Geochemistry of radon

The main chemical reactions of Ra in the natural environment can be summarised with a few equations  

The scavenging effects of clays, organic debris and hydrous oxides outweigh the dissolution of Ra by chloride in the surficial environment. As a result there is a net deficit of Ra in stream waters entering the oceans, even though the water in the oceans contains an excess of Ra (Cochran, 1979). 

With very few exceptions, surface and near surface waters contain an excess of Rn (Table I l-III) compared to Ra (Table 11-lV) and U (Table 11-VI). This Rn must come from Ra in solids such as rocks, soils and sediments. The solubility product of Ra salts is seldom reached in natural waters, because invariably it is adsorbed onto sulphates and carbonates at the surfaces of rocks and minerals. In the zone of oxidation it is also coprecipitated by hydrous oxides of Fe and Mn. Only in the vicinity of strong sources of very saline waters do Ra concentrations rise to 10 or even 10 g/L. 

I lycirogcochcmical /onalily of rocks devoid of organic matter 

Reference (1 round water Stream Lake Ocean 

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