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Phosphorus concentration in the Orlík and Slapy reservoirs: a result of socio-economic trends in the catchment and climate change
Hejzlar, Josef ; Jarošík, Jiří ; Kopáček, Jiří ; Vystavna, Yuliya
Based on existing phosphorus data series in the Slapy and Orlík reservoirs and their main tributaries, we reconstructed P inputs to the reservoirs from the catchment during 1961–2016 and compiled\nempirical models of P retention. P concentrations in both reservoirs increased from the 1960s to 1991 and then declined, with the Slapy Reservoir having a significantly increased year-on-year\nvariability. Trends in the increase and decrease of P reflected the socio-economic development in the Vltava river basin, in particular sewerage, wastewater discharges, fertilizer application, livestock,\nand fishpond fisheries. In the Slapy reservoir after 1991, the P concentrations increased during wet summers and created conditions for growth of phytoplankton, whereas in dry summers they\ndecreased to mesotrophy. Climatic and hydrological processes have now apparently begun to compete with a generally decreasing P pollution and support eutrophication despite the drop in P loads from the catchment.
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Trends in the balance and material flows of phosphorus in the Czech Republic.
Hejzlar, Josef
In developed countries, many voices call for increasing the recycling of phosphorus (P) that is a strategic raw material for agriculture and other production sector; phosphorus is also causing environmental problems, for example. eutrophication. Using the methodology of material flow analysis, van Dijk et al. (Sci. Total Environ. 2016, 552: 1078-1093) quantified the main flows and stocks of P in 27 states of the European Union. The contribution presents and discusses data from that publication for the material flows P in the Czech Republic (CR) and compared with the EU. The P balance of CR shows the dependence on imported P through mineral fertilizers (1 kg/ca/yr), food and feed (1.5 kg/ca/yr) and also draws attention to significant environment losses and unused recycling potential. For example, municipal sludge (0.4 kg/ca/yr) and bone meal (0.25 kg/ca/yr) could replace 70% of the P amount in applied mineral fertilizers. P recycling rate in CR in comparison with EU-27 is below average (68% in livestock production, 21% in food production, 10% for human consumption). Agricultural production in CR still uses P reserves in the soil of mineral fertilizers in the past.
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The influence of nutrient loading, meteorological and hydrological conditions and operating manipulations on phytoplankton in the water suply reservoir Římov.
Hejzlar, Josef ; Jarošík, Jiří ; Nedoma, Jiří ; Seďa, Jaromír ; Znachor, Petr
Analysis of data collected during long-term and complex limnologic monitoring of the Římov reservoir in the period 1983 – 2015, which depict the development of physico-chemical conditions, hydrology and hydrodynamics of the reservoir with links to biological data on phytoplankton, zooplankton etc. showed that the concentration and species composition of phytoplankton depend on the supply and availability of nutrients, but are also influenced by climatic and hydrological conditions and water management operation of the reservoir.\n
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Erosion of agricultural land and its importance for siltation and eutrophication of reservoirs in the Czech Republic
Krása, J. ; Jáchymová, B. ; Bauer, M. ; Dostál, T. ; Rosendorf, P. ; Hejzlar, Josef ; Borovec, Jakub ; Bečička, M.
In 58 large catchments of the Czech Republic (covering ca 35000 km2) the sediment transport processes were assessed. Amount of sediment flux into the streams and reservoirs from agricultural land was estimated. Sediment retention in all reservoirs was considered based on reservoirs‘ outflow. For thousands of small ponds the volumes and outflow had to be estimated based on reservoir areas and specific flow rates in catchments. The distributed approach allowed considering importance of particular agricultural fields for stream silting. The maps of annual sediment flow in all streams were derived. The sediment fluxes cause serious problems not only concerning eutrophication. For example Vltava river watershed up to Slapy dam (12 965 km2) exports 2.34 million tons of sediment by water erosion annually. 626 thousand ton is exported into the streams, and 615 500 t is then deposited in the reservoirs.
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Influence of cage fish farming on water quality in the eutrophic Nechranice Reservoir
Hejzlar, Josef ; Borovec, Jakub ; Zahrádka, V. ; Rosendorf, P.
Influence of cage fish farming on water quality in the eutrophic Nechranice Reservoir was assessed through its contribution to the balance of eutrophication-effective forms of phosphorus (PO4-P) entering the reservoir and through measuring impacts on sediment around farming cages. The study showed that although the contribution of cage fish farming is relatively small (max. in tenths to a few percents of the total PO4-P load) its effect on water quality can not be neglected, because it causes direct pollution and, under certain hydrologic and climatic situations contributes significantly to the eutrophication and to critical deterioration of water quality for recreation and bathing. On the other hand, it is indisputable that the main source of eutrophication of Nechranice Reservoir are discharges of municipal wastewater in the catchment.
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