Speciation of key NORM nuclides in natural waters

Naturally occurring radioactive materials are present everywhere in nature. These may cause harm to organisms. Therefore, it is important to know of their behaviour in the environment. The total concentration of an element does not give enough information about the risk, as it says nothing about the elements distribution in a system. This work focuses on several uranium, and how changes in pH and humic acid content affects its distribution. In addition, a few other elements are mentioned, due to the convenience of analysing multiple elements on the ICP-MS. Alum shale from two different locations were mixed with water for metals to leach into the water. The pH of the two different locations was different after leaching (4 and 8). This difference in pH made it possible to compare the effect of humic acid with low and high pH. After leaching water samples were taken out, and the pH and humic acid content was changed. To compare different sizes, 3 kDa and 45 µm filters were used. The low P-values obtained for the tests (>0.10) meant differences between pHs could not be proven. This was likely due to a low number of observations. To get better results, it would have been beneficial with more observations within each group. The general results from the groups were still used to draw some conclusions. The results showed a decrease in U concentrations with increasing humic acid concentrations. When comparing the two locations, the decrease was much steeper for K34 than RV4G, likely due to the difference in pH. This was expected, and likely a result from the higher charge on the humic acid causing it to have decreased affinity to uranyl ions (UO_2^(2+)).