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Air pollution
1998
Wark, Kenneth | Warner, Cecil Francis | Davis, Wayne T.
Multitracer Study on Absorption of Radionuclides in Atmosphere-Plant Model System
1998
Shinonaga, Taeko | Ambe, Shizuko
The absorption of atmospheric radionuclides by soybean plants was experimentally studied using a radioactive multitracer consisting of radionuclides of Sc, Mn, Co, As, Se, Rb, Sr, Y, Eu, Gd, Yb, Hf, Re, and Ir. The soybean plants were cultivated in soil under no-rain conditions in a box containing air in which multitracer-absorbed cellulose particles were dispersed. The soil was covered with plastic film. After about one-month cultivation, the plants were harvested and washed with dilute HCl solution. The leaves, stems, and beans were subjected to γ-ray measurement. The radionuclides of As, Se, and Re were accumulated in the leaves, and those of Co, Se, and Rb were accumulated in the beans. Among them Se was accumulated to a large extent in the leaves and in the beans. Small amounts of the radionuclides of Co, Se, Rb and Re were found in the roots. Little absorption of these radionuclides into the soil occurred. These results indicate that various radionuclides in the atmosphere were absorbed through the soybean leaves and then transported to the seeds. These findings must be taken into consideration for a complete understanding of the system of uptake of radionuclides by the soybean plant.
Показать больше [+] Меньше [-]Biological Elimination of Volatile Organic Compounds from Waste Gases in a Biofilter
1998
Wu, G. | Chabot, J. C. | Caron, J. J. | Heitz, M.
A great deal of research has been directed towards the problem of reduction and control of volatile organic compounds (VOCs). The aim of this research is to find a process that is both efficient and inexpensive in comparison with traditional air treatment technologies.Our biofilter (one stage system, 2 m in height) is an aerobic system for waste gases containing VOCs using the degradation properties of microbial flora (assorted cultures of Bacillus, Micrococcus, Acinetobacter and yeast). In this process, polluted gas diffuses across a filter bed into which a microbial culture has previously been introduced. Peat is the medium of choice for inoculation with microorganisms because of its adsorption and absorption properties, ability to retain moisture, and buffering capacity. Furthermore, the peat utilized is spherical in shape; thus, it is possible to avoid problems related to compacting.The objective of this study was to eliminate VOCs emitted from a rotogravure process. We were able to achieve promising results from biofiltration of two types of VOCs (a mixed solvent containing isopropyl acetate and 1-nitropropane, and the solvent: 1-nitropropane). The results obtained indicate that the elimination of nitropropane and the mixed solvent in the biofilter are considered to follow zero-order kinetics with reaction rate limitation and diffusion rate limitation, respectively.
Показать больше [+] Меньше [-]Arsenic in Human and Cow's Milk: a Reflection of Environmental Pollution
1998
Ulman, Cevval | Gezer, Semra | Anal, Özden | Töre, I Ruhi | Kirca, Üzeyir
Arsenic, an environmental pollutant, is present in minute but invariable amounts in food, drinking water and ambient air. Izmir is founded on a land of long extinct volcanoes, with vast areas of lava ground suitable for agriculture. It is located at close vicinity to high thermal activity, e.g., hot springs and thermal baths. In the present study, total arsenic level in breast milk was assessed in randomly chosen 35 lactating women of different socioeconomic levels who live downtown in Izmir and in milk of 36 cows grazing on shoulder grass of highways with heavy traffic. Total arsenic was assessed on an atomic absorption spectrophotometer (AA-680 Shimadzu). Mean (± SEM) arsenic was found to be 4.219 ± 0.079 µg L⁻¹ in breast milk, and 4.932 ± 0.38 µg L⁻¹ in cow's milk. Conclusion: in Izmir, arsenic contamination of breast milk was not found so as to be considered noxious for suckling infants, whereas was found relatively higher in cow's milk. It would be prudent to remember breast and cow's milk arsenic contamination in breast fed or milk fed babies living in areas with higher thermal activity or in regions where ground water is with high arsenic content.
Показать больше [+] Меньше [-]Guidelines for evaluating air pollution impacts on wilderness within the Rocky Mountain region
1998
Haddow, Dennis | Blett, Tamara | Fisher, Richard | Musselman, Robert C.