[Temporal and spatial distribution of environmental factors and chlorophyll-a and their correlation analysis in a small enclosed lake].

About four year's field observation was conducted from July 2007 to September 2011, in a small enclosed eutrophic lake located in Qianwei Village, Chongming Island. The temporal and spatial distribution of environmental factors (including physical-chemical factors and hydrodynamic condition) and chlorophyll-a (Chl-a) were studied and their correlation was analyzed. Results indicated that there were significant differences in the spatial and temporal distribution of Chl-a in the lake. Significantly positive correlation was found between Chl-a and water temperature, turbidity, TN and TP. Water temperature and nutrients were the main limited factors of seasonal changes of phytoplankton. It could be the result of phytoplankton growth that caused the seasonal change of turbidity. It was found that hydrological changes were the primary factor affecting the spatial difference of Chl-a concentration. Lower average Chl-a concentration (35. 30 microg.L-1) was recorded in the north watercourse, in condition with higher wind driven flow velocity ranging from 0. 08 m.s- 1 to 0. 22 m.s -1. A strong negative correlation was found between Chl-a concentration and flow velocity. Higher average Chl-a concentration (53. 11 microg.L-1) was frequently found under flow conditions ranged from 0 m.s-1 to 0. 10 m.s-1. These findings indicated that increasing hydrodynamic condition would significantly inhibit the growth of phytoplankton and reduce the risk of algae blooming in summer in these eutrophic water bodies.