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Impact of metabolites of the forest vegetation on the chemistry of throughfall
Skřivan, Petr ; Navrátil, Tomáš ; Vach, Marek ; Špičková, Jitka ; Fottová, D.
The chemistry of throughfall is a result of numerous processes that affect the concentrations of its individual components in the original wet precipitation above the tree crowns. The precipitation entering the tree crowns is generally enriched throughout its interactions with the above - ground part of the vegetation. The samples of open place precipitation and throughfall have been collected since 1989 in the region of Kostelec n. Č.lesy. The monitored area is situated predominantly in the Nature State Reserve Voděradské bučiny on the bedrock of the Říčany and Jevany granites. The exact evaluation of the impact of metabolites on the resultant concentration and fluxes of individual monitored elements in throughfall, based on mere comparison with the corresponding values in open place precipitation, is faced with several problems. First, the chemistry of throughfall reflects more the chemical composition of aerosol from lower parts of the atmosphere, as it is more or less effectively swept out by the above ground growth. The vegetation surface also entraps the reactive atmospheric gasses. Finally, the original precipitation solution is thickened through the evapotranspiration and it is enriched by the excluded and leached metabolites. The estimate of the extent of metabolic activity of the forest trees on the chemistry of throughfall was therefore limited on the comparison of a relative magnitude of normalised fluxes of individual elements in a given type of throughfall. The fluxes of individual elements in a beech- and spruce throughfall were normalised on the Na fluxes, with respect to the supposed zero metabolic share of Na in throughfall and to its predominantly natural sources in the atmospheric aerosol. The calculation of the enrichment factor Ef of the individual elements was then executed by means of the relation EfTFB,TFS (Me) = FBP Na / FTFB,TFS Na* FTFB,TFS Me / FBP Me, where EfTFB,TFS (Me) is the enrichment factor od the particular element in a given type of throughfall, FBP Na a FBP Me are the mean annual deposition fluxes of Na and the element Me on an open place, and FTFB,TFS Na a FTFB,TFS Me are the mean annual fluxes of Na and the element Me in throughfall. Values of the enrichment factor for the individual elements are presented in the article in the Tab. 1. Values higher than 1 should generally indicate the presence of metabolic products of the vegetation. The highest Ef values were found, after expectations, for the basic nutrients and significant essential elements, in a row of K > Mg > Mn > Ca. Together with these elements, significant impact of leached metabolites was also found for Rb, Sr and Ba. The enrichment of throughfall with rubidium is extraordinary high, probably even higher than that of its homologue potassium. Surprisngly high values of the Rb deposition fluxes in both tyes of throughfall certify the extensive input of this element through the root uptake of the forest vegetation, which is contingent on very close chemical characteristics of rubidium and potassium (ionic radii, electronegativity, ionic character of bonding of these alkaline metals in all their chemical compounds etc.). We have not found, however, similar pronounced paralell between Ca, Sr and especially Ba, which is even more abundant in the underlying rocks and soils than Sr.
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Modelování hydrodynamiky a kvality vody v dimiktické nádrži – nádrž Jordán, Česká republika
Hejzlar, Josef ; Jarošík, Jiří ; Borovec, Jakub ; Růžička, Martin
The two-dimensional, dynamic model CE-QUAL-W2 was used to model water quality of a small, highly eutrophic reservoir with intensive nutrient cycling between the water column and bottom sediment. The model was calibrated and evaluated for a 4-year, hydrologically variable period and used in a scenario simulation study to analyse effects of the changing external and internal phosphorus loading and depth of outflow to trophic conditions and water quality. The reservoir hydrodynamics were simulated with good precision in all parts of the seasonal cycle and during the whole period. Water quality and nutrient cycling could be calibrated and simulated with satisfactory results for individual years, however, an extrapolation of model to conditions with different nutrient loading was problematic. It spite of this partial limitation, the model was found appropriate for water quality evaluation and prediction in Jordan Reservoir.
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Transport fosforu v říční síti podhorského povodí se smíšeným využitím uzemí (povodí Malše, ČR)
Turek, Jan ; Hejzlar, Josef ; Žaloudík, Jiří
Phosphorus sources and transport in the river network were evaluated for a medium size (437 km2), upland catchment with mixed land use (forests, farmland, urban) located in South Bohemia during 1999-2003. Dissolved P concentrations in streams in completely forested catchments, farmland catchments, and municipal wastewater treatment plant (WTP) effluents were /~0.015, <0.01 to 0.25, and up to 2 mg/l, respectively. High particulate P concentrations (up to 0.6 mg/l) occurred in all streams during surface runoff events, irrespective to land use, and even higher in WTP effluents (up to /~4 mg/1). Analysis of P fluxes in the river network showed a significant annual retention of both dissolved P (26 to 41% of all sources) and particulate P (27 to 67% of all sources).
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Restoration of aquatic ecosystem and water quality in the drinking-water reservoir Římov after the flood in 2002
Hejzlar, Josef ; Kaštovská, Klára ; Seďa, Jaromír ; Znachor, Petr ; Jarošík, Jiří ; Haider, Z.
The extreme flood event in the catchment of the Malše River in August 2002 markedly changed hydrodynamics of Římov Reservoir (loss of thermal stratification; water residence time dropped from months to single days) and caused problems in water treatment due to a long-lasting increase in concentrations of dissolved organic matter. However, biota of the aquatic ecosystem was influences relatively little. Although large proportions of phytoplankton and zooplankton biomasses were flushed out of the reservoirs the originally dominant species re-established in their original size of biomass within less than one month. The fish community was influenced almost negligibly except for a temporal enrichment by species from streams and fishponds. These results evidence that the reservoir ecosystem is very stable towards fluctuations of hydrologic conditions.
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Model analysis of effects of hydrodynamics and nutrient loading to water-quality in a dimictic reservoir (Jordán)
Jarošík, Jiří ; Hejzlar, Josef ; Borovec, Jakub ; Růžička, Martin
The dynamic, two-dimensional model CE-QUAL-W2 was used to simulate recovery conditions in the eutrophic Jordan Reservoir. The aims were: (i) to calibrate the model and discuss differences between simulated and measured data; (ii) to use the calibrated model to determine the effects of external and internal phosphorus load and the depth of outlet on trophic conditions. After calibration the model reproduced thermal stratification, oxygen regime and concentrations of NO3-N with sufficient precision. Simulation of PO4-P was less exact. The results of mathematical simulation showed that (i) the required mesotrophic level cannot be accomplished without a significant decrease in inflow concentration of total phosphorus; (ii) the internal load of phosphorus is small and become insignificant after decrease of external load; and (iii) the use of bottom outlet is a potentially efficient method to partly decrease trophic level of Jordan Reservoir.
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Possibilities to decrease of the phosphorus concentrations in wateshed and reservoir
Borovec, Jakub ; Hejzlar, Josef ; Maršálek, Blahoslav
P concentrations in the outflow from the watershed result from the group of factors including geology, climate, vegetation cover, morphology of streams and others. Selection of the watershed restoration strategy and its optimalisation depends on the regional, but the common idea for management of both watershed and reservoir should be the recovery to natural processes of nutrient retention together with the idea of sustainable development of the landscape. For the reservoirs, it is always lucrative to precede their overloading by phosphorus. Thinking about the decrease of P in the reservoir, the only possibility is to remove the sediments as the final deposition pool in the P-cycle. In case of the decrease of P in the water column, i.e. available for algae, another procedures of reservoir management can be used.
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