不同营养状态水体中生态浮床对浮游植物群落的影响

为研究不同营养状态下水体中浮游植物群落对生态浮床系统的响应关系及其影响因素,设不同营养水平试验组〔A组ρ(COD_Cr)、ρ(NH₄+-N)、ρ(TP)分别为10.0、2.00、0.200 mg/L,B组分别为100.0、20.00、2.000 mg/L〕,每组设对照、框式浮床2个处理,每个处理3个重复. 自2012年8月5日—10月5日,定期对水体营养盐质量浓度、浮游生物群落特征、浮床植物的生长状况进行检测. 结果显示:①2个试验组浮床植物长势良好,其中B组浮床植物茎叶部分干物质量增加7.9倍,浮床系统对水体N、P的净去除率均在60%以上；②浮床系统能明显抑制浮游植物的大量生长(P＜0.05),对浮游植物密度和总生物量在峰值处的最大抑制率可达75.9%(A组)和83.6%(B组)；③框式浮床处理中浮游植物的群落结构比对照处理复杂,A组中浮游植物优势种为隐藻门的卵形隐藻(Cryptomonas ovata)、尖尾蓝隐藻(Chroomonas acuta)和绿藻门的四尾栅藻(Scenedesmus quadricauda)、小空星藻(Coelastrum microporum),B组为隐藻门的尖尾蓝隐藻和裸藻门的梭形裸藻(Euglena acus)；④B组试验中,框式浮床处理浮游植物Shannon-Wiener多样性指数显著高于对照处理,生态浮床对浮游植物群落的影响更多体现在提升浮游植物的生物多样性上. 研究表明,浮床系统能高效去除水体N、P,抑制浮游植物的增殖,改变浮游植物的群落结构,并且这些作用受到水体营养水平的影响. 

Effects of Ecological Floating Bed System (EFBS) on Phytoplankton Community Structure in Water Bodies with Different Nutrient Levels

Two tests with different nutrient levels (test A:ρ(COD_Cr), ρ(NH₄+-N) and ρ(TP) were 10.0,2.00 and 0.200 mg/L respectively, and test B:ρ(COD_Cr), ρ(NH₄+-N) and ρ(TP) were 100.0,0.00 and 2.000 mg/L respectively), were conducted to study the responses of the phytoplankton community to the ecological floating bed system (EFBS) in water bodies. Both tests included two treatments (control with no EFBS and frame-type EFBS) with three replications. The dynamics of nutrient level, the community structure characteristics of phytoplankton and macrocrustacean and the growth of Cyperusalter nifolius were detected at regular intervals from August 5th to October 5th in 2012. The results indicated that plants on EFBS grew well in the two tests. The dry weight of stem and leaf of Cyperus alternifolius increased up to 8.9 times in test B, and more than 60% of N and P were removed by the EFBS. The EFBS significantly inhibited the growth of phytoplankton as the net removal efficiency on density and total biomass of phytoplankton both reached 75.9% and 83.6% respectively at the peaks. The phytoplankton community structure was more complex in the treatments with EFBS than in the controls, as the dominant species were Cryptomonas ovata and Chroomonas acuta belonging to Cryptophyta, and Scenedesmus quadricauda and Coelastrum microporum belonging to Chlorophyta in test A, while Euglena acus belonging to Euglenophyta and C. acuta in test B. In test B, the Shannon-Weiner index of phytoplankton was significantly higher in treatments with EFBS than in the controls; it seemed that the effect of EFBS on phytoplankton was mainly enhancing its biodiversity when in higher nutrient level water. Our study revealed that EFBS had a high removal efficiency of N and P, inhibited the growth of phytoplankton and enhanced its diversity, and the nutrient levels of water influenced these effects.