The influence of various heavy metal compounds on the development and activity of soil micro-organisms

Abstract The influence of various concentrations of lead, zinc, copper, arsenic and mercury on development and activity of soil microflora are defined. Groups of micro-organisms important for soil fertility were considered. Different factors, e.g. soil type, type of metal compound and its concentrations, influencing the effect of heavy metals on soil microflora were also studied. The relative toxicity of the compounds used could be put in the following order: Hg ( metallic ) > CuSO 4 > HgCl 2 > Hg 2 Cl 2 > HgO > As 2 O 3 > ZnSO 4 > NaHASO 4 > Pb ( NO 3 ) 2 . Of the micro-organisms investigated fungi and actinomycetes were the most resistant to all the metals used. Azotobacter sp. and nitrifiers appeared to be the most sensitive. The results of these investigations suggest that it would be possible to use microbiological methods in order to estimate the degree of soil pollution by various metals and compounds.