Multicomponent Transport of Contaminants Released into the Environment following the Application of Phosphogypsum.

Abstract

The fate of radioactive contaminants released from phosphogypsum, a by-product of the phosphate fertilizer industry, was studied using the multicomponent transport modeling program HP-1. HP-1 combines Hydrus 1D, simulating one-dimensional variably saturated water flow and multicomponent transport in soil systems and sediments, with PHREEQC, which simulates a broad range of low-temperature biogeochemical reactions in water, soil and sediments. A literature research characterized and quantified the most important soil parameters that influence the mobility of radium in the soil. Two PHREEQC approaches were developed using data obtained from literature to account for the dynamic behavior of radium in the vadose zone. Results of these approaches were used in PHREEQC batch experiments and were compared with literature data. HP-1 was then used to model long-term application of phosphogypsum in a typical Dutch agricultural soil profile, the Enkeerdsoil, giving more insight on the long-term behavior of radium after phosphogypsum application.