Study On Optimization Of Groundwater Pollution Monitoring Index In Pinggu District Of Beijing

Pinggu District is an important emergency water source in Beijing.Today,with the increasingly serious groundwater environmental problems,it is of great significance to study the groundwater in Pinggu District.In order to correctly understand the groundwater environmental quality of Pinggu District and make the monitoring of groundwater pollution in Pinggu District more targeted,it is urgent to optimize the existing monitoring indicators.Relying on the National Water Pollution Control and Governance Major Special Project"Key Demonstration Segment of Beijing-Tianjin-Hebei Regional Comprehensive Regulation-Key Technology Research and Engineering Demonstration of Beijing-Tianjin-Hebei Groundwater Pollution Prevention and Control"Project In order to optimize the existing monitoring index system for groundwater pollution in Pinggu District of Beijing,with a view to providing directions for the prevention and control of groundwater pollution in Pinggu District of Beijing.The main research conclusions of the paper are as follows:?1?The BP neural network method was used to evaluate the groundwater quality of Pinggu.The results showed that the overall groundwater situation in Pinggu District was good in the third quarter of 2018.The groundwater types I,II,and III accounted for 40.35%,but the groundwater quality of types IV and V accounted for more than half.The status quo is not optimistic.?2?Based on the analysis of groundwater pollution characteristics,the results show that the excess rate of groundwater indicators in Pinggu District cannot be ignored.The coefficients of variation of turbidity,ammonia nitrogen and other indicators are high,which is greatly affected by man-made and thus show a high degree of dispersion;pH shows weak variability,indicating that its concentration is spatially very stable.K⁺,iron?bivalent?,iron?trivalent?,copper,aluminum,oxygen consumption,turbidity and lead show a downward trend.Nitrate,free carbon dioxide,zinc,arsenic,mercury,anionic synthetic detergent,conductivity and total alkalinity show an upward trend.The trend of remaining indicators are not obvious.?3?Based on the mathematical statistical analysis method,the correlation analysis of each index is carried out,and through the principal component analysis,it is found that most of the indicators have a good correlation with the first principal component.Na⁺,Mg²⁺,Ca²⁺,HCO₃^-,ammonia nitrogen,chloride,SO₄^2-,TDS,manganese,oxygen consumption,total hardness,electrical conductivity,total alkalinity and other indicators respond strongly to the comprehensive water quality status.?4?By solving the weights of analytic hierarchy process and entropy weight method and combining the weights according to AHP-Entropy weight method,the monitoring indicators of groundwater pollution in Pinggu District were determined as nitrate,arsenic,manganese,ammonia nitrogen,TDS,total hardness,SO₄^2-,iron?bivalent?,chloride,oxygen consumption,conductivity,total alkalinity,fluoride,iron?trivalent?,Na⁺,Mg²⁺,Ca²⁺,HCO₃^-,nitrite and pH.