Evaluation of the rare earth elements phytotoxicity on the example of La and Ce

Interest in the study of the toxicity of rare earth elements (REE) naturally increases with an increase in their consumption. The growth of exploration, development and mining of rare earth metals poses a serious threat to the environment, increasing the concentration of REE in air, water and soil. In this work, we assessed the phytotoxicity of cerium and lanthanum, as the most common rare earth lanthanides in the earth’s crust, using test systems with oats (Avena Sativa L.) and onion (Allium cepa L.). For both test objects, the toxic effect of high concentrations of lanthanum and cerium has been proven. In addition to the inhibition of the development of onion roots, a visually determined thickening and yellowing of the root cap, a change in the cells of the root merisystem were noted. For oats at high concentrations of lanthanum and cerium, yellowing of the roots and inhibition of their development, slowing down the growth of seedlings were also noted. At the same time, for oats at low concentrations of the studied substances, the effect of hormesis was noted.