Edafología. Volumen 7-3. Septiembre 2000. pág 47-54.
Soils form two potentially polluted areas in the southern and south-eastern of the Community of Madrid have been studied. Fourteen trace elements concentrations were analyzed. Mean As, Pb and Tl soil concentrations were higher than background values for World Soils. The relationship between Zn and organic matter, Tl and clay fraction, Cr and Ni and CaCO3 were significant at the P=0,001 level.
The total concentration of a metal has no direct bearing on the toxicity, two types of metal extraction agents NH4-Acetate and EDTA have been used for the removal of trace elements from soil. The results showed that the extraction percentages for all metals with EDTA were greater than with NH4-acetate. For Cd, Cr and Ni, the values were similar with both extractants.
The studied soils have showed a high number of microorganisms. The population was conformed of bacteria, molds and in less proportion of yeast, most of them resistant to lead.
KEYWORDS: Trace elements, availability, microorganisms.