International Science and Technology Journal of Namibia

Health Risk Assessment of Natural Radioactivity in Wasteland Soils in Helao Nafidi dumpsite, Namibia

Roswita Hamunyela — 2025-10-30

Humans are exposed to radiation in the soil of wasteland areas because radiation occurs naturally in the environment through cosmic and terrestrial rays. Children and residents from the neighborhood use dumpsites every day to scrounge for food and other items, increasing their exposure to radiation. The aim of the study is to ascertain whether the radioactive compounds found in the Helao Nafidi dumpsite pose a threat to human health. In this work, the activity concentrations of 226Ra, 232Th, and 40K in 19 soil samples were measured using a gamma-ray spectrometer. Several radiological parameters were computed from these actions. The average activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K were 4.83 ±0.58, 4.72 ±0.62 and 51.31±5.41, respectively. The average Ra_eq value from the Wasteland soil was 15.53 Bq/kg. All of the soil samples had Raeq values that were less than the average global value of 370 Bq/kg. The average AEDE value was 0.01 mSv.y-1, less than the 0.48 mSv global recommendation. The Wasteland soil's Annual Gonadal Dose Equivalent (AGDE) value was 50.77 Sv.y-1, which was found to be less than the 298 Sv.y-1 global critical value. The average values of RLI and Hex were found to be 0.11 and 0.04, respectively. These indices were less than the world accepted-limit values. The average value of the excess lifetime cancer risk (ECLR) was found to be 0.03 and lower than world average of 2.9 x . These findings indicate that natural radioactivity in the soil of the Helao Nafidi wasteland area is not now a health risk.

Gravimetric characterization of Pyrite carbothermic reduction in the presence of lime

Odilon Kasongo Ilunga — 2025-10-31

Pyrite carbothermic reduction studies were conducted on pyrite concentrate (40.75 % iron, 48.04 % sulphur, 0.11 % copper) from the Otjihase Mine in the Repubic of Namibia. Additionally, this research included thermal decomposition and ion exchange since they cannot be dissociated from carbo-thermic reduction. The aim was to assess the iron metallization, and the assessement was carried out through mass percent reduction. A factorial research design was adopted, consisting of two factors (time and CaO/C ratio at five levels, and one factor (temperature) at three levels in reducing environment. The analysis of variance (ANOVA) was used for data analysis. At thermal decomposition stage, metallization increased with treatment time, it was flatter at higher temperature but remained consistently higher than at lower temperatures. At ion exchange stage, metallization was random, yet showing much lower magnitude than the metallization at thermal decomposition stage. At carbo-thermic reduction stage, metallization decreased with increased treatment time at 1273K and 1473K for different C/CaO ratio, however the opposite phenomenon occurred at 1373K. In general, higher carbon to calcium oxide ratio triggered more metallization.

Application of portable X-ray fluorescence for exploration of carbonate-hosted sulfide mineralisation, Otavi Mountain Land, Namibia

Ester Shalimba — 2025-07-02

Otavi Mountain Land province forms part of the Damara Orogenic Belt within the Neoproterozoic carbonate platform, which is well-known for its sedimentary-hosted, polymetallic mineralized zones, including the Cu-Pb(-Ag) Kombat deposit. The mineralisation at Kombat is of massive, disseminated, veinlet-controlled and brecciated mineralisation styles it comprises mainly of bornite, chalcopyrite, galena, covellite and chalcocite associated with quartz and calcite as gangue minerals. Mineralized zones are distinctly enriched in chalcophile elements, including Pb, Cu, As and Ag. For the analysis of such rocks, laboratory-based analytical methods, including inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectroscopy (AAS), are well established, in contrast to on-site geochemical analytical methods. This study shows the applicability and limitations of portable X-ray fluorescence (pXRF) in the geochemical exploration of sulfide (Ag, Cu, Fe, Mn, Pb, Zn) ores in carbonate matrix. By using additional ICP-MS/AAS data and certified reference materials, the applicability of such portable tools can be assessed for Kombat-type ores, resulting in pXRF data of excellent or very good precision for elements like Cu, Fe, Mn, Pb and Zn (RSD ≤10%), while other elements (Ag, Sr) show poor precision. The trace element concentrations obtained by pXRF are comparable to ICP-MS results yielding a good correlation (R² ≥0.85) and acceptable accuracy and precision. Portable XRF is identified as a low-cost tool that can be used successfully in the geochemical exploration for a list of elements in carbonate-hosted sulfide ores.

The Prevalence of depression among inpatients and outpatients and key associated sociodemographic and clinical factors, 2010 - 2022: A systematic review

Alberina Mariina Ndinelao Shatri — 2025-07-08

Depression has a higher prevalence than other mood disorders, and the disability it causes is a global burden. Although mental health is an essential component of normal functioning and health, mental disorders such as depression are neglected. The study aimed to summarise the prevalence of depression, gender differences, and associated factors in inpatients and outpatients. A systematic review approach was used, whereby the PubMed, Google Scholar and Scopus electronic databases were searched for studies published between the years 2010 and 2022 to identify observational studies with the above information on different continents. Data characteristics were extracted independently by two investigators. After scanning and evaluation, 52 articles were initially identified. After further screening, 29 articles were reviewed for the study. These 29 cross-sectional studies included a total of 46979 individuals. From the literature reviewed, common factors associated with depression included demographic characteristics, biopsychosocial factors, substance abuse, a history or family history of mental illness, and a history or family history of chronic illness. Women were more prone to depression than men (54.9%). In terms of geographical location, the prevalence of depression was highest in North America at 36.0% and lowest in Europe at 25.0%. Further studies are needed to evaluate the prevalence of depression and associated factors specific to other geographical locations.