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Water quality parameters of floodplain lakes may be indicative of the intensity of groundwater recharge. The main assumption made in the study is that the direct influence of groundwater recharge is reflected in the vertical gradient of temperature and aeration along the whole water column. Considering this, we seasonally monitored physical and chemical properties of 22 oxbow lakes in postglacial river valleys (the Słupia, Drwęca and Łyna rivers) in temperate climate zone in the southern watershed of the Baltic Sea (N Poland). The results were compared with groundwater samples from transects of piezometers located near the floodplain lakes. The floodplain water bodies showed variability (both in vertical and spatial dimensions) in temperature, aeration and electrolytic conductivity, affected mainly by different sources of water supply. The temperatures and dissolved oxygen contents declined not only with the increasing depth of water and a distance from the river channel, but also a significant drop in the parameters’ values have been associated with groundwater recharge within the floodplain edge.
Sclerotium rolfsii is one of the devastating soil-borne phytopathogens which causes severe loss at the time of seedling development. It also causes leaf spots in several crops and wild plants. Petri plates, containing potato dextrose agar medium, were inoculated with S. rolfsii. Two-third area of three, 50% area of three and 100% area of other three plates were sealed with cellophane tape. The other three plates were not sealed. All the plates were incubated at 27±2°C. Two sets of such plates were prepared. One set was incubated in light whereas the other set in the dark. There was no significant difference in mycelial growth and number of sclerotia among them but significant difference was observed when compared to the control, i.e. the plates which were not sealed. Sclerotium and basidiospore formation were directly influenced by air as completely sealed plates failed to produce sclerotia and basidiospores. Basidiospores were produced abundantly in the light and in the dark conditions in unsealed plates only on Cyperus rotundus rhizome meal agar medium.
The research analyzed the influence of pH and aeration of the above-sediment water on the amount of copper released from the contaminated bottom sediments from the Rybnik Reservoir. Leaching of copper from the bottom sediment in the non-aerated systems was the highest when pH reached 2.0-3.5. For the aerated systems, the range was from 2.0 to 4.5. A dependence of the amounts of leached water on the leaching time was also observed. Sulfides were a predominant form of copper occurrence in the bottom sediment (60%). The remaining forms were as follows: organically bound, carbonates > residual > adsorbed > exchangeable.
Four year field and laboratory study and statistical analysis showed a high reduction of BOD5 and COD in sewage from sugar factory collected in aerated and stabilizing storage basins. Nutrient (nitrogen and phosphorus) reduction was, however, much smaller. Concentrations of total suspended solids, BOD5 and COD in sewage discharged from both basins before the subsequent sugar season were markedly higher than standards allowable for sewage which are delivered to surface waters.
Lake Długie in Olsztyn, Poland, received untreated sewage for over 20 years from a housing estate which probably caused its complete degradation. The lake was regarded in the 1970s as one of the most polluted in Poland; its chemical composition was similar to that of diluted sewage. After the sewage diversion, the amount of organic compounds and nutrients in the water diminished, although the aquatic environment conditions did not improve considerably. Improvement of the trophic state of the lake might have been expected only after applying a relevant restoration technique. Our paper presents the results from a study of the effectiveness of a multi-year restoration of Lake Długie, using the artificial aeration method with destratification. Analysis of the obtained results supports the conclusion that the more than 10-year artificial circulation has resulted in a radical improvement of the environmental conditions in the lake displayed by: increase of oxygen content in the whole water volume, reduction of its consumption rate during both stagnation periods, shortening of the anoxia period in the near-bottom waters, and increase of the redox potential. The artificial aeration has caused a radical decrease of nutrients and organic compounds content in the water, and eventually improved the trophic state. Concentration of phosphorus compounds in the water was reduced mainly due to halted release of the phosphate phosphorus from the bottom sediments. In the case of nitrogen compounds, halted release from the bottom sediments, intensification of the nitrification processes but mainly due to the denitrification process. Despite the considerable reduction of nitrogen and phosphorus compound concentrations in the lake waters, the applied treatment has not resulted in sufficient reduction of the nutrients as to limit the primary production. The lake had remained a heavily eutrophic reservoir which was confirmed by still high values of BOD5, chlorophyll a and low transparency measured by Secchi disk. In the following years of artificial aeration a drop in the reduction rate of the phosphorus compound concentrations was observed which at the parallel lack of iron and manganese in the water indicates that in the case of Lake Długie the capacity for further improvement of its trophic condition in this way had been practically exhausted. Better effects may be expected only after the application of a supportive method, consisting of phosphorus precipitation and fixing in the bottom sediments.
W pracy omówiono efekty rekultywacji Jeziora Ełckiego prowadzonej metodą napowietrzania hypolimnionu i chemicznej dezaktywacji fosforu. Oceny efektywności wymienionych zabiegów dokonano na podstawie wyników badań jakości wód jeziora przeprowadzonych w roku 2006 w okresie wiosennej i jesiennej miksji oraz stagnacji letniej. Wykorzystano także wyniki pomiarów monitoringowych uzyskane w latach 1999-2005 przez Stację Hydrobiologiczną Instytutu Ekologii PAN w Mikołajkach. Na podstawie wymienionych danych stwierdzono, że w Jeziorze Ełckim wskutek zastosowanych zabiegów rekultywacyjnych nastąpiła wyraźna poprawa warunków tlenowych. Nie obserwuje się natomiast wyraźnych zmian w produktywności zbiornika. W związku z powyższym efektywność rekultywacji Jeziora Ełckiego oceniono jako częściową. Możliwe przyczyny niepełnego powodzenia renaturyzacji to stały dopływ nutrietów do zbiornika oraz modyfikacje, jakie wprowadzono do technologii napowietrzania.
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