The composition of airborne and grain-dust fungal communities is shaped at regional scale by plant genotypes and farming practices

Chronic exposure to airborne fungi has been associated with different respiratory symptoms and pathologies in occupational populations, such as grain workers. However, the homogeneity in the fungal species composition of these bioaerosols on a large geographical scale and the different drivers that shape these fungal communities remain unclear. In this study, the diversity of fungi in grain dust and in the aerosols released during harvesting was determined across 96 sites at a geographical scale of 560 km(2) along an elevation gradient of 500 m by tag-encoded 454-pyrosequencing of the internal transcribed spacer (ITS) sequences. Associations between the structure of fungal communities in the grain dust and different abiotic (farming system, soil characteristics, geographic and climatic parameters) and biotic (wheat cultivar, previous crop culture) factors were explored. These analyses revealed a strong relationship between the airborne and grain dust fungal communities and showed the presence of allergenic and mycotoxigenic species in most samples, which highlights the potential contribution of these fungal species to work-related respiratory symptoms of grain workers. The farming system was the major driver of the alpha and beta phylogenetic diversity of fungal communities. In addition, elevation and soil CaCO3 concentrations shaped the alpha diversity whereas wheat cultivar, cropping history and the number of freezing days per year shaped the taxonomic beta diversity of these communities.

Reações de ozonólise de olefinas em fase gasosa

Biogenic emissions of volatile organic compounds play a fundamental role in the atmospheric chemistry, vegetation being one of their major sources. Amongst the VOCs emitted by plants, olefins and terpenoids are the most abundant. These compounds, due to the presence of two or more double bonds and other structural features, are very reactive in the atmosphere and act as precursors of the photochemical smog and aerosols. This article presents a review of the reactions of olefins and terpenoids with ozone, in the gas phase, with emphasis toward the mechanisms and kinetic aspects.

Estudo de aerossóis atmosféricos e aplicação de modelos numéricos

The main purpose of the present work is to study the concentration of atmospheric particles (PM10 and PM2.5) in the Candiota (RS) region using HV PM10 and dichotomous samplers. Four sampling sites at a distance of 50 km from the emission source were selected: Aceguá, Aeroporto, 8 de Agosto and Pedras Altas. Samples were collected from December 2000 to December 2001. The values obtained with the ISCST (Industrial Source Complex Term) model and with the samplers were compared on January 21st, April 5th, July 14th, August 1st, and October 13th 2001, and are representative of frontal systems occurring in the study area.

Aerossóis atmosféricos: perspectiva histórica, fontes, processos químicos de formação e composição orgânica

This work starts with a historical perspective of the social and scientific progress related to the understanding of the atmospheric aerosol. Its origin, physical, chemical and optical characteristics, as well as its environmental behaviour are described, retracing the evolution of the concepts related to this subject over the last centuries. The main sources that contribute to atmospheric particulate matter and the modern understanding of its formation processes and constitution, focusing on the chemical pathways leading to it and on its organic components are presented. This discussion is complemented with recent evaluations of the quantities emitted by primary, secondary, biogenic and anthropogenic sources and the effects due to accumulation or dispersion of aerosols, justifying the chemical and environmental interest they engender.

Composição química da chuva e aporte atmosférico na Ilha Grande, RJ

Wet (n = 21) and dry (n = 23) deposition samples were collected from March to September 2002 at the southern coast of Ilha Grande. Rainwater pH varied from 4.3 to 6.3 and ionic concentrations (in µmol L-1) decreased in the order Cl- > Na+ > Mg2+ > SO4(2-) > NO3- ~ NH4+ > K+ ~ H+ > Ca2+. Scavenging of sea-salt aerosols was the major source of Cl-, Na+, Mg2+, and Ca2+. Half of total SO4(2-) was non-sea-salt SO4(2-). Total deposition fluxes of NH4+, NO3-, and non-sea-salt SO4(2-) were respectively 9.3, 17.8, and 16.0 mol ha-1 month-1.

Composição elementar do material particulado presente no aerossol atmosférico do município de Sete Lagoas, Minas Gerais

The main objective of this study was the identification of sources generating particulate matter in the atmospheric aerosols of Sete Lagoas, Minas Gerais. The measurement of the mineral composition was accomplished by X-ray diffractometry and the elemental concentration by neutron activation analysis. The results showed that Al, Cl, Cu, Fe, K, Mg and Na are the predominant chemical elements in the total suspended particles (TPS). The presence of Na, Ba, Cl, Cu, Eu, Fe and Sm in those particles with aerodynamic diameter smaller than 10 µm (PM10), indicates that soil dust and ceramic and pig iron industries are the main sources of air quality degradation in the region.

Size distribution of atmospheric particulate ionic species at a coastal site in Portugal

A Berner impactor was used to collect size-differentiated aerosol samples from March to August 2003 in the city of Aveiro, on the Portuguese west coast. The samples were analysed for the main water-soluble ion species. The average concentration of sulphate, nitrate, chloride and ammonium was 6.38, 3.09, 1.67 and 1.27 µg m-3, respectively. The results show that SO4(2-) and NH4+ were consistently present in the fine fraction < 1 µm, which represents, on average, 72 and 89% of their total atmospheric concentrations, respectively. The NO3-particles were concentrated in the coarse size. Chloride presented the characteristic coarse mode for marine aerosols. During some spring/summer events, an ammonium surplus was observed (NH4+/SO4(2-) molar ratios > 2), possibly due to greater availability of ammonia coming from agricultural activities or from the neighbouring chemical industrial complex. During the remaining periods, the aerosol was found to be somewhat acidic and predominantly in the form of ammonium bisulphate (NH4+/SO4(2-) molar ratios = 0.5-1.25). Samples collected under a major or exclusive influence of maritime air masses were essentially constituted by coarse particles with enrichment in sea salt, while for air masses of continental origin the contribution of water-soluble ionic species in the fine mode was more pronounced.

Inversion and assimilation methods with applications in geophysical remote sensing

Stratospheric ozone can be measured accurately using a limb scatter remote sensing technique at the UV-visible spectral region of solar light. The advantages of this technique includes a good vertical resolution and a good daytime coverage of the measurements. In addition to ozone, UV-visible limb scatter measurements contain information about NO2, NO3, OClO, BrO and aerosols. There are currently several satellite instruments continuously scanning the atmosphere and measuring the UVvisible region of the spectrum, e.g., the Optical Spectrograph and Infrared Imager System (OSIRIS) launched on the Odin satellite in February 2001, and the Scanning Imaging Absorption SpectroMeter for Atmospheric CartograpHY (SCIAMACHY) launched on Envisat in March 2002. Envisat also carries the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument, which also measures limb-scattered sunlight under bright limb occultation conditions. These conditions occur during daytime occultation measurements. The global coverage of the satellite measurements is far better than any other ozone measurement technique, but still the measurements are sparse in the spatial domain. Measurements are also repeated relatively rarely over a certain area, and the composition of the Earth’s atmosphere changes dynamically. Assimilation methods are therefore needed in order to combine the information of the measurements with the atmospheric model. In recent years, the focus of assimilation algorithm research has turned towards filtering methods. The traditional Extended Kalman filter (EKF) method takes into account not only the uncertainty of the measurements, but also the uncertainty of the evolution model of the system. However, the computational cost of full blown EKF increases rapidly as the number of the model parameters increases. Therefore the EKF method cannot be applied directly to the stratospheric ozone assimilation problem. The work in this thesis is devoted to the development of inversion methods for satellite instruments and the development of assimilation methods used with atmospheric models.

Parâmetros bioquímicos foliares das espécies Licania tomentosa (Benth.) e Bauhinia forficata (Link.) para avaliação da qualidade do ar

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

Química entre a microcamada superficial oceânica e os aerossóis marinhos

The sea surface microlayer (SML), although poorly understood, is important in biogeochemical cycling and sea - air exchanges; it is a source or a sink for a range of pollutants. In this paper, an overview of sampling techniques and the role of SML in biogeochemical cycles and climate is presented. The chemical and biological nature of the ocean surface film and its interaction with atmospheric aerosols are discussed. Special attention is given to organic constituents, gel-like compounds, surfactants, halogenated compounds, and metals. Estimates of air - sea exchange fluxes-with focus on organic carbon, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls-are compiled. In addition, research gaps in the chemical composition of marine aerosols and their relationship with SML are described.

Evaluation of two 99mTc-DTPA radioaerosols with different characteristics in lung ventilation studies

Two radioaerosol preparations, TechneScan®-DTPA (99mTc-DTPA, 40 mCi/3 ml; IPEN-CNEN, São Paulo, SP, Brazil) and TechneScan®-DTPA/AEROSOL (99mTc-DTPA/A, 15 mCi/1.5 ml with 0.5 ml ethanol; Mallinckrodt Medical, St. Louis, MO, USA), were compared in pulmonary ventilation studies in terms of total radiocounts and clearance after inhalation. An aerosol with ethanol is supposed to better distribute the radioparticles in the lungs. Twenty normal nonsmoking volunteers (10 men and 10 women), mean age of 23.2 years (range: 20 to 35 years), were studied. Images were obtained immediately and 30, 60 and 90 min after inhalation. Total and regional counts were obtained and the clearance half-lives of both lungs were determined. There was no difference in total counts between the two types of radioaerosol at any time (mean of ~188,000 cpm for male and female subjects at time zero in both aerosols). The highest count was obtained in the middle region of both lungs (P<0.001) with both preparations. The clearance half-life did not differ between aerosols (mean of ~80-88 min for male and female subjects for both aerosols). Small nonsignificant regional differences were observed. No differences between genders or between right and left lung were observed. 99mTc-DTPA/A generated the highest output of radioaerosol. 99mTc-DTPA with alcohol costs approximately five times more than the aerosol without alcohol. The present results show that either kind of aerosol may be adopted routinely for use in pulmonary examinations without affecting diagnosis. We suggest that the amount of 740 mBq (20 mCi) of 99mTc-DTPA in 1.5 ml saline can be used for routine examinations resulting in reduction of costs in pulmonary ventilation studies without diagnostic impairment.

Effect of salbutamol on pulmonary responsiveness in chronic pulmonary allergic inflammation in guinea pigs

Beta-2-agonists have been widely used by asthmatic subjects to relieve their obstructive symptoms. However, there are reports that continuous use could lead to loss of bronchial protection and exacerbation of asthma symptoms. We evaluated the effect of two regimens of salbutamol administration (twice and five times a week) in a model of chronic airway inflammation in male Hartley guinea pigs (protocol starting weight: 286 ± 30 g) induced by repeated exposures to aerosols of ovalbumin (OVA). After sensitization, guinea pigs were exposed to aerosols of 0.1 mg/ml salbutamol solution twice a week (OVA + S2x, N = 7) or five times a week (OVA + S5x, N = 8). We studied allergen-specific (OVA inhalation time) and -nonspecific (response to methacholine) respiratory system responsiveness. Seventy-two hours after the last OVA challenge, guinea pigs were anesthetized and tracheostomized, respiratory system resistance and elastance were measured and a dose-response curve to inhaled methacholine chloride was obtained. Specific IgG1 was also quantified by the passive cutaneous anaphylactic technique. OVA-sensitized guinea pigs (N = 8) showed reduction of the time of OVA exposure before the onset of respiratory distress, at the 5th, 6th and 7th exposures (P < 0.001). The OVA + S2x group (but not the OVA + S5x group) showed a significant increase in OVA inhalation time. There were no significant differences in pulmonary responsiveness to methacholine among the experimental groups. OVA + S2x (but not OVA + S5x) animals showed a decrease in the levels of IgG1-specific anaphylactic antibodies compared to the OVA group (P < 0.05). Our results suggest that, in this experimental model, frequent administration of ß2-agonists results in a loss of some of their protective effects against the allergen.

Prions: the danger of biochemical weapons

The knowledge of biotechnology increases the risk of using biochemical weapons for mass destruction. Prions are unprecedented infectious pathogens that cause a group of fatal neurodegenerative diseases by a novel mechanism. They are transmissible particles that are devoid of nucleic acid. Due to their singular characteristics, Prions emerge as potential danger since they can be used in the development of such weapons. Prions cause fatal infectious diseases, and to date there is no therapeutic or prophylactic approach against these diseases. Furthermore, Prions are resistant to food-preparation treatments such as high heat and can find their way from the digestive system into the nervous system; recombinant Prions are infectious either bound to soil particles or in aerosols. Therefore, lethal Prions can be developed by malicious researchers who could use it to attack political enemies since such weapons cause diseases that could be above suspicion.

Development and characterization of concentric capillary nebulizer used in inductively coupled plasma analysis /

A simple, low-cost concentric capillary nebulizer (CCN) was developed and evaluated for ICP spectrometry. The CCN could be operated at sample uptake rates of 0.050-1.00 ml min'^ and under oscillating and non-oscillating conditions. Aerosol characteristics for the CCN were studied using a laser Fraunhofter diffraction analyzer. Solvent transport efficiencies and transport rates, detection limits, and short- and long-term stabilities were evaluated for the CCN with a modified cyclonic spray chamber at different sample uptake rates. The Mg II (280.2nm)/l\/lg 1(285.2nm) ratio was used for matrix effect studies. Results were compared to those with conventional nebulizers, a cross-flow nebulizer with a Scott-type spray chamber, a GemCone nebulizer with a cyclonic spray chamber, and a Meinhard TR-30-K3 concentric nebulizer with a cyclonic spray chamber. Transport efficiencies of up to 57% were obtained for the CCN. For the elements tested, short- and long-term precisions and detection limits obtained with the CCN at 0.050-0.500 ml min'^ are similar to, or better than, those obtained on the same instrument using the conventional nebulizers (at 1.0 ml min'^). The depressive and enhancement effects of easily ionizable element Na, sulfuric acid, and dodecylamine surfactant on analyte signals with the CCN are similar to, or better than, those obtained with the conventional nebulizers. However, capillary clog was observed when the sample solution with high dissolved solids was nebulized for more than 40 min. The effects of data acquisition and data processing on detection limits were studied using inductively coupled plasma-atomic emission spectrometry. The study examined the effects of different detection limit approaches, the effects of data integration modes, the effects of regression modes, the effects of the standard concentration range and the number of standards, the effects of sample uptake rate, and the effect of Integration time. All the experiments followed the same protocols. Three detection limit approaches were examined, lUPAC method, the residual standard deviation (RSD), and the signal-to-background ratio and relative standard deviation of the background (SBR-RSDB). The study demonstrated that the different approaches, the integration modes, the regression methods, and the sample uptake rates can have an effect on detection limits. The study also showed that the different approaches give different detection limits and some methods (for example, RSD) are susceptible to the quality of calibration curves. Multicomponents spectral fitting (MSF) gave the best results among these three integration modes, peak height, peak area, and MSF. Weighted least squares method showed the ability to obtain better quality calibration curves. Although an effect of the number of standards on detection limits was not observed, multiple standards are recommended because they provide more reliable calibration curves. An increase of sample uptake rate and integration time could improve detection limits. However, an improvement with increased integration time on detection limits was not observed because the auto integration mode was used.