Eutrophication Characteristics And Causes Of Guishi Reservoir In Hezhou City

The water quality of Guishi reservoir has remained in very good level over the years,but as the rapid development of watershed breeding and planting industry,with population increase and urbanization process accelerated,there is an upward trend in total nitrogen in the water of Guishi reservoir,which have already been close to the national surface water V class standard threshold,and the water of Guishi reservoir is in moderate eutrophication level,also it has a rising trend.This article is through sampling and monitoring the reservoir water quality of inside reservoir and in main rivers which flowing into Guishi reservoir in 2016-2017,and through the planktonic algae samples analysis during the spring and summer in 2016,by comprehensive evaluation of Guishi reservoir eutrophication level and characteristics of planktonic algae community and analyzing the direction of main pollutant source in Guishi reservoir,and finally,it put forwards comprehensive control measures for eutrophication.(1)Take a survey of the water environment of the Kameshi Reservoir reservoir area and the main tributaries of the reservoir in the past two years.The survey targets include physical indicators,chemical indicators and biological indicators.The monitoring results show that the reservoir area has exceeded the standards of TP and TN,and the maximum excess of TP is 0.6 times;The maximum excess multiple of TN is 2.7 times,and the water quality of Dayuan River in the river entering the reservoir is exceeded.TP and TN are the main pollution factors of Guishi Reservoir.In the past two years,the nutritional status of Guishi Reservoir is moderately eutrophication.(2)To choose the 21 points in the test analysis of planktonic algae in April and September of 2016,the analysis results show that it is in the majority of in spring phytoplankton species of cyanobacteria and chlorophyta species in Guishi reservoir area,warehousing rivers in the majority is with bacillariophyta species,in summer Guishi reservoir area and inbound branch the number of phytoplankton species are in the majority with diatoms,followed by cyanobacteria and algae;In spring and summer it is given priority to with the pollution state,there are significant pollution levels in main tributary rivers,ranging from light pollution status to severe pollution.(3)Application of statistical analysis software to identify Guishi reservoir eutrophication impact factor for the water temperature,pH,DO,CODMn,TP,TN and chlorophyll a,Guishi reservoir is a typical type of phosphorus limit lakes,of Guishi reservoir eutrophication control measures of the primary is to control the receipt of phosphorus,the second is to reduce the chemical oxygen demand(COD)and total nitrogen receipt.(4)The COD contribution of each river entering the Kameshi Reservoir comes from Fuchuanjiang,accounting for 59.1%,the second Shijiazhuang,accounting for 13.8%,and the third Gongtang River,accounting for 10.3%;The largest contribution of TP comes from Fuchuanjiang,accounting for 55.1%,the second Shijiazhuang,accounting for 15.1%,and the third Gongtang River,accounting for 8.9%;The largest contribution to TN comes from Fuchuanjiang,accounting for 51.2%,the second Shijiazhuang River,accounting for 19.0%,and the third Gongtang River,accounting for 11.1%;According to the type of pollution source,the COD contribution of each source to the Kameshi Reservoir is the largest source of agricultural sources,accounting for 55.1%of the total;The second is the source of aquaculture pollution,accounting for 36.3%;The third is the source of pollution in rural life,accounting for 4.6%.The largest contribution of TP comes from the source of aquaculture pollution,accounting for 72.5%,the second is the source of agriculture,accounting for 21.6%,and the third is the source of rural living pollution,accounting for 2.5%.The largest contribution of TN comes from the source of aquaculture pollution,accounting for 68.7%;The second is the source of agriculture,accounting for 21.4%,and the third is the source of pollution in rural life,accounting for 3.3%.(5)To combine with present situation of environmental protection in Guishi reservoir basin,to analyze the result of quality variation of main outstanding problems,including breeding pollution,agricultural pollution and biological pollution,it puts forward some ideas of various governance.