2种曝气条件对附着硅藻生长的影响

Effects of Two Aeration Conditions on the Growth of Periphytic Diatoms

为研究富营养条件下不同曝气条件对附着藻类的影响,冬季在玻璃温室中给富营养水体(由少量饲料腐烂液、少量的微囊藻水华和自来水混合而成,水体初始叶绿素a浓度为112.04 μg/L)加温(平均温度26.3℃),同时设置空气(对照组)和纯氮气(处理组)2种持续曝气处理,考察不同处理水质指标、浮游植物和附着藻类的差异。结果表明:冬季加温至26.3℃和不同曝气扰动条件下,处理组的DO显著低于对照组(P<0.05),对照组和处理组的总氮浓度分别为6.901±1.905、6.171±1.598 mg/L,总磷浓度分别为1.782±0.812、1.806±1.104 mg/L;对照组和处理组均出现浮游绿藻优势,浮游态的蓝藻和硅藻均没有大量生长;容器内壁上均出现了大量硅藻附着生长,处理组的硅藻附着面积显著大于对照组的(P<0.05);对照组和处理组生长密实处的附着硅藻细胞密度分别高达1.14×10^(6)±8.44×10^(4)、1.27×10^(6)±1.15×10^(5) cells/cm^(2),二者之间没有显著差异(P>0.05),其优势属均为菱形藻属(Nitzschia)和异极藻属(Gomphonema)。这表明在富营养条件下采用不同曝气扰动时,容易大量出现附着硅藻生长,并且氮气曝气形成的低DO条件更有利于硅藻大面积附着生长;附着硅藻的生长可能与富营养条件、曝气扰动等因素有关。这为富营养条件下通过曝气培养附着硅藻提供了研究思路和有益借鉴。

In order to study the effects of two aeration conditions on the growth of periphyton under eutrophic conditions,this experiment was performed in a winter glasshouse with three replications.Air aeration (the control group) and pure nitrogen aeration (the treatment group) were continuously imposed on the prepared eutrophic water to obtain different dissovled oxygen (DO) levels between which the differences in water quality indicators and phytoplankton and periphyton growth and species were investigated.The prepared eutrophic water was a mixture of rotten fish feed solution,Microcystis bloom and tap water,initially containing 112.04 μg/L of chlorophyll-a and 6.33×10^(7) cells/L of Microcystis bloom.During the 34-day experiment,the water temperature was averagely maintained at 26.3℃ using aquarium heater.The results showed that the DO in the treatment group was significantly lower than the control (P<0.05).The total nitrogen concentration in the control and treatment groups was 6.901±1.905 and 6.171±1.598 mg/L,respectively;and the total phosphorus concentration was 1.782±0.812 and 1.806±1.104 mg/L,respectively.Planktonic green algae dominated in both the control and treatment groups,while a massive growth of planktonic blue-green algae and diatoms was not found.Meanwhile periphytic diatoms appeared aboundantly in all the containers,and Nitzschia and Gomphonema were dominant diatoms in both the control and treatment groups;the cell density of the periphytic diatoms in the control and treatment groups was as high as 1.14×10^(6)±8.44×10^(4),and 1.27×10^(6)±1.15×10^(5) cells/cm^(2),respectively,with no significant difference from each other (P>0.05);their attachment area in the treatment group was significantly higher than that in the control group (P<0.05).These results indicated that different aeration disturbances under eutrophic conditions in winter promote the dominance of periphytic diatoms other than Microcystis,especially the low DO level caused by pure nitrogen aeration was more conducive to the massive growth of periphytic diatoms.The growth of periphytic diatoms may be related to eutrophic conditions,aeration disturbance and other factors,which provides a good idea and reference for the culture of periphytic diatoms.