Model for the study of the impact of atmospheric heavy metals on soil microbial biomass

In the Castelporziano (Rome) protected area the inputs of atmospheric heavy metals on the soil-plant system were evaluated by the analysis of stem-flo wing water from Quercus ilex L. The heavy metals detected in the soil under the canopies exhibited higher concentrations near to the tree trunks, high lighting the tree's capacity to concentrate such polluting substances. Micr obial biomass, its specific respiration and the biomass calculated as a per centage of total soil organic matter, were utilised as indicators of the st ate of the soil and consequently also its quality with respect to heavy met al contamination.