activity in the spring and summer months, the spread in model results increases, and the agreement between ozonesonde measurements and the individual models deteriorates further.

    At selected sites calculated contributions to ozone levels in the free troposphere from intercontinental transport are shown. Intercontinental transport is identified based on differences in model calculations with unperturbed emissions and

  13. Effects of cold fronts on ozone in the Houston-Galveston-Brazoria Area

    Science.gov (United States)

    Lei, R.; Talbot, R. W.; Wang, Y.; Wang, S. C.; Estes, M. J.

    2017-12-01

    A cold front may have confounding effects on ozone by bringing in contaminated air masses to an area and causing lower temperatures which likely lead to low ozone production rates. Literature reports on individual cold front events showing increasing and decreasing effects on ozone. The Houston-Galveston-Brazoria (HGB) area as the energy capital of USA suffers relatively high ozone levels. The effect of cold fronts on HGB ozone in the long-term range remains unknown. Weather Prediction Center (WPC) Surface Analysis Archive from National Oceanic and Atmospheric Administration (NOAA) which records cold fronts' positions since 2003 has been employed in this study. The results show the count of cold fronts passing the HGB area shows no clear trend but great interannual variation. Cold front appearance in summer is much less than in other seasons. In general, both mean MDA8 and background ozone during cold front days increased compared non-cold front days. This increasing effect has been enhanced during post-front days and summer season. Cluster analysis on meteorological parameters shows cold front days with high precipitation or wind speed could lower the MDA8 and background ozone but the proportion of those days are low in all cold front days. It may explain why cold fronts show increasing effects on ozone in the HGB area.

  14. Ground-level ozone in the Pearl River Delta and the roles of VOC and NO(x) in its production.

    Science.gov (United States)

    Shao, Min; Zhang, Yuanhang; Zeng, Limin; Tang, Xiaoyan; Zhang, Jing; Zhong, Liuju; Wang, Boguang

    2009-01-01

    In many regions of China, very rapid economic growth has been accompanied by air pollution caused by vehicle emissions. In one of these regions, the Pearl River Delta, the variations of ground-level ozone and its precursors were investigated. Overall, the ambient concentrations of NO(2) increased quickly between 1995 and 1996, but then slightly decreased due to stringent nitrogen oxide (NO(x)) emission controls. Nonetheless, ambient NO(2) levels in the Pearl River Delta remained high. The regional average concentrations of volatile organic compounds (VOCs) were 290 ppbC in summer and 190 ppbC in autumn. Local emissions and long-distance transportation of pollutants play important roles in the regional distribution of VOCs. Ambient O(3) production is significant in urban areas and also downwind of cities. The relative incremental reactivities (RIRs), determined by an observation-based model, showed that ground-level ozone formation in the Guangzhou urban area is generally limited by the concentrations of VOCs, but there are also measurable impacts of NO(x).

  15. Evaluation of physiological, growth and yield responses of a tropical oil crop (Brassica campestris L. var. Kranti) under ambient ozone pollution at varying NPK levels

    International Nuclear Information System (INIS)

    Singh, Poonam; Agrawal, Madhoolika; Agrawal, Shashi Bhushan

    2009-01-01

    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 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 3 . - NPK level above recommended alleviates the adverse effects of ambient ozone on a tropical mustard cultivar

  16. Sensitivity Modeling Study for an Ozone Occurrence during the 1996 Paso Del Norte Ozone Campaign

    Directory of Open Access Journals (Sweden)

    Duanjun Lu

    2008-11-01

    Full Text Available Surface ozone pollution has been a persistent environmental problem in the US and Europe as well as the developing countries. A key prerequisite to find effective alternatives to meeting an ozone air quality standard is to understand the importance of local anthropogenic emissions, the significance of biogenic emissions, and the contribution of long-range transport. In this study, an air quality modeling system that includes chemistry and transport, CMAQ, an emission processing model, SMOKE, and a mesoscale numerical meteorological model, WRF, has been applied to investigate an ozone event occurring during the period of the 1996 Paso del Norte Ozone Campaign. The results show that the modeling system exhibits the capability to simulate this high ozone occurrence by providing a comparable temporal variation of surface ozone concentration at one station and to capture the spatial evolution of the event. Several sensitivity tests were also conducted to identify the contributions to high surface ozone concentration from eight VOC subspecies, biogenic VOCs, anthropogenic VOCs and long-range transportation of ozone and its precursors. It is found that the reductions of ETH, ISOP, PAR, OLE and FORM help to mitigate the surface ozone concentration, and like anthropogenic VOCs, biogenic VOC plays a nonnegligible role in ozone formation. But for this case, long-range transport of ozone and its precursors appears to produce an insignificant contribution.

  17. Sensitivity modeling study for an ozone occurrence during the 1996 Paso Del Norte Ozone Campaign.

    Science.gov (United States)

    Lu, Duanjun; Reddy, Remata S; Fitzgerald, Rosa; Stockwell, William R; Williams, Quinton L; Tchounwou, Paul B

    2008-12-01

    Surface ozone pollution has been a persistent environmental problem in the US and Europe as well as the developing countries. A key prerequisite to find effective alternatives to meeting an ozone air quality standard is to understand the importance of local anthropogenic emissions, the significance of biogenic emissions, and the contribution of long-range transport. In this study, an air quality modeling system that includes chemistry and transport, CMAQ, an emission processing model, SMOKE, and a mesoscale numerical meteorological model, WRF, has been applied to investigate an ozone event occurring during the period of the 1996 Paso del Norte Ozone Campaign. The results show that the modeling system exhibits the capability to simulate this high ozone occurrence by providing a comparable temporal variation of surface ozone concentration at one station and to capture the spatial evolution of the event. Several sensitivity tests were also conducted to identify the contributions to high surface ozone concentration from eight VOC subspecies, biogenic VOCs, anthropogenic VOCs and long-range transportation of ozone and its precursors. It is found that the reductions of ETH, ISOP, PAR, OLE and FORM help to mitigate the surface ozone concentration, and like anthropogenic VOCs, biogenic VOC plays a nonnegligible role in ozone formation. But for this case, long-range transport of ozone and its precursors appears to produce an insignificant contribution.

  18. Increase of ozone concentrations, its temperature sensitivity and the precursor factor in South China

    Directory of Open Access Journals (Sweden)

    Y. C. Lee

    2014-08-01

    Full Text Available Concerns have been raised about the possible connections between the local and regional photochemical problem and global warming. The current study assesses the trend of ozone in Hong Kong and the Pearl River Delta (PRD in South China and investigates the interannual changes of sensitivity of ozone to air temperature, as well as the trends in regional precursors. Results reveal, at the three monitoring sites from the mid-1990s to 2010, an increase in the mean ozone concentrations from 1.0 to 1.6 µg m−3 per year. The increase occurred in all seasons, with the highest rate in autumn. This is consistent with trends and temperature anomalies in the region. The increase in the sensitivity of ozone to temperature is clearly evident from the correlation between ozone (OMI [Ozone Monitoring Instrument] column amount and surface air temperature (from the Atmospheric Infrared Sounder displayed in the correlation maps for the PRD during the prominently high ozone period of July–September. It is observed to have increased from 2005 to 2010, the latter being the hottest year on record globally. To verify this temporal change in sensitivity, the ground-level trends of correlation coefficients/regression slopes are analysed. As expected, results reveal a statistically significant upward trend over a 14-year period (1997–2010. While the correlation revealed in the correlation maps is in agreement with the corresponding OMI ozone maps when juxtaposed, temperature sensitivity of surface ozone also shows an association with ozone concentration, with R=0.5. These characteristics of ozone sensitivity are believed to have adverse implications for the region. As shown by ground measurements and/or satellite analyses, the decrease in nitrogen oxides (NO2 and NOx in Hong Kong is not statistically significant while NO2 of the PRD has only very slightly changed. However, carbon dioxide has remarkably declined in the whole region. While these observations concerning

  19. Ozone flux of an urban orange grove: multiple scaled measurements and model comparisons

    Science.gov (United States)

    Alstad, K. P.; Grulke, N. E.; Jenerette, D. G.; Schilling, S.; Marrett, K.

    2009-12-01

    There is significant uncertainty about the ozone sink properties of the phytosphere due to a complexity of interactions and feedbacks with biotic and abiotic factors. Improved understanding of the controls on ozone fluxes is critical to estimating and regulating the total ozone budget. Ozone exchanges of an orange orchard within the city of Riverside, CA were examined using a multiple-scaled approach. We access the carbon, water, and energy budgets at the stand- to leaf- level to elucidate the mechanisms controlling the variability in ozone fluxes of this agro-ecosystem. The two initial goals of the study were 1. To consider variations and controls on the ozone fluxes within the canopy; and, 2. To examine different modeling and scaling approaches for totaling the ozone fluxes of this orchard. Current understanding of the total ozone flux between the atmosphere near ground and the phytosphere (F-total) include consideration of a fraction which is absorbed by vegetation through stomatal uptake (F-absorb), and fractional components of deposition on external, non-stomatal, surfaces of the vegetation (F-external) and soil (F-soil). Multiplicative stomatal-conductance models have been commonly used to estimate F-absorb, since this flux cannot be measured directly. We approach F-absorb estimates for this orange orchard using chamber measurement of leaf stomatal-conductance, as well as non-chamber sap-conductance collected on branches of varied aspect and sun/shade conditions within the canopy. We use two approaches to measure the F-total of this stand. Gradient flux profiles were measured using slow-response ozone sensors collecting within and above the canopy (4.6 m), and at the top of the tower (8.5 m). In addition, an eddy-covariance system fitted with a high-frequency chemiluminescence ozone system will be deployed (8.5 m). Preliminary ozone gradient flux profiles demonstrate a substantial ozone sink strength of this orchard, with diurnal concentration differentials

  20. Three-dimensional investigation of ozone pollution in the lower troposphere using an unmanned aerial vehicle platform.

    Science.gov (United States)

    Li, Xiao-Bing; Wang, Dong-Sheng; Lu, Qing-Chang; Peng, Zhong-Ren; Lu, Si-Jia; Li, Bai; Li, Chao

    2017-05-01

    Potential utilities of instrumented lightweight unmanned aerial vehicles (UAVs) to quickly characterize tropospheric ozone pollution and meteorological factors including air temperature and relative humidity at three-dimensional scales are highlighted in this study. Both vertical and horizontal variations of ozone within the 1000 m lower troposphere at a local area of 4 × 4 km 2 are investigated during summer and autumn times. Results from field measurements show that the UAV platform has a sufficient reliability and precision in capturing spatiotemporal variations of ozone and meteorological factors. The results also reveal that ozone vertical variation is mainly linked to the vertical distribution patterns of air temperature and the horizontal transport of air masses from other regions. In addition, significant horizontal variations of ozone are also observed at different levels. Without major exhaust sources, ozone horizontal variation has a strong correlation with the vertical convection intensity of air masses within the lower troposphere. Higher air temperatures are usually related to lower ozone horizontal variations at the localized area, whereas underlying surface diversity has a week influence. Three-dimensional ozone maps are obtained using an interpolation method based on UAV collected samples, which are capable of clearly demonstrating the diurnal evolution processes of ozone within the 1000 m lower troposphere. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. OZONE CONCENTRATION ATTRIBUTABLE PREMATURE DEATH IN POLAND

    Directory of Open Access Journals (Sweden)

    Krzysztof Skotak

    2010-03-01

    Full Text Available Ozone in the lower part of the atmosphere (troposphere, strong photochemical oxidant, is not directly emitted to the atmosphere but formed through a series of complex reactions. Ozone concentrations depends on ozone precursors air contamination (mainly nitrogen dioxide and non-methane volatile organic compounds and meteorological conditions (temperature and solar radiation. The main sectors emitted ozone precursors are road transport, power and heat generation plants, household (heating, industry, and petrol storage and distribution. Ozone and some of its precursors are also transported long distances in the atmosphere and are therefore considered a transboundary problem. As a result, the ozone concentrations are often low in busy urban areas and higher in suburban and rural areas. Nowadays, instead of particulate matter, ozone is one of the most widespread global air pollution problems. In and around urban areas, relatively large gradients of ozone can be observed. Because of its high reactivity in elevated concentrations ozone causes serious health problems and damage to ecosystems, agricultural crops and materials. Main ill-health endpoints as a results of ozone concentrations can be characterised as an effect of pulmonary and cardiovascular system, time morbidity and mortality series, development of atherosclerosis and asthma and finally reduction in life expectancy. The associations with increased daily mortality due to ozone concentrations are confirmed by many researches and epidemiological studies. Estimation of the level selected ill-health endpoints (mortality in total and due to cardiovascular and respiratory causes as a result of the short-term ozone exposure in Poland was the main aim of the project. Final results have been done based on estimation method elaborated by WHO, ozone measurements from National Air Quality Monitoring System and statistical information such as mortality rate and populations. All analysis have been done in

  2. Ozone Nonattainment Areas - 1 Hour

    Data.gov (United States)

    U.S. Environmental Protection Agency — This data layer identifies areas in the U.S. where air pollution levels have not met the National Ambient Air Quality Standards (NAAQS) for Ozone - 1hour (Legacy...

  3. Ecosystem Effects of Ozone Pollution

    Science.gov (United States)

    Ground level ozone is absorbed by the leaves of plants, where it can reduce photosynthesis, damage leaves and slow growth. It can also make sensitive plants more susceptible to certain diseases, insects, harsh weather and other pollutants.

  4. Lower tropospheric ozone over India and its linkage to the South Asian monsoon

    Science.gov (United States)

    Lu, Xiao; Zhang, Lin; Liu, Xiong; Gao, Meng; Zhao, Yuanhong; Shao, Jingyuan

    2018-03-01

    Lower tropospheric (surface to 600 hPa) ozone over India poses serious risks to both human health and crops, and potentially affects global ozone distribution through frequent deep convection in tropical regions. Our current understanding of the processes controlling seasonal and long-term variations in lower tropospheric ozone over this region is rather limited due to spatially and temporally sparse observations. Here we present an integrated process analysis of the seasonal cycle, interannual variability, and long-term trends of lower tropospheric ozone over India and its linkage to the South Asian monsoon using the Ozone Monitoring Instrument (OMI) satellite observations for years 2006-2014 interpreted with a global chemical transport model (GEOS-Chem) simulation for 1990-2010. OMI observed lower tropospheric ozone over India averaged for 2006-2010, showing the highest concentrations (54.1 ppbv) in the pre-summer monsoon season (May) and the lowest concentrations (40.5 ppbv) in the summer monsoon season (August). Process analyses in GEOS-Chem show that hot and dry meteorological conditions and active biomass burning together contribute to 5.8 Tg more ozone being produced in the lower troposphere in India in May than January. The onset of the summer monsoon brings ozone-unfavorable meteorological conditions and strong upward transport, which all lead to large decreases in the lower tropospheric ozone burden. Interannually, we find that both OMI and GEOS-Chem indicate strong positive correlations (r = 0.55-0.58) between ozone and surface temperature in pre-summer monsoon seasons, with larger correlations found in high NOx emission regions reflecting NOx-limited production conditions. Summer monsoon seasonal mean ozone levels are strongly controlled by monsoon strengths. Lower ozone concentrations are found in stronger monsoon seasons mainly due to less ozone net chemical production. Furthermore, model simulations over 1990-2010 estimate a mean annual trend of 0

  5. Evaluation of hydrogen and oxygen impurity levels on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kenny, M.J.; Wielunski, L.S.; Netterfield, R.P.; Martin, P.J.; Leistner, A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1996-12-31

    This paper reports on surface analytical techniques used to quantify surface concentrations of impurities such as oxygen and hydrogen. The following analytical techniques were used: Rutherford and Backscattering, elastic recoil detection, time-of-flight SIMS, spectroscopic ellipsometry, x-ray photoelectron spectroscopy. The results have shown a spread in thickness of oxide layer, ranging from unmeasurable to 1.6 nm. The data must be considered as preliminary at this stage, but give some insight into the suitability of the techniques and a general idea of the significance of impurities at the monolayer level. These measurements have been carried out on a small number of silicon surfaces both semiconductor grade <111> crystalline material and silicon which has been used in sphere fabrication. 5 refs., 1 fig.

  6. 3D QSPR models for the removal of trace organic contaminants by ozone and free chlorine.

    Science.gov (United States)

    Lei, Hongxia; Snyder, Shane A

    2007-10-01

    Endocrine-disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs) have been detected at low levels in water resources around the world and one impact of their detection is the continuous concern on their fate and removal by various water treatment processes. In this research, a 3D quantitative structure-property relationship (QSPR) model characterized by the utilization of 3D molecular structures is explored as a potential tool to prescreen these compounds and help focus research on more persistent compounds during typical water treatment processes. Monte Carlo (MC) statistical mechanics simulations were utilized to generate 3D molecular descriptors and physicochemical properties for the development of multiple linear regression analysis. The relevance of each parameter to removals of target compounds by ozone (O3) and free chlorine was determined based on data matrices generated in bench- and pilot-scale experiments. Calculated removals were correlated with experimental data with linear regression coefficients of 0.84 for ozonation and 0.71 for chlorination. The increased predictability of ozone removal reflects the fundamental simplicity of ozone reaction mechanisms, which is dominated by oxidation reactions. Interestingly, the weakly polar surface area, in addition to the pi surface area of these molecules, seems critical to ozone removal. The removal of these compounds by free chlorine is related to their ozone removal, ionization potential and three other parameters. The developed QSPR models help disclose the removal mechanism during ozonation and chlorination.

  7. Ozone and cardiovascular injury

    Directory of Open Access Journals (Sweden)

    Rainaldi Giuseppe

    2009-06-01

    and mortality 3. Most of the evidence comes from studies of ambient particles concentrations. However, in Europe and elsewhere, the air pollution profile has gradually changed toward a more pronounced photochemical component. Ozone is one of the most toxic components of the photochemical air pollution mixture. Indeed, the biological basis for these observations has not been elucidated. In the present review, the role of ozone as chemical molecule will be firstly considered. Secondly, pathogenetic mechanisms connecting the atmospheric ozone level and cardiovascular pathology will be examined. Thirdly, the literature relating hospitalization frequency, morbidity and mortality due to cardiovascular causes and ozone concentration will be studied. The correlation between ozone level and occurrence of acute myocardial infarction will be eventually discussed.

  8. Model Calculations of Changes in Tropospheric Ozone Over Europe and the Role of Surface Sources and Aircraft Emissions

    Energy Technology Data Exchange (ETDEWEB)

    Hov, Oe. [Bergen Univ. (Norway)

    1996-01-01

    This conference paper deals with a study of the impact of various sources of NO{sub x} on the ozone production in the free troposphere. A comprehensive two-dimensional zonally averaged chemistry/transport model and a three-dimensional meso-scale chemical transport (MCT) model are used in the study. Using the two-dimensional model, three surches of NO{sub x} in the upper troposphere were examined covering NO{sub x} produced by lightening, NO{sub x} (and NO{sub y}) brought to the upper troposphere from the planetary boundary layer by rapid vertical transport processes, and NO{sub x} emitted from aircraft. 4 refs.

  9. Stratospheric ozone changes under solar geoengineering: implications for UV exposure and air quality

    Directory of Open Access Journals (Sweden)

    P. J. Nowack

    2016-03-01

    Full Text Available Various forms of geoengineering have been proposed to counter anthropogenic climate change. Methods which aim to modify the Earth's energy balance by reducing insolation are often subsumed under the term solar radiation management (SRM. Here, we present results of a standard SRM modelling experiment in which the incoming solar irradiance is reduced to offset the global mean warming induced by a quadrupling of atmospheric carbon dioxide. For the first time in an atmosphere–ocean coupled climate model, we include atmospheric composition feedbacks for this experiment. While the SRM scheme considered here could offset greenhouse gas induced global mean surface warming, it leads to important changes in atmospheric composition. We find large stratospheric ozone increases that induce significant reductions in surface UV-B irradiance, which would have implications for vitamin D production. In addition, the higher stratospheric ozone levels lead to decreased ozone photolysis in the troposphere. In combination with lower atmospheric specific humidity under SRM, this results in overall surface ozone concentration increases in the idealized G1 experiment. Both UV-B and surface ozone changes are important for human health. We therefore highlight that both stratospheric and tropospheric ozone changes must be considered in the assessment of any SRM scheme, due to their important roles in regulating UV exposure and air quality.

  10. Trace-level mercury removal from surface water

    International Nuclear Information System (INIS)

    Klasson, K.T.; Bostick, D.T.

    1998-01-01

    Many sorbents have been developed for the removal of mercury and heavy metals from waters; however, most of the data published thus far do not address the removal of mercury to the target levels represented in this project. The application to which these sorbents are targeted for use is the removal of mercury from microgram-per-liter levels to low nanogram-per-liter levels. Sorbents with thiouronium, thiol, amine, sulfur, and proprietary functional groups were selected for these studies. Mercury was successfully removed from surface water via adsorption onto Ionac SR-4 and Mersorb resins to levels below the target goal of 12 ng/L in batch studies. A thiol-based resin performed the best, indicating that over 200,000 volumes of water could be treated with one volume of resin. The cost of the resin is approximately $0.24 per 1,000 gal of water

  11. Surface drainage in leveled land: Implication of slope

    Directory of Open Access Journals (Sweden)

    Antoniony S. Winkler

    Full Text Available ABSTRACT In the lowlands of Rio Grande do Sul, land leveling is mostly carried out with no slope for the purpose of rice production. In this environment, soils with a low hydraulic conductivity are predominant owing to the presence of a practically impermeable B-horizon near the surface. Land leveling leads to soil accommodation resulting in the formation of depressions where water accumulates after heavy rainfalls, subsequently leading to problems with crops implanted in succession to rice, such as soybeans. The objective of this research was to quantify the areas and volumes of water accumulation in soil as a function of the slope of land leveling. Five typical leveled lowland areas were studied as a part of this research. The original areas presented slopes of 0, 0.20, 0.25, 0.28 and 0.40%, which were used to generate new digital elevation models with slopes between 0 and 0.5%. These newly generated digital models were used to map the depressions with surface water storage. In conclusion, land leveling with slopes higher than 0.1% is recommended to minimize problems with superficial water storage in rice fields.

  12. Sea level: measuring the bounding surfaces of the ocean.

    Science.gov (United States)

    Tamisiea, Mark E; Hughes, Chris W; Williams, Simon D P; Bingley, Richard M

    2014-09-28

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  13. Sea level: measuring the bounding surfaces of the ocean

    Science.gov (United States)

    Tamisiea, Mark E.; Hughes, Chris W.; Williams, Simon D. P.; Bingley, Richard M.

    2014-01-01

    The practical need to understand sea level along the coasts, such as for safe navigation given the spatially variable tides, has resulted in tide gauge observations having the distinction of being some of the longest instrumental ocean records. Archives of these records, along with geological constraints, have allowed us to identify the century-scale rise in global sea level. Additional data sources, particularly satellite altimetry missions, have helped us to better identify the rates and causes of sea-level rise and the mechanisms leading to spatial variability in the observed rates. Analysis of all of the data reveals the need for long-term and stable observation systems to assess accurately the regional changes as well as to improve our ability to estimate future changes in sea level. While information from many scientific disciplines is needed to understand sea-level change, this review focuses on contributions from geodesy and the role of the ocean's bounding surfaces: the sea surface and the Earth's crust. PMID:25157196

  14. Dobson spectrophotometer ozone measurements during international ozone rocketsonde intercomparison

    Science.gov (United States)

    Parsons, C. L.

    1980-01-01

    Measurements of the total ozone content of the atmosphere, made with seven ground based instruments at a site near Wallops Island, Virginia, are discussed in terms for serving as control values with which the rocketborne sensor data products can be compared. These products are profiles of O3 concentration with altitude. By integrating over the range of altitudes from the surface to the rocket apogee and by appropriately estimating the residual ozone amount from apogee to the top of the atmosphere, a total ozone amount can be computed from the profiles that can be directly compared with the ground based instrumentation results. Dobson spectrophotometers were used for two of the ground-based instruments. Preliminary data collected during the IORI from Dobson spectrophotometers 72 and 38 are presented. The agreement between the two and the variability of total ozone overburden through the experiment period are discussed.

  15. Heterogeneous nano-Fe/Ca/CaO catalytic ozonation for selective surface hydrophilization of plastics containing brominated and chlorinated flame retardants (B/CFRs): separation from automobile shredder residue by froth flotation.

    Science.gov (United States)

    Mallampati, Srinivasa Reddy; Lee, Byoung Ho; Mitoma, Yoshiharu; Simion, Cristian

    2017-02-01

    One method of weakening the inherently hydrophobic surface of plastics relevant to flotation separation is heterogeneous nano-Fe/Ca/CaO catalytic ozonation. Nano-Fe/Ca/CaO-catalyzed ozonation for 15 min efficiently decreases the surface hydrophobicity of brominated and chlorinated flame retardant (B/CFR)-containing plastics (such as acrylonitrile-butadienestyrene (ABS), high-impact polystyrene (HIPS), and polyvinyl chloride (PVC)) in automobile shredder residue (ASR) to such an extent that their flotation ability is entirely depressed. Such a hydrophilization treatment also stimulates the ABS, HIPS, and PVC surface roughness, wetting of the surface, and the thermodynamic equilibrium conditions at the surface and ultimately changes surface polarity. SEM-EDS, AFM, and XPS analyses of the PVC and ABS surfaces demonstrated a marked decrease in [Cl/Br] and a significant increase in the number of hydrophilic groups, such as C-O, C=O, and (C=O)-O. Under froth flotation conditions at 50 rpm, about 99.5 % of ABS and 99.5 % of HIPS in ASR samples settled out, resulting in a purity of 98 and 98.5 % for ABS and HIPS in ASR samples, respectively. Furthermore, at 150 rpm, we also obtained 100 % PVC separation in the settled fraction, with 98 % purity in ASR. Total recovery of non-B/CFR-containing plastics reached nearly 100 % in the floating fraction. The amount of nano-Fe/Ca/CaO reagent employed during ozonation is very small, and additional removal of surface contaminants from the recycled ASR plastic surfaces by ozonation makes the developed process simpler, greener, and more effective.

  16. Impact of ambient and elevated levels of ozone on growth, reproductive development and yield of two cultivars of rice ( Oryza sativa L.)

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, S. B.; Abhijit, S.

    2009-07-01

    Tow locally grown high yielding varieties of rice (Oryza sativa L. var Malviya dhan 36 and var shivani), were transplanted within the open top chambers (OTCs) at the age of 20 days. five different experimental plots were designed as open plot (OP), non-filtered chamber (NFCs), NFCs with 10 ppb ozone (O{sub 3}), NFCs with 30 ppb O{sub 3} and filtered chamber (FCs) to assess the impact of ambient and elevated levels of O{sub 3} on rice. Twelve hourly monitoring of O{sub 3} and measurements of meteorological variables were done at experimental site during the growth period of rice plants. Morphological, reproductive, physico logical and biochemical parameters were assessed to evaluate the responses of rice cultivars to ambient and elevated levels of O{sub 3}. (Author)

  17. Ozone decay in chemical reactor for ozone-dynamical disintegration of used tyres

    International Nuclear Information System (INIS)

    Golota, V.I.; Manuilenko, O.V.; Taran, G.V.; Dotsenko, Yu.V.; Pismenetskii, A.S.; Zamuriev, A.A.; Benitskaja, V.A.

    2011-01-01

    The ozone decay kinetics in the chemical reactor intended for used tyres disintegration is investigated experimentally and theoretically. Ozone was synthesized in barrierless ozonizers based on the streamer discharge. The chemical reactor for tyres disintegration in the ozone-air environment represents the cylindrical chamber, which feeds from the ozonizer by ozone-air mixture with the specified rate of volume flow, and with known ozone concentration. The output of the used mixture, which rate of volume flow is also known, is carried out through the ozone destructor. As a result of ozone decay in the volume and on the reactor walls, and output of the used mixture from the reactor, the ozone concentration in the reactor depends from time. In the paper, the analytical expression for dependence of ozone concentration in the reactor from time and from the parameters of a problem such as the volumetric feed rate, ozone concentration on the input in the reactor, volume flow rate of the used mixture, the volume of the reactor and the area of its internal surface is obtained. It is shown that experimental results coincide with good accuracy with analytical ones.

  18. [The relationship between the ozone layer and skin cancer].

    Science.gov (United States)

    Sánchez C, Francisca

    2006-09-01

    In the recent decades, a sustained increase in the worldwide incidence of skin cancer has been observed and Chile is not the exception. The most important risk factor is the exaggerated and repeated exposure to ultraviolet radiation coming from the sun. The ozone layer restricts the transmission of type B and C ultraviolet light. Since 1980, a sustained depletion of stratospheric ozone levels is occurring, specially in middle latitudes (-30 to -60). Along with this depletion, the amount of ultraviolet light that reaches the earth surface is increasing. This article reviews some basic concepts about the ozone layer and the association between its depletion and skin cancer. The general population should be informed about the risks of inadequate and exaggerated exposure to sunlight.

  19. Low modeled ozone production suggests underestimation of precursor emissions (especially NOx) in Europe

    OpenAIRE

    Oikonomakis, Emmanouil; Aksoyoglu, Sebnem; Ciarelli, Giancarlo; Baltensperger, Urs; Prévôt, André Stephan Henry

    2018-01-01

    High surface ozone concentrations, which usually occur when photochemical ozone production takes place, pose a great risk to human health and vegetation. Air quality models are often used by policy makers as tools for the development of ozone mitigation strategies. However, the modeled ozone production is often not or not enough evaluated in many ozone modeling studies. The focus of this work is to evaluate the modeled ozone production in Europe indirectly, with the use of t...

  20. The Antarctic Ozone Hole

    Science.gov (United States)

    Jones, Anna E.

    2008-01-01

    Since the mid 1970s, the ozone layer over Antarctica has experienced massive destruction during every spring. In this article, we will consider the atmosphere, and what ozone and the ozone layer actually are. We explore the chemistry responsible for the ozone destruction, and learn about why conditions favour ozone destruction over Antarctica. For…

  1. Contributors to ozone episodes in three US/Mexico border twin-cities.

    Science.gov (United States)

    Shi, Chune; Fernando, H J S; Yang, Jie

    2009-09-01

    The Process Analysis tools of the Community Multiscale Air Quality (CMAQ) modeling system together with back-trajectory analysis were used to assess potential contributors to ozone episodes that occurred during June 1-4, 2006, in three populated U.S.-Mexico border twin cities: San Diego/Tijuana, Imperial/Mexicali and El Paso/Ciudad Juárez. Validation of CMAQ output against surface ozone measurements indicates that the predictions are acceptable with regard to commonly recommended statistical standards and comparable to other reported studies. The mean normalized bias test (MNBT) and mean normalized gross error (MNGE) for hourly ozone fall well within the US EPA suggested range of +/-15% and 35%, respectively, except MNBT for El Paso. The MNBTs for maximum 8-h average ozone are larger than those for hourly ozone, but all the simulated maximum 8-h average ozone are within a factor of 2 of those measured in all three regions. The process and back-trajectory analyses indicate that the main sources of daytime ground-level ozone are the local photochemical production and regional transport. By integrating the effects of each process over the depth of the daytime planetary boundary layer (PBL), it is found that in the San Diego area (SD), chemistry and vertical advection contributed about 36%/48% and 64%/52% for June 2 and 3, respectively. This confirms the previous finding that high-altitude regional transport followed by fumigation contributes significantly to ozone in SD. The back-trajectory analysis shows that this ozone was mostly transported from the coastal area of southern California. For the episodes in Imperial Valley and El Paso, respectively, ozone was transported from the coastal areas of southern California and Mexico and from northern Texas and Oklahoma.

  2. Ozone Effect On the Properties of Aramid Fabric

    Directory of Open Access Journals (Sweden)

    Wang Yan

    2017-06-01

    Full Text Available The limitation of aramid fiber is its surface property, which results in its very poor interfacial adhesion to most of commercial resins. In order to improve the surface property of the aramid fiber, ozone treatment was carried out in this work. The aramid fabrics were evaluated in terms of surface morphology, wicking effect, tensile property, and ball bursting test. The results showed that the surface morphology of aramid fabrics did not undergo an obvious change; the wicking effect increased slightly with an increase in ozone treatment time; the tenacity and elongation of aramid fibers and fabrics did not significant change after ozone treatment, but the tenacity and elongation of aramid yarns showed significant improvement after ozone treatment, and increased with the increase of ozone treatment time; the ball bursting load and penetration displacement had a slight increase as well after ozone treatment. Therefore, ozone treatment could be one method to improve the surface property of the aramid fiber.

  3. Ab initio surface core-level shifts and surface segregation energies

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1993-01-01

    We have calculated the surface core-level energy shifts of the 4d and 5d transition metals by means of local-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method. Final-state effects are included by treating the core-ionized atom as an impurity located...

  4. Matrix elements for level shifts and widths of hydrogenic levels in ion-surface interactions

    Energy Technology Data Exchange (ETDEWEB)

    Thumm, U.; Kuerpick, P.

    1996-05-01

    The authors present a derivation of basic one-electron matrix elements involved in the ion-metal surface scattering theory. Their method allows for the convenient generation of matrix elements for high principal quantum numbers of the projectile states and thus provides basic building blocks for the ab-initio description of highly charged ion-surface interactions. The matrix elements related to the energy shifts can be evaluated for an arbitrary one-dimensional potential therefore allowing the inclusion of electronic and nuclear self-image potentials. The authors extend these concepts to wave functions generated from an arbitrary one-dimensional surface potential and show applications to various surface potentials, projectile nuclear charges and hydrogenic levels.

  5. Radiative effects of ozone on the climate of a Snowball Earth

    Directory of Open Access Journals (Sweden)

    J. Yang

    2012-12-01

    Full Text Available Some geochemical and geological evidence has been interpreted to suggest that the concentration of atmospheric oxygen was only 1–10 % of the present level in the time interval from 750 to 580 million years ago when several nearly global glaciations or Snowball Earth events occurred. This low concentration of oxygen would have been accompanied by a lower ozone concentration than exists at present. Since ozone is a greenhouse gas, this change in ozone concentration would alter surface temperature, and thereby could have an important influence on the climate of the Snowball Earth. Previous works that have focused either on initiation or deglaciation of the proposed Snowball Earth has not taken the radiative effects of ozone changes into account. We address this issue herein by performing a series of simulations using an atmospheric general circulation model with various ozone concentrations.

    Our simulation results demonstrate that, as ozone concentration is uniformly reduced from 100 % to 50 %, surface temperature decreases by approximately 0.8 K at the Equator, with the largest decreases located in the middle latitudes reaching as high as 2.5 K. When ozone concentration is reduced and its vertical and horizontal distribution is simultaneously modulated, surface temperature decreases by 0.4–1.0 K at the Equator and by 4–7 K in polar regions. These results here have uncertainties, depending on model parameterizations of cloud, surface snow albedo, and relevant feedback processes, while they are qualitatively consistent with radiative-convective model results that do not involve such parameterizations and feedbacks. These results suggest that ozone variations could have had a moderate impact on the climate during the Neoproterozoic glaciations.

  6. High Concentrations of Ozone Air Pollution on Mount Everest: Health Implications for Sherpa Communities and Mountaineers.

    Science.gov (United States)

    Semple, John L; Moore, G W Kent; Koutrakis, Petros; Wolfson, Jack M; Cristofanelli, Paolo; Bonasoni, Paolo

    2016-12-01

    Semple, John L., G.W. Kent Moore, Petros Koutrakis, Jack M. Wolfson, Paolo Cristofanelli, and Paolo Bonasoni. High concentrations of ozone air pollution on Mount Everest: health implications for Sherpa communities and mountaineers. High Alt Med Biol. 17:365-369, 2016.-Introduction: Populations in remote mountain regions are increasingly vulnerable to multiple climate mechanisms that influence levels of air pollution. Few studies have reported on climate-sensitive health outcomes unique to high altitude ecosystems. In this study, we report on the discovery of high-surface ozone concentrations and the potential impact on health outcomes on Mount Everest and the high Himalaya. Surface ozone measurements were collected during ascending transects in the Mount Everest region of Nepal with passive nitrite-coated Ogawa filter samplers to obtain 8-hour personal exposures (2860-5364 m asl). In addition, the Nepal Climate Observatory-Pyramid, a GAW-WMO Global Station sited in the Khumbu Valley (5079 m asl), collected ozone mixing ratios with photometric gas analyzer. Surface ozone measurements increased with altitude with concentrations that exceed 100 ppb (8-hour exposure). Highest values were during the spring season and the result of diverse contributions: hemispheric background values, the descent of ozone-rich stratospheric air, and the transport of tropospheric pollutants occurring at different spatial scales. Multiple climate factors, including descending stratospheric ozone and imported anthropogenic air masses from the Indo-Gangetic Plain, contribute to ambient ozone exposure levels in the vicinity of Mount Everest that are similar to if not higher than those reported in industrialized cities.

  7. Ozone Enhances Pulmonary Innate Immune Response to a Toll-Like Receptor–2 Agonist

    Science.gov (United States)

    Oakes, Judy L.; O’Connor, Brian P.; Warg, Laura A.; Burton, Rachel; Hock, Ashley; Loader, Joan; LaFlamme, Daniel; Jing, Jian; Hui, Lucy; Schwartz, David A.

    2013-01-01

    Previous work demonstrated that pre-exposure to ozone primes innate immunity and increases Toll-like receptor–4 (TLR4)–mediated responses to subsequent stimulation with LPS. To explore the pulmonary innate immune response to ozone exposure further, we investigated the effects of ozone in combination with Pam3CYS, a synthetic TLR2/TLR1 agonist. Whole-lung lavage (WLL) and lung tissue were harvested from C57BL/6 mice after exposure to ozone or filtered air, followed by saline or Pam3CYS 24 hours later. Cells and cytokines in the WLL, the surface expression of TLRs on macrophages, and lung RNA genomic expression profiles were examined. We demonstrated an increased WLL cell influx, increased IL-6 and chemokine KC (Cxcl1), and decreased macrophage inflammatory protein (MIP)-1α and TNF-α in response to Pam3CYS as a result of ozone pre-exposure. We also observed the increased cell surface expression of TLR4, TLR2, and TLR1 on macrophages as a result of ozone alone or in combination with Pam3CYS. Gene expression analysis of lung tissue revealed a significant increase in the expression of genes related to injury repair and the cell cycle as a result of ozone alone or in combination with Pam3CYS. Our results extend previous findings with ozone/LPS to other TLR ligands, and suggest that the ozone priming of innate immunity is a general mechanism. Gene expression profiling of lung tissue identified transcriptional networks and genes that contribute to the priming of innate immunity at the molecular level. PMID:23002100

  8. Effects of argon sputtering and UV-ozone radiation on the physico-chemical surface properties of ITO

    Science.gov (United States)

    Che, Hui; El Bouanani, M.

    2018-01-01

    X-ray photoelectron spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS) were used to evaluate and determine the effects of 1 KeV Ar+ irradiation (sputtering) on the surface chemical composition and work function of Indium Thin Oxide (ITO). While Ar+ sputtering removes carbon-based surface contaminants, it also modifies the Sn-rich surface of ITO and leads to a reduction of the oxidation state of Sn from Sn4+ to Sn2+. The decrease in the work function of ITO is directly correlated to the decrease of Sn atomic concentration in the Sn-rich top surface layer and the reduction of the oxidation state of surface Sn.

  9. Surface core-level shifts for simple metals

    DEFF Research Database (Denmark)

    Aldén, Magnus; Skriver, Hans Lomholt; Johansson, Börje

    1994-01-01

    We have performed an ab initio study of the surface core-level binding energy shift (SCLS) for 11 of the simple metals by means of a Green’s-function technique within the tight-binding linear-muffin-tin-orbitals method. Initial- and final-state effects are included within the concept of complete....... We furthermore conclude that the unexpected negative sign of the SCLS in beryllium is predominantly an initial-state effect and is caused by the high electron density in this metal....

  10. Development of Compact Ozonizer with High Ozone Output by Pulsed Power

    Science.gov (United States)

    Tanaka, Fumiaki; Ueda, Satoru; Kouno, Kanako; Sakugawa, Takashi; Akiyama, Hidenori; Kinoshita, Youhei

    Conventional ozonizer with a high ozone output using silent or surface discharges needs a cooling system and a dielectric barrier, and therefore becomes a large machine. A compact ozonizer without the cooling system and the dielectric barrier has been developed by using a pulsed power generated discharge. The wire to plane electrodes made of metal have been used. However, the ozone output was low. Here, a compact and high repetition rate pulsed power generator is used as an electric source of a compact ozonizer. The ozone output of 6.1 g/h and the ozone yield of 86 g/kWh are achieved at 500 pulses per second, input average power of 280 W and an air flow rate of 20 L/min.

  11. Ozone kinetics in low-pressure discharges

    Science.gov (United States)

    Guerra, Vasco; Marinov, Daniil; Guaitella, Olivier; Rousseau, Antoine

    2012-10-01

    Ozone kinetics is quite well established at atmospheric pressure, due to the importance of ozone in atmospheric chemistry and to the development of industrial ozone reactors. However, as the pressure is decreased and the dominant three-body reactions lose importance, the main mechanisms involved in the creation and destruction of ozone are still surrounded by important uncertainties. In this work we develop a self-consistent model for a pulsed discharge and its afterglow operating in a Pyrex reactor with inner radius 1 cm, at pressures in the range 1-5 Torr and discharge currents of 40-120 mA. The model couples the electron Boltzmann equation with a system of equations for the time evolution of the heavy particles. The calculations are compared with time-dependent measurements of ozone and atomic oxygen. Parametric studies are performed in order to clarify the role of vibrationally excited ozone in the overall kinetics and to establish the conditions where ozone production on the surface may become important. It is shown that vibrationally excited ozone does play a significant role, by increasing the time constants of ozone formation. Moreover, an upper limit for the ozone formation at the wall in these conditions is set at 10(-4).

  12. Ozonation control and effects of ozone on water quality in recirculating aquaculture systems.

    Science.gov (United States)

    Spiliotopoulou, Aikaterini; Rojas-Tirado, Paula; Chhetri, Ravi K; Kaarsholm, Kamilla M S; Martin, Richard; Pedersen, Per B; Pedersen, Lars-Flemming; Andersen, Henrik R

    2018-04-15

    To address the undesired effect of chemotherapeutants in aquaculture, ozone has been suggested as an alternative to improve water quality. To ensure safe and robust treatment, it is vital to define the ozone demand and ozone kinetics of the specific water matrix to avoid ozone overdose. Different ozone dosages were applied to water in freshwater recirculating aquaculture systems (RAS). Experiments were performed to investigate ozone kinetics and demand, and to evaluate the effects on the water quality, particularly in relation to fluorescent organic matter. This study aimed at predicting a suitable ozone dosage for water treatment based on daily ozone demand via laboratory studies. These ozone dosages will be eventually applied and maintained at these levels in pilot-scale RAS to verify predictions. Selected water quality parameters were measured, including natural fluorescence and organic compound concentration changes during ozonation. Ozone reactions were described by first order kinetics. Organic matter, assessed as chemical oxygen demand and fluorescence, decreased by 25% (low O 3 ), 30% (middle O 3 ) and 53% (high O 3 ), while water transmittance improved by 15% over an 8-day period. No fish mortality was observed. Overall, this study confirms that ozone can improve RAS water quality, provides a better understanding of the ozone decay mechanisms that can be used to define further safe ozone treatment margins, and that fluorescence could be used as a monitoring tool to control ozone. This study might be used as a tool to design ozone systems for full-scale RAS by analysing water sample from the specific RAS in the laboratory. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. Dynamics of gas-surface interactions atomic-level understanding of scattering processes at surfaces

    CERN Document Server

    Díez Muniño, Ricardo

    2013-01-01

    This book gives a representative survey of the state of the art of research on gas-surface interactions. It provides an overview of the current understanding of gas surface dynamics and, in particular, of the reactive and non-reactive processes of atoms and small molecules at surfaces. Leading scientists in the field, both from the theoretical and the experimental sides, write in this book about their most recent advances. Surface science grew as an interdisciplinary research area over the last decades, mostly because of new experimental technologies (ultra-high vacuum, for instance), as well as because of a novel paradigm, the ‘surface science’ approach. The book describes the second transformation which is now taking place pushed by the availability of powerful quantum-mechanical theoretical methods implemented numerically. In the book, experiment and theory progress hand in hand with an unprecedented degree of accuracy and control. The book presents how modern surface science targets the atomic-level u...

  14. The signs of Antarctic ozone hole recovery.

    Science.gov (United States)

    Kuttippurath, Jayanarayanan; Nair, Prijitha J

    2017-04-03

    Absorption of solar radiation by stratospheric ozone affects atmospheric dynamics and chemistry, and sustains life on Earth by preventing harmful radiation from reaching the surface. Significant ozone losses due to increases in the abundances of ozone depleting substances (ODSs) were first observed in Antarctica in the 1980s. Losses deepened in following years but became nearly flat by around 2000, reflecting changes in global ODS emissions. Here we show robust evidence that Antarctic ozone has started to recover in both spring and summer, with a recovery signal identified in springtime ozone profile and total column measurements at 99% confidence for the first time. Continuing recovery is expected to impact the future climate of that region. Our results demonstrate that the Montreal Protocol has indeed begun to save the Antarctic ozone layer.

  15. Effects of ozone on crops in north-west Pakistan

    International Nuclear Information System (INIS)

    Ahmad, Muhammad Nauman; Büker, Patrick; Khalid, Sofia; Van Den Berg, Leon; Shah, Hamid Ullah; Wahid, Abdul; Emberson, Lisa; Power, Sally A.; Ashmore, Mike

    2013-01-01

    Although ozone is well-documented to reduce crop yields in the densely populated Indo-Gangetic Plain, there is little knowledge of its effects in other parts of south Asia. We surveyed crops close to the city of Peshawar, in north-west Pakistan, for visible injury, linking this to passive measurements of ozone concentrations. Foliar injury was found on potato, onion and cotton when mean monthly ozone concentrations exceeded 45 ppb. The symptoms on onion were reproduced in ozone fumigation experiments, which also showed that daytime ozone concentrations of 60 ppb significantly reduce the growth of a major Pakistani onion variety. Aphid infestation on spinach was also reduced at these elevated ozone concentrations. The ozone concentrations measured in April–May in Peshawar, and used in the fumigation experiment, are comparable to those that have been modelled to occur over many parts of south Asia, where ozone may be a significant threat to sensitive crops. -- Highlights: ► Visible ozone injury to onion, cotton and potato was identified in north-west Pakistan. ► The symptoms on onion were reproduced by exposure to elevated ozone. ► Elevated ozone levels also significantly reduced onion growth. ► Levels of aphid infestation on spinach were lower under elevated ozone. ► These effects were observed at ozone levels that have been modelled to occur widely across south Asia. -- Ozone concentrations in NW Pakistan have adverse effects on sensitive crop species

  16. Absorption of ozone by porous particles

    Energy Technology Data Exchange (ETDEWEB)

    Afanas' ev, V.P.; Dorofeev, S.B.; Sinitsyn, V.I.; Smirnov, B.M.

    1981-11-01

    The absorption of ozone by porous zeolite, silica gel, and activated carbon particles has been studied experimentally. It was shown that in addition to absorption, dissociation of ozone on the surface plays an important and sometimes decisive role. The results obtained were used to analyze the nature of ball lightning.

  17. Foliar nutrient status of Pinus ponderosa exposed to ozone and acid rain

    International Nuclear Information System (INIS)

    Anderson, P.D.; Houpis, J.L.J.

    1991-01-01

    A direct effect of foliar exposure to acid rain may be increased leaching of nutrient elements. Ozone exposure, through degradation of the cuticle and cellular membranes, may also result in increased nutrient leaching. To test these hypotheses, the foliar concentrations of 13 nutrient elements were monitored for mature branches of three clones of Pinus ponderosa exposed to ozone and/or acid rain. The three clones represented three distinct levels of phenotypic vigor. Branches were exposed to charcoal filtered, ambient, or 2 x ambient concentrations of ozone and received no acid rain (NAP), pH 5.1 rain (5.1), or pH 3.0 (3.0) rain. Following 10 months of continuous ozone exposure and 3 months of weekly rain applications, the concentrations of P and Mg differed significantly among rain treatments with a ranking of: 5.1 < NAP < 3.0. The S concentration increased with rain application regardless of pH. For the clones of moderate and low vigor, the concentration of N decreased with increasing rain acidity. There was no evidence of significant ozone or ozone x acid rain response. Among the three families, high phenotypic vigor was associated with significantly greater concentrations of N, P, K, Mg, B and An. These results indicate generally negligible leaching as a result of exposure to acid rain and/or ozone for one growing season. Increases in foliar concentrations of S, Mg and P are possibly the result of evaporative surface deposition from the rain solution

  18. Extensive halogen-mediated ozone destruction over the tropical Atlantic Ocean.

    Science.gov (United States)

    Read, Katie A; Mahajan, Anoop S; Carpenter, Lucy J; Evans, Mathew J; Faria, Bruno V E; Heard, Dwayne E; Hopkins, James R; Lee, James D; Moller, Sarah J; Lewis, Alastair C; Mendes, Luis; McQuaid, James B; Oetjen, Hilke; Saiz-Lopez, Alfonso; Pilling, Michael J; Plane, John M C

    2008-06-26

    Increasing tropospheric ozone levels over the past 150 years have led to a significant climate perturbation; the prediction of future trends in tropospheric ozone will require a full understanding of both its precursor emissions and its destruction processes. A large proportion of tropospheric ozone loss occurs in the tropical marine boundary layer and is thought to be driven primarily by high ozone photolysis rates in the presence of high concentrations of water vapour. A further reduction in the tropospheric ozone burden through bromine and iodine emitted from open-ocean marine sources has been postulated by numerical models, but thus far has not been verified by observations. Here we report eight months of spectroscopic measurements at the Cape Verde Observatory indicative of the ubiquitous daytime presence of bromine monoxide and iodine monoxide in the tropical marine boundary layer. A year-round data set of co-located in situ surface trace gas measurements made in conjunction with low-level aircraft observations shows that the mean daily observed ozone loss is approximately 50 per cent greater than that simulated by a global chemistry model using a classical photochemistry scheme that excludes halogen chemistry. We perform box model calculations that indicate that the observed halogen concentrations induce the extra ozone loss required for the models to match observations. Our results show that halogen chemistry has a significant and extensive influence on photochemical ozone loss in the tropical Atlantic Ocean boundary layer. The omission of halogen sources and their chemistry in atmospheric models may lead to significant errors in calculations of global ozone budgets, tropospheric oxidizing capacity and methane oxidation rates, both historically and in the future.

  19. Reconciliation of Halogen-Induced Ozone Loss with the Total-Column Ozone Record

    Science.gov (United States)

    Shepherd, T. G.; Plummer, D. A.; Scinocca, J. F.; Hegglin, M. I.; Fioletov, V. E.; Reader, M. C.; Remsberg, E.; von Clarmann, T.; Wang, H. J.

    2014-01-01

    The observed depletion of the ozone layer from the 1980s onwards is attributed to halogen source gases emitted by human activities. However, the precision of this attribution is complicated by year-to-year variations in meteorology, that is, dynamical variability, and by changes in tropospheric ozone concentrations. As such, key aspects of the total-column ozone record, which combines changes in both tropospheric and stratospheric ozone, remain unexplained, such as the apparent absence of a decline in total-column ozone levels before 1980, and of any long-term decline in total-column ozone levels in the tropics. Here we use a chemistry-climate model to estimate changes in halogen-induced ozone loss between 1960 and 2010; the model is constrained by observed meteorology to remove the eects of dynamical variability, and driven by emissions of tropospheric ozone precursors to separate out changes in tropospheric ozone. We show that halogen-induced ozone loss closely followed stratospheric halogen loading over the studied period. Pronounced enhancements in ozone loss were apparent in both hemispheres following the volcanic eruptions of El Chichon and, in particular, Mount Pinatubo, which significantly enhanced stratospheric aerosol loads. We further show that approximately 40% of the long-term non-volcanic ozone loss occurred before 1980, and that long-term ozone loss also occurred in the tropical stratosphere. Finally, we show that halogeninduced ozone loss has declined by over 10% since stratospheric halogen loading peaked in the late 1990s, indicating that the recovery of the ozone layer is well underway.

  20. Pulmonary biochemical alterations resulting from ozone exposure

    Energy Technology Data Exchange (ETDEWEB)

    Mustafa, M.G.; Lee, S.D.

    1976-07-01

    Metabolic response of lung tissue to ozone was studied in rats and monkeys after exposure of animals to various levels of ozone (0.1 to 0.8 ppM) for 1 to 30 days. In rats, 0.8 ppM ozone exposure resulted in a 40 to 50 percent augmentation of oxygen utilization in lung homogenate in the presence of an added substrate (e.g., succinate or 2-oxoglutarate). Activities of marker enzymes, viz. mitochondrial succinate-cytochrome c reductase; microsomal NADPH-cytochrome c reductase and cytosolic glucose-6-phosphate dehydrogenase, increased maximally (40 to 70 percent over control) after 3 to 4 days of exposure, and remained elevated throughout the 0.8 ppM ozone exposure for 30 days. In monkeys, the observations were the same except that the magnitude of biochemical changes was relatively smaller. Exposure of animals to lower levels of ozone resulted in proportionately smaller biochemical changes in the lung, and ozone effects were detectable up to the 0.2 ppM level. While 0.1 ppM ozone exposure was ineffective, dietary deficiency of vitamin E, a natural antioxidant, increased the sensitivity of rat lungs to this concentration of ozone. The results suggest that low-level ozone exposures may cause metabolic alterations in the lung, and that dietary supplementation of vitamin E may offer protection against oxidant stress.

  1. Processes Influencing Ozone Levels in Alaskan Forest Fires Plumes during Long-Range Transport over the North Atlantic

    Science.gov (United States)

    Real, E.; Law, K. S.; Wienzierl, B.; Fiebig, M.; Petzold, A.; Wild, O.; Methven, J.; Arnold, S.; Stohl, A.; Huntrieser, H.; hide

    2006-01-01

    well reproduced by multiple model runs even if slope values are slightly underestimated suggesting small underestimation of photochemical processes. The possible impact of this biomass burning plume on O3 levels in the Europe boundary layer is also examined by running the model for a further 5 days, and comparing with data collected at surface sites, such as Jungfraujoch, which showed small O3 increases and elevated CO levels. The model predicts significant changes in O3 over this 10 days due to photochemistry but the signal is largely lost due to the effects of dilution. However, measurement in several others BB plumes over Europe show that O3 impact of Alaskan fires can be punctually significant over Europe.

  2. Numerical simulation for regional ozone concentrations: A case study by weather research and forecasting/chemistry (WRF/Chem) model

    Energy Technology Data Exchange (ETDEWEB)

    Habib Al Razi, Khandakar Md; Hiroshi, Moritomi [Environmental and Renewable Energy System, Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu City, 501-1193 (Japan)

    2013-07-01

    The objective of this research is to better understand and predict the atmospheric concentration distribution of ozone and its precursor (in particular, within the Planetary Boundary Layer (Within 110 km to 12 km) over Kasaki City and the Greater Tokyo Area using fully coupled online WRF/Chem (Weather Research and Forecasting/Chemistry) model. In this research, a serious and continuous high ozone episode in the Greater Tokyo Area (GTA) during the summer of 14–18 August 2010 was investigated using the observation data. We analyzed the ozone and other trace gas concentrations, as well as the corresponding weather conditions in this high ozone episode by WRF/Chem model. The simulation results revealed that the analyzed episode was mainly caused by the impact of accumulation of pollution rich in ozone over the Greater Tokyo Area. WRF/Chem has shown relatively good performance in modeling of this continuous high ozone episode, the simulated and the observed concentrations of ozone, NOx and NO2 are basically in agreement at Kawasaki City, with best correlation coefficients of 0.87, 0.70 and 0.72 respectively. Moreover, the simulations of WRF/Chem with WRF preprocessing software (WPS) show a better agreement with meteorological observations such as surface winds and temperature profiles in the ground level of this area. As a result the surface ozone simulation performances have been enhanced in terms of the peak ozone and spatial patterns, whereas WRF/Chem has been succeeded to generate meteorological fields as well as ozone, NOx, NO2 and NO.

  3. The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China.

    Directory of Open Access Journals (Sweden)

    Jingxin Xu

    Full Text Available Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L. at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb, Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb, and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb, with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system. These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R(2 = 0.85 & T2: R(2 = 0.89 of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m(-2 of cumulative ozone uptake. At the regional level, dry matter

  4. The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China.

    Science.gov (United States)

    Xu, Jingxin; Zheng, Youfei; He, Yuhong; Wu, Rongjun; Mai, Boru; Kang, Hanqing

    2016-01-01

    Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L.) at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb), Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb), and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb), with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system). These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R(2) = 0.85 & T2: R(2) = 0.89) of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m(-2) of cumulative ozone uptake. At the regional level, dry matter loss in winter

  5. Structural changes in wood during ozonation

    Science.gov (United States)

    Ben'ko, E. M.; Manisova, O. R.; Murav'eva, G. P.; Lunin, V. V.

    2013-07-01

    It is found that ozone treatment of aspen wood leads to changes in its structural characteristics, i.e., its specific surface area and the crystallinity index of cellulose. Using optical microscopy, it is shown that ozonation is accompanied by a decrease in the average size and visible surface of wood particles. The values for the specific area of the outer surface of samples are calculated. The specific surface area available to the enzyme molecules is determined from data on the adsorption of inert protein hemoglobin on wood. It is shown that this value is an order of magnitude higher than that of the outer surface and increases considerably for an ozonized sample. Based on the results from X-ray analysis, it is established that the structure of cellulose is disordered during ozone delignification, as is indicated by a reduction in the crystallinity index and crystallite sizes.

  6. The influences of pepsin concentrations and pH levels on the disinfective activity of ozone nanobubble water against helicobacter pylori.

    Science.gov (United States)

    Kawara, Fumiaki; Inoue, Jun; Takenaka, Mamoru; Hoshi, Namiko; Masuda, Atsuhiro; Nishiumi, Shin; Kutsumi, Hiromu; Azuma, Takeshi; Ohdaira, Takeshi

    2014-01-01

    To investigate the utility of ozone nanobubble water (NBW3) for the treatment of Helicobacter pylori in the stomach, we tested the influence of pepsin concentrations and pH levels on the disinfective activity of NBW3, and the cytotoxicity of NBW3 against mammalian cells and mucosa. Different concentrations of pepsin were dissolved in NBW3, and the bactericidal activity was tested on H. pylori. NBW3 was adjusted to different pH levels (2.0-7.4) and the bactericidal activity on H. pylori was also tested. To examine the cytotoxicity of NBW3, AGS cells, human gastric epithelial cells, were treated with NBW3 and the viability of the cells was evaluated in vitro. Furthermore, NBW3 was administered to mice and gastric mucosal damage was evaluated by histology. Pepsin reduced the disinfective activity of NBW3 on H. pylori in a pepsin concentration-dependent manner. NBW3 showed stable disinfective activity at all pH levels examined. Cytotoxicity of NBW3 against human gastric epithelial cells and gastric mucosa was not observed in our experimental setting. NBW3 can sustain its disinfective activity in wide range of pH levels and show no cytotoxicity on mammalian cells and tissue. Pepsin can inhibit NBW3 activity in a dose-dependent manner. © 2014 S. Karger AG, Basel.

  7. BAERLIN2014 – the influence of land surface types on and the horizontal heterogeneity of air pollutant levels in Berlin

    Directory of Open Access Journals (Sweden)

    B. Bonn

    2016-06-01

    -wise measurement of volatile organic compounds (VOCs at representative sites for traffic- and vegetation-affected sites. The quantification displayed notable horizontal heterogeneity of the short-lived gases and particle number concentrations. For example, baseline concentrations of the traffic-related chemical species CO and NO varied on average by up to ±22.2 and ±63.5 %, respectively, on the scale of 100 m around any measurement location. Airborne observations revealed the dominant source of elevated urban particulate number and mass concentrations being local, i.e., not being caused by long-range transport. Surface-based observations related these two parameters predominantly to traffic sources. Vegetated areas lowered the pollutant concentrations substantially with ozone being reduced most by coniferous forests, which is most likely caused by their reactive biogenic VOC emissions. With respect to the overall potential to reduce air pollutant levels, forests were found to result in the largest decrease, followed by parks and facilities for sports and leisure. Surface temperature was generally 0.6–2.1 °C lower in vegetated regions, which in turn will have an impact on tropospheric chemical processes. Based on our findings, effective future mitigation activities to provide a more sustainable and healthier urban environment should focus predominantly on reducing fossil-fuel emissions from traffic as well as on increasing vegetated areas.

  8. A COUPLED LAND-SURFACE AND DRY DEPOSITION MODEL AND COMPARIS