Succession Characteristics Of Aglae In Lakes And Reservoirs In Xi'an And Study On Technologies Of Algae Control And Avoidance

Algae functional group is an important tool for the study of algal community succession.In order to understand the application of morphologically-based functional groups(MBFG)in the research on phytoplankton community structure and variation of deep-water reservoir,the phytoplankton communities finded in Jinpen reservior were classified to MBFG,and the relations between MBFG succession and envirionment cases were explored with redundancy analysis(RDA)method.In this paper,FG and MBFG were used to study the succession characteristics of algae in different lakes and reservoirs in Xi'an and the differences of the application of the two classification methods were compared and analyzed.In the study of algae control technology in lakes and reservoirs,the technology of algae control by aeration has been more mature,but its mechanism is still not clear.The physiological characteristics of algal cells were studied in this paper,and the mechanism has been more refined.In order to ensure the quality of raw water,a algae avoidance device for water tower was put forward.The main conclusions are:(1)Five MBFG were found in the Jinpen Reservoir,namely II,IV,V,VI,VII,and MBFG VI had a dominant position in the whole study period and different depths.The succession of algal functional groups in the reservoir has spatiotemporal characteristics,a variety of MBFG coexisted in spring and summer,while reservoir algal functional groups were relatively simple in autumn and winter;meanwhile,the dominant MBFG were found in all the water layers,and the density decreased with the increase of water depth.From the redundancy analysis,MBFG VI and IV were respectively affected by temperature;the other water level of the reservoir MBFG VI was significantly affected by TN content.(2)In this paper,two different functional groups were used to study the succession of phytoplankton in four lakes and reservoirs in Xi'an,and the functional groups of the four lakes were similar:there are FG B,P,D,X1,S1,MP,J,IV and MBFG IV,VI,VII.But there were differences in the dominant functional groups in each reservoir or lake: by functional group classification,B and P alternately became the dominant functional groups in Shibianyu Reservoir,B was the dominant functional group in Tangyu Reservoir,there were mostly B and D in Qujing Lake,the functional groups of Xingqing lake were mainly D and XI;by morphologically-based functional groups,the dominant functional groups of the four lakes were the same: the morphological functional group VI.RDA analysis of MBFG and FG with environmental factors showed the response relationship of functional group classifications with the related environmental factors,and indicated that the composition and structure of algal functional groups were different,mainly for the differences of biological density,to some extent,it reflected the water quality of lakes and reservoirs,however,the environmental factors that significantly affected FG and MBFG dominant functional groups were different.(3)In the study of algae control mechanism by aeration,during the day,the algae were only treated with aeration,the cell density of Chlorella increased,but when using aeration condition to make the algae liquid form a certain circulation,the growth of Chlorella was inhibited;under the effect of night aeration,regardless of whether or not the circulation,Chlorella cell density declined.When the growth of Chlorella was inhibited,the physiological characteristics of Chlorella vulgaris were consistent: the cell density decreased,the content of chlorophylla decreased,the specific activity of SOD enhanced,the content of MDA and soluble protein increased.(4)The algae avoidance device could effectively purify the water quality around the water intake and its linkage realized the cycle operation;by energy conversion,it achieved energy saving and low carbon environmental protection.