翡翠水庫藻類族群結構分析及分層系統動態模擬

林明郁(Ming-Yu Lin)

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(2004年)

https://doi.org/10.6342/NTU.2004.00791

摘要

水庫的水質一直是水資源相關研究單位所關切的重點，優養化是其中最常見的問題，而優養化和水中的營養鹽與藻類的生長有關，藻類在短時間內大量生長則稱之為藻華現象，會嚴重影響水庫水質。本研究以動態模擬的方法來探討光線、溫度、營養鹽等限制因子及水體混合情形對藻類生長的影響。本研究將環境因子的空間梯度納入考慮，以動態系統模擬軟體STELLA建立分層系統模式，用以模擬2000~2003年翡翠水庫大壩表水的總藻體積變化以及三種藻種共存系統之體積變化的情形。以2001年的藻類實測資料校正模式參數，以2000、2002及2003年的資料進行驗證。
總藻模擬的校正結果良好，但驗證結果欠佳。以敏感度分析來探討環境因子對藻類的生長影響，發現磷供應是其中較為關鍵的因素，因現場資料不足亦可能是模擬欠佳的原因之一。三種藻種共存的結果顯示，在非穩態的條件下競爭排斥效應並不一定會發生。將分層模式改為完全混合模式，與原分層模式兩者所進行的穩態分析結果加以推理探討，本研究認為「環境因子的時間變異性與空間變異性有利於不同藻種共存」的想法應該是對的，且可用以解釋現實世界中生物多樣性的存在。
後續研究可嘗試改變分層的方式以檢驗混合機制對模擬的影響。另外，以實驗方式研究非穩態系統下，各藻類的生長參數以及其限制因子，對於藻類生長模式的發展應該甚有幫助。

關鍵字

混合係數 ； 藻類 ； STELLA ； 動態模擬 ； 翡翠水庫 ； 生物多樣性 ； 限制因子

並列摘要

Water quality in reservoirs is an important issue of concern interms of water supply nowadays. Abnormally high amount of phytoplankton in water, is one of the causes of water quality deterioration. Concentration of phytoplankton may increase greatly in a short period of time once the conditions in water are suitable for its growth. Light, temperature, nutrients and mixing conditions are key factors controlling algae growth. How they affect the growth of phytoplankton was studied by the method of dynamic modeling in this study. A conceptual stratified system was established to mimic the reservoir water column which showed gradients of environmental factors. Modeling tool, STELLA, was utilized to simulate the variation of the total volume of phytoplankton, and the volume of each of the three algal groups. Field data were collected in the surface water near the dam in Feitsui Reservoir. Data in 2001 were used for calibration and data in 2000, 2002 and 2003 were used for validation.
Calibration of the dynamic model was successful but the validation of the model was not satisfying. The results of sensitivity analyses are helpful to the understanding of the relationship between algae growth and the environmental factors. One of the sensitive factors is phosphorus supply, a process controlled by mixing and the concentration underneath the euphotic layer. Due to the lack of field investigation and available data, poorly calibrated mixing coefficient might account for the unsuccessful validation. There was co-existence of three different algal species under non-steady state condition and competitive exclusion was not necessarily to happen. The analyses of the stratified model and the completely mixing model indicate that the variation on time and space may help to the co-existence of multible species. This may be one of the reasons why biodiversity is maintained in the real world.
To improve the simulation results, different approaches of segmentation of the water column as well as the experiments to investigate the influences of growth parameters of phytoplankton under non-steady state deserve a try in the future.

並列關鍵字

mixing coefficient ； STELLA ； biodiversity ； Feitsui Reservoir ； Phytoplankton ； growth limiting factor ； dynamic modeling

參考文獻

Alam, M. G. M., Jahan, N., Thalib, L., Wei, B. and Maekawa, T. (2001) Effects of envionmental factors on the seasonally change of phytoplankton populations in a closed freshwater pond. Environ. Int. 27: 363-371.

Burmaster, D. (1979) The continuous culture of phytoplankton: mathematical equivalence among three steady state models. Am. Nat. 113: 123-134.

Coles, J. F. and Jones, R. C. (2000) Effects of temperature on photosynthesis-light response and growth of four phytoplankton species isolated from a tidal freshwater river. J. Phycol. 36: 7-16.

Droop, M. R. (1973) Some thoughts on nutrient limitation in algae. J. Phycol. 9: 264-272.

Elliott, J. A., Irish, A. E., Reynolds C. S. and Tett, P. (2000) Modelling freshwater phytoplankton communities: an exercise in validation. Ecol. Model. 128: 19-26