Photosynthetic Efficiency And Purification Mechanism Of Aquatic Plants In Water Diversion Project

For many years,researchers from various disciplines conducted multiaspect research on aquatic plants in waters like rivers,lakes and wet lands and so on from different perspectives and purpose and obtained many significant achievements.However,there is little research on aquatic plants in the water diversion project.Although most of the water diversion projects are hard structures,its sediment can still be the stroma for aquatic plants to adhere to.In the water,aquatic plants growing abundantly.Aquatic plants are the key factor for material circulation and energy flow in the ecosystem water diversion project.Jingmi diversion canal is an important river course in the water diversion project.The study on the photosynthetic characteristics of its main aquatic plants has the vital significance on mastering the operation,the health status,plants protection and water quality improvement of the ecosystem of the water diversion project.This paper tests and analyzes the photosynthetic efficiency of Jingmi diversion canal's main aquatic plants-potamogeton pectinatus,c.demersum and hydrilla verticillata through utilizing the physical model experiments,using modulate chlorophyll Fluoremeter-junior-PAM and testing the quality of water in the scene and in the model experiments which reveal and analyze the essence of the water flow phenomenon in water diversion project.The paper clarifies the corresponding relationship between the physiological characteristics of aquatic plants in water diversion project and the changes of main water quality indexes.It establishes artificial control mechanism for aquatic plants in favor of water diversion and water quality protection and maintains the normal growth process of aquatic plants.Through the experiments of planting potamogeton pectinatus,it can be found that the simultaneous changes in water temperature and water velocity affect the photosynthetic efficiency and purification mechanism of aquatic plants to some extent.In the static water,temperature increment has no significant change to healthy potamogeton pectinatus.However,the sudden drop of temperature causes plants to be coerced.When the water flows,keeping the temperature constant,proper water velocity promotes plant's photosynthetic efficiency.However,the exorbitant water velocity will weaken the photosynthetic efficiency.The purification mechanism positively correlated with photosynthesis efficiency.When the temperature and water velocity change simultaneously,there is a direct and obvious interaction between the two factors.Under different conditions,the effects of plant's fluorescence characteristics and the purification mechanism are different.However,the specific quantitative influence still needs further research.In the diurnal variation of chlorophyll fluorescence parameters,from the view of photosynthetically active radiation,in the diurnal process from 8:00 am to 8:00 pm,illumination intensity shows a single peak change in clear weather.Potamogeton pectinatus' potential maximum electron transfer rate rETRm and half-saturation light intensity Ek also shows a single peak change.In other words,plant's photosynthetic rate and ability to tolerate strong light increase with the rise of illumination intensity.From dawn to dusk,the initial slope ? of potamogeton pectinatus shows a double peak change trend with low value at noon.Through the experiments of planting c.demersum and hydrilla verticillata simultaneously,it can be found that under the same conditions,the changes and effects of photosynthetic efficiency of different plants are also different;plant combination's purification is slightly obvious.The purification positively correlated with its own photosynthesis efficiency.Through setting up five velocity contrast plants,it is found out that under the condition of changing the water velocity,the c.demersum and Hydrilla verticillata,cultured under the velocity of 0.09m/s,has the strongest photosynthetic effect.It is proper to plant c.demersum and hydrilla verticillata in waters which has similar velocity with Jingmi diversion canal.For basin which often has high velocity,more hydrilla verticillata can be planted.Compared with potamogeton pectinatus,c.demersum and hydrilla verticillata can only be planted in seasons with high temperature.