Study On The Change Of Water Quality Of The Process In Long Distance Water Transfer Of The Project Of Water Diversion From Yellow River Into Qingdao

The project of water diversion from Yellow River into Qingdao is is a large-scaleinter-basin water transfer project, and Jihongtan Reservoir which is responsible forwater supply to Qingdao and surrounding areas is its regulating reservoir. The projecthas1.597billion cubic meters water supply to Qingdao since operation21years and itmade great economic, social and environmental benefits. Previous study showed that sJihongtan Reservoir eutrophication index has been raised in recent year, and nitrogenpollutants are most prominent. Jihongtan Reservoir is closed system relatively, itsinternal pollution mainly are nutrient regression in sediments and biology deathdecomposition, and its exogenous pollutions mainly come from nutrient regression inwater diversion. The project is long for more than250kilometers, and it have morethan400buildings along the process of the project. The complicated ecologicalcondition include grit chamber, Xiaoqinghe sink, natural bank and so on, and there islackede of systematic study anout water quality change along the process ofthe project at present.In this study, the project of water diversion from Yellow River into Qingdao wasas the research object. Jihongtan Reservoir present situation of water environment wasanalyzed to find pollutant sources firstly, then the changes of water quality of thecanal head and the process of the project were analyzed, and the pollutantscontribution from the project to Jihongtan Reservoir was inferred at last. Theconclusions of the study were shown as follows:（1） Among reservoir nutrient indicators, except for total nitrogen, the content ofammonia nitrogen, total phosphorus and COD_Mncould reach the Ⅳ standard ofGB3838-2002《Surface Water Environment Quality Standard》. Total nitrogen contentand nitrate nitrogen content were higher in winter and spring, lower in summer andautumn. And total phosphorus content and chlorophyll a content were the opposite.Ammonia nitrogen, nitrite nitrogen, and COD_Mncontent were not changed much. Except for nitrite nitrogen releasing weakly, reservoir sediments had adsorption onammonia nitrogen, nitrate nitrogen, total nitrogen, total phosphorus and COD_Mn.（2） The analyzed about canal head water quality change showed that: The rangesof sediment concentration and turbid were0.28⁰.87kg/m³and232.5⁶73NTU.Sediment concentration was higher in August, lower in May. Turbid was higher inApril, lower in May. The range of sediment median diameter was0.015⁰.044mm,and it was higher in April, lower in July. The ranges of the contents of total nitrogen,nitrate nitrogen, ammonia nitrogen and nitrite nitrogen were5.11⁴.02mg/L,3.40⁵.20mg/L,2.70⁵.00mg/L,0.080⁰.250mg/L and0.005⁰.230mg/L. Totalnitrogen content was highest in May, and lowest in September. As the major form ofnitrogen pollution, nitrate nitrogen content was highest in May, and lowest in August.Ammonia nitrogen content and nitrite nitrogen content were low, and changed little.The ranges of total phosphorus content was0.010⁰.087mg/L. Its content was lowestin May and changed slightly. The ranges of COD_Mncontent was2.14³.54mg/L, andits content was lowest in July. The ranges of Chlorophyll a content was1.1⁷.6mg/m3and its content was highest in July.（3） The analyzed about the process of the project water quality change showedthat: The changes of sediment concentration and turbid dropped when the water gotout grit chamber and gradually stability, and sediment median diameter turned smaller.Nitrate nitrogen was the major form of nitrogen pollution. Except18th April, nitratenitrogen content was had notable positive correlation with total nitrogen that theyshowed a downward trend along the process of the project, however, the trend wasdifferent in different months. Concentration of ammonia and nitrite nitrogen were low,but there were obvious difference in different months. They fluctuated slightly alongthe process of the project. Total phosphorus content was low and showed a downwardtrend in different extent along the process of the project. But it was not obvious on29th April. COD_Mncontent showed different degree of increased along the process ofthe project. But it was not obvious on18th April. Chlorophyll a content was upwardwhen the water got out grit chamber and gradually stability, and fluctuated slightly. ⑥Total bacterial count and total coliform showed downward–upward a trend alongthe process of the project.（4） The pollutant contribution from the project to Jihongtan Reservoir from Aprilto June as follows: total nitrogen （296.03±20.06） t, nitrate nitrogen （234.15±3.35） t,ammonia nitrogen （13.88±8.70） t, nitrite nitrogen （3.74±0.60） t, total phosphorus（2.83±0.36） t, COD_Mn（259.45±12.43） t.