Radioactivity level and soil radon measurement of a volcanic area in Cameroon

• Published in: Journal of environmental radioactivity Vol. 99; no. 7; pp. 1056 - 1060
• Main Authors: Ngachin, M., Garavaglia, M., Giovani, C., Kwato Njock, M.G., Nourreddine, A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2008; Elsevier
• Subjects: 137Cs; Absorbed dose rate; Applied sciences; Biological and medical sciences; Biological effects of radiation; Cameroon; Chemical Sciences; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Geography; Natural radioactivity; Pollution; Pollution sources. Measurement results; Pollution, environment geology; Radiation Monitoring - methods; Radiochemistry; Radiocontamination; Radium - analysis; Radium equivalent; Radon; Radon - analysis; Soil and sediments pollution; Soil Pollutants, Radioactive - analysis; Tissues, organs and organisms biophysics; Volcanic Eruptions - analysis; Volcanic soils; Cameroon; Africa; USA, New York; Cameroon, Limbe; Absorbed dose rate; Volcanic soils; Natural radioactivity; Radium equivalent; Radon; 137Cs; Human; Natural origin pollution; Cesium 137; Radioactive pollution; Potassium 40; Radioactive contamination; Radioisotope; High-purity Ge detectors; Soil pollution; Radium 226; Thorium 232; Radioactivity measurement; Solid-state nuclear track detectors; Fission product; Geogenic factor; Dosimetry; Anthropogenic factor; Gamma spectrometry; radon; radium equivalent; volcanic soils; (CS)-C-137; natural radioactivity; absorbed dose rate
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2007.12.022

The radioactivity level of soils in a volcanic area in Cameroon was determined and discussed. Thirty soils samples were collected from Buea and Limbé cities located in the south-western Cameroon. These two regions are known for theirs volcanic grounds due to the presence of Mount Cameroon Mountain. The activity concentrations of natural radionuclides as well as that of the fission product were evaluated by gamma-ray spectrometry using a hyper-purity germanium detector (HPGe). The ranges of concentrations in the surveyed soils were 11–17 Bq kg −1, 22–36 Bq kg −1 and 43–201 Bq kg −1 for 226Ra, 232Th and 40K, respectively. The radioisotope 137Cs was also found but in a very small amount. The outdoor absorbed dose rate 1 m above ground with the corresponding annual effective dose rate, assuming a 20% occupancy factor was estimated. The radium equivalent and the external hazard index were also evaluated and results are compared with available data from other studies and with the world average value [United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), 1988. Sources, Effects and Risks of Ionizing Radiation. Report to the General Assembly on the Effects of Atomic Radiation. United Nations, New York; UNSCEAR, 2000. Sources and Effects of Ionizing Radiations. Report to the General Assembly with Scientific Annexes. United Nations, New York]. A solid state nuclear track detector (SSNTD), LR-115 was used for soil radon measurements at a depth of 50 cm. The ranges of soil radon concentrations were 6.7–10.8 kBq m −3 and 5.5–8.7 kBq m −3 in Buea and Limbé, respectively. A positive correlation was found between concentrations of radium measured with γ-spectrometry and the soil radon concentrations measured with the nitrate cellulose detectors. The results of this study provide the radioactivity level in soil of a volcanic area, which has been found to be within the safety limits. The south-western Cameroon can be considered as having normal natural background radiation.