Study For The Migration Of Adsorptive Solute Cr(â…¥) In Soil Into Surface Runoff

Water pollution is a common topic and has been received extensive attention from all fieldof life recently, and agricultural non-point source pollution is one of the most serious waterenvironment pollution. Runoff scouring and eluviation under heavy rain, pollutants in the soilput into the earth’s surface by the surface runoff and into the underground water by waterpenetration, resulting in non-point source pollution. To shallow soil pollution monitoring andmanagement work, the migration of pollutants in soil water is need to be studied, and simulatedprediction.In this article, we complete the solute adsorption of Cr(VI) erosion law research with surfacerunoff through indoor simulated rainfall experiment. We complete the isothermal adsorptionexperiment and soil moisture characteristic experiment at the same time, on the basis of theHydrus-1D we establish one-dimensional unsaturated solute migration numerical model, andestablish the forecast model to study the effect of those parameters for the migration regularity ofCr(VI) in the soil. Software Hydrus-1D is used to solve prediction model to validate theexperiments data, exploring model parameters for the solute migration of the adsorptive Cr (VI)in soil.The research results show that in a simulated rainfall experiment, the concentration of soilsolute migration towards the surface runoff gradually decreases with time, the main experimentalconditions including soil initial water content, maximum ground water depth and the bottom ofthe drainage condition, etc. Loss of solute concentration in surface runoff increase with theincrease of initial water content; The higher the maximum water depth in soil surface, the smallerthe Cr (VI) concentration of migration towards the surface runoff; the better the bottom drainagecondition, the greater the concentration of solute migration to lower soil, the smaller theconcentration of solute migration towards the surface runoff.According to the soil sample isothermal adsorption experiments of Cr(VI), and use linearisothermal equation, the Langmuir equation and the Freundlich equation to fit. It is concludedthat the Langmuir equation and the Freundlich equation has higher fitting degree correlationcoefficient. The correlation coefficient is a significant level respectively as99.17%and98.81%. We solve the loss of solute concentration with surface runoff model through the Hydrus-1D,the simulated values and the observed value of the solute concentrations in surface runoff werewell consistent. The concentration of solute migration in surface runoff initially for1e-5mg/Lwith rainfall concentration decline after300minutes, the solute concentration in surface runoffhave come down an order of magnitude. After540minutes the solute concentration become for1e-10mg/L(total loss).We take sensitivity analysis based on the maximum water depth, the initial moisture content,saturated hydraulic conductivity and coefficient of isothermal adsorption parameters, found thatthe change of the isothermal adsorption coefficient has the greatest effect on the loss of soluteconcentration with surface runoff on the prophase of precipitation. Loss of solute concentrationin surface runoff is sensitive to the initial water content and soil saturated hydraulic conductivityon the late prophase of rainfall, but only have a little impact.