Levels and chemistry of atmospheric particulates induced by a spill of heavy metal mining wastes in the Donana area, Southwest Spain

As a result of the collapse of the storage lake dam (property of the Bolide n company), pyrite-rich mud layer covered the Guadiamar valley (north of th e Donana Natural Park, SW Spain). The present work focuses on the physico-c hemical characterisation of suspended particles during high atmospheric par ticulate events caused by soil reclamation activities. Intensive sampling o f atmospheric particulates during the period 20 May-27 December was carried out at two monitoring stations located at Aznalcazar and in the Guadiamar valley. At Aznalcazar mean daily levels of 191.2 mu gTSP m(-3) were recorde d for the soil reclamation period (July-August 1998), with maximum daily le vels of 490 mu gTSP m(-3). After the reclamation activities TSP progressive ly decreased down to levels of 90 mu gTSP m(-3) in September-October, and 4 0 mu gTSP m(-3) in November-December. Very high levels of major and trace e lements were recorded at the two sampling sites. As for TSP, ambient air le vels of major and trace elements increased sharply (two orders of magnitude ) in July and August compare with the levels recorded in May and June, and gradually decreased during the autumn and winter seasons. Mean daily levels for July and August at Aznalcazar attained values-close to 2 ng m(-3) for Ag, Cd, Sn and Tl, 10 ng m(-3) for Ni, 100 ng m(-3) for Mn, 200 ng m(-3) fo r As and Cu, and 450 ng m(-3) for Pb and Zn. In the Guadiamar valley (where the major soil reclamation activities were carried out), the levels achiev ed were higher than those of Aznalcazar by a factor of 3. In September, the levels recorded at both monitoring stations decreased but were still highe r than the initial values by a factor of 5, showing lower standard deviatio ns than those in July-August. Finally, the levels recorded in December were very similar to those of May. As regards the grain-size distribution of mi nor and trace elements, Cu, Mn and Zn exhibit from 17 to 36% and 59 to 70% Of their bulk; levels in TSP in the PM2.5 and PM10 fractions, respectively. However, As, Cd, Co, Pb, Sb Se and Tl showed proportions from 20 to 48% an d from 80 to 90% TSP in the PM2.5 and PM10 fractions, respectively. The wat er extractable fraction of major, minor and trace elements in TSP was diffe rent for the elements studied. Thus, Cd, Co, Tl, Mn and Se showed a water e xtractable proportion from 27 to 92% of their bulk content in TSP, Ni, As, Zn and Cu showed an intermediate soluble fraction which ranged from 8 to 10 %,and Pb, Sb and Cr were mobile in a proportion < 4%. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.