The Research On Water Characteristics And Protection For Dongchang Lake, Liaocheng City, Shandong

The Dongchang Lake which is known as "Jiangbei Shuicheng",is an artificial city lake,located at the southwest of Liaocheng City,Shandong Province.The lake is around the old city,and forms an artificial lake more one thousand years.The lake is of an area of 5.1 km² and depth of 2-3 m.The Dongchang Lake is the largest area of artificial freshwater lake in the city of northern China.It is of a special natural landscape,formed a unique urban character "town in a lake,Lake in the city,the Town and Lake become one body," for many years.The Dongchang Lake plays an important role to control the city climate and for the abundance of city landscapes. The lake is an important supplies water for industry,agriculture,fisheries and other production and livelihood of city,supports the rapid development of regional economy,and it is also an important groundwater supply sources in Liaocheng City, hence,it is of high conservation value.In this paper,the Dongchang Lake environmental monitoring data was collected, the status of Dongchang Lake environment was analyzed,the dynamic changes of the 2003-2005 water quality were analyzed,to identify the impact of Dongchang Lake water quality by major pollutants and sources of pollution were identified through the analysis of Dongchang Lake water pollution and eutrophication.The causes of Dongchang Lake water pollution,the protection of the environmental status,as well as control strategies of environmental protection were further analyzed.The Dongchang Lake,divided into six sections,was investigated to collect information of hydrology,water quality data for every sections.Water temperature, pH,dissolved oxygen(DO),COD_Cr,Permanganate Index(COD_Mn),ammonia (NH₃-N),total nitrogen(TN),total phosphorus(TP)of sampling water were investigated and measured.The status of the water quality of six sections of Dongchang Lake were investigated and evaluated in 2005.The results showed that: pH values for sampling water belonged to a normal range,and with a little alkaline, DO values are better than the classâ…¡of national water quality standards,COD, COD_Mnvalues belonged toâ…£Class of national water quality standards,monitoring values of ammonia are all in a Classâ…¢of national water quality standard,TP content in Classâ…£of national water quality standards,TN content inâ…¢orâ…£Class of national water quality standards.The results showed that major pollutants in lake were the COD_Cr,TN,TP,COD_Mn.The seasonal and inter-annual variation of eight parameters of water quality were analyzed.The Composite Index for water eutrophication of Dongchang Lakes was used to evaluate Dongchang Lake water eutrophication in the 2005.The evaluation result showed that:east of South Gate Bridge,west of South Gate Bridge,north of West Gate Bridge cross-sections were of more serious eutrophication,reached a middle level of eutrophication.The other three sections are less eutrophication.Water quality on the whole Lakes area was belonged to middle eutrophic level.Based on the distribution analysis of pollutants contents,serious eutrophication parts are mainly distributed in the north-east of the main lake water body,the southwest part of the main lake water body was of the least level of eutrophication.Based on a comprehensive analysis of the whole lake water quality,and the conservation measurements of lake environmental protection by local government,a essential management measurement for Dongchang Lake environmental protection was proposed,which is that "prevention pollution is essential,control pollution is supplement" basic principles.The environmental condition of Dongchang Lake, associated protective measures,the sources of pollution control measures,ecological restoration,and the lake water management strategies were proposed.In this paper,based on the investigation of the state of water quality,water pollution and eutrophication,and the main pollutants in Dongchang Lake.The source of water pollution of Dongchang Lakes,water pollution control strategies were discussed,which provides a reliable basis for the management of lake environment,as well as provide information and scientific data for local government for Dongchang Lake environment management.