環境因子對微囊藻團粒化影響之研究-以新山水庫為例

Effects of Environmental Factors on the Colonial Aggregation of Microcystis in Shin-Shan Reservoir

周展鵬(Chan-Peng Chou)

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(2012年)

https://doi.org/10.6342/NTU.2012.02919

摘要

在河川、湖泊及水庫中，經常發生藻華之現象，其中又以微囊藻(Microcystis)為常見的藻華物種。在水庫發生藻華時，不僅會造成淨水成本的增加，也可能造成許多環境問題。微囊藻具有團聚之生理現象，此一特殊之生理現象能幫助微囊藻在水體中垂直上下移動，以便獲取充足之陽光及攝取營養鹽，並可以抵抗原生動物之掠食。過去研究認為微囊藻能形成藻團是其在分層水體中取得優勢的特殊能力，因此微囊藻常在具有熱分層現象湖泊或是水庫取得優勢，大量生長成為優勢藻種。

本研究利用基隆市新山水庫中從2010年及2011年採樣而製作之藻類定性片，觀察微囊藻團在水體中粒徑分佈之情形。其結果顯示2011年微囊藻在夏季時取得優勢，藻團之粒徑分佈較為偏大。然而2010年微囊藻並非優勢藻種，藻團之粒徑分佈偏小。此外本研究利用不同粒徑表示法與新山水庫各項水質做相關性分析，發現藻團粒徑與卡爾森指數、葉綠素a和水中導電度有顯著之正相關。由於水庫中導電度來源主要為進流水中之鹽類，此結果顯示因外來營養鹽濃度高時，可能導致微囊藻生長，造成葉綠素a濃度上升，且此時會發現較大團粒之藻團，使得微囊藻在水體中取得優勢。

本研究又在不同之光強度(25μEm-2s-1、65μEm-2s-1及125μEm-2s-1)下培養微囊藻，並且觀察微囊藻團粒徑與光強度之關係，發現各個光強度下培養之藻團粒徑皆會上升之後趨於穩定，但其變化與光線強度沒有明顯關係，可能原因為微囊藻在高營養鹽濃度下無須競爭營養鹽，且光之強度尚未對微囊藻造成影響所導致。

關鍵字

微囊藻 ； 藻團 ； 粒徑分佈 ； 光強度 ； 營養鹽濃度 ； 新山水庫

並列摘要

Algal blooms in reservoir will not only result in increased water purification costs, may also cause many environmental problems. Microcystis, which is one of the most notorious bloom-forming cyanobacteria occurring in freshwaters, forms large colonial aggregates. Forming Colonies is helpful to vertical migration, nutrient storage, and to defense against predation pressure. Therefore, aggregation or formation of bigger colonies is believed to be a special ability of Microcysits to dominate over other phytoplanktons in the thermally stratified lakes or reservoirs.
Water samples from Hsin‐shan water Reservoir from 2010 to 2011 were examined for the particle size distribution of Microcystis colonies. The result shows that the particle sizes were larger in 2011 when Microcystis was dominant in summer. On the contrary, the averaged particle size was smaller in 2010 when Microcystis was not dominant. In addition, we have used different calculation methods to represent particle size and analyse the correlations among the water quality parameters in Hsin‐shan reservoir. The results show that the colony size is significantly correlated with CTSI, concentration of chlorophyll a and water conductivity. Because the source of the major conductivity in reservoir water may be from polluted inflow, which also has higher nutrient concentration and leads to the growth of Microcystis. Higher conductivity gave rise to chlorophyll a concentration, and larger colonies of Microcystis, which all are the advantages of Microcystis in the water.
In this study, the relationship of the Microcystis colony size and light intensity was also examined under different light intensity (25μEm-2s-1, 65μEm-2s-1 and 125μEm-2s-1). No significant difference on the change of colony size was observed. The particles grew bigger for the first and second days then became unchanged. The reasons may be that Microcystis do not need to compete for nutrients under high nutrient concentration and the value of light intensity is too small to influence Microcystis to form colony.

並列關鍵字

Microcystis ； colony ； particle size distribution ； light intensity ； nutrient concentrations ； Hsin‐shan water reservoir

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