Studies On The Composition Of Periphyton And Its Relationship With Aquatic Environment Factors In Wuli Lake

With the enhancement of human activities,eutrophication process is being intensified and becoming one of the most significant environmental problems.Water security has become an important factor in the threat to human survival and development.Periphyton in lake is an important carrier of element cycle in the lake,the periphyton composition of elements and the level of species,biomass and productivity of algae and other environmental factors,is an important parameter reflecting the concentration and migration of elements in the lake.As one of the important primary producers in water ecosystems,periphyton has a complex structure with great biofilm area which can exchange more material with water rapidly.Its growth and proliferation process can consume a lot of nitrogen in water,phosphorus and other nutrient salts.Periphyton as a food web in a ring,can feed scraped feeding fish or other small,miniature aquatic animals in water.The progress can make nitrogen and phosphorus recycle into the ecosystem which will not cause secondary pollution.Periphyton also has good enrichment for mental,therefore,the use of Periphyton has good prospects and development potential in ecological restoration of eutrophication water.This paper aims to study the periphytons in Wuli Lake,Regarding the middle and lower reaches of ChangJiang River in eutrophic lake as the study area,based on the principle of ecology,comprehensive research methods related to application of aquatic ecology,ecological restoration and water environmental science and other disciplines,through the study of nutritional status in the lake Wuli and the eutrophic lakes natural substrates graduated of periphyton community elements,to explore the nitrogen and phosphorus in eutrophic lakes under the imbalance,response of periphytons elements stoichiometric changes in water quality,in order to study of human pollution further and make preliminary study on the basis of the whole ecosystem elements affecting circulation.Ranged from July 15,2014 to December 15,2014,the water of Wuli Lake was sampled and analyzed during the period of 3 seasons while simultaneously,the lake water component analysis of eutrophication as well as the evaluation of the ecological environment was taken into investigation.As the results revealed,together with phosphorus pollution,organic pollution lightly existed in Wuli Lake yet nitrogen and heavy metal pollution were relatively more severe.The content of TP,DTP,TN,NH4+-N and NO2-N within all sampling points,in spatial distribution,were significantly different from each other.Meanwhile,the nutrient content basically indicated the regular pattern(normal season>dry season>wet season)in temporal distribution.Through the analysis of Carlson trophic state index,the eutrophication of Wuli Lake was probed in the moderate level currently.PCA analysis demonstrated that TP,TN,pH and DO together constituted the primary influence factors of water quality.The content of C,N,H and S in periphyton was determined by vario EL III element analyzer while the content of P in periphyton was mensurated through the method of molybdenum antimony colorimetry and correlation analysis was conducted between these elements and environmental factors in the lake.As the results indicated,the ratio(N:P),throughout the three seasons,was significant positive correlated to the N content as well as the radio(TN:TP)in the water.In the wet season,simultaneously,significant negative correlation(P<0.01)could be drawn between DO and the ratio(N:P)within the algae while in the normal season,the ratio(N:P)had significant positive correlation to the pellucidity and little correlation to the other indicators.Moreover,in the dry season,positive correlation between the ratio(N:P)and conductivity was also significant and little correlation could be discovered between the ratio(N:P)and other water factors.Consequently,the changes of water environmental factors could bring out some certain response from the radio of N:P in the algae.The content of K,Ca,Na,Mg,Fe,Cu,Zn,Se and other heavy metal in periphyton was determined through ICP-OES and the enrichment coefficient of algae to the content of metal was calculated so as to analyze the correlation with water environmental factors.It turned out that in periphyton,diverse distribution characteristics of metal elements were observed in different seasons.The ion concentration of K and Zn,in wet season,was relatively in high level while that of Na and Mg was distinctly lower than the other two seasons.The highest level within the algae,meanwhile,belonged to Ca and Se in normal period.Moreover few differences of the ion concentration of Fe and Cu could be drawn among three seasons(P>0.05).Pattern of different season revealed the characteristics of enrichment coefficient in periphyton toward water elements,followed by K>Zn>Cu>Mg>Fe>Ca>Na>Se in wet season,K>Mg>Cu>Zn>Ca>Fe>Na>Se in normal season,K>Zn>Mg>Cu>Ca>Fe>Na>Se in dry season and it appeared to be a favorable enrichment toward the heavy metal except Se ion.The ion content of K and Fe was significant correlated between the water and the algae in the aspect of correlation(P<0.05).Partially,the ion content of Ca was significant correlated between the water and the algae in the normal period while there was no certain significant correlation between the water and the algae in both wet and dry periods.the ion content of Cu was significant correlated between the water and the algae in the wet periods(P<0.05).