Spatial And Seasonal Variation Of Water Quality Salinization In Binhai Reservoir

Salinization of water quality is a common problem in coastal reservoirs.In this study,Beidagang Reservoir in Tianjin Binhai area was selected as the research object.Using the method of field investigation and data analysis,samples were taken from different locations of the reservoir in spring and summer to analyze the p H,TDS,total hardness and the contents of Na⁺,K⁺,Ca²⁺,Mg²⁺,Cl^-,SO₄^2-,HCO₃^-,CO₃^2-,study the variation law of water quality salinization in Beidagang Reservoir in different seasons and locations,and discuss the salinization mechanism of the reservoir.The main conclusions are as follows:（1）Horizontal distribution characteristics of water quality in Beidagang Reservoir in different seasonsThe pH value,Ca²⁺and HCO₃^-contents of water body in spring are higher than those in summer,and the contents of TDS,Na⁺,K⁺,total hardness,Mg²⁺,Cl^-,and SO₄^2-are higher than those in spring.From west to east along the flow direction,TDS,Na⁺,total hardness,Ca²⁺,Mg²⁺,Cl^-,SO₄^2-and HCO₃^-all show the distribution characteristics of"upstream gate of reservoir>downstream gate of reservoir"in spring and summer,while p H value and K⁺are just the opposite.（2）Vertical distribution of water quality in Beidagang Reservoir in different seasonsThe vertical distribution of water body indexes of Beidagang Reservoir in spring and summer can be divided into two types:"mixed type"and"layered type".The"mixed"water bodies are mostly distributed at the West intake gate（south bank intake gate,zhaolianzhuang gate,Maquan intake gate,Dagang farm gate and liugangzhuang gate）at the upstream of the reservoir and Shajingzi gate in the southeast of the reservoir."Layered"water bodies are mostly distributed in the downstream direction of the flow in the northeast of the reservoir,namely No.3 sluice gate,No.10 regulating gate and salt discharge gate.At the same time,each index of"stratified"water body increases vertically with the increase of depth,among which the vertical distribution characteristics of No.3 sluice gate are the most obvious,and the stratification phenomenon is more obvious in spring than in summer.（4）The release of salt in reservoir sediments will also affect the salinization of reservoir water quality.