Open AccessHourly and daily variability in nitrogen and phosphorus in a lake restored by the hypolimnetic withdrawal method
Author(s) -
Justyna Sieńska,
Julita Dunalska,
Daniel Szymański
Publication year - 2015
Publication title -
oceanological and hydrobiological studies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.271
H-Index - 22
eISSN - 1897-3191
pISSN - 1730-413X
DOI - 10.1515/ohs-2015-0036
Subject(s) - hypolimnion , epilimnion , eutrophication , phosphorus , nutrient , nitrogen , environmental chemistry , anoxic waters , environmental science , ammonium , thermocline , chemistry , ecology , biology , organic chemistry
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 P tot and 75% of N tot . 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.