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1

Comparison of saprobical analyses using plankton in the tributaries of the upper Tisa, Hungary In 2001-2002

100%
Imre A.
Oceanological and Hydrobiological Studies
|
2004
|
issue 2
63-75
EN
Saprobiological investigation using plankton is a part of everyday monitoring practice for determination of water quality in Hungary. However there is an important question: Is this way of using plankton (mainly phytoplankton) good enough and bringing enough information? We can hear, this method is too old and its result are not collateral with different chemical way?s describing saprobity. Another problem of this biological method is being so labor-intensive, demanding a well qualified knowledge on algology and protozoology. To solve these problems and questions we examined saprobiological and the chemical results, describing water quality of tributaries of Hungarian Upper-Tisa, in years 2001-2002. Summarizing results of our investigations, we can say: biological (saprobiological) method of analyses for saprobity is not worse than chemical ways and can give us more information about ecological parameters.
2

Oxygen and nutrients in the southern Baltic Sea

88%
Trzosinska A., Lysiak-Pastuszak E.
Oceanological Studies
|
1996
|
vol. 25
|
issue 1-2
41-76
EN
Temporal variations (1979-1993) in oxygen and nutrient distribution were inveastigated in the Polish sector of the Baltic Sea with reference to hydrological and biological factors.The most strinking differnce in oxygen condiotions in 1989-1993, as compared with the previous decade consist in much earlier and greater supersaturation of the euphotic zone and a significant reduction of oxygen deficiency in the deep water layers.The overall negative trens in oxygen concentrations observed at the bottom of the Gdansk Deep since the 1960s has been reversed.No hydrogen sulphide was found there from spring 1990 until late 1994.In 1989-1993 the winter accumulation peaks of all nutrients shifted from MaArch to February.InN the coastal areas both phosphate and silicate winterpools were reduced to their lowest levels already in spring; in the off-shore waters their respective minimal concentrations were reached in summer and autumn.Nitrates were used by May/June in all areas, except for the Vistula estuarya where their stock was sustained throughout the whole year.Distinct changes in the winter accumulation of nutrients in the surface water were found.In the Gdansk Deep the strong negative trend in silicates ceased, probably due to the declining demand for this nutrient.Rapid accumulation of nitrates was no longer in evidence, but the increasing N/P ratio could be traced in the Gulf of Gdansk as far as the Gdansk Deep.Moreover the coincidence of an effective phosphate sink and low denitrification activity has prompted a significant increase in the N/P ratio in the deep waters of the Gdansk Basin.The input of nutrients from rivers, with a considerablre surplus of nitrogen over phosphorus, is the most obvious reason for the advanced eutrophication in the Polish marine sea.Regional differences in the trophic levels are discussed on the basis of the N/P ratio in the water and the nitrogen and phosphorus uptake ratio.
3

Oxygen transfer during citric acid biosynthesis in 7 and 15 000 liters stirred tank reactors

88%
Podgorski W., Lesniak W.
Biotechnologia
|
2004
|
issue 1
187-200
EN
In laboratory scale, submerged citric acid fermentation enabled to obtain similar to the industrial bioreactor volumetric oxygen transfer rate (kLa) amounted to 240 h-1. Nevertheless, such level of kLa seems not to be necessary for the process. Bioreactors used for the production of citric acid using Aspergillus niger W78B strain, assuring kLa at the 120 h-1 level in a overproduction phase, allowed achieving the oxygen uptake rate by cells in the range 12-15 mmol dm-3 h-1 and a product on substrate yield factor (YP/S) higher then 0.8 g g-1. Thus, the resignation from the widespread in literature strategy of pO2 maximization as an essential prerequisite for high citric acid yield, allowed obtaining the significant 20% improvement in the yield of product formation in the case of molasses media and 7% on synthetic one. Therefore, it can be stated that excessive media aeration during submerged citric acid biosynthesis is not suitable for yield and/or cost of product formation.
4

Oxygen transfer rate in zones of the draft-tube air reactor

88%
Kawalec-Pietrenko B., Holowacz I.
Biotechnologia
|
1993
|
issue 3
31-37
EN
The stepped course of the initial part of the curve has been observed during the aeration time. The sharpness of the stepped course is weaker during the aeration time. The steps decay if the time of the aeration reaches from three up to nine circulation time in the experimental range of parameters. The time of the steps decay depends on the and on the .
5

Measurements of oxygen and inorganic nitrogen fluxes between sediments and water near the water outflow from the sewage treatment plant in Swarzewo

75%
Geringer d. O. M., Wolowicz M.
Oceanological Studies
|
1996
|
vol. 25
|
issue 3
67-78
EN
Between May and October 1994 a number of experiments were carried out focusing on the estimation of oxygen and nitrogen fluxes between sediments and near - bottom waters in the region of water outflow from the sewage treatment plant in Swarzewo. It was revealed that sediments play an important role in removal processes of excess inorganic nitrogen when its concentration rapidly increases in the waters. In the investigated area nitrogen is released from sediments into water at the rate of 40 mmol?m-2?h-1. Additionally, the intense production of oxygen by organisms which create microphytobenthos was confirmed. Outside the algae bloom period the primary production in the water in this region was smaller than the produc-tion in the surface layer of the sediments.
6

Nutrients and oxygen in the Gulf of Gdansk

75%
Falkowska L., Bolalek J., Nowacki J.
Oceanological Studies
|
1993
|
issue 64/3
131-162
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