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Vliv nádrže Orlík na kvalitu vody ve Slapské nádrži
Straškrábová, Viera
Přísun fosforu (P) do Slapské nádrže byl hodnocen v letech 1959 – 1960 a v letech 1963 – 1964. Po napuštění nádrže Orlíku se koncentrace P ve Slapech snížila a následně došlo ke snížení letního rozvoje fytoplanktonu, zvláště sinicového vodního květu. Dlouhodobě byly hodnoceny zimní koncentrace fosforu a následný sezónní rozvoj fytoplanktonu. V letech 1960 – 1992 zimní koncentrace P vzrůstaly (vliv zvýšení P v detergentech?), pak opět klesaly. Letní koncentrace chlorofylu se zvyšovaly do 2000, pak se postupně snižují (v důsledku meziroční variability zatím neprůkazné).
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Sediments of the Orlík resevoir
Borovec, Jakub ; Hejzlar, Josef ; Jan, Jiří ; Mošnerová, P.
Cílem příspěvku je shrnutí informací o vlastnostech a živinovém režimu sedimentů v podélném profilu nádrže v průběhu vegetační sezóny. Jsou ukázány rozdíly v jejich základním složení a ovlivňování vodního sloupce. Zejména je věnována pozornost rozdílu složení sedimentujících částic a sedimentu, teoretickému uvolňování živin ze sedimentů a jejich potenciálu zadržovat fosfor.
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An analysis of the hierarchy of importance of point and diffuse phosphorus sources in the Lomnice River catchment for the eutrophication of Orlík Reservoir
Hejzlar, Josef ; Polívka, Josef ; Žaloudík, Jiří
P sources in the Lomnice River catchment were analysed in two ways: (i) with a balance method of comparing P fluxes at monitored profiles on streams against the sums of partial P sources within their catchments that was reduced by P retention in the stream network and (ii) with the SIMCAT model of the Environmental Agency UK. Both methods appointed as the main source of high concentrations of total P (i.e., mean and 90% percentile of 0,28 and 0,45 mg/l, respectively, at the mouth of the Lomnice River to Orlík Reservoir in 2004-2008) municipal wastewater discharges and intensive fish pond production (55 and 25 % of P sources in the catchment, respectively) while the exports from agricultural and forested areas were 15 and 3 %, respectively. Scenario calculations by both methods indicated that the level of P concentration in the Lomnice River without eutrophication impacts on the reservoir cannot be achieved without measures both in the purification of wastewaters and fisheries.
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Concentrations and forms of phosphorus in the runoff from small agricultural catchments in the catchment of Orlík Reservoir
Richtr, J. ; Hejzlar, Josef ; Semančíková, E.
Concentrations of major P forms were monitored in the runoff from 21 small agricultural catchments with dominant arable land or grassland within the basin of Orlík Reservoir during one seasonal cycle. Mean concentrations of dissolved reactive P (DRP) and dissolved non-reactive P (DNP) were low and not differed at the arable land and grassland catchments (DRP 32 and 24 μg/l, DNP 8 and 9 μg/l, respectively). Particulate P (PP) concentrations varied significantly between these two types of catchments (77 and 20 μg/l, respectively). Apparently, PP did not originated from recent erosion of land surface but from sediment resuspension or bank erosion in streams. Significant relationships between P concentrations in oxalate extracts of upper (0–15 cm) and deep (50–70 cm) soil layers and between the phosphate saturation index in the 50–70 cm soil layer and the DRP concentration in runoff demonstrated existence of relationship between soil available P and P concentration in catchment runoff.
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Pollution input and transformation along the longitudinal profile of the Vltava stretch in the Orlík
Nedoma, Jiří ; Šimek, Karel ; Hejzlar, Josef
In the Vltava inflow to the Orlík reservoir there are recurrently detected not only highest phosphorus concentrations, but also largest amount of bacteria, algae and cyanobacteria. These parameters showed a downstream decreasing trend indicating efficient self-purification processes. However, the key reservoir problem is the fact that (1) the current phosphorus and biomass loads in the inflow river are so high that without their effective reduction in the Vltava and Lužnice watersheds no real improvement in water quality in the main reservoir body can be expected and, moreover, (2) phosphorus accumulating in sediments could release.
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