| This research investigated the concentrations of microcystins and environmental factors in three freshwaters of Zhejiang such as Taihu Lake (Huzhou section), Tiesha River and a blooming lagoon. The relativities between microcystins and environmental factors were studied by the methods of correlation analysis, principal components analysis, cluster analysis and stepwise multiple linear regression. The results show that the concentrations of MCLR and MCRR range from 0.049μg/L to 12.30μg/L and from 0.032μg/L to 7.90μg/L, respectively, and the concentrations of microcystins at the bottom of the waters are higher than the aquatic surface. Significant positive relationships (p<0.01) were observed between MCLR and TN, NH4+-N, NO2--N and TP, and also between MCRR and NO3--N, N:P ratio; Significant negative relationships (p<0.01) were observed between MCLR and water temperature, DO and N:P ratio (p<0.01), and between MCRR and pH, DOC, CODMn and optical density. Our research indicated TP and NO2--N possibly be the main factors for the biosynthesis of MCLR, while NO3--N and N:P ratio would be important for MCRR. NO2--N and NO3--N are possible the main nitrogen resources for the biosynthesis of MCLR and MCRR, respectively. |
