Effects of organic component on the immobilization of selenium on iron oxyhydroxide

The immobilization of selenourea and selenomethionine (organic forms of selenium) onto iron oxyhydroxide (a model mineral) was studied and compared to that of selenite (inorganic Se). Selenourea and selenomethionine were immobilized to a much lesser extent than selenite and while percentage immobilization onto a fixed mass of ferric oxyhydroxide decreased with increasing amount of selenite, that for selenourea and for selenomethionine increased. The presence of organic matter seemed to enhance selenite immobilization but decreased selenourea and selenomethionine immobilization. These results suggest that selenite and organic Se interact differently with ferric oxyhydroxide, with and without the organic matter present, resulting in a different immobilization behaviour.