Geochemical Modeling of Lead in Vadose Zone

by K. V. Nedunuri,
R. S. Govindaraju,
A. P. Schwab,
L. E. Erickson,

Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water


In recent years, researchers have used multicomponent reactive transport models to study the mobility of potentially toxic heavy metals in the subsurface. In this study, such a mathematical model for understanding the fate of lead in unsaturated soils is developed. The entire model comprises of water flow, lead transport and geochemical reactions. Local equilibrium assumption (LEA) is used to separate the geochemical reactions from the transport equations. Experimental evidence indicates that lead in the soil solution, reacts with phosphate minerals in the soil, resulting in the formation of stable pyromorphites. Computer simulations are carried out to study the influence of these phosphate minerals in immobilizing lead in unsaturated soils. Various geochemical mechanisms, involved in the formation of pyromorphites, are discussed. The study reveals the importance of utilizing phosphate minerals in remediating lead contaminated soils.

Subject Headings: Soil pollution | Lead (chemical) | Mathematical models | Groundwater pollution | Phosphate | Minerals | Vadose zone

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