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Sensitivity of Lakes to Inorganic Enrichment Stress ‐ Some Results of Experimentally Induced Fertilization
Author(s) -
HillbrichtIlkowska Anna,
Zdanowski Bogusław
Publication year - 1983
Publication title -
internationale revue der gesamten hydrobiologie und hydrographie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 0020-9309
DOI - 10.1002/iroh.19830680202
Subject(s) - nutrient , eutrophication , macrophyte , environmental science , productivity , human fertilization , sedimentation , littoral zone , zoology , environmental chemistry , hydrology (agriculture) , ecology , chemistry , sediment , agronomy , biology , geology , paleontology , geotechnical engineering , economics , macroeconomics
The introduction of P and N loads exceeding 4‐14 and 1‐2 times, respectively, the amount of these nutrients stored in the waters of four lakes (dystrophic and eutrophic, stratified and unstratified) resulted in stronger, two‐phased changes in P tot standing stock and in rather insignificant and non‐directed changes in N tot in all lakes. In the waters there was the immediate increase of P tot followed by a decrease (together with a decrease in the N : P ratio) but the final level was still higher than in the control. In the top layer of off‐littoral sediments there was a temporary accumulation of nutrients followed by their release to a level significantly lower than that in the control year. Visible changes in the nutrient content and total biomass of above‐ground parts of macrophytes were noted only in the lake which was previously highly dystrophic, after it had been limed. This lake reacted strongest to the P load, and the release of nutrients from its deposits started simultaneously with fertilization. It is hypothesized that the reduction in the N : P ratio in the lake waters was mainly responsible for the lack of assimilation of further doses of P and that the acceleration of denitrification process caused by the higher overall lake productivity was responsible for the stabilization and removal of the N load. The activation of bacterial decomposition in the sediments due to the increase in lake productivity and sedimentation rate was considered as the probable reason for the acceleration of the nutrients release from the top layers of the sediments and their further physical transport to deeper layers.