The effect of diurnal movement on the dynamic vertical density profile and the growth of Microcystis
Date Issued
2009
Date
2009
Author(s)
Chen, Wan-Ching
Abstract
Eutrophication in reservoirs is of great concern in terms of water quality management nowadays. Eutrophication in reservoirs often comes with algal blooms, and causes water quality deteriorating. In reservoirs for drinking water supply, cyanobacteria can be a nuisance because of taste and odor problem. In addition, some cyanobacteria may be harmful to human and aquatic lives. One of the examples is Microcystis sp., which produces toxin, for example, the microcystin. he aim of this research was to investigate the factors that cause the dominance of Microcystis sp. in reservoirs. A notable feature of bloom-forming Microcystis sp. is the presence of gas vesicles in the cell, which combined with the carbohydrate content in the cells, regulates the vertical movement of algae in density-stratified water bodies. The density change of algal cell has been reported to be the result of two simultaneous processes: (i) a light-dependent increase in density due to photosynthesis; (ii) a time-dependent decrease related to respiration and the history of irradiation intensity. A significant correlation between the received light dose and the buoyancy loss was found.n order to understand the relationship among environmental factors and the cell buoyancy, samples were taken at different depths in the reservoir for 24 hours. The dynamic changes of the distribution of Microcystis sp. population, physical and chemical parameters were monitored. Models were established and simulations were performed to provide better understanding of the mechanisms responsible for the complex movement of Microcystis sp. resulted from the change in buoyancy and the mixing of the water column in the reservoir.
Subjects
eutrophication
cyanobacteriaMicrocystis sp.,vertical movement
cell buoyancy
physical parameters
chemical parameters
Type
thesis
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