Study On Relationship Between Water Eutrophication And Environmental Factors In Yao Lake

With the high-speed development of a city, more and more urban lakes will soon oralready have eutrophication problem. Yao Lake that is a closed shallow urban lake located atsuburb which is in the eastern of Nanchang city. The situation of each lakeshore is different.There are farmlands in the eastern and the northwest, and in the southwest are all kinds of thebuildings. Universitys, factory, aquaculture farm and Yao Lake aquatic sports center are alllocated here. Therefore, the correlation study of water eutrophication in Yao Lake, not onlygiving us a chance to know Nanchang urban lakes situation, also providing necessary datasupports for eutrophication control in urban lakes.The main task of this paper is to study the relationship between water eutrophication andenvironmental factors in Yao Lake. Specific as: water quality monitoring in Yao Lake for oneand half a years; two methods are used to lay out water quality monitoring points in the lake;using factor analysis to sort the environmental factors; cluster the result coming from thefactor analysis; evaluating whole part and each section’s water eutrophication by usingcomprehensive eutrophication state index method, and then studying the results; studying thespatio-temporal variability of some environmental factors; analyzing correlation betweenChlorophyll-a and other first part environmental factors that were pretreated, findingspatio-temporal impact factors of Chlorophyll-a through establishing mathematical model.The main results are summarized as follows:(1) Both matter element analysis and dynamic similarity method can have almost sameresult, and the14monitoring points in Yao Lake can be optimized to9monitoring points.This provides the theoretical basis for improving the efficiency of the monitoring, and hasvery important practical significance.(2) Factor analysis can make Yao Lake16environmental factors into four parts.(3) Using Q-type analysis classified Yao Lake as A, B, C and D part from south to north.This is prepared for the study of eutrophication assessment and spatio-temporal variabilitycoming next.(4) The whole Yao Lake is in light eutrophic state. The state have spatio-temporalvariation.(5) Yao Lake is a phosphorus limitation in the most of time. Phosphorus content, totalalkalinity, Chlorophyll-a, transparency and nitrogen content in the water have spatio-temporalvariation, but permanganate index, dissolved oxygen, electrical conductivity and pH didn’thave spatio-temporal variation clearly. (6) After the pretreatment,7environmental factors in the first part changing into:(Chl.a)0.1、lg(TP)、lg(TA)、(SD)0.1、(N/P)0.1、lg(DP)、(COD0Mn).1. The results tell that eachlake has its own transformation form.(7) A significant correlation is observed between (Chl.a)0.1and other first partenvironmental factors that were pretreated. lg(TP)、lg(TA) and (Chl.a)0.1have an directproportion relation,(SD)0.1、(N/P)0.1and (Chl.a)0.1have an inverse proportion relation.(8) Mathematical model shows that spatio-temporal impact factors of Chlorophyll-a aredifferent from part to part. Permanganate index, transparency and N/P are the spatial impactfactors. Permanganate index, transparency, N/P and total Phosphorus are the time impactfactors. In the whole lake permanganate index, transparency, N/P, total alkalinity anddissolved Phosphorus are the impact factors.