微囊藻在日夜週期內移動能力對垂直分佈動態及生長之影響

The effect of diurnal movement on the dynamic vertical density profile and the growth of Microcystis

陳琬菁(Wan-Ching Chen)

指導教授 ： 吳先琪

國立臺灣大學/工學院/環境工程學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.03037

摘要

台灣水庫的水質問題以優養化影響層面最大。優養產生藻華現象所造成問題甚多，新山水庫在每年4月中旬至下旬時，發現藍綠藻華的形成，並且發現銅綠微囊藻（Microcystis aeruginosa）為藻華發生時之優勢種。
由於以往的藻類資料採集，在應用上皆視為採樣當日平均值，並無法得知藻類一天在水體中移動之情形。24小時監測分析結果可知，水體之溫度、溶氧及酸鹼值，一天之中的差異性不大，因此在考慮微囊藻消長變化這些基本的水質參數日變化可視為定值。當微囊藻在水體下層可利用的光線較弱時，微囊藻細胞密度變小，浮力變大，因此微囊藻上浮至表水並且待白天光線變強時行光合作用，但是行光合作用產生了密度較重的碳水化合物，使得微囊藻細胞密度變重，而微囊藻失去浮力，緩慢的向下沉降。
本研究藉由水庫24小時藻類資料採集，觀測微囊藻在水體中一日內實際位置移動之情形，實驗結果顯示不同時間採樣，微囊藻於光線較弱時，上浮至表水，待白天光線變強時，緩慢的向下沉降。

關鍵字

優養化 ； 微囊藻 ； 細胞密度 ； 浮力 ； 垂直移動 ； 24小時

並列摘要

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.
The 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.
In 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.

並列關鍵字

eutrophication ； cyanobacteriaMicrocystis sp.,vertical movement ； cell buoyancy ； physical parameters ； chemical parameters

參考文獻

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