Long-range ozone transport and its impact on respiratory and cardiovascular health in the north of Portugal

Ozone dynamics depend on meteorological characteristics such as wind, radiation, sunshine, air temperature and precipitation. The aim of this study was to determine ozone trajectories along the northern coast of Portugal during the summer months of 2005, when there was a spate of forest fires in the region, evaluating their impact on respiratory and cardiovascular health in the greater metropolitan area of Porto. We investigated the following diseases, as coded in the ninth revision of the International Classification of Diseases: hypertensive disease (codes 401-405); ischemic heart disease (codes 410-414); other cardiac diseases, including heart failure (codes 426-428); chronic obstructive pulmonary disease and allied conditions, including bronchitis and asthma (codes 490-496); and pneumoconiosis and other lung diseases due to external agents (codes 500-507). We evaluated ozone data from air quality monitoring stations in the study area, together with data collected through HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model analysis of air mass circulation and synoptic-scale zonal wind from National Centers for Environmental Prediction data. High ozone levels in rural areas were attributed to the dispersion of pollutants induced by local circulation, as well as by mesoscale and synoptic scale processes. The fires of 2005 increased the levels of pollutants resulting from the direct emission of gases and particles into the atmosphere, especially when there were incoming frontal systems. For the meteorological case studies analyzed, peaks in ozone concentration were positively associated with higher rates of hospital admissions for cardiovascular diseases, although there were no significant associations between ozone peaks and admissions for respiratory diseases.

Effects of gamma ray bursts in Earth`s biosphere

We continue former work on the modeling of potential effects of Gamma Ray Bursts on Phanerozoic Earth. We focus on global biospheric effects of ozone depletion and model the spectral reduction of light by NO(2) formed in the stratosphere. We also illustrate the current complexities involved in the prediction of how terrestrial ecosystems would respond to this kind of burst. We conclude that more biological field and laboratory data are needed to reach even moderate accuracy in this modeling.

Within-canopy sesquiterpene ozonolysis in Amazonia

Through rapid reactions with ozone, which can initiate the formation of secondary organic aerosols, the emission of sesquiterpenes from vegetation in Amazonia may have significant impacts on tropospheric chemistry and climate. Little is known, however, about sesquiterpene emissions, transport, and chemistry within plant canopies owing to analytical difficulties stemming from very low ambient concentrations, high reactivities, and sampling losses. Here, we present ambient sesquiterpene concentration measurements obtained during the 2010 dry season within and above a primary tropical forest canopy in Amazonia. We show that by peaking at night instead of during the day, and near the ground instead of within the canopy, sesquiterpene concentrations followed a pattern different from that of monoterpenes, suggesting that unlike monoterpene emissions, which are mainly light dependent, sesquiterpene emissions are mainly temperature dependent. In addition, we observed that sesquiterpene concentrations were inversely related with ozone (with respect to time of day and vertical concentration), suggesting that ambient concentrations are highly sensitive to ozone. These conclusions are supported by experiments in a tropical rain forest mesocosm, where little atmospheric oxidation occurs and sesquiterpene and monoterpene concentrations followed similar diurnal patterns. We estimate that the daytime dry season ozone flux of -0.6 to -1.5 nmol m(-2) s(-1) due to in-canopy sesquiterpene reactivity could account for 7%-28% of the net ozone flux. Our study provides experimental evidence that a large fraction of total plant sesquiterpene emissions (46%-61% by mass) undergo within-canopy ozonolysis, which may benefit plants by reducing ozone uptake and its associated oxidative damage.

Ozone formation potentials of volatile organic compounds and ozone sensitivity to their emission in the megacity of Sao Paulo, Brazil

In the present study, a three-dimensional Eulerian photochemical model was employed to estimate the impact that organic compounds have on tropospheric ozone formation in the Metropolitan Area of Sao Paulo (MASP). In the year 2000, base case simulations were conducted in two periods: August 22-24 and March 13-15. Based on the pollutant concentrations calculated by the model, the correlation coefficient relative to observations for ozone ranged from 0.91 to 0.93 in both periods. In the simulations employed to evaluate the ozone potential of individual VOCs, as well as the sensitivity of ozone to the VOC/NO(x) emission ratio, the variation in anthropogenic emissions was estimated at 15% (according to tests performed previously variations of 15% were stable). Although there were significant differences between the two periods, ozone concentrations were found to be much more sensitive to VOCs than to NO(x) in both periods and throughout the study domain. In addition, considering their individual rates of emission from vehicles, the species/classes that were most important for ozone formation were as follows: aromatics with a kOH>2x 10(4) ppm(-1) min(-1); olefins with a kOH 7 x 10(4) ppm(-1) min(-1); olefins with a kOH 7 x 10(4) ppm(-1) min(-1); ethene; and formaldehyde, which are the principal species related to the production, transport, storage and combustion of fossil fuels.

Anthocyanins and tannins in ozone-fumigated guava trees

Psidium guajava ""Paluma"", a tropical tree species, is known to be an efficient ozone indicator in tropical countries. When exposed to ozone, this species displays a characteristic leaf injury identified by inter-veinal red stippling on adaxial leaf surfaces. Following 30 days of three ozone treatments consisting of carbon filtered air (CF - AOT40 = 17 ppb h), ambient non-filtered air (NF - AOT40 = 542 ppb h) and ambient non-filtered air + 40 ppb ozone (NF + O(3) - AOT40 - 7802 ppb h), the amounts of residual anthocyanins and tannins present in 10 P. guajava (""Paluma"") saplings were quantified. Higher amounts of anthocyanins were found in the NF + O(3) treatment (1.6%) when compared to the CF (0.97%) and NF (1.30%) (p < 0.05), and of total tannins in the NF + O(3) treatment (0.16%) compared to the CIF (0.14%). Condensed tannins showed the same tendency as enhanced amounts. Regression analyses using amounts of tannins and anthocyanins, AOT40 and the leaf injury index (LII), showed a correlation between the leaf injury index and quantities of anthocyanins and total tannins. These results are in accordance with the association between the incidence of red-stippled leaves and ozone polluted environments. (C) 2009 Elsevier Ltd. All rights reserved.

Highly Sensitive Fluorescent Method for the Detection of Cholesterol Aldehydes Formed by Ozone and Singlet Molecular Oxygen

Cholesterol oxidation gives rise to a mixture of oxidized products. Different types of products are generated according to the reactive species being involved. Recently, attention has been focused on two cholesterol aldehydes, 3 beta-hydroxy-5 beta-hydroxy-B-norcholestane-6 beta-carboxyaldehyde (1a) and 3 beta-hydroxy-5-oxo-5,6-secocholestan-6-al (1b). These aldehydes can be generated by ozone-, as well as by singlet molecular oxygen-mediated cholesterol oxidation. It has been suggested that 1b is preferentially formed by ozone and la is preferentially formed by singlet molecular oxygen. In this study we describe the use of 1-pyrenebutyric hydrazine (PBH) as a fluorescent probe for the detection of cholesterol aldehydes. The formation of the fluorescent adduct between la with PBH was confirmed by HPLC-MS/MS. The fluorescence spectra of PBH did not change upon binding to the aldehyde. Moreover, the derivatization was also effective in the absence of an acidified medium, which is critical to avoid the formation of cholesterol aldehydes through Hock cleavage of 5 alpha-hydroperoxycholesterol. In conclusion, PBH can be used as an efficient fluorescent probe for the detection/quantification of cholesterol aldehydes in biological samples. Its analysis by HPLC coupled to a fluorescent detector provides a sensitive and specific way to quantify cholesterol aldehydes in the low femtomol range.

An event of stratospheric air intrusion and its associated secondary surface cyclogenesis over the South Atlantic Ocean

This work presents an analysis of a lowermost stratospheric air intrusion event over the coast of Brazil, which may have been responsible for a secondary surface cyclogenesis over the southwestern Atlantic Ocean. The surface cyclone initiated at 0600 UTC 17 April 1999 in a cold air mass in the rear of a cold front after a primary cyclone developed over the same region. The analysis of the secondary cyclone revealed the presence of lowermost stratospheric air intrusion characterized by anomalous potential vorticity (PV), dry air, and high concentration of ozone in atmospheric column. The system developed on the eastern side of an upper level core of PV anomaly, which induced a cyclonic wind circulation at lower levels and favored the onset of the secondary cyclone. In midlevels (500 hPa), the cutoff low development contributed to reduce the propagation speed of the wave pattern. This feature seemed to (1) allow the low-level cold/dry air to heat/moisten associated with sensible and latent fluxes transferred from the ocean to the atmosphere, which intensified a baroclinic zone parallel to the coast, and (2) contribute to the long duration of the system. The present analysis indicates that this secondary cyclone development could be the result of the coupling between the PV anomaly in the upper levels and low-level air-sea interaction.

Tibouchina pulchra (Cham.) Cogn., a native Atlantic Forest species, as a bio-indicator of ozone: Visible injury

Tibouchina pulchra saplings were exposed to carbon filtered air (CF), ambient non-filtered air (NF) and ambient non-filtered air + 40 ppb ozone (NF + O-3) 8 h per day during two months. The AOT40 values at the end of the experiment were 48, 910 and 12,895 ppb h(-1), respectively, for the three treatments. After 25 days of exposure (AOT40=3871 ppb h(-1)), interveinal red stippling appeared in plants in the NF + O-3 chamber. In the NF chamber, symptoms were observed only after 60 days of exposure (AOT40 = 910 ppb h(-1)). After 60 days, injured leaves per plant corresponded to 19% in NF + O-3 and 1% in the NF treatment; and the average leaf area injured was 7% within the NF + O-3 and 0.2% within the NF treatment. The extent of leaf area injured (leaf injury index) was mostly explained by the accumulated exposure of ozone (r(2) = 0.89; p < 0.05). (C) 2007 Elsevier Ltd. All rights reserved.

Leaf antioxidant fluctuations and growth responses in saplings of Caesalpinia echinata Lam. (brazilwood) under an urban stressing environment

We intended to establish how efficient the leaf antioxidant responses of C. echinata are against oxidative environmental conditions observed in an urban environment and their relations to growth and biomass parameters. Plants were grown for 15 months in four sites: Congonhas and Pinheiros, affected by pollutants from vehicular emissions; Ibirapuera, affected by high O(3) concentrations; and a greenhouse with filtered air. Fifteen plants were quarterly removed from each site for analysis of antioxidants, growth and biomass. Plants growing in polluted sites showed alterations in their antioxidants. They were shorter, had thicker stems and produced less leaf biomass than plants maintained under filtered air. The fluctuations in the levels of antioxidants were significantly influenced by combined effects of climatic and pollution variables. The higher were the antioxidant responses and the concentrations of pollutant markers of air contamination in each site the slower were the growth and biomass production. (C) 2009 Elsevier Inc. All rights reserved.

The genotoxic effects of DNA lesions induced by artificial UV-radiation and sunlight

Solar radiation sustains and affects all life forms on Earth. The increase in solar UV-radiation at environmental levels, due to depletion of the stratospheric ozone layer, highlights serious issues of social concern. This becomes still more dramatic in tropical and subtropical regions where radiation-intensity is still higher. Thus, there is the need to evaluate the harmful effects of solar UV-radiation on the DNA molecule as a basis for assessing the risks involved for human health, biological productivity and ecosystems. In order to evaluate the profile of DNA damage induced by this form of radiation and its genotoxic effects, plasmid DNA samples were exposed to artificial-UV lamps and directly to sunlight. The induction of cyclobutane pyrimidine dimer photoproducts (CPDs) and oxidative DNA damage in these molecules were evaluated by means of specific DNA repair enzymes. On the other hand, the biological effects of such lesions were determined through the analysis of the DNA inactivation rate and mutation frequency, after replication of the damaged pCMUT vector in an Escherichia coli MBL50 strain. The results indicated the induction of a significant number of CPDs after exposure to increasing doses of UVC, UVB, UVA radiation and sunlight. Interestingly, these photoproducts are those lesions that better correlate with plasmid inactivation as well as mutagenesis, and the oxidative DNA damages induced present very low correlation with these effects. The results indicated that DNA photoproducts play the main role in the induction of genotoxic effects by artificial UV-radiation sources and sunlight. (C) 2010 Elsevier B.V. All rights reserved.

Using non-homogeneous Poisson models with multiple change-points to estimate the number of ozone exceedances in Mexico City

In this paper, we consider some non-homogeneous Poisson models to estimate the probability that an air quality standard is exceeded a given number of times in a time interval of interest. We assume that the number of exceedances occurs according to a non-homogeneous Poisson process (NHPP). This Poisson process has rate function lambda(t), t >= 0, which depends on some parameters that must be estimated. We take into account two cases of rate functions: the Weibull and the Goel-Okumoto. We consider models with and without change-points. When the presence of change-points is assumed, we may have the presence of either one, two or three change-points, depending of the data set. The parameters of the rate functions are estimated using a Gibbs sampling algorithm. Results are applied to ozone data provided by the Mexico City monitoring network. In a first instance, we assume that there are no change-points present. Depending on the adjustment of the model, we assume the presence of either one, two or three change-points. Copyright (C) 2009 John Wiley & Sons, Ltd.

Estimating the number of ozone peaks in Mexico City using a non-homogeneous Poisson model

In this paper, we consider the problem of estimating the number of times an air quality standard is exceeded in a given period of time. A non-homogeneous Poisson model is proposed to analyse this issue. The rate at which the Poisson events occur is given by a rate function lambda(t), t >= 0. This rate function also depends on some parameters that need to be estimated. Two forms of lambda(t), t >= 0 are considered. One of them is of the Weibull form and the other is of the exponentiated-Weibull form. The parameters estimation is made using a Bayesian formulation based on the Gibbs sampling algorithm. The assignation of the prior distributions for the parameters is made in two stages. In the first stage, non-informative prior distributions are considered. Using the information provided by the first stage, more informative prior distributions are used in the second one. The theoretical development is applied to data provided by the monitoring network of Mexico City. The rate function that best fit the data varies according to the region of the city and/or threshold that is considered. In some cases the best fit is the Weibull form and in other cases the best option is the exponentiated-Weibull. Copyright (C) 2007 John Wiley & Sons, Ltd.

Using stochastic volatility models to analyse weekly ozone averages in Mexico City

In this paper we make use of some stochastic volatility models to analyse the behaviour of a weekly ozone average measurements series. The models considered here have been used previously in problems related to financial time series. Two models are considered and their parameters are estimated using a Bayesian approach based on Markov chain Monte Carlo (MCMC) methods. Both models are applied to the data provided by the monitoring network of the Metropolitan Area of Mexico City. The selection of the best model for that specific data set is performed using the Deviance Information Criterion and the Conditional Predictive Ordinate method.

fac-/mer-[RuCl(3)(NO)(P-N)] (P-N = [o-(N,N-dimethylamino)phenyl]diphenylphosphine): Synthesis, characterization and DFT calculations

Complex fac-[RuCl(3)(NO)(P-N)] (1) was synthesized from the reaction of [RuCl(3)(H(2)O)(2)(NO)] and the P-N ligand, o-[(N,N-dimethylamino)phenyl]diphenylphosphine) in refluxing methanol solution, while complex mer,trans-[RuCl(3)(NO)(P-N)] (2) was obtained by photochemical isomerization of (1) in dichloromethane solution. The third possible isomer mer, cis-[RuCl(3)(NO)(P-N)] (3) was never observed in direct synthesis as well as in photo-or thermal-isomerization reactions. When refluxing a methanol solution of complex (2) a thermally induced isomerization occurs and complex (1) is regenerated. The complexes were characterized by NMR ((31)P{(1)H}, (15)N{1H} and 1H), cyclic voltammetry, FTIR, UV-Vis, elemental analysis and X-ray diffraction structure determination. The (31)P{(1)H} NMR revealed the presence of singlet at 35.6 for (1) and 28.3 ppm for (2). The (1)H NMR spectrum for (1) presented two singlets for the methyl hydrogens at 3.81 and 3.13 ppm, while for (2) was observed only one singlet at 3.29 ppm. FTIR Ru-NO stretching in KBr pellets or CH(2)Cl(2) solution presented 1866 and 1872 cm(-1) for (1) and 1841 and 1860 cm(-1) for (2). Electrochemical analysis revealed a irreversible reduction attributed to Ru(II)-NO(+) -> Ru(II)-NO(0) at -0.81 V and -0.62 V, for (1) and (2), respectively; the process Ru(II) -> Ru(III), as expected, is only observed around 2.0 V, for both complexes. Studies were conducted using (15)NO and both complexes were isolated with (15)N-enriched NO. Upon irradiation, the complex fac-[RuCl(3)(NO)(P-N)] (1) does not exchange (14)NO by (15)NO, while complex mer, trans-[RuCl(3)(NO)(P-N)] (2) does. Complex mer, trans-[RuCl(3)((15)NO)(P-N)] (2`) was obtained by direct reaction of mer, trans-[RuCl(3)(NO)(P-N)] (2) with (15)NO and the complex fac-[RuCl(3)((15)NO)(P-N)] (1`) was obtained by thermal-isomerization of mer, trans-[RuCl(3)((15)NO)(P-N)] (2`). DFT calculation on isomer energies, electronic spectra and electronic configuration were done. For complex (1) the HOMO orbital is essentially Ru (46.6%) and Cl (42.5%), for (2) Ru (57.4%) and Cl (39.0%) while LUMO orbital for (1) is based on NO (52.9%) and is less extent on Ru (38.4%), for (2) NO (58.2%) and Ru (31.5%). (C) 2011 Elsevier B. V. All rights reserved.

Study of the phenanthroline-Mn-imidazole bonding in Mn(I) triscarbonyl complex: A X-ray and DFT computational analysis

355 nm light irradiation of fac-[Mn(CO)(3)(phen)(imH)](+) (fac-1) produces the mer-1 isomer and a long lived radical which can be efficiently trapped by electron acceptor molecules. EPR experiments shows that when excited, the manganese(I) complex can be readily oxidized by one-electron process to produce Mn(II) and phen(.-). In the present study, DFT calculations have been used to investigated the photochemical isomerization of the parent Mn(I) complex and to characterize the electronic structures of the long lived radical. The theoretical calculations have been performed on both the fac-1 and mer-1 species as well as on their one electron oxidized species fac-1+ and mer-1+ for the lowest spin configurations (S = 1/2) and fac-6 and mer-6 (S = 5/2) for the highest one to characterize these complexes. In particular, we used a charge decomposition analysis (CDA) and a natural bonding orbital (NBO) to have a better understanding of the chemical bonding in terms of the nature of electronic interactions. The observed variations in geometry and bond energies with an increasing oxidation state in the central metal ion are interpreted in terms of changes in the nature of metal-ligand bonding interactions. The X-ray structure of fac-1 is also described. (C) 2011 Elsevier B.V. All rights reserved.