**Acknowledgements**

If *rj*

372 Water Quality

sections.

= 0 (the suspended fractions are absent), then, all *ai,j* = 0.

the location of the water-bottom interface.

*Rn*

*Rn*

*S\_calc, R\_calc* are the calculated ones)

*District reset MCC*

*Island Atamanovsky*

*Island Atamanovsky*

*S0*

*R0*

Knowing the contamination level in the initial section *Rn*

Stage 5. Estimation of the concentrations of the suspended and bottom sediments as well as

 *ai*, <sup>∂</sup>*H*,*<sup>j</sup>* = *Sn*+1 ⋅ *ρ*<sup>−</sup><sup>1</sup> ⋅ 100 (7) Stage 7. Estimation of the bottom sediment radioactive contamination in the calculation

*<sup>i</sup>*,*<sup>j</sup>* = *λ<sup>i</sup> Sn*

*<sup>i</sup>*,*<sup>j</sup>* ⋅ ( *So*

The influence of the suspension-sedimentation processes on the admixture transport in the river flow close to the right bank of the River Yenisei in the studied area has been estimated. The calculations made show that the concentrations of the lightest fraction in the calculation area almost do not change, while for the heavier fractions the decline of the suspended sediment concentrations is observed and the level of the radionuclide contamination also decreases (**Table 3**). In the field data, the increase of the coarse fraction concentration is observed which is not connected with the suspension-sedimentation process. (*S\_nat, R\_nat* are the measured values,

*<sup>i</sup>*,0 *= λ<sup>i</sup> Sn*

*<sup>i</sup>*,*<sup>j</sup>* ) <sup>−</sup><sup>1</sup> ⋅ *Rn*

*<sup>i</sup>*,*<sup>j</sup>* (8)

*<sup>i</sup>*,0, it is possible to estimate the

*<sup>i</sup>*,0 (9)

Stage 6. Calculation of the granulometric composition of the bottom sediment:

Each fraction is assumed to be uniformly contaminated by radionuclides:

level of the radionuclide contamination in the sections downstream the river

*<sup>i</sup>*,*<sup>j</sup>* = *Sn*

In the next time interval, the calculations are repeated (from stage 3 to stage 7).

*d***, мм 0.00020 0.00045 0.005 0.01**

, г/л 0.0001 0.0005 0.0043 0.0031

, Бк/кг 118.904 0.1728 0.1165 1.8224

*S\_nat* 0 0.0001 0.0009 0.0583 *S\_calc* 0.0001 0.0005 0.0039 0.0021

*R\_nat* 2.4727 0.01101 0.01596 0.0853 *R\_calc* 118.9009 0.1727 01044 1.2065

**Table 3.** Concentrations of particulate matter size fractions: real and calculated data.

This investigation was made with financially supported by the Russian Bureau of fundamental researches N-16-05-00205
