Microbial biomass carbon (C_mic) and soil enzyme activities were measured at 12 sites along a gradient of former emissions of phosphate fertilizer production. Seven years after close down of operation, still moderate to high total concentrations of the dust constituents cadmium (up to 33 mg kg⁻¹ dw), fluoride (5300 mg kg⁻¹ dw) and phosphorous (120,000 mg kg⁻¹ dw) were found in topsoils of contaminated sites. Accumulation of partially decomposed plant matter, soil respiration and dehydrogenase activity paralleled the increase of dust deposits, whereas microbial biomass decreased along the gradient. A significant negative correlation was obtained between the C_mic-to-C_org-ratio and the concentration of contaminants. In contrast, the C_mic-specific respiration (qCO₂) and the dehydrogenase activity-to-C_mic-ratio were positively correlated. The low C_mic-values and the enhanced activities in the contaminated soils are suggested as a response of microbial communities to environmental stress or ecosystem disturbances. The apparently missing detrimental effects of the alkaline deposits on soil microbial activities are probably due to the low bioavailability of contaminants in the calcareous soil.