Diffuse pollution from rare earth elements in phosphogypsum amended Brazilian soils K.A.P. Oliveira*, M.A.B.C. Menezes*, V.M.F. Jacomino*, E.,von Sperling** * Nuclear Technology Development Centre of Brazilian Nuclear Energy Commission, Belo Horizonte, Brazil. **Professor at the Department of Sanitary and Environmental Engineering of Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. ( * ** This paper presents a different approach, related to the possible presence of rare earth elements in agricultural soils. The study refers to the widespread use of phosphogypsum (PG) (a by-product of phosphoric acid factories) in agriculture as an example of minimization of the impacts of its production and the consequent preservation of natural gypsum reserves. Introduction The authors would like to express appreciation for the support of the sponsors: Results & Discussion PG may contain several toxic elements, such as radionuclides and rare earth elements (REE) that can be transferred to soil, plants and water sources. In the present work variable doses of PG were applied to two types of Brazilian soils (sandy and clayey). This research focused particularly on REE transfer factor (TF) from PG amended soil to selected vegetables. Conclusions Figure 1: Overview of stockpiles of phosphogypsum Greenhouse experiments were carried out at an experimental area of Viçosa Federal University’s Soil Department (Viçosa, MG, Brazil), REE concentration in all samples was determined by instrumental neutron activation analysis (INAA), k0 method. Fonte: Google Earth Figure 3. Sequence of events for reactions (n, γ) Figure 2. Lettuce, corn and soybeans in greenhouse experiment The results (Figure 4) indicated that Brazilian PG is rich in REE. This is due to a type of phosphate rock that has igneous origin, usually high in REE, monazite and thorium and with widespread occurrence in Brazil, Russia and South Africa. The different doses of PG used in soil samples did not influence the REE Transfer Factor to crops. The really important factor in REE Transfer Factor was the type of soil, since sandy soils generally present lower concentrations of organic matter and a limited capacity to retain elements, making them easily available to the plants. Moreover there is a trend that Brazilian soils have higher values of Transfer Factor than in temperate climate soils. Such results can be explained by the fact that soils are more leached in tropical climates (poor in organic matter), resulting in a lower capacity to retain elements and promoting hence a higher mobility of elements for plants and an elevation of Transfer Factor values. This demonstrates that the viability of PG use must be analyzed by studying the type of soil where it will be applied in order to minimize eventual diffuse contributions to soil and surrounding waters. Figure 4. Rare earth elements concentrations in studied soils The authors would like to thank Dr. Jaime Mello and M.Sc. David Faria of Federal University of Viçosa for collecting soil samples and company Fosfértil for samples of PG.