曝气联合生物制剂对白洋淀沟壕水体的修复效果研究

The effect of ecological restoration on ditches of Baiyangdian Lake District

本研究于2019年7-10月采用底部层流曝气+硅藻促生+微生态菌剂联合应用的方法对白洋淀沟壕水体进行了修复,测定并比较了修复前后水体理化指标和藻类群落结构的变化。结果显示:底部层流曝气+硅藻促生+微生态菌剂联合应用的修复技术可以减小水体表层和底层间的pH、水温、DO差异,并增加水体pH、透明度、底层溶解氧。8月份开始,试验区氮磷相关指标值均低于对照区(除NO_(3)^(-)-N外),COD_(Mn)与对照区无显著差异。试验期间从各采样点样本中共观察到浮游藻类8门108属169种。种类组成最多的是绿藻门,共41属66种,其次是硅藻门,23属45种,再次足蓝藻门,28属32种,试验区和对照区藻类物种组成无显著差异。试验区和对照区浮游植物数量变化范围分别为3.65×10^(6)~25.85×10^(6) cells/L和13.54×10^(6)~50.33×10^(6) cells/L,生物量变化范围分别为7.10~66.40 mg/L和28.60~177.20 mg/L,对照区浮游植物的数量和生物量的最大值出现在8月份,试验区则在9月份,9-10月份,试验区的浮游植物数量和生物量显著低于对照区。7-9月份,绿藻门、蓝藻门和隐藻门的贡献率>90%,9-10月份硅藻门的比率逐渐升高,试验区硅藻门占比最高达22.92%,显著高于对照区;多样性指数均表现为试验区高于对照区。伪鱼腥藻属和拟柱孢藻属、隐藻属和蓝隐藻属等陆续成为水体中的优势藻种,其中伪鱼腥藻一直是水体中的优势种。结果表明该水体修复方法对试验区水质有一定的改善作用。

The experiment of combined application of bottom lamina aeration,diatom growth promotion and microecologics on the water quality and algae community structure was carried out at Baiyangdian Lake.A relatively closed trench with a length of 1000 m and a width of about 12 m was selected to carry out experiments.A total of 6 sampling points,which C1 and C2 were located in the control area and T1-T4 were located in the experimental area.The control area and experimental area were separated by purse Seine,and the control area was connected to the lake district.Twenty bottom aerators were arranged in the practical area,and the running time was 10:00-16:00.The microecological agent and diatom promoter were added once every 15 days,with the concentration of 5 g/m^(2) and 40μL/m^(2),respectively.During the experiment,physical and chemical water indexes were sampled every 15 days and phytoplankton indexes were tested every 30 days.The experiment lasted four months.The results showed that compared with the control area,the comprehensive restoration technology could reduce the differences between the surface and bottom of the water in pH,water temperature and DO,and increase the pH,transparency and dissolved oxygen of the bottom.One month after the beginning of the experiment,the relevant indexes of nitrogen and phosphorus were lower than those of the control area(except NO_(3)^(-)-N),and there was no significant difference in COD_(Mn) between the experimental area and control area.A total of 169 species belonging to 8 phyla and 10^(8) genera were identified from each sampling site.Among them,66 species were Chlorophyta,45 were Bacillariophyta and 32 were Cyanophyta.The quantity of phytoplankton in the test area and the control area varied from 3.65×10^(6) to 25.85×10^(6) cells/L and 13.54×10^(6) to 50.33×10^(6) cells/L,respectively.The biomass varied from 7.10 to 66.40 mg/L and 28.60 to 177.20 mg/L,respectively.The maximum quantity and biomass of phytoplankton in the control area appeared in August,and the value in the test area appeared in September.From September to October,the quantity and biomass of phytoplankton in the test area were significantly lower than those in the control area.From July to September,the contribution rates of Chlorophyta,Cyanophyta and Cryptophyta.With the decrease of temperature,the proportion of diatom gradually increased.The highest proportion of diatom in the test area reached 22.92%,which was significantly higher than that in the control group.The value of species richness,Shannon index,Simpson index and evenness index of test area were all smaller than that of the control area.With the change of temperature,Pseudanabaena mucicola,Cylindrospermopsis rackiborskii,Cryptomonas and Chroomonas was the dominant species successively,among them,Pseudanabaena mucicola was the dominant species in water for a long time.The experimental results showed that this comprehensive water restoration method could improve water quality,but the eutrophication state of water in the experimental area had not been changed.