خيارات البحث
النتائج 231 - 240 من 345
Chlorinated hydrocarbons in marine sediments of the Baja California (Mexico)-California (USA) border zone
1998
Gutierrez-Galindo, E.A. | Mendoza, L.M.R. | Munoz, G.F. | Celaya, J.A.V. (Instituto de Investigaciones Oceanologicas Universidad Autonoma de Baja California, P.O. Box 2516 Ensenada, Baja California (Mexico))
Comparison of selected element concentrations in tall and short forms of Spartina alterniflora
1998
Ornes, W.H. | Sajwan, K.S. | Loganathan, B.G. | Chetty, C.S. (Department of Biology and Geology, University of South Carolina, Aiken, SC 29801 (USA))
Effects of nesting yellow-legged gulls (Larus cachinnans pallas) on the heavy metal content of soils in the Cies Islands (Galicia, North-West Spain)
1998
Perez, X.L.O. (Departamento de Edafoloxia e Quimica Agricola, Facliltade de Bioloxia, 15 706 Santiago de Compostela (Spain))
Occurrence of persistent organic contaminants and related substances in Hong Kong marine areas: an overview
1998
Connell, D.W. | Wu, R.S.S. | Richardson, B.J. | Leung, K. | Lam, P.S.K. | Connell, P.A. (Centre for Environmental Science and Technology, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong (China))
Comparisons and temporal trends of organochlorines and heavy metals in fish from the Gulf of Bothnia
1998
Vuorinen, P.J. | Haahti, H. | Leivuori, M. | Miettinen, V. (Finnish Game and Fisheries Research Institute, P.O. Box 6, FIN-00721, Helsinki (Finland))
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.
اظهر المزيد [+] اقل [-]Influence of pH and Zinc Concentration on Cadmium Sorption in Acid, Sandy Soils
1998
Wilkins, B. J. | Brummel, N. | Loch, J. P. G.
Batch adsorption experiments were carried out with samples from an A-, Bh- and C-horizon of contaminated sandy soil of podzolic character from the Kempen region at the Dutch-Belgian border. Cadmium sorption was studied on 3 soil samples at 3 different pH-levels (3.6, 4.3 and soil buffered pH) and 3 different additions of zinc (0–40 mg l⁻¹).Adsorption of cadmium by acid sandy soils can be fitted by a Freundlich adsorption isotherm. Although zinc competes with cadmium for the sorption sites, we observe a two to three times stronger competition effect of the proton cation, which is explained by the chemical properties of both ions. The cadmium adsorption coefficient KF decreases considerably by an increase of the proton activity used in the sorption experiments. Organic matter content explains for a large part the variation of KF of te three soil samples. Desorption data do not fit the proposed regression model for adssorption. Not all the cadmium, intitially present in the polluted soil, will fylly desorb reversibly. Thus, part of the cadmium may be irreversible bound.
اظهر المزيد [+] اقل [-]Bioaccumulation and Toxicity of Zinc in Spirogyra Fluviatilis Hilse (Chlorophyta)
1998
Saygideger, S.
The bioaccumulation and toxicity of zinc in Spirogyra fluviatilis Hilse, from two populations in the River Seyhan, Adana, Turkey, were examined in laboratory flowing-water channels. Plants were subjected to zinc concentrations ranging from 0 to 4.0 mg L⁻¹ at current velocities of 25–35 cm s⁻¹ for up to 3 h. There was little difference in zinc bioaccumulation between Spirogyra from the site showing mild organic pollution and that from the site subjected to considerable inputs from urban and motorway runoff. Uptake of zinc increased with increasing concentration in the test solution and was linear and proportional up to 0.5 mg L⁻¹. Cellular damage was evident in Spirogyra subjected to 0.5 mg L⁻¹ zinc, and increased with increasing zinc concentration.
اظهر المزيد [+] اقل [-]On-line Analysis of Stack Gas Composition by a Low Resolution FT-IR Gas Analyzer
1998
Jaakkola, Petri T. | Vahlman, Tuula A. | Roos, Aappo A. | Saarinen, Pekka E. | Kauppinen, Jyrki K.
Stack gases of wood and oil burning boilers were analyzed by a low resolution FT-IR gas analyzer. Concentrations of carbon dioxide (CO₂), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO₂), nitrous oxide (N₂O), hydrogen cyanide (HCN), sulfur dioxide (SO₂), methane (CH₄), and water vapor (H₂O) were predicted in real time by multicomponent analysis. Detection limits, linearity, analysis accuracy and long time repeatability were experimentally determined for selected gas components. Applicability of the measurement method was demonstrated by analysis of stack gas mixtures of known concentrations. The results indicate that all the primary stack gas components can be measured by the low resolution FT-IR gas analyzer with comparable results to single component measurement methods.
اظهر المزيد [+] اقل [-]Anthropogenic Mercury Deposition to Arctic Lake Sediments
1998
Hermanson, Mark H.
The history of atmosheric mercury inputs to remote arctic regions can be measured in lake sediment cores using lead-210 chronology. In this investigation, total mercury deposition is measured in sediments from Imitavik and Annak Lakes on the Belcher Islands in southeastern Hudson Bay, an area in the southern Canadian Arctic with no history of local industrial or agricultural sources of contamination. Both lakes received background and atmospheric inputs of mercury while Annak also received mercury from raw domestic sewage from the Hamlet of Sanikiluaq, a growing Inuit community of about 550 established in the late 1960's. Results from Imitavik show that anthropogenic mercury inputs, apparently transported through the atmosphere, began to appear in the mid-eighteenth century, and continued to the 1990's. Annak had a similar mercury history until the late 1960's when disposal of domestic sewage led to increased sediment and contaminant accumulation. The high input of mercury to Annak confirms that Sanikiluaq residents are exposed to mercury through native food sources.
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