The Study On The N And P Nutrient Of Several Common Green Algae、Blue Algae And Brown Algae In Three Gorges Reservoir

Three Gorges Project is the world’s largest hydroelectric project, this project will produce huge benefits in controling flood, generating power, shipping, it will also impact extensively on the ecological environment of reservoir. As we all know, algae is an important component of river, reservoirs and other aquatic ecosystems, it also plays an important role in the stability and health of the whole ecosystem. After impounding of the Three Gorges reservoir, the velocity is slow down, a lot of nitrogen and phosphorus particles sink, the transparency increase, the self-purification capacity of water is reduced greatly, eutrophication degree increases, algal blooms occur frequently.In natural water body, the different nutriental water had different bloom species. In addition to temperature, light and other possible factors, whether the nutrient of uptake rapidly and utilization of different algaes are also two reasons of this phenomenon. Nitrogen and phosphorus are the important composition of phytoplankton, the two elements play a key role on the growth of phytoplankton, so we can conclude that the important link between nutriental absorption and utilization of algae and algal bloom. In order to explain the causes of algal bloom, we stimulated the summer, spring/autumn and winter conditons in room, then we cultured green algae (Pandorina morum (Mull.) Bory. Chlorella pyrenoidosa Chich、Scenedesmus obliqnus (Turp.) Kutzing)、blue algae (Synechocystis sp. Microcystis aeruginosa Kutzing、Merismopedia glanca) and brown algae (Cyclotella meneghiniana Kutzing、Fragilaria capucina Grunow).and the growth, absorption and utilization of P and N of these algaes are measured, and the results as following:1. The Chl concentration of green algae increased with the date of culture; diatom which cultured in low nutrient of spring/autumn condition had no exponential phase; the Chl concentration of blue algae decreased gradually in spring/autumn and it did not grow good in winter. For every algae. The μ of middle and high nutrient were significantly higher than that of low nutrient in summer, in spring/autumn condition, the μ of green algae and diatom in low nutrient were significantly lower than that in other nutriental levels, but the μ of different nutriental levels of blue algae had no significant difference, in winter condition, the effect of nutriental level was covered. Of course, the effects of season and nutriental level on μ of six algaes.were also different.2. In most cases, the effects of diffeent factors on Phosphorus absorption and nitrogen absorption in24hours(P24, N24) had a very significant difference(p≤0.01). In summer of high nutrient, P24of three algaes had no significant difference, but P24of green and blue algae were higher than diatom in other culture conditions; in every nutritional conditions of spring/autumn and winter, N24of green and blue algae were higher than diatom, in low and middle nutrient of summer, N24of blue algae was higher, in high nutrient of summer, N24of green algae was higher; P24of diatom cultured in low nutrient and blue algae cultured in middle nutrient had no seasonal difference, P24and N24of summer were higher in other nutriental conditions; P24of blue algae cultured in winter had no nutriental difference, P24and N24of high nutrient of algae were highest; nutriental level on change percentage of24h chla of each algae had no effects. Of course, the trend of P24and N24of different algal species was also different, P24and N24of every algae had their own characteristics.3. In most culture conditions, UP and UN of green algae were higher, both in the nutriental level, for each algae,.UP, UN of summer were significantly higher than that in the other seasonal conditions. In summer, UP, UN of diatom in middle nutriental level were significantly higher than that in the other nutriental levels, Up, UN of middle, high nutrient for diatom and green algae had no significant difference, but the values were higher than that of low nutrient, under spring/autumn condition, the results of diatom were the same as the results of diatom and green algae of summer, but Up, UN of high nutrient for green algae were higher than that of low and middle nutrient. UP, UN of blue algae cultured in spring/autumn condition and three algaes cultured in winter condition had no nutriental level difference. Of course, the differences of algal species could not be ignored, the trends of UP and UN of six species had their own characteristics.