The Water Quality Dynamic Of Xijin Reservoir Water Areas

Xijin reservoir lies along the upper reaches of the Yujiang River, in the south part of the Heng County,and forms the first of fresh lakes from Xijing electricity dam builted in1964. The area of flood season is150km2.It assumes of generating electricity irrgating suppling water in the Guangxi Autonomous Region.There are many estuaries and shallow areas within reservoir.lots of little islands lie in the Xijin reservoir of envirommental protection.It play important role to develop tourism.We went to study physics and chemistry of water, plankton from September2009to September2010.We analyze the pertinence of physics and chemistry of water,dynamic of plankton.comprehensiving the physics and chemistry of water and Shannon-Wieaver index,venness Index,Margalef index of plankton judge evaluation of the reservoir. We provide a basis for evaluation reservoir,environmental protection.The main research results are as follows:1.the physics and chemistry of the waterDO was between4.23mg/l and9.99mg/l,concerned with the temperature of the water and culture;COD was between2.41mg/1and5.83mg/l,D0will be fall when COD goes up;NH4+-N was between0.490mg/1and0.993mg/l,concerned with the temperature of the water and pH;NO2+-N was between0.089mg/l and0.151mg/l,concerned with the temperature pH,and DO,TP was between0.055mg/1and0.106mg/1,soid wash by rain,rest of bait,dung of fish,died of plankton and so on were the reason that the reservoir was eutrophy;TN was between0.655mg/1and1.254mg/l,average was1.035mg/l.chlorophyllous a was between9.03mg/1and20.05mg/l,concerned with the temperature of the water,culture,TN,TP and so on.2.phytoplankton(1) The anniversary phytoplankton of XiJin reservoir identified:103species belonging to68genera,8divisions.40species in chlorophyta,22species in bacillariophyta,17species in cyanophyta,6species in euglenophyta,5species in pyrrophyta,5species in chrysophyta,4species in cryptophyta,1species in xanthophyta.reason change,summer most (74species in july),winter lowest (58species in january).biological density is between154.8and183.5million/1, chlorophyta most, xanthophyta lowest. Biomass is between1.746mg/1and2.287mg/1, summer most, winter lowest.(2) The most common phytoplankton dominant species are:Scenedesmus、 Chlorella、Pediastum、Chroococcu、Merismopedia、Melosira、Cyclotella。 reason change,the temperature lower in winter,Melosira, Cyclotella of fiting lower temperature, Scenedesmus become dominant species,the temperatur go up in spring, Scenedesmus、Chlorella、Pediastum、Melosira、Cyclotella、 Merismopedia become dominant species. Chroococcu、Merismopedia、 Scenedesmus、Chlorella、Pediastum become dominant species in summer.every dominant species appear expcet Chlorella in autumn. bacillariophyta replace cyanophyta in november.3.zooplankton(1) The anniversary zooplankton of Yongjiang identified:37species belonging to23genera,3divisions.15species,6genera belong to Rotifera;12species,8genera belong to Protozoa;8species,7genera belong to Cladocera and2species,2genera belong to Copepoda. biological density between1.51million/1to2million/1.Rotifera most,Copepoda lowest. Biomass between0.774mg/1to1.019mg/1. summer lotest,winter leastest.(2)dominant species are:B.calyciflorus、Asplanchna、Keratella、Amaeba、 Voricella、D.pulex、Bosmina、Mallomonas、reason change, the temperature lower in winter, Bosmina and Mallomonas become dominant species; the temperatur go up in spring every dominant species appear expcet Voricella;8species dominant species appear water in summer; B.calyciflorus and Cladocera exit dominant species in autumn.4Comprehensive nutrition state(1)We fund that the water achieved I stair of the best in november2009and january2010, II stair in march, III stair in may, IV stair of worst in july, III stair in september from comprehensive,the water quality was change with the temperature of water,culture.(2) the water quality of Xijin reservoir has been in a middle pollution level by the mothods of Shannnon-Wiener diversity index, Even index. Margalef index indicates that the water quality of Xijin reservoir is a middle pollution except january.the water quality is little pollution in january.(3)Comprehensive nutrition state index indicate that the water quality of Xijin reservoir is middle pollution level except january between57.2and70.6.