The features of Cs sorption onto peaty-podzolic-gleyic soil.

This article studies sorption regularities and estimates the strength of 137Cs fixation by various soil horizons in peaty-podzolic-gleyic soils under a model experiment. The interaction time varied from 1 week to 3 months while Cs concentration varied from trace to micromolar concentrations. To understand the interaction mechanisms of cesium with individual soil components, we used the method of sequential removal of organic matter and non-silicate iron compounds from the soil before the sorption experiment. Illite and vermiculite were found to be the main soil components for radiocesium sorption in the mineral soil horizons. The highly selective positions (FES - frayed edge sites) of the abovementioned minerals fixed radiocesium so strongly that even strong acid solutions could not extract it from soil. Organic matter significantly contributed to the fixation of radiocesium in the soil only in the ELih horizon which contained 4.71% Corg. In the ELg horizon, a small amount of organic matter was able to inhibit sorption by blocking highly selective to radiocesium FES. The Tessier sequential extraction method of radiocesium revealed that all the studied soil samples could strongly fix the radionuclide. Increasing the interaction period up to three months under periodic wetting and drying contributed to the increased proportion of strongly bound 137Cs. The results of sorption experiments carried out before and after the removal of non-silicate iron compounds from the soil indicate that 137Cs has little or no sorption on the surface of iron hydroxides.

Current state and dynamics of heavy metal soil pollution in Russian Federation-A review.

The assessment of the current state and dynamics of heavy metal (HM) soil pollution in Russia is compiled based on the data published in open scientific journals and reporting documents of the environmental agencies using a number of indicators (background concentration, maximum permissible concentrations (MPC), tentative permissible concentrations (TPC) and total pollution index Z). The main attention is paid to the situation with punctual pollution of the heavily contaminated sites, and to the diffuse pollution of urban soils and agricultural lands. In impact zones of large industrial centres, because of the decrease in HM emissions, no additional soil pollution was registered since 2007. However, despite a sharp decline in HM input into soils, the level of pollutants in soils next to industrial enterprises remains high, because soils accumulate metals in the bound species. For urban soils and suburbs, a decrease in Pb content was documented in sites, where soil remediation measures have been implemented. The results of the survey compiled in 2008-2017, for settlements located in different regions of the Russia, showed that according to state regulations, the 1.7% of investigated lands can be considered as "dangerous", 9.1% as "moderately dangerous" and 89.2% as "permissible", in respect to soil HM pollution. For agricultural lands, it was showed that the average content of mobile species of Cu, Zn, Cd, Pb, Ni, Cr and Hg are below the permissible limits and tend to decrease. The agricultural soils with the HM concentrations above the critical limits constitute a few percent of the total area of the surveyed arable lands. For a better assessment of soil pollution of Russia, it is necessary to increase the area of surveys, to unify approaches to select the pollution indicators and to develop regulatory standards dependent on land use.