Study On PH Value Characteristics And Its Change Mechanism Of The Main Rivers Flowing Into Dianchi Lake

pH value of water is one of the important indicators to evaluate water quality,as well as a comprehensive reflection of hydrochemical characteristics.The study has carried out systematic monitoring of pH value of four main rivers'?Panlong River,Baoxiang River,Chai River and Laoyu River?channel runoff that flowing into the Dianchi Lake,and pH value of“farmland ditch water and water of sewage draining exit”that on the Baoxiang River Basin,to find out pH value and its variation mechanism of the main rivers flowing into Dianchi Lake and to analyze pH value's variation characteristics of the main rivers into Dianchi Lake and the main factors resulting in pH value's variation of these rivers,thus finding out scientific evidences for disposal of water pollution in Dianchi Lake Basin.The results are as following:?1?pH values of the main rivers into Dianchi Lake are regularly distributed:pH value of the upper course of the rivers is about 6.5 to 6.97 and the average value is6.77,while that of“middle and lower reaches of rivers”with more human activities is gradually increasing from weak acidity to alkalescence,the highest value is7.77;According to the land use type,the pH value are woodland<wetland<farmland<urban land.And the pH value of rainy season is higher than the dry season in a year.?2?The correlation analysis of the pH value and water quality parameters:The pH value has a significant positive correlation with DO,EC,and TDS,and significant negative correlation with Eh,low correlation with T,TN and TP.The correlation analysis of the pH value and main ions:The correlation coefficient is 0.7726 with pH value and HCO₃^-,indicate that the[CO₂-H₂CO₃-HCO₃^--CO₃^2-]is one of the main controlling factors of the pH value.The correlation coefficient is 0.7458 with pH value and Ca²⁺+Mg²⁺,the 0.8437 with HCO₃^-and Ca²⁺+Mg²⁺.It shows that Ca²⁺—CaCO₃(Mg²⁺—MgCO₃)plays an important role in the change of pH value.But the ion balance system is the most comprehensive and detailed description of the change mechanism of the pH value.Because the correlation coefficient is 0.8218 of the pH value and the ANC value.?3?Through the analysis of the main ion sources:The direct contribution of Precipitation Factors is negligible,the Ca²⁺,Mg²⁺and HCO₃^-are mainly influenced by natural factors in the basin,the K⁺,Na⁺,Cl^-,NO₃^-,SO₄^2-are mainly caused by human activities.Among this,the K⁺,NO₃^-,SO₄^2-indicate the effects of agricultural activities on the water environment,the Na⁺and Cl^-mainly indicate the effects of urban domestic sewage.In addition,agricultural activities have effect on the increase of calcium ion.