Search

The experiment was established in a set of containers. Every container held a 10 cm thick layer of profundal sediments and water from a badly polluted lake. The following five preparations were tested (brand names): AQUAKALGON+, BIOGEN REMEDIANT, BIODENN K, ECOTABS 1(TABLETS), ECOTABS 2(POWDER). The biological preparations were applied twice: phase I lasted 56 days and phase II was continued for 21 days. The research results demonstrated that considerably higher values, compared to the control, were initially (day 3) obtained for TOC after the application of ECOTABS 1, for total nitrogen - after BIODENN K and ECOTABS 1, and for total phosphorus - after BIODENN K, ECOTABS 1 and BIOGEN REMEDIANT. Multiplying bacteria might have been an additional source of organic matter in water, which was subsequently deposited in the bottom sediments as implicated by a higher percentage (by 1 to 7% of d.w.) of organic matter in the sediments at the termination of the experiment. Our preliminary experiment did not provide any justification for using the tested preparations in lake restoration efforts. Subsequent studies should focus on the question whether mineral phosphorus released to the lake water or a drastic change in the environmental conditions would not lead towards the dominance of invasive and highly toxic cyanobacteria. [ABSTRACT FROM AUTHOR]

An excess of nitrogen and phosphorus causes an increase in productivity, leading to degradation of a water reservoir. In order to reduce the eutrophication, protective and restoration methods are used. The objective of the paper was to determine the hourly and daily variability in nitrogen and phosphorus compounds in a lake restored by the hypolimnetic withdrawal method. In the epilimnion, the organic form dominates: 97% of Ptot and 75% of Ntot. Hourly variations in the concentration of the investigated compounds indicate that the highest values occurred at night and in the morning, whereas lower measurements were recorded at noon and in the evening. Such a distribution of the concentrations of nutrients during a day is strongly associated with photosynthesis. Along with depth, the proportion of this form decreased in favor of mineral forms. A high content of mineral phosphorus (70%) and ammonium ions (75%) in the hypolimnion results from their release from bottom sediments under anaerobic conditions. As a result of the generated thermocline, they are blocked and accumulated. At the experimental station, the concentration of mineral compounds was at a lower level than at the reference station since their amount was systematically reduced by the outflow of over-fertilized waters from the hypolimnion. [ABSTRACT FROM AUTHOR]