Lindane Diffusion in Soil

Abstract

AbstractVapor and “nonvapor” diffusion of lindane was measured in Gila silt loam at various soil‐water contents. The apparent vapor diffusion coefficient (Dv′) increased rapidly as water content increased to 4%. There was a gradual decrease in Dv′ as water content increased from 4 to 20% and then a rapid decrease at water contents greater than 20%. The “nonvapor” apparent diffusion coefficient (Ds′) also reached a maximum at 4% water content and declined at water contents between about 4 and 20%. Ds′ increased as water content was increased above 20%.Apparently diffusion in the “nonvapor” phase occurs at the water‐air and water‐solid interface as well as in the water. The contribution of these pathways to the total transfer is dependent upon water content. It was assumed that the water‐solid diffusion coefficient would be constant at water contents above 4%. The air‐water interface diffusion was highest at 4% water content and decreased at higher water contents. Diffusion in water was essentially zero at water contents below 15% and increased with increasing water contents above this value.