National Repository of Grey Literature 16 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Diel variations of selected elements in arsenic-rich stream at the Mokrsko
Nováková, Barbara ; Drahota, Petr (advisor) ; Skřivan, Petr (referee)
The filtration and ultrafiltration experiment was applied on the stream water at the Mokrsko gold deposit and the results revealed that most of the elements were in the dissolved form and the 0,45 or 0,1 m filters could be used. During two 24-h field experiments, water samples were collected at 1-h intervals in order to prove the diel changes in the concentration and speciation of several trace elements. The determination of sorption processes at the surface of or within the veneer of biofilm has been determined by collecting natural and artificial priphyton. The results showed regular diel changes of As, Sb and Mo with highest concentrations occurring after the moon and the lowest concentrations in the early morning. The dissolved concentrations of other elements are conservative or their values were closed to their detection limits. The diel cycles are caused by changes in adsorption/desorption equilibria induced by diel cycles of temperature. The samples of biofilm revealed increased concentrations of the elements under the study and their diel variation were significant (approximatelly 35-96%); however, biofilm-controlled diel cycles of dissolved concentrations have not been proved.
The comparison of geochemical characteristics of Fe, Co, Ni
Kubínová, Petra ; Skřivan, Petr ; Navrátil, Tomáš ; Rohovec, Jan
The purpose of this paper is to compare the geochemical characteristics of iron, manganese, nickel and cobalt. In addition, the evaluation of the main fluxes of the selected elements in the model catchment is made.
Distribution of the rare earth elements in the small catchment Lesní potok
Špičková, Jitka ; Navrátil, Tomáš ; Skřivan, Petr ; Rohovec, Jan ; Mihajlevič, M.
Lanthanides (REE) are particularly useful as tracers of natural processes such as crust and mantle processes, weathering, sedimentary processes, geochemical processes in surface and groundwaters and transport of particulate material through the atmosphere. The aim of this study was to contribute to explanation of the REE cycling by evaluating their concentration in particular components of the ecosystem and by comparing their distributions between these components.
Comparison of chemical composition of throughfall and deposited precipitation
Chaloupecký, Pavel ; Špičková, Jitka ; Fišák, Jaroslav ; Skřivan, Petr
Since June 2004 throughfall samples in beech and spruce vegetation have been taken at the observatory Milesovka. Ever since 1998 fog water samples have been taken there as well. In this paper are compared the concentrations of main ions and trace elements in throughfall and in deposited precipitation. The concentrations of main ions and trace elements in throughfal are primarily affected by the volume of samples. The highest concentrations of monitored sustances in throughfall were recorded in September and in October when the lowest rainfall totals were measured. The concentrations of monitored sustances were in throughfall mostly higher in spruce vegetation in comparison with beech vegetation. It is probably due to the thicker treetop in spruce vegetation on Milesovka observatory. Due to the thicker treetop a smaller volume of throughfall is let fall and the substances from ambient air are captured more effectively in comparison with beech vegetation. In the case of main ions the lowest concentrations were measured in fog water samples. For trace elements wasn´t data. From comparison with reference locality Lesni potok is obvious that concentrations of monitored sustances in throughfall on Milesovka exceed sharply concentrations in locality Lesni potok. This difference is considerably higher by spruce vegetation in comparison to beech vegetation which indicate that it is necessary take not only local air quality into account but also type of vegetation and thick of treetop which can very significantly contribute to the chemical composition of throughfall.
Comparison of both quantitative and qualitative water balance regimes on the Lesní potok catchment
Kovář, P. ; Korytář, M. ; Skřivan, Petr
Analysis of the hydrological balance at the Lesní potok catchment and comparison of results with the balance of selected chemical elements. The analysis was performed using the hydrological balance model WBCM-6.

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