[Stimulation of the natural self-purification of soil]

Connected with the elaboration of the sanitary norm of cadmium in soil were performed examinations to appoint the self-purification index. This index is the highest permissible concentration of a noxious chemical substance in soil not yet injuring irreversible the process of natural self-purification. As criterions of the self-purification were selected normal and potential respiration, quantity of bacteria, actinomyceta, fungi, proteolytic, nitrifying, and cellulolytic micro-organisms, inhibition of Bacillus subtilis and Phormidium autumnale, survival and increasing ability of Escherichia coli, Streptococcus faecalis and Salmonella give. Among the influence of various concentrations of cadmium was find out the self-purification index of 500 mg Cd++/kg. By experience are offered methodical improvements at the elaboration of self-purification indices.