Toxicity to Tradescantia of technogenic radionuclides and their mixture with heavy metals

The genotoxic effects on Tradescantia of 137 Cs, 90 Sr, and 236, 242 Pu, a heavy metal mixture [Cd, Cr(VI), Cu, Mn(II), Ni, Pb, Zn] and of a complex mixture of these toxicants were determined. The impact of radionuclides on plants subjected to ionizing radiation exposure was estimated. The number of somatic mutations and the quantity of nonviable stamen hairs were used as end points in the testing. An increase in the quantity of nonviable stamen hairs was observed with increasing internal exposure to 137 Cs, 90 Sr, and 236, 242 Pu; however, the number of somatic mutations was not observed to be dependent on ionizing radiation. The internal dose of individual radionuclides necessary to decrease the quantity of viable stamen hairs in Tradescantia by 50% can be arranged in the following sequence: 236, 242 Pu > 137 Cs > 90 Sr. Tradescantia died in the mixture of the radionuclides 90 Sr, 137 Cs, and 236 Pu (5 x 10 -2 , 7 x 10 -5 , and 4 x 10 -10 Gy, respectively) after 14 days, whereas the heavy metal mixture caused somatic mutations in 3% of the Tradescantia and nonviable stamen hairs in 7% but no mortality. However, the Tradescantia died in a combined mixture of these heavy metals and the radionuclides after 14 days. On the basis of all these observations, it can be concluded that the toxic effect of radionuclides was more significant than that of heavy metals.