Quality reference values for rare earth elements in soils from one of the last agricultural frontiers in Brazil

Environmental impacts caused by the addition of rare earth elements (REEs) to agricultural soils are a growing concern. The sedimentary basin Gurguéia River is located in one last frontiers Brazil; nevertheless, data regarding quality reference values (QRVs) for REEs still scarce. objective this study was therefore determine natural concentration and establish QRVs watershed, Brazil. Fifty-five composite soil samples were collected at sites under no or minimal anthropic interference. average REE concentrations from watershed lower than those found other regions Brazil worldwide, following order (mg kg−1): Ce (14.01) > Nd (6.19) La (5.52) Pr (2.51) Sm (1.45) Gd (0.93) Dy (0.63) Er (0.42) Yb (0.39) Tb (0.28) Eu (0.26) Lu (0.20). parent material main factor that controlled distribution soils. followed (18.8) (7.92) (6.32) (3.3) (1.97) (1.35) (0.85) (0.55) (0.47) (0.37) (0.25). These serve as basis assist development legislation, including thresholds Brazilian