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Prediction of phosphorus concentration and trophic conditions in reservoirs
Hejzlar, Josef ; Kopáček, Jiří ; Vystavna, Yuliya
The model prediction of phosphorus (P) concentration in reservoirs is important for controlling water quality and trophic conditions, e.g. to determine to what level external P load should be reduced in order to decrease trophic conditions and achieve good ecological potential. The mass balance of P for 26 reservoirs and lakes in the Czech Republic showed that the relationship between the inflow P concentration and the in-reservoir P concentration is not determined solely by hydrological parameters (water residence time or hydraulic load) or inflow P concentration but is fundamentally influenced by the internal P loading from sediments and in-reservoir P cycling. These are individual characteristics of each reservoir and may change, for example with sediment accumulation or changes in external P load. Therefore, the prediction models need to be assembled and calibrated for each reservoir individually and the model structure should be adapted to their specific conditions.
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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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