Search results for "Ozone"

2009

Abstract. The emission of nitric oxide (NO) by soils (SNOx) is an important source of oxides of nitrogen (NOx=NO+NO2) in the troposphere, with estimates ranging from 4 to 21 Tg of nitrogen per year. Previous studies have examined the influence of SNOx on ozone (O3) chemistry. We employ the ECHAM5/MESSy atmospheric chemistry model (EMAC) to go further in the reaction chain and investigate the influence of SNOx on lower tropospheric NOx, O3, peroxyacetyl nitrate (PAN), nitric acid (HNO3), the hydroxyl radical (OH) and the lifetime of methane (τCH4). We show that SNOx is responsible for a significant contribution to the NOx mixing ratio in many regions, especially in the tropics. Furthermore, …

Dependence on collision energy of the stereodynamical properties of the 18O + 32O2 exchange reaction

2018

We report a quantum stereodynamical study of the 18O + 16O16O(v = 0, j = 1) → 18O16O(v′ = 0, j′) + 16O oxygen exchange reaction at four different collision energies. We calculated the polarisation ...

Quantum mechanical study of the 16O + 18O18O → 16O18O + 18O exchange reaction: Integral cross sections and rate constants

2018

The isotopic exchange reaction, 16O + 18O18O → 16O18O + 18O, involving excited ozone, O3*, as intermediate complex, was investigated by means of a time independent quantum mechanical approach using the TKTHS potential energy surface (PES) [V. G. Tyuterev et al., J. Chem. Phys. 139, 134307 (2013)] of ozone. State-to-state integral cross sections were calculated for collision energies lower than 0.4 eV. Then specific and thermal rate constants were computed between 10 K and 350 K using these cross sections. The full quantum thermal rate constant is found to be in better agreement with the most recent experimental data than with previous studies where other O3 PESs were employed, confirming th…

Do current levels of UV‐B radiation affect vegetation? The importance of long‐term experiments

2021

Physiological,anatomical and biomass partitioning responses to ozone in the Mediterranean endemic plant Lamottea dianae

2011

Ozone effects on the perennial forb Lamottea dianae were studied in an open-top chamber experiment. Ozone was found to induce reductions in CO 2 assimilation and water use efficiency in the leaves of this species. These reductions were mainly related to a decline in the in vivo CO 2 fixation capacity of Rubisco (V c,max), rather than to stomatal limitations or photoinhibitory damage (F v:F m). In addition to chloroplast degeneration, other observed effects were callose accumulation, formation of pectinaceous wart-like cell wall exudates and phloem alterations. Moreover, ozone exposure significantly reduced root dry biomass. The possible relevance of these adverse effects for Mediterranean f…

Biogeography of the Pleistocene pleniglacial malacofaunas in Europe. Stratigraphic and climatic implications

1990

Abstract As determined by Lozek, malacological associations are significant of a particular vegetal environment. In Quaternary sequences, different types of associations are recognized which can be assimilated to the present types of malacofaunas. There are associations of grass group, of forest group and of the ecotone of these two biogeographical entities. On the European scale, in Pleistocene sequences, the interglacial faunas indicate similarly the same differences as today, being of stratigraphic interest. On the contrary, pleniglacial faunas, which are mainly preserved in the loess belt, seemed not interesting for stratigraphy since they indicate more generalized and more homogeneous …

The combined effect of CO2, ozone, and drought on the radical scavenging system of young oak trees (Quercus petraea) — A phytothron study

1998

In order to study the combined effects of CO 2 , ozone, and drought, we simulated in a controlled environment the climatic conditions of a German oak stand with high ozone (daytime: 80 ppb, control: 20 ppb) during one vegetative period under a regime of low and high CO 2 concentration (370 vs 720 ppm) and drought (4 weeks < -800 hPa). To investigate the effects of CO 2 , ozone and drought on the radical scavenging system, we monitored the level of glutathione, ascorbate, and α-tocopherol. However, it is important that, under the regime of elevated CO 2 , the antioxidative behaviour of glutathione and ascorbate appears to be masked by their function as storage molecules for sulfur or carbon.

Similar Effects of Ozone on Four Cultivars of Lettuce in Open Top Chambers During Winter

2002

Ozone is the major phytotoxic air pollutant that reduces the yield of several agricultural crops in the Spanish Mediterranean area. We studied four lettuce cultivars (Lactuca sativa L.) for the effects of different O3 concentrations during the winter on chlorophyll (Chl) a fluorescence, lipid peroxidation, and root length in outdoor open-top chambers. Under O3 the photosynthetic quantum conversion declined while heat emissions increased in all cultivars; these results provide more evidence of non-filtered air with additional ozone (NFA+O3) treatment compared with non-filtered air (NFA) and charcoal filtered ozone-free air (CFA). Changes in the Chl a fluorescence may be associated with an in…

2018

Abstract. As part of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project, an airborne campaign was designed to measure a large range of atmospheric constituents, focusing on the effect of anthropogenic emissions on regional climate. The presented study details results of the French ATR42 research aircraft, which aimed to characterize gas-phase, aerosol and cloud properties in the region during the field campaign carried out in June/July 2016 in combination with the German Falcon 20 and the British Twin Otter aircraft. The aircraft flight paths covered large areas of Benin, Togo, Ghana and Côte d'Ivoire, focusing on emissions from large urban conurbations such …

Environment Exposure to Pollutants

2015

Effects of exposure to welding fume on lung function: results from the German WELDOX study. M. Lehnert, F. Hoffmeyer, K. Gawrych, A. Lotz, E. Heinze, H. Berresheim, R. Merget, V. Harth, R. Van Gelder, J.-U. Hahn, A. Hartwig, T. Weiss, B. Pesch, and T. Bruning, for the WELDOX Study Group Disability-Adjusted Life Years in the Assessment of Health Effects of Traffic-Related Air Pollution. L. Adamkiewicz, A.J. Badyda, A. Gayer, and D. Mucha Impact of Traffic-Related Air Pollution on Health. J. Jakubiak-Lasocka, J. Lasocki, R. Siekmeier, and Z. Chlopek Traffic-related air pollution and respiratory tract efficiency. A.J. Badyda, P. Dabrowiecki, P.O. Czechowski, G. Majewski, and A. Doboszynska Dif…