人工浮島水生植物交互作用對水質淨化之影響

Abstract

人工浮島除了在生物棲地、環境景觀、消坡護岸、水生養殖等方面具有一定程度的助益外，對於水質之淨化亦具有相當不錯的成效。在台灣大學安康農場設置38個PVC製人工浮島與32個竹製人工浮島，研究20種栽植於浮島上水生植物生長狀態，進行平均每週一次共四個月的觀察。其中生長狀況較顯著者有燈心草，比生長速率分別為0.034/day；培地茅為0.022/day；開卡蘆為0.030/day；莞為0.024/day；香蒲為0.033/day；單葉鹹草為0.034/day；甜荸薺為0.025/day；過長沙為0.024/day、3.8株m2•month 。 選出香蒲、燈心草、過長沙三種植物，分別以單一栽種與兩兩混合栽種進行室內試驗，將小型浮島放置於水桶中進行平均每週一次共三個月的觀察與水質採樣。過長沙對香蒲及燈心草影響的競爭係數分別為−0.32與−1.01，有正面的幫助；而香蒲與燈心草對過長沙影響的競爭係數為−0.07與0，影響極小；另外香樸會抑制燈心草的生長，其競爭係數為+0.32。 在水質方面，水生植物會吸收水中營養鹽，其中香蒲單一栽種對氮與磷的吸收率為17.5%與13.1%；燈心草單一栽種吸收率為25.7%與22.6%；而過長沙單一栽種吸收僅有5.1%與7.6%。在混合栽種方面，香蒲與過長沙混種對氮與磷的吸收率為21.0%與17.2%；燈心草與過長沙混種吸收率為26.0%與23.4%。

Artificial floating islands not only contributed greatly to biological habitat, landscape environment, bank protection, and aquatic cultivation, they also enhanced water purifications. 32 floating islands made from bamboo and 38 made from polyethylene were constructed in the pond of An-Kang Farm, NTU. The growth states of 20 aquatic macrophyres were observed weekly from August to November, 2005. Juncus effusu, Vetiveria zizanioides, Phragmites karka, Schoenoplectus validus, Typha orientalis, Cyperus malaccensis, Eleocharis dulcis, and Bacopa monnieri had significant growths with specific growth rate of 0.034/day, 0.022/day, 0.030/day, 0.024/day, 0.033/day, 0.034/day, 0.025/day, and 0.024/day, respectively. Three kinds of aquatic macrophytes, Typha orientalis, Juncus effusus, and Bacopa monnieri were chosen for laboratory experiments which were cultivated individually or mixed. Every pair of the three species was mixed in three kinds of different assemblages. The small-scale models of artificial floating islands were set up in the buckets. The growth state and water quality were observed weekly for three months. The competition coefficients of Bacopa monnieri which had positive effect on Typha orientalis and Juncus effusus were -0.32 and -1.01, respectively. The competition coefficients of Typha orientalis and Juncus effusus which had little effect on Bacopa monnieri were -0.07 and 0, respectively. In addition, there was negative effect of Typha orientalis on Juncus effuses which had a competition coefficient of +0.32. In water purification, aquatic plants absorb nutrition from water. In single planting, the nitrogen absorption of Typha orientalis, Juncus effuse, and Bacopa monnieri were 17.5%%, 25.7%, 5.1%, and the phosphorous absorption were 13.1%, 22.6%, and 7.6%. In mixing planting, the nitrogen and phosphorous absorption of Typha orientalis and Bacopa monnieri mixing planted were 21.0% and 17.2%; Juncus effuse and Bacopa monnieri mixing planted were 26.0% and 23.4%, respectively.