EFFECTS OF HEAVY-METAL CONTAMINATION ON SOIL MICROBIAL-POPULATION

In order to estimate the effect of heavy metal pollution on soil microorganisms, a field survey was carried out in a heavy-metal-contaminated (Cd, 1.1-2.7 mg/kg soil; Zn, 234-571 mg/kg soil; Cu, 310-751 mg/kg soil) fallow paddy field. Although the number of actinomycetes and bacteria decreased significantly with increasing heavy metal content, there was no significant correlation between the number of fungi and heavy metal content. Actinomycetes were affected by heavy metals most strongly. The degree of tolerance to heavy metals appears to be: fungi > bacteria > actinomycetes. These results suggest that the relatively low concentrations of heavy metals in the research area affected the soil microbial population.