North Of Beijing Chemical Characteristics Of Water Sources Of Water And Sulfur Isotope Changes

In this paper we choose the water source area (Miyun Reservoir and its two tributary rivers of Chao River and Bai River) of northern Beijing as the research object,controlled with Yeyahu Lake Wetland,Wenyuhe River and Beiyunhe River,according to the hydro-chemistry characteristics of the research area and changes of sulfur isotopic composition characteristic values,we analyze the dissolved load sources, then calculate the rocks weathering and the relative contribution to sulfur, in order to reflect natural and regional effects on the research area, furtherly, to explain Miyun Reservoir's response to the global environmental change during a certain period of time. For time being of 2009, hydro-chemical and sulfur isotopic characteristics of wet and dry seasons are analysed to draw the conclusions below:1 Ca2+ and HCO3- are the dominant ions in northern Beijing's water source area, accounting for 52.2% and 86.3% of total cations and anions, following with Mg2+ and SO42- occupying 23.7% and 7.7% respectively.2.Piper diagram of anions and cations and equivalent curves of Ca2+ + Mg+ and HCO3- in the water source area of northern Beijing's water supply show that primary ions in the region is mainly affected by chemical weathering of carbonate rocks.3.According to Gibbs chart, the surface water in Beijing's water source area is "the type of rock weathering",it shows a transition trend to turn to "evaporate-concentrated type". Ionic composition of the river basin is effected by the weathering of rocks strongly and on the other hand, the effects of the input by precipitation and evaporation are relatively small.4.According to mass conservation principle, the direct contributions to the major ions in the river from the atmospheric input in the study area are Na+:10.63%;K+:46.76%;Mg2+ 3.05%; Ca2+:7.76%; SO42-:35.77%.5. Values of 834S ranged from 4.9‰to 10.7‰, with an average of 7.9‰in wet period..Average values ofδ34S in the study area,Chao River and Bai River are 8.7‰,6.0‰and 8.2‰,respectively. Miyun Reservoir has the highestδ34S values, while Chao River has the lowestδ34S values.According to the mass conservation principle, we know that 30.72% 42.47% sulfur comes form the sulfate dissolved rock,and 21.74%～33.49% sulfur comes from sulfide oxidation; 35.77% sulfur comes from the atmosphere input.