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Oligochaetes community as an indicator of accelerated eutrophication process in the second oxidation lake Palic [Serbia, Yugoslavia]
1998
Djukic, N. (Poljoprivredni fakultet, Novi Sad (Yugoslavia)) | Maletin, S. | Miljanovic, B. | Tepavcevic, D. | Teodorovic, I.
During the 1981-1996 period, qualitative and quantitative structure of oligachaeta communities as indicator of the eutrophication process was investigated in the lake Palic (the 2nd oxidation lake), Serbia (Yugoslavia). The mean annual number of oligochaetes was related to nutrient concentration (total nitrogen and total phosphorus). The analysed data for both oligochaete community and nutrients, leads to the conclusion that the second oxidation lake Palic can be classified as an highly eutrophic environment, with tendency towards dystrophic, particularly in past two years.
اظهر المزيد [+] اقل [-]Nitrogen in Dutch freshwater lakes: trends and targets
1998
Molen, D.T. van der | Portielje, R. | Nobel, W.T. de | Boers, P.C.M. (Institute for Inland Water Management and Waste Water Treatment, Lelystad (Netherlands))
Chiral pesticides as tracers of air-surface exchange
1998
Bidleman, T.F. | Jantunen, L.M. | Harner, T. | Wiberg, K. | Wideman, J.L. | Brice, K. | Su, K. | Falconer, R.L. | Aigner, E.J. | Leone, A.D. | Ridal, J.J. | Kerman, B. | Finizio, A. | Alegria, H. | Parkhurst, W.J. | Szeto, S.Y. (Atmospheric Environment Service, 4905 Dufferin St, Downsview, Ontario, M3H 5T4 (Canada))
Alternative strategies for reducing nitrogen loading
1998
Jensen, J.J. | Skop, E. (National Environmental Research Institute, Department of Policy Analysis, P.O. Box 358, DK-4000, Roskilde (Denmark))
Air concentrations of organochlorine insecticides and polychlorinated biphenyls over Green Bay, WI, and the four lower Great Lakes
1998
McConnell, L.L. | Bidleman, T.F. | Cotham, W.E. | Walla, M.D. (US Department of Agriculture, Agricultural Research Service, Building 007, Room 225, Beltsville, MD 20705 (USA))
Modelling the effect of atmospheric deposition on shallow heathland lakes in the Netherlands: dry deposition on water - now you see it, now you don't
1998
Wortelboer, F.G. (National Institute of Public Health and the Environment (RIVM), Bilthoven (Netherlands))
Effects of Alkalinity and External Sulphate and Phosphorus Load on Water Chemistry in Enclosures in an Eutrophic Shallow Lake
1998
Bellemakers, Martijn J. S. | Maessen, Mario
As a result of changes in hydrology, the former mesotrophic, shallow lake Naardermeer, has been eutrophicated during the last decades. To compensate for shortage of water, eutrophicated water with different chemical characteristics has been supplied. In order to determine the effects of alkalinity, acidity and external sulphate and phosphorus load on eutrophication processes, developments in water chemistry have been studied in enclosures. A decrease of the phosphorus load of the lake did not improve water quality on the short term. This observation was confirmed by this enclosure experiment. Reduction of alkalinity did improve water quality, particularly by reductions of turbidity and chlorophyll-a content. The significant increase in sulphate load in the water layer led to deterioriation of the water quality and an increased biomass of sessile algae by internal eutrophication, probably as a result of increased sulphate reduction in the sediment. Therefore, it seems that lowering of sulphate concentrations in the inlet water after the removal of phosphorus is necessary to improve the water chemistry. The best option, however, is to restore the former hydrological conditions after which the system will be fed only by seepage of groundwater poor in nutrients and sulphate.
اظهر المزيد [+] اقل [-]Airborne Pollution in Five Drainage Basins in Eastern Finnmark, Norway: an Evaluation of Overbank Sediments as Sampling Medium for Environmental Studies and Geochemical Mapping
1998
Langedal, Marianne | Ottesen, Rolf Tore
To study whether airborne pollution can be detected in overbank sediments, samples collected from five overbank sediment profiles in eastern Finnmark, Norway, at 1 cm depth intervals, were subjected to chemical analysis and ²¹⁰Pb dating. The studied drainage basins constitute parts of an area polluted by emissions from two Ni-Cu smelters in Russia. In the most polluted catchment area, the surface sample showed a 5-fold higher Ni concentration and a 3-fold higher Cu concentration than the pre-industrial sediments at depth. The increases started at the same time as the smelters. Slight Ni increases were also detected in the neighbouring drainage basin, while no significant concentration change was seen in drainage basins previously shown to be only weakly influenced by the smelter emissions. In the most polluted drainage basin, the increase in Ni accumulation rate did not equal the airborne deposition rate. Selective surface erosion of fine grained particles with adhering airborne Ni has probably caused excess Ni accumulation in both overbank and lake sediments. On the contrary, opening of minerogenic point sources may dilute the pollutant concentrations in the drainage sediments. Thus, dating of the sediment profiles is necessary to determine the airborne pollutant accumulation rates. However, dating is not necessary to map the resultant concentration increase, that may show the increased exposure of humans and biota in contact with the sediments.
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.
اظهر المزيد [+] اقل [-]Effects of acidification due to emissions from the Kola Peninsula on fish populations in lakes near the Russian border in Northern Norway
1998
Hesthagen, T. (Norwegian Inst. of Nature Research, Trondheim (Norway).) | Langeland, A. | Berger, H.M.