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Aura
|
1998
|
nr 06
12-14
The unique nature of natural values of the Tatra Mts., good management and some fashion for the Tatra Mts. have led to a constant increase in tourist traffic in recent years. The problem lies not only in huge numbers of tourists visiting the Tatra National Park but also in their uneven distribution during the season and in various parts of the park. Consequently, the most attractive and naturally precious areas are under the strongest pressure. The author discusses the issue using the route to the Morskie Oko Lake as an example.
Chromium contamination in the area of the Radomka river basin in Poland has lead to significant environmental problems. Therefore, chromium redox transformations were investigated in the aquatic environment under conditions as close to natural as possible ± at intermediate pH and in the presence of original bottom sediment and dissolved oxygen. Reduction of Cr(VI) in the Radomka river water occurs at a low rate (t1/2 = 19 h). The rate of Cr(VI) reduction increased in the river water spiked by HA (t1/2 = 0.5 h), and Fe(II) (t1/2 = 2 min). The kinetics of Cr(VI) reduction by Fe(II) was dependent on the evolution of the forms of Cr(VI) and the competing Fe(II) oxidation reaction by dissolved oxygen. The reduction of Cr(VI) by humic acids appeared to be a significantly slower process than Fe(II) oxidation by O2. Chromium(III) present in the tanning liquor used and the aged solution of chromium sulphate was less prone to oxidation by MnO2 than Cr(III) introduced with chromium nitrate and sulphate solutions (7% and 10% conversion over 1 h in comparison with 55% and 32%, respectively). Chromium deposits in bottom sediment turned out to be resistant to oxidation by MnO2.
The total content of chromium in natural waters does not generally exceed several mg/l. Thus, it is obvious that various forms of chromium will occur at the levels of tenths or hundredths of mg/l. Their determination requires the application of a sufficiently sensitive method, but an important role to play has its specificity in the case of chemical individuals or selectivity in regard to speciation of a group of compounds, e.g. valency states or organic chromium complexes. Generally, however, there is a lack of specific and selective methods, and the concentrations of various forms of the analyte occur often at the level of detection limits of even such sensitive techniques as atomic absorption spectrometry. This paper presents a review of currently available analytical possibilities of chromium speciation investigations in natural water samples. Analytical procedure schemes enabling "total speciation analysis" have been discussed in some detail. A large group of methods used in the speciation analysis of chromium(III) and chromium(VI), both in off-line and on-line mode, has also been discussed.
The impact of traffic emissions on the environment close to an arterial road often is assessed on the basis of heavy metal pollution of road dust collected directly from or close to the road surface. In our work we propose an assessment of a potential environmental hazard on the basis of an analysis of the content of heavy metals in the road dust trapped on vertical acoustic barriers installed directly by roads. This kind of road dust appeared to be a good indicator of traffic related to heavy metals emissions. The pollution level of Cu and Zn reached the category of “extreme level.” An increased level of Cu was found on a decelerating activity section. A good correlation between Cu, Mn, and Fe may imply that brake wear is also an important source of iron and manganese. It has been shown that high concentration of Zn is a result of its release from zinc-plated road furniture.
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