Ambient Environmental Factors Research Articles

Effect of ambient environmental factors on indoor formaldehyde levels

The effect of ambient (outdoor) environmental parameters on formaldehyde levels in a temperature controlled urea-formaldehyde foam-insulated (UFFI) house and a mobile home was investigated over a 9-month period (July–March). Strong correlations between formaldehyde levels, solar radiation, ambient temperatures, inside/outside temperature differences and water vapor pressure were observed in the UFFI house and in the mobile home. Stepwise regression revealed a significant independent effect of solar radiation values on indoor formaldehyde levels in the UFFI house but not in the mobile home. Stepwise regression revealed no significant independent effect of the other environmental variables evaluated. The independent effect of solar radiation on formaldehyde levels in the UFFI house indicates that solar radiation can have a significant effect on formaldehyde concentrations, and this effect may explain anomolous results in whole house source interaction studies.

Concept of planktonic species diversity in small water bodies – a case study of lake Rangasagar (Udaipur: Rajasthan)

AbstractThe quantitative and qualitative relationships within phyto‐ and zooplanktonic communities were examined for a period of one year in a small eutrophic lake in Udaipur, through the application of diversity indices. The results revealed that a higher plankton diversity needs not necessarily lead to a greater community diversity or evenness of species diversity. The phytoplankton species diversity was related to nutrients and ambient environmental factors. Within zooplankton groups, the diversity index was found influenced by the evenness and richness of the species. On the other hand, the strong correlation between individual species density and community diversity in the cladocera was influenced by food availability. The total zooplankton diversity was also strongly correlated (P < 0.01) with the number of species and equality. There was no spatial variation in species composition because of smaller spread of the water body. It is felt that the diversity indices could get influenced by the dominance or scarcity of one or more species or communities giving a deceptive picture of planktonic panorama.

Multivariate analysis of ambient environmental factors and respiratory effects.

Relationships between respiratory health and environmental conditions (pollen, pollution and meteorology) are investigated in 204 subjects in four symptom groups in four geographical clusters in Tucson. Techniques used are principal components, factor and path analysis. Daily respiratory symptoms and peak expiratory flows were recorded during a three-year period. Ambient pollutants, meteorological conditions and pollen types were monitored in or near the clusters. Factor-based scales, which are climate and season specific, are developed for the environmental variables. Three pollutant/meteorological scales represent 'Summer', 'Winter', and 'Humidity'. Four pollen scales represent early and late spring, summer and fall pollen types. Relationships between environmental variables, respiratory symptoms and peak expiratory flow are analyzed with path diagrams, after accounting for age, sex, smoking habits and stove type. The different effects of the environment on asthmatics, allergics and airways obstructive disease subjects have been demonstrated. Many relationships were found between environmental factors and respiratory responses. The pollutant and meteorological variables are related to respiratory symptoms and peak flow directly as well as through interactions with pollen types. Some of the largest positive coefficients are seen in association with seasonal pollen types, specifically, rhinitis and dyspnoea.

Low oxygen concentration extends the lifespan of cultured human diploid cells.

THE pioneering studies of Hayflick1 showed that normal human diploid cells of the WI-38 strain have a limited lifespan of approximately 50±10 population doublings (PDL) in vitro. It is still not known to what extent this phenomenon is the result of the artificiality of the cell culture system : factors such as nutrition and ambient environmental factors may restrict the ability of these cells to express their true genetic potential. To what extent genetic and environmental factors act to constrain the lifespan of human diploid cells in culture is open to experiment. In the present study we have evaluated one important ambient factor of the environment, the oxygen concentration, on the growth and lifespan of two human diploid cell strains, WI-38 and IMR-90. Our results show that growth at oxygen concentrations less than 20% is enhanced and that an extension of about 25% of the lifespan of both cell types was realised by long term cultivation under 10% oxygen. This indicates that the potential for long term growth in culture of normal diploid cells may be appreciably enhanced by more exact control of environmental factors.

Seed pelleting to improve nodulation of tropical and sub-tropical legumes. 1. An examination of the validity of 'grow-out' nodulation tests in tubes

Nodulation resulting from various seed pelleting treatments of Lotus pedunculatus, Desmodium intortum, and D. uncinatum was investigated by the 'grow-out technique', in which single treated seeds are dropped into seedling nutrient agar tubes which are assessed for presence or absence of nodules after a standard time. Two cellulosic stickers, Cellofas A and Methofas were used, and pelleting materials included lime, gypsum, kaolin, calcium silicate, and four rock phosphates. Calcium silicate was quickly lethal to rhizobia. Malt extract was included in the sticker in several experiments and had a protective action on rhizobia. Significant effects of pellet treatment were observed on both seed germination and amount of nodulation. Results indicate that the relative performance of different pelleting treatments can be influenced both by ambient environmental factors and by the type of mineral nutrient agar chosen for the performance of the test. It is suggested that such tests may be quite misleading, and that they provide no real guide to what may occur in the field.