Effect of N, P concentration on growth rate and biomass of phytoplankton in eutrophical water

Total nitrogen, total phosphorus, biomass in three eutrophic waters were investigated in the rapid-growth season of phytoplankton (July-October). Chloromonas rosae was cultivated in water samples from three eutrophic waters and diluted water samples from Lake Donghu to determine the effect of N and P concentrations on growth rate. The relationship between biomass and N and P concentrations, analyzed by regression, showed that phosphorus was the limiting factor for algae growth in eutrophic water. The relationship between growth rate and P concentration can be described with the regression equation y= 0.08061nx + 0.4658, (R super(2)=0.889). Growth rate increased linearly with the increase of P concentration when it was below 0.05 mg/L, Growth rate was less increased when the P concentration was above 0.05 mg/L, and was almost unaffected when the P concentration exceeded 0.2mg/L. The P concentration corresponding to growth rate "0" (deduced from a regression equation) was 0.003mg/L, close to the minimal P conce