خيارات البحث
النتائج 1 - 10 من 21
The impact of inorganic tin on the planktonic cyanobacterium Synechocystis aquatilis: the effect of pH and humic acid
1997
Pawlik-Skowronska, B. | Kaczorowska, R. | Skowronski, T. (Institute of Ecology, Polish Academy of Sciences, Experimental Station, 20-080 Lublin, Niecala 18/3 (Poland))
Changes in gill morphology of Atlantic salmon (Salmo salar) smolts due to addition of acid and aluminum to stream water
1997
Jagoe, C.H. | Haines, T.A. (Department of Zoology, University of Maine, Orono, ME 04469-5751 (USA))
Stemflow chemistry of urban street trees
1997
Takagi, M. | Sasaki, S. | Gyokusen, K. | Saito, A. (Department of Silviculture, Faculty of Agriculture, Kyushu University, Fukuoka 812 (Japan))
Interactions between the Encelia leaf beetle and its host plant, Encelia farinosa: the influence of acidic fog on insect growth and plant chemistry
1997
Redak, R.A. | Trumble, J.T. | Paine, T.D. (Department of Entomology, University of California, Riverside, CA 92521 (USA))
Fluorogenic compound hydrolysis as a measure of toxicity-induced cytoplasmic viscosity and pH changes
1997
Grabowski, J. | Hsiao KeCheng | Baker, P.R. | Bornman, C.H. (Institute of Physics, Poznan University of Technology, ul. Piotrowo 3, 60-965 Poznan (Poland))
Toxicity of acid-sulphate soil leachate and aluminium to the embryos and larvae of Australian bass (Macquaria novemaculeata) in estuarine water
1997
Hyne, R.V. | Wilson, S.P. (Ecotoxicology Section, Environment Protection Authority NSW, at EPA/UTS Centre for Ecotoxicology, University of Technology - Sydney, Westbourne St., Gore Hill, NSW 2065 (Australia))
Impact of high aluminium loading on a small catchment area (thuringia slate mining area) —geochemical transformations and hydrological transport
1997
Peiffer, Stefan | Beierkuhnlein, Carl | Sandhage-Hofmann, Alexandra | Kaupenjohann, Martin | Bär, Silke
A field study was performed on the effects of acid mine leachate from slate mine tailings seeping into a small river passing through the tailings. Before entering the tailings the river water has high alkalinity which neutralizes acidity upon mixing with leachate within the tailings. Donwstreams of the tailings the pH of the river water ranges about pH = 8, the water contains high concentrations of sulfate (≈1500 μmol/1 and particulate bound aluminium (≈80 μmol/I), but low concentrations of dissolved aluminium (≈3 μmol/1). It is therefore assumed that AI(OH)₃ colloids are precipitated during the neutralisation process and transported out of the tailings. The concentration of particulate bound aluminium along the river shows a strong correlation with the concentration of sulfate, which indicates that particulate bound aluminium is conservative. It therefore seems that under dry weather conditions (under most of the sampling was performed) no chemical retention mechanism exists which confines the distribution of aluminium to a restricted part of the catchment area. In contrast, the white river sediment is rich in both aluminium and sulfate, which suggests the temporary formation of aluminium hydroxosulfate minerals. Favorable (i.e. acidic) conditions may prevail at high discharges where the acidity accumulated in the tailings is flushed into the river with its subsequent acidification.
اظهر المزيد [+] اقل [-]Major pathways for nitrogen removal in waste water stabilization ponds
1997
Lai, Patrick C. C. | Lam, Paul K. S.
A study on the factors influencing nitrogen removal in waste water stabilization ponds was undertaken in an eight-pond series in Werribee, Australia. Nitrogen species including Kjeldahl nitrogen, total ammonia nitrogen, nitrite and nitrate were monitored monthly from March 1993 to January 1994. At the same time, pH, temperature, chlorophylla content and dissolved oxygen were also recorded. Highest nitrogen removal occurred during the period with highest levels of chlorophylla content and dissolved oxygen, but the rate of nitrogen removal was not related to temperature and pH. Enhanced photosynthetic activities resulting from an increased phytoplankton abundance due to prolonged detention time caused an increase in dissolved oxygen, and created an optimum condition for nitrification to occur. In this process, ammonia was oxidized to nitrite and nitrate which were subsequently reduced to elemental nitrogen. Apart from nitrification-denitrification which was the major nitrogen removal pathway in the study system, algal uptake of ammonium, nitrate and nitrite as nutrient sources also contributed to the nitrogen removal. The role of phytoplankton and zooplankton in the treatment process in waste stabilization ponds was discussed.
اظهر المزيد [+] اقل [-]The difference in brown trout (Salmo Trutta L.) blood composition from acidic and limed sites of two rivers in Western Norway
1997
Galina, Maria S.
Certain blood morphology parameters: red blood cell (RBC) sizes; percentage of polymorphonuclear leukocytes and ratio polychromatocyte/RBC in Brown trout (Salmo trutta L.) from acidified water (mean pH value 4.94) and limed water (mean pH value 5.66) were investigated. The sizes of RBC long axises were significantly larger in fish from acidic environment than from limed condition (14.37 and 12.96μm respectively). The percentage of polymorphonuclear cells (7.86 and 3.32) and polychromatocyte/RBC ratio (0.079 and 0.019) were also significantly larger in fish from the acidified environment. Blood morphology parameters are concluded to be usefull for testing and detection of long-term acidic stress in fish in nature.
اظهر المزيد [+] اقل [-]Pigment changes in norway spruce induced by dust pollution
1997
MANDRE, MALLE | TUULMETS, LIIVI
The influence of alkaline dust pollution (pH of water solution of dust 12.3–12.7) from a cement plant (Kunda town, Estonia) on chlorophylls and carotenoids of the needles of 60–80 year old Norway spruce was studied on sample plots established at different distances from the emission source. The highest sensitivity to dust impact was measured in the content of Chl a, Chl b, carotenoids and elements regulating or participating in the biosynthesis of pigments (Mg, Fe, N, Mn).
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