Uptake of traffic-related heavy metals and platinum group elements (PGE) by plants

The distribution of the platinum group elements (PGE) caused by traffic emissions from autoexhaust catalysts has been determined in soils and different types of plants. The plants (spinach, cress, phacelia, stinging nettle) were cultivated on different soils collected from areas adjacent to a German highway and on uncontaminated sandy and clayey soils. The main result of the experiments was a measurable transfer of PGE from contaminated soil to plants. Following the definition of Sauerbeck (1989), Pt, Rh and Pd transfer coefficients are within the range of immobile to moderately mobile elements, such as Cu. The transfer coefficient decreases from Pd > Pt greater than or equal to Rh, palladium therefore is the most biologically available of this element group. (C) 1998 Elsevier Science B.V.