Bioaccumulation of As, Cd, Cu, Fe and Pb in wild grasses affected by the Aznalcóllar mine spill (SW Spain)

16 pages, 3 figures, 7 tables, 40 references. We thank M.H.Hurtado and J.M. Alegre for their help in sampling and Dr C. Romero for plant determination.T race element concentrations in plants were determined in the Centre for Scientific Instrumentation (University of Granada).The collapse of the tailing dam in the Aznalco´ llar pyrite mine (SW Spain) occurred in April 1998 and affected approximately 4300 ha along the Agrio and Guadiamar valleys.An urgent soil cleaning up and remediation programme was started just after the accident.Eighteen months later, mineral nutrients and trace elements concentration in soil and two wild grasses — Cynodon dactylon and Sorghum halepense — have been studied.Thr ee types of conditions are distinguished: (a) unaffected soils (control); (b) cleaned up and remediated soils (remediated); and (c) sludgecovered soils left in a fenced plot (non-remediated). As, Cd, Cu and Pb in grasses reached toxic levels for the food web in the non-remediated plot, while on remediated soils only Cd reached a toxic level in grass tissues.However , Pb and, to a lesser extent As and Fe, reached also toxic levels in unwashed plants (as they would be ingested by animals) in remediated soils. Both native grasses seem tolerant of trace elements pollution and suitable for stabilisation of spill-affected soils.This study was carried out under the framework of the ‘Programa de investigación del corredor verde (picover)’, supported by funds of the ‘Consejería de Medio Ambiente de la Junta de Andalucía, Seville, Spain.Peer reviewe