## 3 Results and Discussion
### Results of the Calculation of the Diffusion Model of Radon Transport  
In previous work [23], we calculated the main radiation and physical parameters of rocks that comprise a typical kimberlite field of the Arkhangelsk diamondiferous province:  
Figure 4: Graph of the dependence of the soil permeability parameter and radon radiation (abnormal permeability values excluded). Figure 3: Graph of the dependence of the soil permeability parameter and radon radiation. overlying sediments, rocks from exocontacts of kimberlite pipes, tuffaceous-sedimentary rocks of the pipe crater, and diatreme kimberlites. Table 1 shows the ranges of the studied parameters and their average values. Additionally, we calculated the radiation and physical parameters for the sandstones with siltstone interlayers of Ediacaran sedimentary rocks using the algorithms and methods given in [23]. Due to the lack of data on the rates of radon convection, we used a diffusion model for a homogeneous and single-layer object to calculate the transfer rate. Due to the small thickness of the overlying Quaternary sediments (Q, Figure 1) in the northern part of the Chidvinskaya pipe, we did not take into account their effect on the radon radiation in the calculation. Therefore, only one layer was included in the calculation for each vertical profile. In addition, we did not consider the time factor, so the model was calculated in a stationary mode. The diffusion coefficient (D) was derived from the literature [47] in accordance with the physical parameters of the studied samples. To calculate the transport model, we used the average values of radium-226 activity (ARA226), the emanation coefficient (K\({}_{\text{emanation}}\)), and rock density (Density). Figure 5 shows the vertical distributions of radon radiation in the studied rock profiles, calculated according to Equation (2), for three profiles: pipe, country rocks, and sandstones with siltstone interlayers of Ediacaran sedimentary rocks. The actual depth of the Chidvinskaya kimberlite pipe exceeds 400 m from the surface. Considering the diffusion coefficient, the radon radiation values reached an equilibrium state after eight metres. Variations in radon in the surface atmospheric air, due to its low radiation level, do not affect the diffusion process at the soil-atmosphere boundary. Therefore, at the edge point of transfer at x = 0, the radon radiation in the atmosphere was regarded as zero [47]. Despite some assumptions and a general simplification of the model, the calculated results clearly show that the country rocks had the greatest potential for increased radon radiation and, accordingly, the formation of radiation anomalies. The calculated values of the radon radiation produced by the near-pipe rocks exceeded 9000 Bq-m\({}^{-3}\). A small amount of radon was also produced by diatreme kimberlites; this calculated value of radon radiation for diatreme kimberlites with average radiation and physical parameters was at a level of 2500 Bq-m\({}^{-3}\). Future work will be carried out in order to determine the velocities of movement of radon along the three above-mentioned profiles. We will determine the velocities of the movement of radon on the basis of the radiation and physical characteristics of the pipe rocks, as well as the values of radon radiation at different depths. This will allow the peculiarities of the geological structure of the kimberlite body to be considered, for example, the zones of fractures and faults at the boundaries of the pipe, when calculating the already convective model of vertical radon transport along the rock mass.