柠檬酸调节水体酸碱度抑制黄丝藻藻华的研究

Growth inhibition of Tribonema bloom by acidification using citric acid

用柠檬酸调节试验水体p H值,并保持在5.0、5.5、6.0和6.5四个梯度下,将采自养殖池塘的黄丝藻(Tribonema sp.)藻华的10 g藻丝体放入试验水体,每隔48 h采样一次,观察黄丝藻藻丝体外部形态、显微结构的变化。同时测定其叶绿素a(Chl a)、丙二醛(MDA)的含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性。结果表明:96 h黄丝藻藻丝体大量下沉,有些藻丝体断裂,无气泡产生,水体开始混浊;192 h水体混浊、藻丝体断裂并溶解的现象进一步明显;192 h各试验组藻细胞内叶绿体集于中央,并呈现不同程度的解体,细胞结构也变得模糊,细胞质膜与细胞壁之间的空隙增大。四个试验组Chl a含量明显低于对照组。对于SOD、CAT的活性,p H5.0的试验组呈现下降趋势,而p H 5.5、6.0、6.5的试验组呈现先增长后下降的趋势;各个试验组MDA明显高于对照组,这说明192 h后黄丝藻藻丝体受到严重的破坏,开始解体、死亡。试验得出结论:用柠檬酸降低水体p H值,可以有效抑制或杀死了黄丝藻,从而控制了黄丝藻藻华。

The Tribonema filaments,weighing 10 g,taken from aquacultural ponds were added to four different acidic experimental water（ constant p H 5. 0,5. 5,6. 0,and 6. 5） driven by citric acid. The external morphology and microscopic structures of Tribonema filaments were observed every 48 h. Meanwhile,the contents of chlorophyll a（ Chl a） and malondialdehyde（ MDA）,and the activities of superoxide dismutase（ SOD） and catalase（ CAT） were measured. The results showed that after 96 h exposure,lots of Tribonema filaments sank and a fraction of them broke; cloudy water began to appear but free of bubbles. After 192 h exposure,the phenomenon of cloudy-water,and fracture and dissolving of algal filaments became further conspicuous. The intracellular chloroplasts of each test group gathered in the center of cells and showed different levels of disintegration; cell structure became fuzzy; the gap between cell membrane and cell wall increased. The contents of Chl a of each experimental group were significantly lower than that of the control. The group of p H 5. 0 showed a tendency to decrease the activities of SOD and CAT,while the other groups increased at first and then decreased on that. MDA contents of each experimental group were significantly higher than that of the control,indicating that Tribonema filaments were severely damaged and began to disintegrate and die after 192 h exposure. It was concluded that acidic water driven by citric acid could effectively inhibit or kill Tribonema sp. and thus control Tribonema blooms.