Change of the cadmium, lead and uranium species after addition of biochar into the soils
Using the method of chemical fractionation the change in the reserve of Cd, Pb and U in exchangeable forms (Meex) in sod podzolic sandy and medium loamy and peaty soils after adding 5 wt. % biochar has been investigated. It was found that in the presence of biochar in sandy soil, the content of Cdex, Pbex, and Uex decreased by 20, 50 and 46 %, respectively. In medium loamy soil, the content of Cdex and Pbex is reduced by 26 and 63 %, and in peat soil, the content of Pbex and Uex is decreased by 8.5 and 46 %, respectively. However, in the peat soil, the addition of biochar had practically no effect on the content of Cdex, and in medium loamy soil, it led to an increase in the content of Uex. The results of the study show that biochar at a dose of 5 wt. % can improve the quality of soils (decrease acidity, increase the content of exchangeable K and Ca) and reduce the mobility and biological availability of Cd and Pb in sandy and medium loamy soils, and U in sandy and peaty soils in regions with an increased content of them.