CARACTERIZACIÓN DE METALES TÓXICOS EN POLVOS DE LA CIUDAD DE MÉXICO

A study on toxic heavy metals fOtUld in dust collected in two sites with diflerent traffic aflluence in Mexico City is reported. The total amount oflead, copper and manganese were detennlned. These concentrations were higher than nonnal concentrations found in non-polluted soils and also higher than the limit values given in Holland for soil usage. Granulometric separation ofdusts was also perfonned and heavy metals concentration was determined by granulometric class. More than 50% of the measured dust particles had diameters > 0.250 mm and they contained the highest concentrations of lead, copper and manganese. Using a speciation scheme of consecutive extractions, metals mobility was assessed. Lead was observed as the most mobile metal, more than 60% of the total lead concentration and more than 25% of the total manganese concentration could be dissolved in a slightly acid medium; almost 100% of the total copper amount was mobile in oxidant conditions.