Radium migration

Nikiforova, Y.H. and Yufa, B.Ya., 1970. Features of uranium and radium migration in mountain landscapes and their role in radiometric prospecting. Moscow, Univ., Vestn., Ser. Gcogr., 4 75-81. 

Joly observed elevated "Ra activities in deep-sea sediments that he attributed to water column scavenging and removal processes. This hypothesis was later challenged with the hrst seawater °Th measurements (parent of "Ra), and these new results conhrmed that radium was instead actively migrating across the marine sediment-water interface. This seabed source stimulated much activity to use radium as a tracer for ocean circulation. Unfortunately, the utility of Ra as a deep ocean circulation tracer never came to full fruition as biological cycling has been repeatedly shown to have a strong and unpredictable effect on the vertical distribution of this isotope. 

Figure 1. Schematic illustration of factors influencing the production and migration of radon in soils and into buildings. Geochemical processes affect the radium concentration in the soil. The emanating fraction is principally dependent upon soil moisture (1 0) and the size distribution of the soil grains (d). Diffusion of radon through the soil is affected primarily by soil porosity ( ) and moisture content, while convective flow of radon-bearing soil gas depends mainly upon the air permeability (k) of the soil and the pressure gradient (VP) established by the building.

Factors influencing the production and migration of radon in soils have been examined, and various sources of geographic data have been discussed. Two significant soil characteristics include air permeability and, less importantly, radium concentration. While there are, at present, few opportunities to compare the larger-scale data with on-site field measurements, those comparisons that have been made for both surface radium concentrations and air permeability of soils show a reasonable correspondence. Further comparisons between the aerial radiometric data and surface measurements are needed. Additional work and experience with SCS information on soils will improve the confidence in the permeability estimates, as will comparisons between the estimated permeabilities and actual air permeability measurements performed in the field. 

Yang HS, Nozaki Y, Sakai H, et al. 1986. Natural and man made radionuclide distributions in Northwest Pacific deep sea sediments Rates of sedimentation, bioturbation and radium-226 migration. Geochem J 20 29-40. 

RlTCEY, G. M. 1990. Weathering Processes in Uranium Tailings and the Migration of Contaminants. In The Behaviour of Radium, IAEA Technical Report Series 310, IAEA, Vienna, 27-82. 

This information seems to preclude the present-day precipitation site as the major source of high radium values, so we are left with several alternatives (1) that the boundary between the freshwater zone and the transitional zone (hence the site of uranium accumulation) was once further west and that it has migrated eastward in the recent geologic past, or (2) that the source of radium is the high-Cl brine. 

The first alternative is attractive in that it can account for both the location of the high radium values and the lack of anomaly in the water. However, there is neither independent evidence that such an upgradient migration has occurred nor any apparent reason why it should have moved such a long distance so rapidly. 

Radiogenic helium, radon and radium, each with a different mechanism of migration, should be effective even in completely reduced systems. Examples of these occurrences are tabular Colorado Plateau type deposits related to reducing conditions in a palaeo-river bed and rereduced host rocks where roll fronts are no longer in proximity to surface oxidation. 

Radon is a naturally occurring radioactive gas that is odourless and colourless. It is formed where uranium and radium are present in the soil (at very small concentrations) and can migrate vertically into any buildings built over the source. It poses a chronic rather than acute risk because if it accumulates in a building at unacceptably high concentrations it will increase the risk of lung cancer. 

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