Studies on influence of exogenous nutrient on algal growth in Taipinghu Reservoir

Abstract

1992年11月~1993年10月,在安徽太平湖水库,同时用藻类生长潜力测试法(AGP试验)和外源添加营养的黑白瓶测定初级生产力法,对陵山站的水体分季度进行了分析测试。其结果表明,这两种方法对太平湖水库的营养评价均是行之有效的.而且二者的结果也能相互比较、相互验证;太平湖水库的不同季节,其主要营养限制性因子也各异。在枯水期,磷是藻类种群和密度的第一限制性营养元素;丰水期,由于各营养元素都相对缺乏,磷此时作为限制性因子的作用下降。因而认为,在进行象太平湖水库这样的大水域野外工作中,若能同时运用这两种方法进行检验和比较分析,就能克服二者各自的片面性,得出较为客观的结论。同时,本实验的结果对太平湖水库施肥养殖也有一定指导意义。;The influence of exogenous nutrients on algal growth was studied in Lingshan Station of Taipinghu Reservoir,Anhui Province during the algal growth season of 1992~1993.Two short-term algal bioassays, i.e., algal growth potential (AGP) test and black-light bottle test-the main experimental method of determining nutrient limitation for phytoplankton and green macroalgae-were performed integratedly in various seasons in the site experiments.The main additive used included phosphorus (NaH₂P0₄) and nitrogen (KN0₃).The algae was Scenedesmus obliqus. According to these experiments, the results show; (1) The two methods were effective to reveal the trophic state of Taipinghu Reservoir and the results can be extended to large and medium reservoirs in the Changjiang River Basin.The respective one-side defect coaid be avoided and the two methods be used integratedly. (2) The nutrient limitation of algae varied widely during the study period.In early summer,only the addition of P evoked a clear increase in the growth of algae, revealing that P was the primary limiting nutrient of algal population, biomass and primary production.In late summer and autumn, neither the addition of P nor the addition of N stimulated algal growth as in early summer because of the relative deficiency of other nutrition by the dilution of rainwater in summer rainy season, and the limiting action of P was declining. (3) The optimum P concentration for S.obliqus growth was 0.20mg/L. The aforementioned analysis can be used for guiding technique of artificial fertilization in large water bodies.Many nutritions should be supplied when P and N are added in late summer and autumn in the Reservoir.