Physico-chemical characterisation of atmospheric aerosols in a rural area affected by the aznalcollar toxic spill, south-west Spain during the soil reclamation activities

High levels of atmospheric contamination due to the re-suspension of pyrite particles from the mining waste slurry were recorded in the Guadiamar vall ey (the Guadiamar is a tributary of the Guadalquivir river) after the toxic spill of Aznalcollar, north of the Donana Natural Park (SW Spain). Major h igh-particulate events occurred during the extraction of the pyrite-rich mu d layer, which covered an extensive area of the valley downstream of the co nfluence of the Agrio and Guadiamar rivers. This study deals with the monit oring of the ambient air quality at two stations near the village of Aznalc azar in the central part of the flooded area. Although the Spanish legal li mit for atmospheric particles and lead in environmental air were not exceed ed, high daily levels of total suspended particles (TSP) and of some elemen ts with an environmental significance (As, Cd, Cu, Mn, Ni, Pb, Sn, Tl and Z n) were recorded at Aznalcazar and in the Guadiamar valley during soil recl amation (July-August 1998). Despite a progressive decrease in TSP levels th rough September-October 1998, background was higher than the levels for the May-June period. Evolution of levels for most of the elements studied show ed a similar trend. The exceptions were copper, which was partially increas ed by other emission sources such as fumigation activities, and sodium, whi ch remained at relatively constant levels during the study period because o f its marine origin. The physico-chemical characterisation of the atmospher ic particulates allowed us to determine the major grain size modes of the p yrite related elements and the solubility of the potentially toxic elements , and to identify the major particulate types present in the atmosphere in the area. Secondary and tertiary aromatic amines (i.e. alkyldiphenylamines and phenylcarbazoles, respectively) were identified in the suspended partic les and in the vapour phase collected at the same station as the TSP sample s. As some of these aromatic amines had been previously identified in the p yrite sludge, it is assumed that fine sludge particles containing aromatic amines were re-suspended in the atmosphere. The highest concentrations of a romatic amines in the particulate phase were recorded in August 1998 during the pyrite slurry extraction in the proximity of the Aznalcazar sampling s ite. Despite a sharp drop in the suspended particles of the aromatic amine concentrations, a significant concentration was detected in the vapour phas e (<1.2 mm) during autumn, probably because of longer residence time in the atmosphere. Although health hazards associated with the presence of these aromatic amines are unknown, their acute toxicity exceeded that of urban ae rosols. (C) 1999 Elsevier Science B.V. All rights reserved.