化學因子對於微囊藻團聚之影響

Effects of Some Chemicals on the Colonial Aggregation of Microcystis

蕭孟儒(Meng-Ju Hsiao)

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(2017年)

https://doi.org/10.6342/NTU201702948

摘要

湖泊水庫經常發生優養化的現象，微囊藻是優養化水體中之常見物種，每到夏季更是水體中的優勢藻種。一旦水庫大量滋生藻華的現象，會影響水處理場的淨水效率，增加處理成本，亦可能造成環境問題。因為微囊藻在水體中具有形成團聚之能力，能夠在水體中自由垂直移動，獲取足夠的營養鹽與光照，幫助藻團取得生長優勢。已有許多學者針對影響微囊藻團聚的因子進行研究，包括生物與非生物因子，目前仍沒有明確的說法能夠解釋微囊藻團聚的機制。
本研究根據文獻採用乙醛酸及氯化鈣兩種化學物質，設計五種不同濃度並模擬水庫現地的環境條件，對含有微囊藻的水體進行實驗，觀察水質變化情形與微囊藻團粒徑變化。在相似的環境條件下，純藻培養之微囊藻較水庫採集之微囊藻生長狀況差，實驗室培養之微囊藻無法抵抗高強度日照而死亡。化學因子對微囊藻的影響實驗結果顯示，實驗中添加的化學物質對於微囊藻或其他藻類的生長有抑制的影響，五天實驗裡藻類的生長狀況皆不如對照組來的良好，尤其是在乙醛酸較高且添加鈣離子之組別生長情形最差。而藻團粒徑的分佈結果發現，在本實驗的環境條件下，五組的實驗中沒有太明顯的粒徑增加趨勢，而微囊藻的粒徑多集中於30~70 μm的範圍內，唯有兩種化學物質皆添加之組別反而會使微囊藻團粒徑變小。
此外，本研究也發現，使用乙醛酸做為控制水庫優養化現象之化學物質較不適合，乙醛酸本身的化學特性可能會影響水體生態的正常生長。鈣離子雖有促使藻團粒徑變大的傾向，但使用的濃度及副作用仍有疑慮，需要進一步的研究才能判斷使用的可行性。

關鍵字

微囊藻 ； 藻團 ； 粒徑分佈 ； 乙醛酸 ； 鈣離子

並列摘要

The algal blooms in lakes and reservoirs caused by eutrophication bring about series of water quality and environmental problems. Microcystis, a group of common bloom-forming cyanobacterial species, is of significant concern during the occurrence of eutrophication worldwide. The ability of forming colonies helps on Microcystis’ vertical migration, nutrient storage, and defense against predation. Therefore, such characteristic is believed to be the main reason for Microcystis to dominate over other phytoplankton in the thermally stratified lakes or reservoirs. Factors and mechanisms abiotic or biotic affecting the aggregation of colonies are not clearly identified and studied.
In this study, we applied two possible allelochemicals, glyoxylic acid and calcium chloride, in the water to observe their effects on the aggregation of Microcystis cells and water quality. Laboratory cultured Microcystis aeruginosa, died in two days due to the destructive irradiation of high intensity of light. Laboratory cultured algae cannot endure drastically change of environmental conditions. By using algae collected in the field, two chemicals retarded the growth rate of algae, especially glyoxylic acid at high concentration. However, no significant change of colony size was observed in treatments for both chemicals. Colony size distributions were ranging from 30 to 70 μm for five different conditions. And colony radii of the two treatments with simultaneous addition of two chemicals were smaller than those of other treatments.
Moreover, there have been some shortages in the application of glyoxylic acid as eutrophication controller. Glyoxylic acid is an organic compound. Pouring it in the reservoirs will cause the decrease of pH value and damage the water quality and ecosystem. Although calcium chloride tends to make particles bigger, we still need more study before applying calcium into reservoirs to control the growth of Microcystis.

並列關鍵字

Microcystis ； colony formation ； size distribution ； glyoxylic acid ； calcium ion

參考文獻

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