54
In both mineral and organic soils, portions of U exch and U mob , as a rule, considerably exceeded the portions of uranium in pore solutions. The obtained data indicate
the presence in the solid phase of soils of a significant reserve of reversibly sorbed
uranium capable of entering the pore solutions and being included in biogeochemical migration of uranium in terrestrial ecosystems. The uranium remaining in the
solid phase of the soil complex (in this case, not passing into a solution of 1 M HCl)
is in the soil in a fixed form. The relative quantity of uranium associated with fixed
fraction (U fix ) in the soil samples is shown in Fig. 6.
As can be seen from the obtained data, in the soils widely distributed in Belarus,
the main amount of uranium (85–96%) is in fixed form.
In general, in the studied soils, the portion of uranium in the mobile (conditionally biologically available) form did not exceed 15% of the total uranium content in
soil samples. According to the authors of the work (Vandenhove et al. 2014), in
natural and anthropogenic affected soils with different contamination histories and
uranium concentration, portion of U exch was in the range of ≤2–19.7, and portion of
uranium associated with exchangeable and acid soluble fraction (corresponding in
our case to a mobile form) was in the range of 0.3–13.7%. Our data on the content
of uranium in appropriate forms are in good agreement with these results.
In the same time, in semi-hydromorphic and hydromorphic soils of the Southern
Urals (in the area of the Itkul and Sinara lakes), which have been subjected to
anthropogenic impact, the portions of uranium in mobile form reached 90% (Poludin
et al. 2013). According to the Vodyanitskiy and Bol’shakov (1998), the presence of
uranium in mobile form in excess of 20–30% of its total content in soil unambiguously indicates the technogenic contamination of the soil with uranium.
The higher percentages of U exch and U mob in sandy soils compared to loamy soils
are in accord with the higher uptake of uranium by plants. The uptake of uranium is
generally higher on sandy soils compared to loamy soils (Sheppard and Evenden
1988; Mortvedt 1994; Vandenhove et al. 2009).
Fig. 6 Portions of fixed uranium (U fix , %) in the soil samples
G. A. Sokolik et al.
In both mineral and organic soils, portions of U exch and U mob , as a rule, considerably exceeded the portions of uranium in pore solutions. The obtained data indicate
the presence in the solid phase of soils of a significant reserve of reversibly sorbed
uranium capable of entering the pore solutions and being included in biogeochemical migration of uranium in terrestrial ecosystems. The uranium remaining in the
solid phase of the soil complex (in this case, not passing into a solution of 1 M HCl)
is in the soil in a fixed form. The relative quantity of uranium associated with fixed
fraction (U fix ) in the soil samples is shown in Fig. 6.
As can be seen from the obtained data, in the soils widely distributed in Belarus,
the main amount of uranium (85–96%) is in fixed form.
In general, in the studied soils, the portion of uranium in the mobile (conditionally biologically available) form did not exceed 15% of the total uranium content in
soil samples. According to the authors of the work (Vandenhove et al. 2014), in
natural and anthropogenic affected soils with different contamination histories and
uranium concentration, portion of U exch was in the range of ≤2–19.7, and portion of
uranium associated with exchangeable and acid soluble fraction (corresponding in
our case to a mobile form) was in the range of 0.3–13.7%. Our data on the content
of uranium in appropriate forms are in good agreement with these results.
In the same time, in semi-hydromorphic and hydromorphic soils of the Southern
Urals (in the area of the Itkul and Sinara lakes), which have been subjected to
anthropogenic impact, the portions of uranium in mobile form reached 90% (Poludin
et al. 2013). According to the Vodyanitskiy and Bol’shakov (1998), the presence of
uranium in mobile form in excess of 20–30% of its total content in soil unambiguously indicates the technogenic contamination of the soil with uranium.
The higher percentages of U exch and U mob in sandy soils compared to loamy soils
are in accord with the higher uptake of uranium by plants. The uptake of uranium is
generally higher on sandy soils compared to loamy soils (Sheppard and Evenden
1988; Mortvedt 1994; Vandenhove et al. 2009).
Fig. 6 Portions of fixed uranium (U fix , %) in the soil samples
G. A. Sokolik et al.