Relation of reactive solute-transport parameters to basic soil properties

摘要

Solute-transport parameters are needed to assess the pollution risks of soil andgroundwater resources. A reliable estimate of these parameters from easily measurablesoil properties is therefore important. So, the correlations of the transport parameters forone metalloid compound (NaAsO2), six heavy metal compounds (Cd(NO3)2, Pb(NO3)2,Ni(NO3)2, ZnCl2, CuSO4 and Co(NO3)2), two pesticides (cartap and carbendazim) and oneinert salt (CaCl2) with some basic properties of eight agricultural soils of Bangladesh wereinvestigated. The purpose of this study was to generate information for development ofnon-parametric pedo-transfer functions for reactive solute transport through soils. Thetransport experiments with the solutes were done in repacked soil columns underunsaturated steady-state water flow conditions. The major solute-transport parameters –velocity of transport (V), dispersion coefficient (D), dispersivity (?), retardation factor (R)and Peclet number (P) – were determined by analysing solute breakthrough curves(BTCs). The basic soil properties pertinent to solute transport: clay content, median graindiameter (D50), pore-size distribution index (n), bulk density (?), organic carbon content(C) and pH were determined. The associations of the solute-transport parameters withthese soil properties were investigated and evaluated. Both the solute dispersivity andretardation factor increased significantly (p0.05) (? linearly and R following power law)with the increase in soil clay content. Dispersivity significantly decreased with theincrease in median grain diameter following power law. The V, D, ? and P values wereweakly and negatively correlated with the soil bulk density. Retardation factor, R, wasmoderately and positively correlated with the ratio of clay content to organic carboncontent. Dispersivity decreased but P increased, both significantly, with increasing poresizedistribution index, n. V, D and P were positively correlated with soil pH, while R and ?were negatively correlated with it. The correlation of the solute-transport parameterswith soil properties being significant (p 0.05), in most cases, provides strong possibilityof predicting solute-transport parameters from the basic soil properties through thedevelopment of pedo-transfer functions.