Assessment of the Ecotoxicity of Platinum Oxide Based on the Biological Indicators of Ordinary Black Earth

The effect of contamination of ordinary black earth with platinum oxide (PtO2) on biological properties: root length and germination of radish, total number of bacteria, abundance of bacteria of the genus Azotobacter, activity of catalase and dehydrogenases have been studied. The concentrations studied were 0.01, 0.1, 1, 10 and 100 mg/kg in 10, 30 and 90 days after contamination. A stimulating effect (hormesis) of platinum oxide at a concentration of 0.01 mg/kg on the biological properties of ordinary black earth was recorded. It was found that in other cases, platinum oxide has a negative effect on the studied parameters, and exhibits the greatest toxicity after 30 days after contamination, followed by restoration of soil properties after 90 days. It was concluded that the most sensitive (highest degree of reduction) indicators to platinum oxide contamination were the total number of bacteria, germination and length of radish roots. Early diagnosis of the degree of soil contamination with platinum compounds is recommended in order to obtain a prompt assessment of the impact and prevent possible negative consequences.