An Overview of Radon Emanation Measurement System for South African Communities

The aim of the study is to evaluate radon emanation levels in South African communities and to implement possible strategies to reduce radon levels in order to minimize potential health hazards. The major contributing factor to high levels of radon is the history of mining. To precisely measure emanation levels of radon indoors and outdoors, calibrated radon detectors are necessary. In this study, areas of high radon emanation levels are spotted, and based on the radon emission point or entry points in buildings, applicable and possible mitigation strategies are discussed for implementation

Assessment of heavy metals and radionuclides in dust fallout in the West Rand mining area of South Africa

Windblown dust can contain radioactive materials from mining. These radionuclides when inhaled in dust produce ionizing radiation which damages the cells and tissues in the body. The aim of this study was to assess dust fallout radionuclides in the West Rand mining area of South Africa. Dust fallout monitoring was done using the method (ASTM) D-1739 of 1998 employing multi-directional buckets. Results show that all 9 locations investigated in the different seasons recorded dust fallout rates within stipulated residential limit according to the National Dust Control Regulations (NDCR) (Government Gazette 36974, 1 Nov 2013). Locations 3 in spring (301.93 mg/m2/day) and 6 in winter (589.8 mg/m2/day) recorded dust fallout rates with values above the target value of 300 mg/m2/day according to guidelines by South African Standards (SANS 1929:2011). The ANOVA tests (p-value < 0.05) indicate that the mean dust fallout rate is significantly different across the seasons, mean dust fallout rate in summer is significantly (p-value < 0.05) more than the autumn by 103.15 mg/m2/day. Moderate, positive correlations (0.4 ≤ r < 0.7) exist between average dust fallout rate and wind speed. A weak, negative correlation exist between average dust fallout rate and rainfall with a value of -0.393. All the investigated elements had Enrichment Factor (EF) greater than 1. Cadmium (Cd) and lead (Pb) were extremely enriched (68.36 and 43.48, respectively), whereas Thorium (Th) (7.26) and Chromium (Cr) (9.79) had significant enrichment. Activity concentrations obtained for 226Ra, 238U, 232Th and 40K were 53.59 ± 20.45 Bq/kg, 15.20 ± 6.74 Bq/kg, 6.62 ± 2.76 Bq/kg and 278.51 ± 84.39 Bq/kg, respectively. Activity concentrations were within world averages except 226Ra which exceeded the 32 Bq/kg world average. Statistically significant (p-value < 0.05), strong (0.7≤ r< 0.9) and positive correlation exists between 226Ra and 40K. A moderate, positive correlation (0.4 ≤ r < 0.7) exist between 238U and 232Th. Since EF values showed that the elements in the dust had anthropogenic influence, further studies should look at contributions of different sources to the elements found in dust

Rare earth elements in uranium ore deposits from Namibia: A nuclear forensics tool

Rare earth elements (REE) concentrations and pattern remains largely unchanged during the process of milling and can thus provide strong evidence of the origin of the material. The aim of this study was to determine the rare earth elements in uranium ore deposits as a nuclear forensics tool. Uranium ore from three mines were collected and analyzed using an inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of rare earth elements. A non-parametric Kruskal-Wallis test and a pair wise comparison test was used to test for significant difference in the concentration of REEs between the mines followed by principal component analysis (PCA). The REE concentration were normalized with C1-Chondrite values to determine the REE pattern. The total concentration of the REE ranged from 131.38 to 161.77 ppb, 266.27 to 840.37 ppb, 177.86 to231.51 for Mine 1, 2 and 3, respectively. The mean ∑REE obtained was in the order M2>M3>M1. The pairwise comparison test of the pair M1 and M2 was found to be less than 0.05, indicating a significant difference in the samples. The REE pattern is mostly similar for all the ore samples with pronounce Eu anomaly, enriched LREE and depleted flat HREE. The PCA results indicates that the ore samples can be distinguished from each other

The impact of radiation dose variability on the response of radiophotoluminescence glass dosimeters – an experimental approach

The dosimetric properties of radiophotoluminescence glass dosimeters (RPLGDs) make them valuable tools for accurately measuring doses in various radiation fields. Over the years, thermoluminescence dosimeters have been used for both personal and environmental monitoring in South Africa, although they have certain limitations. We investigated the exceptional properties of RPLGDs by characterising their response to different radiation doses, using radiation sources of 60Co, 137Cs, and 241Am. The objective was to assess the ability of RPLGDs to be read multiple times without losing the original signal, and to explore their potential to replace TLDs in diverse radiation environments. A substitution method was employed to determine the reference measurements across all radiation source set-ups. In this approach, the RPLGD, serving as the unit under test, was exposed to the same dose as the ionisation chambers, which acted as reference detectors to accumulate the radiation signal, which was then corrected to determine the air kerma and absorbed dose to water. All relevant corrections affecting the unit under test response were applied to the final readings to characterise the RPLGDs, which were compared with the prescribed dose. The findings of this research are valuable to medical facilities and radiation workers as they offer both technical and economic benefits through improving the accuracy and reliability of radiation dose monitoring. Significance: • Radiophotoluminescence glass dosimeters (RPLGDs) were successfully characterised with 60Co, 137Cs, and 241Am radiation beams. • The glass dosimeters were annealed and irradiated at a temperature of 400 °C. • The RPLGD calibration coefficients, air kerma rate and absorbed dose to water measurements were established. • RPLGDs are capable of being re-read multiple times without losing any signal

An Assessment of Land Use and Land Cover Changes and Its Impact on the Surface Water Quality of the Crocodile River Catchment, South Africa

The degradation of surface water by anthropogenic activities is a global phenomenon. Surface water in the upper Crocodile River has been deteriorating over the past few decades by increased anthropogenic land use and land cover changes as areas of non-point sources of contamination. This study aimed to assess the spatial variation of physicochemical parameters and potentially toxic elements (PTEs) contamination in the Crocodile River influenced by land use and land cover change. 12 surface water samplings were collected every quarter from April 2017 to July 2018 and were analyzed by inductive coupled plasma spectrometry-mass spectrometry (ICP-MS). Landsat and Spot images for the period of 1999–2009 - 2018 were used for land use and land cover change detection for the upper Crocodile River catchment. Supervised approach with maximum likelihood classifier was used for the classification and generation of LULC maps for the selected periods. The results of the surface water concentrations of PTEs in the river are presented in order of abundance from Mn in October 2017 (0.34 mg/L), followed by Cu in July 2017 (0,21 mg/L), Fe in April 2017 (0,07 mg/L), Al in July 2017 (0.07 mg/L), while Zn in April 2017, October 2017 and April 2018 (0.05 mg/L). The concentrations of PTEs from water analysis reveal that Al, (0.04 mg/L), Mn (0.19 mg/L) and Fe (0.14 mg/L) exceeded the stipulated permissible threshold limit of DWAF ( 0.05) between the wet season and the dry season. The spatial distribution of physicochemical parameters and PTEs were strongly correlated (p > 0.05) being influenced by different land use type along the river. Analysis of change detection suggests that; grassland, cropland and water bodies exhibited an increase of 26 612, 17 578 and 1 411 ha respectively, with land cover change of 23.42%, 15.05% and 1.18% respectively spanning from 1999 to 2018. Bare land and built-up declined from 1999 to 2018, with a net change of - 42 938 and − 2 663 ha respectively witnessing a land cover change of −36.81% and − 2.29% respectively from 1999 to 2018. In terms of the area under each land use and land cover change category observed within the chosen period, most significant annual change was observed in cropland (2.2%) between 1999 to 2009. Water bodies also increased by 0.1% between 1999 to 2009 and 2009 to 2018 respectively. Built-up and grassland witness an annual change rate in land use and land cover change category only between 2009 to 2018 of 0.1% and 2.7% respectively. This underscores a massive transformation driven by anthropogenic activities given rise to environmental issues in the Crocodile River catchment

Environmental Monitoring of Tritium (3H) and Radiocarbon (14C) Levels in Mafikeng Groundwater Using Alpha/Beta Spectrometry

With the current state of water scarcity in Mafikeng, South Africa, due to low water levels and an increasing population, it is therefore crucial to ensure the sustainability and availability of the existing water resources. In this study, the levels of tritium and radiocarbon in groundwater (boreholes) at selected villages in Mafikeng were determined using the Perkin Elmer Ultra Low Liquid Scintillation Counter 2000. The mean activity concentrations of tritium are 3.61304 ± 0.00612 Bq/L and 3.86014 ± 0.00739 Bq/L for samples from Dibate and Lokaleng villages, respectively, whereas 1.83392 ± 0.02265 Bq/L is for Moletsamongwe, Lekung, Airport View and Seweding. Moreover, the mean activity concentrations of radiocarbon from Dibate and Lokaleng are 0.59296 ± 0.00886 Bq/L and 0.8333 ± 0.0126 Bq/L, respectively, whereas for, Moletsamongwe, Lekung, Airport View and Seweding, they are 1.3752713 ± 0.01968 Bq/L. Two (2) out of the forty (40) samples analysed for radiocarbon are below the minimum detectable activity of 0.33627 Bq/L. The average annual effective dose (AED) of tritium for analysed samples from Dibate and Lokaleng villages are 0.04754 μSv/y and 0.05079 μSv/y, respectively, whereas it is 0.02413 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding. The average AED for radiocarbon is 0.251404 μSv/y and 0.36604 μSv/y for samples from Dibate and Lokaleng, respectively, whereas it is 0.58309 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding village. The evaluated lifetime cancer risk for mortality and morbidity in adults is lower than the radiological cancer risk limit of 1.63 × 10−3 set by regulatory agencies; hence, the consumption of the studied groundwater from the selected villages will not pose any health risks in terms of tritium and radiocarbon levels

Assessment of Potentially Toxic Elements as Non-Point Sources of Contamination in the Upper Crocodile Catchment Area, North-West Province, South Africa

The concentration of potential toxic elements (PTEs) in the Upper Crocodile river catchment area in North-west Province, South Africa, was investigated. Water and sediment samples were collected among different land uses in the upper Crocodile River catchment area and analysed using inductively-coupled plasma–mass spectrometry (ICP–MS). Several guidelines were used to gauge the level of contamination and possible toxic effect of PTEs. The physicochemical analysis showed that electrical conductivity (EC), pH, and total dissolved solids (TDS) values complied with the recommended values of Department of Water and Forestry (DWAF) guidelines for South Africa. The average concentration of Cu, Pb, Cd, Zn, As, Cr, Al, and Mn in the water samples were lower than the recommended levels for water-quality guidelines for aquatic environments except for Fe, which exceeded the recommended values of DWAF of 0.1 mg/L and EPA (US) of 0.3 mg/L. The level of contamination was measured using the enrichment factor, contamination factor, and geoaccumulation index. The level of Cr was above the stipulated threshold limit of the sediment quality guideline for adverse biological effects, suggesting an ecotoxicology risk of anthropogenic origin, which was confirmed by statistical analysis. The non-point sources of PTEs are spatially distributed according to land-use types and are strongly correlated to land use