The Correlations of Algae Density Distribution with Water Quality and Wind Effect in the Hongze Lake

In order to investigate the correlations of algae density distribution with water quality and wind effect in the Hongze Lake, point sampling was conducted all over the lake area in 2013 to collect data of water quality and algae density. Then, combined with data of wind scale and direction, the partial correlation method was used to analyze the correlations of algae density distribution with water quality and wind effect. The results suggest that: the algae density in spring and summer is 12.3×10⁵ ind./L and 32.9×10⁵ ind./L respectively; the algae density in spring is lower than that in summer; and the density in the northern part is higher than that in other regions. The concentrations of TN and TP are 2.23 mg/L and 2.35 mg/L in spring, and 0.1 mg/L and 0.187 mg/L in summer. The concentrations of TN and TP are higher in summer than in spring. Meanwhile, the concentrations of TN and TP around the inlet of the Huaihe River are higher than those in other sampling points. The partial correlation analysis results suggest that: the algae density in spring is not correlated with TN, TP or wind scale, while the density in summer is positively correlated with the concentration of TN. TN is still the limiting factor for algae outbreak in the Hongze Lake in summer. It should also be noted that the Hongze Lake has not developed to the serious eutrophication state. The inlet/outlet rivers and the lake current pattern are important factors that influence the algae density distribution in the Hongze Lake.