pH及无机氮化合物对小浮萍生长的影响

Effect of Inorganic Nitrogen Compounds and pH on the Growth of Duckweed

利用浮萍科植物吸收转化污水中的无机氮磷正在成为水处理研究的热点 .本研究以我国常见的小浮萍(LemnaminorL .)为研究对象 ,在完全培养液的基础上模拟生活污水的NH+ 4 N、NO- 3 N浓度和 pH范围 ,研究了培养条件对小浮萍生长的影响 .结果表明 ,低 pH对小浮萍的生长具有抑制作用 ,小浮萍对pH耐受的低限在 5～ 6之间 ,在 6～ 9的pH范围内 ,能够正常生长 .水中非离子态的NH3和NH+ 4都会对小浮萍的生长产生抑制作用 ,前者的抑制作用更明显 .在NH+ 4 N为唯一氮源的条件下 ,非离子态的NH3浓度大于 0 2mg/L时就会对小浮萍的生长产生明显的抑制作用 ,大于 2mg/L时 ,小浮萍基本上不能生长 .NO- 3在本研究的浓度范围内对小浮萍的生长没有影响 ,NH+ 4 N和NO- 3 N浓度的增加可使小浮萍的鲜叶片的叶绿素含量增加 ,另外在相同氮的浓度下 ,由于生长受抑制 ,NH+ 4 N中生长的小浮萍过氧化物酶活性高于NO- 3

The use of duckweed in domestic wastewater treatment was paied increasing attention recently. But inorganic nitrogen compounds and pH of wastewater possibly affect the growth of duckweed. The effect of ammonia, nitrate and pH on the growth of Lemna minor L., a common spiece in China, was assessed with laboratory scale experiments. The experiments used artificial culture with different levels of pH, ammonia and nitrate concentrations. The experimental results indicated that the lowest value of pH Lemna minor can tolerate was between 5 ～6, and it can grow well in pH from 6 to 9. The growth rate of Lemna minor was inhibited gradually with increasing concentration of ammonia. The toxicity of ammonia was a result of both forms, NH 3 and NH + 4. Compared to NH + 4, the effect of NH 3 was much stronger. Nitrate had few inhibitory on the growth of Lemna minor. The increases in ammonia and nitrate concentrations can increase the chloropyll content of Lemna minor . Activity of peroxidase of Lemna minor in ammonia culture was higher than that in nitrate culture because of the toxicity of ammonia.