Distribution of nutrients and chlorophyll-a and eutrophicate evaluation of South Lake,Changchun

Series of surface and bottom water samples of different seasons were collected from South Lake,Changchun,to determine the temporal and spatial distribution of TP,TN and chlorophyll-a in the water and analyze the correlation between nutrients and Chlorophyll-a.The eutrophication extent of South Lake was evaluated by TLI method.The results showed that the temporal and spatial distribution of Chlorophyll-a,TP and TN were significantly affected by temperature,rainfall and human activities.The concentrations of Chlorophyll-a,TP and TN were highest in wet season (September) and lowest in icebound season (February).Chlorophyll-a in bottom water was higher than that in surface water,but for TP and TN,their spatial distribution varied with season.The concentration of TP followed the sequence of 3rd zone2nd zone1st zone,and the concentrations of TN and Chlorophyll-a followed the sequence of 3rd zone1st zone2nd zone.At icebound season,concentrations of TP,TN and Chlorophyll-a in water were higher than that in ice,and TP and Chlorophyll-a in 3rd zone were higher than that in 2nd zone,while TN was in contrast.Chlorophyll-a was better correlated to TP than to TN which indicated that TP was the key factor control the growth of the phytoplankton.Eutrophicate evaluation showed that the risk of eutrophication was in the order of SeptemberMayFebruary temporally and 3rd zone1st zone2nd zone spatially.The study provide scientific basis for controlling and preventing eutrophication.