不同形态氮对洋河水库螺旋鱼腥藻和惠氏微囊藻生长的影响

利用室内培养试验比较研究了硝酸盐氮和氨氮对洋河水库螺旋鱼腥藻和惠氏微囊藻生长的影响.结果表明:ρ(氨氮)和ρ(硝酸盐氮)均在0.05～10 mg/L内时,螺旋鱼腥藻的生长曲线无显著性差异,氨氮更有利于螺旋鱼腥藻的生长;在0.05～10 mg/L内,ρ(氨氮)和ρ(硝酸盐氮)的升高能明显促进惠氏微囊藻的生长,但高浓度的氨氮可能会抑制其生长.当ρ(硝酸盐氮)为0.05 mg/L时,螺旋鱼腥藻比生长速率(0.239 d-1)大于惠氏微囊藻(0.166 d-1);ρ(氨氮)为0.05和0.5mg/L时,螺旋鱼腥藻的比生长速率分别为(0.266±0.012)和(0.303±0.005)d-1,大于惠氏微囊藻的比生长速率(0.096±0.004)和(0.272±0.008)d-1.提示在ρ(氨氮)和ρ(硝酸盐氮)较低的培养条件下,螺旋鱼腥藻比生长速率更高,更易成为优势藻种.洋河水库近2年优势种逐渐从螺旋鱼腥藻转变为惠氏微囊藻,可能是水体中ρ(氮)的变化所致.

Effects of Different Forms of Nitrogen on the Growth of Anabaena sp.and Microcystis sp.from Yanghe Reservoi

Using the indoor culture method, the effects of nitrate nitrogen and ammonia nitrogen on the growth of Anabaena sp. and Microcystis sp. were studied and compared. The results indicated that when the concentrations of ammonia nitrogen and nitrate nitrogen were in the range of 0.05-10 mg/L, there was no significant difference between the growth curves of Anabaena sp. At the same concentration, ammonia nitrogen was more beneficial to the growth of Anabaena sp. Increasing the concentrations of nitrate and ammonia nitrogen in the range of 0.05-10 mg/L clearly promoted the growth of Microcystis sp. However, higher concentrations of ammonia nitrogen may inhibit its growth. When the concentration of nitrate nitrogen was 0.05 mg/L, the specific growth rate of Anabaena sp. (0.239 d^-1) was bigger than that of Microcystis sp. (0.166 d^-1). When the concentration of ammonia nitrogen was 0.05,0.5 mg/L, the specific growth rate of Anabaena sp. (0.266±0.012, 0.303±0.005 d^-1) was bigger than that of Microcystis sp. (0.266±0.012, 0.303±0.005 d^-1). The results show that, at low nitrogen concentrations, the specific growth rate of Anabaena sp. was far bigger than that of Microcystis sp.. Anabaena sp. is preferred as the dominant species. The changing proportions of different forms of nitrogen maybe the reason why Microcystis sp. has been the dominant species in recent years.