No abstract

This work presents a preliminary study on groundwater samples carried out from selected groundwaters of some localities of Yaounde, Cameroon. Radon concentration was ranged from 0.11 Bq•l −1 to 1 Bq•l −1 , with an average of 0.48 Bq•l −1 . The comparison between the physico-chemical parameters and the radon concentrations in groundwater showed a good correlation between these radon concentrations and the values of Electroconductivity (EC). The annual effective dose due to ingestion of radon in water ranged from 0.30 µSv•y -1 to 7.90 µSv•y -1 with an average of 1.93 µSv•y -1 . The obtained results of this study were shown that the concentrations of radon in groundwaters and annual effective doses due to ingestion of this groundwater were below the references recommended by WHO.

In this work the performance of a screening analytical method for Energy Dispersive X-Ray Fluorescence (EDXRF) analysis in terms of accuracy and precision was evaluated through analysis of rock standard reference materials. The method allowed the division of elements into four groups taking into account the excitation energies and measurement conditions of the sample. Two standard reference materials were used and 15 sample replicates were prepared and analyzed, then statistics were applied to assess the precision and accuracy of analytical results. The obtained results show that major compounds or elements (SiO 2 , P 2 O 5 , K 2 O, CaO, Fe 2 O 3 , Ti) can be determined in fine powder sample with a deviation lower than 15%, and a relative standard deviation in the range (1 -10)%. The deviation was found to be lower than 5% for major compounds such as K 2 O, and CaO, which suggest that the EDXRF is accurate in evaluating major elemental concentrations in rock samples. It was also found that the method seems to be more accurate and precise for major elements than for trace element investigation. This screening analytical method can be used for routine analysis with acceptable results, even though the method should be optimized to increase its precision and accuracy.