Influence of organic fertilization on the sorption mechanisms of 241 Am in tropical soils

In this work the mechanisms involved in the sorption of 241Am were investigated depending on the physicochemical properties of some Brazilian soils and on alterations promoted by organic amendment. This experimental study was conducted in a controlled area, where pots containing different kinds of soils (histisol, ferralsol and nitisol), with different organic amendment doses (without amendment; 2 kg m-2 and 4 kg m-2) were artificially contaminated by radioactive solution water, which contained 241Am. Migration studies, distribution (or partition) coefficient (KJ), bioavailability and organic matter were carried out in these soils, with ar without organic amendment. In order to evaluate the effective bioavailability of radionuclides, radish (Raphanus sativus L.) was cultivated in these pots, and later the concentration of 241Am in radish's roots was measured. The main results show that 241Am tends to be strongly attached to organic matter and that organic amendment in tropical soils minimizes the radionuclide studied desorption. Also, distribution (or partition) coefficient values for 241Am were generated and these values are smaller than those ones determined for soils from temperate zones. Physical and chemical fractioning of organic matter were carried out. (author)