Th e study of cadmium behavior in soil — soil solution — plant system in a model experiment using a radioactive indicator.

Abstract

The article discusses the processes of transition to the aqueous phase and uptake from it by plants of stable (Cd) and radioactive (¹⁰⁹Cd) isotopes. Regularities of the distribution of Cd/¹⁰⁹Cd between different forms of their chemical compounds in the soil were revealed by means of sequental extraction procedure (SEP) according to the Tessier-Förstner method. It was shown that content of labile and conditionally labile forms of compounds (fraction F1-F3) of stable Cd was 1,2–1,8 times less than that of radioactive ¹⁰⁹Cd and, conversely, 2,4–5,3 times more fixed conservative forms of metal compounds (fraction F4-F6). The Cd concentration, ¹⁰⁹Cd activity concentration, distribution and concentration coefficients of natural Cd and ¹⁰⁹Cd radionuclide, accumulation and removal of metal by plants were evaluated. Values of enrichment coefficients of natural (stable) Cd contained in sequentially extracted chemical fractions by ¹⁰⁹Cd radioisotope were determined, the value of stock of labile cadmium compounds in studied soil was calculated. Based on the results of solid-state ¹³C NMR spectrometry, the qualitative composition of high-molecular organic compounds of the soil solution was determined and their ability to specifically sorb heavy metal cations was assessed.