Experimental Study Of Multi-component Solute Transport And Transformation In Unsaturated Zone Of Sanquan Reservoir

The Sanquan reservoir is located in the outcropping area of the spring mouth of the famous big spring Guidui spring area of Shanxi province.The reservoir is recharged by the leakage of the Sanquan reservoir to achieve the ecological restoration of Guidui spring,which brings new vitality to the society,but at the same time brings the corresponding water quality problems.This paper selects the middle and lower reaches of the Sanquan reservoir as the research area,and uses the method of static adsorption-desorption,reaction kinetics and indoor soil column simulation test to study the adsorption analytical characteristics of the multi component solute in the unsaturated zone,the law of reaction kinetics and the movement law of the multi component solute in the unsaturated zone soil under the condition of reservoir infiltration.It reveals the chemical behavior of multi component solute in unsaturated zone during reservoir water leakage.The main conclusions are as follows:?1?Adsorption desorption law of multi component solute and influenceThe results of isothermal adsorption test showed that F^-and SO₄^2-had desorption reaction during the test,and Fe,Mn,Ca²⁺,Mg²⁺and Na⁺adsorbed.The?non?linear isothermal adsorption equation is used to fit the?non?linear isothermal adsorption equation of reservoir surface sediments to 7 kinds of ions.The desorption volume of F^-increases with the increase of p H value.Under different pH conditions,the trend of the analytical curve is the same,rising rapidly-slowly rising-tends to be stable.Desorption of F^-on silt at different temperatures showed a general law of rapid rise and slow stability.40?was the best time for desorption of F^-.Fe,Mn and SO₄^2-have positive correlation with the general trend of F^-desorption,and Mg²⁺and Ca²⁺are negatively correlated.?2?Reaction kinetics of multi component solute in unsaturated zoneThe five ions are similar in the change of the reaction rate.The initial part is roughly divided into three parts.The initial part is steep.The ion concentration in the solution is very fast,the second phase diffusion rate slows down,the ion concentration change rate slows down.The curve no longer changes with the time.The slow curve means the final result is reached.Adsorption equilibrium,at this time the diffusion rate is very small.The influence factors of the test are pH value and soil organic matter,and the effect of pH value on anions is not obvious,but the effect on cations is relatively obvious.The greater the pH value,the greater the adsorption binding amount of the relative cations.Soil organic matter can increase the ability of soil to adsorb ions through surface complexation,ion exchange and surface precipitation.?3?Vertical migration of multi component solutes in unsaturated zoneDuring the vertical seepage of reservoirs,the ions that may threaten the groundwater in the area include COD,Fe,Mn²⁺and F^-.The most active layer of redox environment of reservoir deposits is over 50cm.Under the condition of water storage,the layer is basically in the reduction environment,and the Eh can be lower to-400mv,which directly affects the migration and transformation of variable valence elements.High pH reservoir water infiltration silt layer makes the acid and alkali environment of soil water changes,pH tends to increase,and then affects the balance of adsorption and desorption of soil and the balance of carbonate system.The low mineralized reservoir water leakage causes the soluble salt components in the silt to migrate to the lower unsaturated zone.F^-is a relatively polluted ion.The superposition of high fluorine water and the dissolved fluorine in this layer makes the lowest F^-content of the soil column up to 16 times as high as that of the initial solution.From the pollution factors such as F^-,Fe and TDS,the environmental negative effect of sediment in the cauda?T1?is greater than that in the reservoir?T2?.