浮萍对罗非鱼越冬池水体的净化作用

Study of Water Purification in Greenhouse Pond for Overwintering Tilapia Using Duckweed

在温室罗非鱼（Oreochromis niloticus）越冬池内架设浮萍（Lemna minor Linn）草床，设置5组不同重量梯度的浮萍和空白对照组，通过平行试验和连续试验测定浮萍生长速度以及浮萍对池水中溶解氧、 pH 及营养盐（总磷、总氮、氨氮、亚硝氮）等理化指标的影响。结果表明，不同密度条件下浮萍的生长速度不同，适宜的浮萍密度可增加池水溶氧、抑制 pH 的降低、吸收氮磷、净化水质。其中当浮萍密度为660～675g／m^2时，对池水的净化效果最好，可为温室体系内浮萍净水的最佳投入量提供依据。

Floating duckweed( Lemna minor Linn) frames were set up in greenhouse ponds where Nile tilapia( Oreochromis niloticus) was cultured. The floating duckweed frames were divided into six groups containing various amounts of duckweeds. The growth speed of duckweed and the water parameters,including dissolve oxygen,p H and nutritious salts( total phosphorus,total nitrogen,ammonia nitrogen,nitrite nitrogen) were monitored during the whole courseof the experiments. The results showed that the growth speeds of duckweed were dependent on the densities of the duckweed. Duckweeds with appropriate densities were able to enhance the dissolve oxygen,stabilize the p H,absorb the nutritious salts in the cultured ponds,so as to purify the cultured water and keep water quality. The density of the duckweed with 660 ~ 675 g /m2 was optimal for keeping the water fresh. The results will shed a new light on the greenhouse pond water management using floating duckweed frame.