Meteorological effects on variation of airborne algae in Mexico

Sixteen species of algae were collected from 73.8 m³ of air. Eleven were obtained in Minatitlán and eleven in México City. The data show that similar diversity occurred between the two localities, in spite of the difference in altitude. This suggests that cosmopolitan airborne microorganisms might have been released from different sources. Three major algal divisions (Chlorophyta, Cyanophyta and Chrysophyta) formed the airborne algal group. Also, a large concentration of 2220 algae m^–3 was found near sea-level, while lower amounts were recorded at the high altitude of México City. The generaScenedesmus, Chlorella andChlorococcum dominated. Striking relationships were noted between the concentration of airborne green and blue-green algae, and meteorological conditions such as rain, vapour pressure, temperature and winds for different altitudes. In Minatitlán a linear relationship was established between concentration of algae and both vapour pressure (mbar) and temperature (° C), while in México City the wind (m s^–1) was associated with variations in the algal count.     

The Synthesis of α-Methylamino Acids

α-Methyltryptophan, α-methylhistidine, and α-methyldopa were prepared by the reaction of α-isocyanopropionates with gramine methiodide, the acetoxymethylimidazole derivative, and protected 3,4-dihydroxybenzyl bromides, respectively.     

Study of seasonal and daily variations in airborneOlea europaea L. pollen in Jaén (Spain), 1993–1995

A study is made of the seasonal and daily variations in the concentrations of pollen ofOlea europaea L. over three consecutive years (1993–1995) in the atmosphere of Jaén (southern Spain). A Burkard volumetric spore trap was used for sampling. The results show that the highest concentrations of airborne olive pollen occur during May and the first 2 weeks of June, when levels often exceed 500 grains/m³ and occasionally reach nearly 5000 grains/m³ (the levels of allergenic pollen in the atmosphere of Jaén are among the highest in Europe). Over the 3-year study period a significant seasonal variation was detected, not only in the development of the principal pollination period, but also in the value of the maximum pollen concentrations recorded.     

An annual study of airborne pollen in northern Mexico City

An investigation of airborne pollen in northern Mexico City was carried out for one year. A total of 24 taxa were identified and classified according to the growing form in pollen of trees, weeds and grasses. Pollen grains were recorded all year round with a peak in December. The trees group showed the highest quantity of pollen as well as taxa diversity, although its peak period was in the dry season. The weeds and grasses emitted a larger quantity of pollen in the rainy season. The dominant taxa wereAlnus, Casuarina, Compositae and Gramineae. As for their relation with meteorological parameters, we found that the increase of pollen concentration was related to high temperatures, low relative humidity and high wind speed, the latter causing an increase of airborne pollen with no dilution at all. The hours with the highest pollen concentration where from 16:00 to 18:00.     

Comparative study of the formation of oxidative damage marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) adduct from the nucleoside 2'-deoxyguanosine by transition metals and suspensions of particulate matter in relation to metal content and redox reactivity

An association between exposure to ambient particulate matter (PM) and increased incidence of mortality and morbidity due to lung cancer and cardiovascular diseases has been demonstrated by recent epidemiological studies. Reactive oxygen species (ROS), especially hydroxyl radicals, generated by PM, have been suggested by many studies as an important factor in the oxidative damage of DNA by PM. The purpose of this study was to characterize quantitatively hydroxyl radical generation by various transition metals in the presence of H₂O₂ in aqueous buffer solution (pH 7.4) and hydroxylation of 2'-deoxyguanosine (dG) to 8-hydroxy-2'-deoxyguanosine (8-OHdG) under similar conditions. The order of metals' redox reactivity and hydroxyl radical production was Fe(II), V(IV), Cu(I), Cr(III), Ni(II), Co(II), Pb(II), Cd(II). Then, we investigated the generation of hydroxyl radicals in the presence of H₂O₂ by various airborne PM samples, such as total suspended particulate (TSP), PM₁₀, PM_2.5 (PM with aerodynamic diameter 10 and 2.5 μm), diesel exhaust particles (DEP), gasoline exhaust particles (GEP) and woodsmoke soot under the same conditions. When suspensions of PMs were incubated with H₂O₂ and dG at pH 7.4, all particles induced hydroxylation of dG and formation of 8-OHdG in a dose-dependent increase. Our findings demonstrated that PM's hydroxyl radical (HO√) generating ability and subsequent dG hydroxylation is associated with the concentration of water-soluble metals, especially Fe and V and other redox or ionizable transition metals and not their total metal content, or insoluble metal oxides, via a Fenton-driven reaction of H₂O₂ with metals. Additionally, we observed, by Electron paramagnetic resonance (EPR), that PM suspensions in the presence of H₂O₂ generated radical species with dG, which were spin-trapped by 2-methyl-2-nitroso-propane (MNP).     

Research on wind dispersion of rose-mildew spores (Sphaerotheca pannosa) in field,glasshouse and climate room

Powdery mildew on roses gives the impression of being an insignificant disease, but for several reasons more attention to the disease is justifiable. Apart from the economic value of the attacked host plant, we have to do with a very interesting combination of host and parasite. Roses are grown under different environmental conditions (glasshouse, field) and the parasite is a windborne, obligatory parasite, the dispersal of which is strongly related to the environment.     

A comparative study on the airborne fungi in Athens,Greece, by viable and non-viable sampling methods

Airborne fungi were studied in the city of Athens using two complementary methods in which 136 concurrent samplings were carried out during the 12-month period from January until December 1998. A portable Burkard air sampler for agar plates was used for trapping the culturable portion of the mycobiota. Nineteen genera of fungi were identified and assessed in terms of total numbers and fluctuations in concentration (Alternaria, Arthrinium, Aspergillus, Aureobasidium, Botrytis, Chrysonilia, Cladosporium, Drechslera, Epicoccum, Fusarium, Mucor, Nigrospora, Paecilomyces, Penicillium, Rhizopus, Sclerotinia, Scopulariopsis, Trichoderma and Ulocladium), with the exception of those included in the Sphaeropsidales, the yeasts, and the non-sporulating fungi, which were counted as groups. A volumetric Burkard air sampler for glass slides was operating simultaneously for detecting the total mycobiota, including the non-culturable and the non-viable portion. Ascospores, basidiospores, spores of Myxomycetes, Ustilaginales, Uredinales and Erysiphales, teliospores of Puccinia, as well as conidia of the genera Curvularia, Helminthosporium, Periconia, Pestalotiopsis, Pithomyces, Polythrincium, Stachybotrys, Stemphylium and Torula were also recorded. Only seven of the genera were recovered by both samplers. The total numbers of fungal spores, which had a maximum concentration of 3,175 spores/m³, as well as the spore concentrations of the genera Cladosporium (2,565 spores/m³) and Alternaria (280 spores/m³) were underestimated by the viable method (2,435 CFU/m³ for the total, 2,169 CFU/m³ for Cladosporium and 180 CFU/m³ for Alternaria). The non-viable method fails to resolve the identification of the genera Penicillium and Aspergillus, which are major components of the airborne mycobiota (1,068 CFU/m³ and 204 CFU/m³, respectively) based on recovery by the viable method.     

重度霾污染时空气细菌群落特征及与关键环境因子的相关性

【背景】近年来频繁发生的霾污染事件严重威胁着人类的正常生活和社会经济发展。目前对霾污染颗粒物的重要组成部分生物气溶胶的关注较少。【目的】明确霾污染时空气微生物的特征,为进一步研究空气微生物对霾污染的形成及反馈机制奠定基础。【方法】采集了北京地区重度霾污染的样品,测定颗粒物的化学组分,通过高通量测序技术分析空气细菌群落结构特征,并明确其与环境因子的相关性。【结果】霾污染显著改变空气细菌群落结构、降低α多样性。霾污染使空气中变形菌门相对丰度显著上升,放线菌门相对丰度下降。颗粒物浓度及化学组分是重度霾污染中影响空气细菌群落结构的关键环境因子。与气态污染物SO₂和NO₂相比,水溶性离子硫酸盐、硝酸盐和铵盐对空气细菌群落结构的影响更大。【结论】解析了重度霾污染时空气细菌群落特征和关键环境因子之间的相关性,为大气环境微生物的研究、空气质量的评价及霾污染的有效防治提供了数据参考。     

Vertical variation in urticaceae airborne pollen concentration

The pollen contents at different heights (1.5 and 15 m) of species of the Urticaceae family have been studied by sampling with Hirst type volumetric samplers. In order to achieve this, the two pollen types belonging to this family have been treated separately,Urtica urens-Parietaria sp. on the one hand andUrtica membranacea on the other, the latter having a smaller pollen grain. The results show that meteorological factors are bound to influence the behaviour of both these types of pollen in relation to height. With damp weather the pollen contents vary very slightly at different heights while when the weather is dry and calm, differences in pollen content at different heights become more significant. Nevertheless, when the atmosphere is stratified, the behaviour of each pollen type is different. The results show that, for most of the months considered, there is a higher pollen content ofU. membranacea at upper heights, whileU. urens-Parietaria sp. has higher levels of pollen content at a lower height. High temperatures, absence of rain and calm weather conditions favour the presence of convective phenomena which in turn create a favourable atmosphere for the vertical transportation of the small pollen grains ofU. membranacea, which are better represented in the samplers placed at 15 m.     

Preliminary survey of indoor and outdoor airborne microfungi at coastal buildings in Egypt

Forty six species and two sterile fungi and yeast species were isolated from samples collected both indoors and outdoors of coastal buildings located in an Egyptian coastal city. Twenty flats from ten buildings were investigated; children living in these buildings have been reported to suffer from respiratory illnesses. Samples were taken using a New Brunswick sampler (model STA-101) operating for 3.0 min at a flow rate of 6.0 l/min. Most of the species isolated have been associated with symptoms of respiratory allergies. Indoors the total culturable fungal count was 1548 CFU/m³; outdoors, it was 1452 CFU/m³. Indoor values of culturable fungal count, total spores count and ergosterol content ranged from 52 to 124 CFU/m³, 100 to 400 spore/m³ and 5 to 27.7 mg/m³, respectively, whereas outdoor levels typically varied between 25 and 222 CFU/m³, 110 and 900 spore/m³ and 3.3 and 67.2 mg/m³, respectively. The maxima for these parameters were detected indoors in house no. 6 and outdoors, outside of house no. 7. The most abundant species were primarily mitosporic (2832 CFU/m³). The most frequent species in both the indoor and outdoor samples were Cladosporium cladosporioides followed by Alternaria alternata and Penicillium chrysogenum,with inside:outside ratios of 1.4, 1.8 and 1.9, respectively. The patterns of fungal abundance were influenced to some extent by changes in the relative humidity and temperature. Other factors, such as type of culture media, rate of sedimentation, size, survival rates of spore and species competition,also affected fungal counts and should be taken into consideration during any analysis of bioaerosol data.