The Impact Of Environmental Factors On Release Of Internal Phosphorus In Sediment Of Erhai Lake

Eutrophication is the most important one of the water environment problem. Limiting factor for eutrophication mainly are N and P. most of our country lakes are controled by phosphorus. Due to most of lakes'exogenous phosphours are in control, so the release of the Internal phosphorus of the sedimen can afford the Algae growth, which palys a important role in extrophication. While, the release and absorb of the sediment is limited by many factors, which includes physical and chemical properties of sediment and pH, redox status, temperature and so on. This article researhs the overlying water of the early eutrophication of Erhai lake, taking the internal phosphours in sediments as the main object. In order to show the feature of internal phosphorus characteristics of Erhai sediment and phosphorus release law of internal phosphorus of sediment in overlying water and the role of environmental factors which can affect the phosphours release in the sediment. Which can give a reference to us about eutrophication.The research picks up 5 points of Erhai lake in Yunan province, to show the result of the research:(1) the whole potential of phosphorus release was high in the central region, followed by southern and northern distribution of the lower in Erhai lake. And the release of internal phosphorus is easing at the first 20 days of simulation, the release of internal phosphorus mainly focus on 30 days.(2) When the pH=6,the release of internal phosphorus in Erhai lake is low, when the pH=8, release of internal phosphorus in Erhai lake will be larger. When the pH=10, release of internal phosphorus in Erhai lake is largest. When the pH=10 at 3 point, The release of internal phosphorus include SRP,DTP, will get maximum, and the value is followed by 0.294mg/1,0.327 mg/1. The release of internal phosphorus (TP)will get maximum at 4,5point when the pH=10,the value is also 0.506 mg/1.(3) The release of the internal phosphorus in the Erhai lake sediments is less in the aerobic condition, and the difference is less between the points. On the anaerobic condition the release of the internal phosphorus in the Erhai lake sediments is large, relative to aerobic condition the release of internal phosphorus (SRP,DTP,TP) will be from 2 to 15 times,2 to 18 times,2 to 20 times. On the anaerobic condition it accelerates the release of internal phosphorus, and vice versa.(4) The more the value of Fe2+, the more the release of internal phosphorus(SRP) will be, but the speed of SRP is slower than Fe2+. On the anaerobic, alkaline condition, the release of SPR, Fe2 will get maximum, which can get a lesson that the Fe-P plays a important role in the release of internal phosphorus in Erhai lake sediments.According to the above analysis, Erhai Lake is in the early stage of eutrophication, south and north regions of Erhai lake are polluted by human activities. The release of internal phosphorus in Erhai lake is not significant. Therefore, within the Lake Erhai sediment phosphorus release studies to assess the risk of Erhai Lake sediment phosphorus release,which can help to solve the problem of eutrophication in Erhai Lake.