| Facing the current situations that it‘s difficult to effectively control eutrophicationproblem and it‘s hard to wipe off algae from raw water using traditional water treatmentprocesses, the paper use the characteristics of algae growth and suspension as the entrypoint to probe the law of algae growth and changes in the deep channel reservoir. Theresearch combined the methods of on-line monitoring and laboratory analysis, firstusing the theory of phytoplankton functional group to the field of reservoir research.focusing on the following four points:â‘ The characteristics of the succession ofvertical algae structure and vertical migration of algae under the effect of waterwithdrawal;â‘¡Functional groups and its succession under the effect of watertemperature stratification, longitudinal nutritional gradient and water inflow;â‘¢Scenario simulation basing on the characteristics of algae structure in outflow water;â‘£The development of safety water withdrawal structures. The main conclusions are asfollows:(1) Effects of season succession to algae in the reservoir area are mainlymanifested in two aspects of the algae biomass and algae species structure. It has anobvious effect on algal biomass in the surface water, while has little effect on the algaeunder the depth of10m. Algae peak more often appears in July and August. Themaximum is8.22×106cells L-1, while the number is3.00×106cells L-1under the depthof10m. During the study period, there are6phyla,30genera in Jin-pen reservoir,mainly constituted by Bacillariophyta and Chlorophyta, having the proportion of83.9%.There are several species algae appearing in summer and autumn, while algae structureis single in other seasons. Chlorophyta and Cyanophyta algae are located in the surface, and diatoms algae are distributed throughout the longitudinal.(2) Affected by the effect of water withdrawal, algae biomass in the water columnwhich has the same depth with water intake is less than that near the water intake;besides, algae biomass below the water intake is more than that above the water intake.The effect of withdrawal also changes the algae proportion, but has little effect on thealgae population structure. Algae biomass in the raw water and algae in the reservoirarea is not a simple linear relationship. The relationship between reservoir water level,inflow, outflow and the changes algae biomass is not obvious.(3)10functional group codes were found in the reservoir. Wherein, codes B, P, F,X1and MP were comparatively common functional groups. The quantities of codes B,D, P, X1and X3were more than others. The temperature was the most important factorwhich influences spatiotemporal succession of algae functional groups by analyzingchanges of environment factors. The succession of algae growth strategy followed thelaw: R/CR in springâ†'CR/C in late spring and early summerâ†'C/CR/R/CS/S in latesummer and early autumnâ†'CR/R in late autumn and winter.(4) Basing on the characteristics of algae structure in outflow water, scenariosimulation is carried out in this paper. According to the simulation, scheduling solutionfor safety water withdrawal are put forward: algae biomass was lower in outflow waterfrom November to March when the depth of water intake was less than20m. The samesituation would appear from April to October when the depth of water intake was morethan10m, and more than30m was best. Besides, it‘s best not to use the water intakewhen the depth was about30m from September to October. According to the research ofexisting water intake structures, the pre-purification selective water intake structure wasinvented. It is not only able to achieve the function of the selective water withdrawal,but also reduce the algae biomass in raw water. |
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