| Recently the eutrophication has been an important environmentalproblem of the water resources management. The extensive nutrient elementsin the water are the causes of the eutrophication. Among the main elements,the nitrogen and phosphorus are the main controlling factors, and in manylakes the phosphorus is the restricting factor of the phycophyta's growth. Thispaper is completed based on the fifth topic——"The Water EnvironmentPollution,the Pollution Transport and Environmental Effects of the MiyunReservoir" of the Project of Country's Major Basic ResearchDevelopment(973 Project) ——"The Pollution and the Control Principle ofthe Atmosphere, Water and Soil Environment in the Capital Beijing and itssuburb". As the unique surface drinking water source, the water quality ofMiyun Reservoir affects the people's life and heath directly. The topic mainlystudies the source of the total phosphorus, migration, transforming law,behavior characteristic and restriction factor, and offers reliable scientific basisto protect the water quality of Miyun Reservoir and to prevent it fromeutrophication. This text is based on the foundation of investigation on waterenvironmental chemistry of reservoir in detail, and studies in chemical form,vertical section in the sediment, etc. to the phosphorus, combine indoorsimulation experiment and statistical analysis, has announced thegeochemistry behaviors and potential environmental effects of the sedimentaryphosphorus, by which the bearing capacity of the total phosphorus in the waterbody is calculated.There is little phosphorus compound in the Miyun Reservoir, and thetotal phosphorus in the reservoir is about 0.028 mg·L-1 on average. From theevolvement stage, it is known that the water body in Miyun Reservoir ismid-eutrophication. So the protection of the water environment of thereservoir should be strengthened, and the discharge of the nitrogen andphosphorus pollutant to the reservoir should be decreased or avoided. The ratioof the nitrogen and phosphorus is 38.4:1. So it is obvious that there is littlephosphorus in the water, which indicates that phosphorus is the restrictedelement of the alga population density and quantity.The distribution law of the phosphorus in Miyun Reservoir is that: theconcentration of the total phosphorus in summer is higher than winter;inhorizontal direction, the concentration of the total phosphorus of the internallake is higher than that of the eastern and western part, and concentration ofthe reservoir entrance is higher than that of the reservoir exit, but theconcentration at the bottom of the two the reservoir entrances is lower thanthat of the two reservoir exits;in vertical direction, with the increase of waterdepth, the concentration of the total phosphorus increased obviously. Thespatial distribution characteristics of the water body in the reservoir have closerelation with the source of the total phosphorus, runoff, actions of the substratesludge and the biological actions. The soil and water loss conditions are thedirect affecting factors of the changes of the total phosphorus. The verticaldistribution characteristics are controlled by the hydrodynamic conditions, thethermocline and substrate sludge. The change with time is mainly affected bythe source of phosphorus, and the biological actions are the major factorswhich affect the change of phosphorus with.Reservoir top layer sediment relies mainly on inorganic phosphorus, andit is the highest with Ca-P content in the inorganic phosphorus. It is in themedium level to see the accumulating amount of total phosphorus in sedimentof Miyun Reservoir from distributing vertically, and the average content of TPis 599-887 μ g/gs. The analysis results indicate, the reservoir relies mainly oninorganic phosphorus in sediment. The inorganic phosphorus in the reservoirarea relies mainly on Ca-P, is made up of Fe-P and Ca-P mainly in the inlandlake. Not only geology of receiving of distribution of different formphosphorus in sediment of the reservoir——the control of the geochemistrybackground, and is closely related with the industrial activity of the upperreaches of Chaohe River and Baihe River, human factor. Indicate to theresearch of the organic phosphorus (OP) of sediment and organic matter( thecarbon) that the content of the organic carbon in sediment of Miyun Reservoiris relatively low, prove that the present nutrition state of the reservoir is good;through showing the section characteristic research of the phosphorusinterstitial water in sediment of the reservoir, upper water body of surficialsediment dissolve content of phosphorus very low, and interstitial waterdissolving content of phosphorus obviously higher than water bodies in MiyunReservoir, interstitial water phosphorus have moving and releasing potentialability to reach the water body upwards. Continuing the research that thesediment phosphorus form, TOC and TP in interstitial water influences tophosphorus releasing, counts the software and correlated with analyzinglinearly, find Fe-P, Al-P, DP and TDP in upper water of surficial sedimenthave relatively high correlation, with OP and TDP in upper water of surficialsediment have negative correlation, TP in interstitial water and TOC and TDPin upper water of surficial sediment has higher correlation too, the phosphorusin upper water of surficial sediment come from Fe-P, Al-P, DP 3 kinds of formof phosphorus in the mud of the bottom mainly on explaining, TP in interstitialwater and TOC content to TDP in upper water of surficial sediment havestronger influence. Carry on different environmental factor Miyun Reservoirbottom simulation of the phosphate release the experiment of the mud underlaboratory terms, drawing: Temperature rises, the increase thereupon ofintensity of release of the mud of the bottom;on upper water of surficialsediment pH value rise release favorable to phosphorus in sediment. Theamount of phosphorus cleared up of mud of the bottom is 10 times under agood oxygen condition under detesting oxygen condition. Sink andaccumulate phosphorus of thing know reservoir water quality it produces to berelatively heavy influence in suitable environmental conditions.Using the conventional monitoring data of the two rivers ——ChaoheRiver and Baihe River, which enter the Miyun Reservoir, the exogenouspollution load of the total phosphorus in the catchment is estimated byAverage Concentration Method. By indoor experimental simulation, thereleasing amount of phosphorus from the deposit and the used amount by thephycophyta in the reservoir are also estimated. The result shows that 80%～86% TP of the exogenous phosphorus is from the non-point-source pollution.The amount of phosphorus taken into the water body by the soil and water lossaround the reservoir, the releasing amount of phosphorus from the deposit andthe used amount of phosphorus by the phycophyta in the reservoir are 2.04t·a-1,11.343 t·a-1,8.273 t·a-1. If the water quality in the reservoir is controlledby the Ⅱ water-quality standard, the bearing capacity of the total phosphorusin the reservoir 88.966～103.066t·a-1, which indicates the reservoir has nobearing capacity;if the water quality in the reservoir is controlled by the Ⅱwater-quality standard, the bearing capacity of the total phosphorus in thereservoir 88.966～103.066t·a-1, which indicates the reservoir still has somebearing capacity, and the bearing capacity of the high-flow year, mid-flowyear, low-flow year is 28.181～41.727,31.080～44.626,41.060～55.606 t·a-1.
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