Experimental Study Of Nitrate Transportation And Reduction In Saturated Zone

Nitrate pollution in groundwater is more and more serious since 1960s. Because of its quality stabilization and big solubility, it has already become the furthest universal environmental pollute of groundwater pollution in many areas today, and its contaminated degree is uninterruptedly increased. Nitrate pollution reducing technology research has already brought many scholastic high attention. Nitrate contamination of groundwater is an important research aspect in hydrogeology of nowadays. So it is very much the important that control the process of nitrate transportation and reduction, final substance and forecast its concentration.This study is supported by Natural Science Foundation of China. Based on the study about nitrate contamination in groundwater at home and abroad. A set of experiment physical equipment simulating nitrate transportation and reduction in groundwater is designed. We deeply research the change of that hydraulic gradient and aquiferous thickness how to affect nitrate transportation and reduction. And nitrate transportation and reduction experiment of every layer and group at the changeless of hydraulic gradient and aquiferous thickness is completed. It is exposed the rules of nitrate transportation and reduction and established its forecasted model. The conclusions are drawn as followings: (1) Under the same condition, with the accretion of hydraulic gradient, pH value of each sampling point falls, conductance ratio, COD, NH₄⁺-N, NO₃^--N concentration of every sampling point augments; (2) Under the same condition of hydraulic gradient, pH value of each layer increases, the concentration of conductance ratio, COD, NH₄⁺-N, NO₂^--N, NO₃^--N decreases. Nitrite and pH value of every group increase, conductance ratio, COD, NH₄⁺-N, NO₃^--N decreases; (3) spacial distributing character of nitrate in groundwater saturated zone is obtained: whole variation of nitrate in radial decrease along with increase of distance; whole variation of nitrate in length decrease along with increase of depth of groundwater; (4) nitrate transportation and reduction in saturated zone is influenced by a lot of factors, the result of statistics: pH value and NO₂^--N increase, conductance ratio, COD and NH₄⁺-N decrease along with decrease of nitrate in radial; pH value and NO₂^--N increase, conductance ratio, COD and NH₄⁺-N decrease along with increase of nitrate in length; (5) ensure flow condition of groundwater is laminar flow, one-dimension convection-dispersion equation of transportation and reduction of nitrate in groundwater saturated zone is established, and forecasts the trend of nitrate transportation and reduction, its forecasted curve has finer precision.