Monitoring of airborne metals in grass and depositions

Samples of standardized grass cultures and depositions collected according to BERGERHOFF revealed differing concentration gradients of Pb, Sb and Cd vs. distance to heavily traveled roads. Results suggest varying suitability of the methods with regard to indication of metal pollution. Bioaccumulation of Pb in grass (in terms of deposition plus incorporation) was moderate compared to Pb depositions. Bioaccumulation of Sb, however, showed stronger concentration gradients compared to Sb depositions. Positive correlations (r = 0.6 to 0.8) between deposition and grass contents of Pb and Sb were found. Pb and Sb contents in grass, sampled at roadside locations correlated significantly, too. It is being suggested that varying bioaccumulation mechanisms of the metals are due to their predominance on different sizes of particles and to their individual prevalence in a number of different metal compounds.