Browsing by Author "Mohammed, Najat"

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Health Risk Assessment of Trace Elements in Soil for People Living and Working in a Mining Area
(Hindawi, 2021-07-02) Focus, Erasto; Rwiza, Mwemezi; Mohammed, Najat; Banzi, Firmi
The present study used soils collected from a small-scale gold mine area to determine the health risks due to trace elements to the at-risk population in the study area. The work involved 74 soil samples from four sampling categories: 29 samples were from the mining pits (MD), 18 samples from the first washing area (WA), 17 samples from the second washing area (WB), and 10 samples from the control area (C). All samples were analyzed for Cr, Cu, As, Pb, Cd, Co, Ni, Zn, and Hg using the Energy Dispersive X-Ray Florescence (ED-XRF) method. Trace element levels were found to vary across the four sampling categories. The concentrations of trace elements recorded from different sampling categories varied in an increasing order of MD > WA > WB > C. Mercury was detected in the highest levels (max. 3.72 ± 0.15) at WB while it was not detected in the samples from C. Samples from MD indicated that Cu (max. 737.66 ± 1.3 mg/kg) was found in the highest levels whereas Hg (mean = 0.007 mg/kg) was the lowest. At WA, Cu (max. = 178.97 ± 2.46 mg/kg) registered the highest average concentration while Hg (mean = 0.05 mg/kg) had the lowest concentration. For WB, Cu (max. = 230.66 ± 3.99 mg/kg) was found in the highest concentration. The hazard index value for all exposure routes was found to be 1.77, making noncarcinogenic effects significant to the adult population. For children, the hazard index value was 9.11, showing a severe noncarcinogenic effect on children living in the study area. For the noncancer effects through the inhalation pathway, the risk posed by Ni, Cu, Zn, and Pb was negligible for both adults and children, while Co posed the highest noncancer risk for children. Cobalt also indicated the highest noncancer risk for children through the dermal pathway, while As indicated the highest noncancer risk to children through ingestion. For the cancer risk, the adults were more at risk compared to children, except for As and Co through the dermal pathway posing the highest threat. Trace element concentrations, hazard quotient, and hazard index values indicated that the area was polluted and that noncarcinogenic and carcinogenic effects on residents and miners were significant. Therefore, there is a need to put in place mining regulations aimed at protecting the at-risk human population in the study area.
The influence of gold mining on radioactivity of mining sites soil in Tanzania
(International Journal of Environmental Quality, 2022-02-17) Focus, Erasto; Rwiza, Mwemezi; Mohammed, Najat; Banzi, Firmi
The activity of 226Ra, 232Th and 40K in soil samples were measured by gamma spectrometry using high purity germanium detector. The study involved 40 samples from four divisions: 10 samples each were drawn from the control area (CTR), washing area 1 (W1), washing area 2 (W2) and the mining pits (MP). Radium and Thorium were measured in highest value (80.44 and 94.62) Bq/kg, respectively at MP-9 while the lowest levels (1.56 and 0.96) Bq/kg, respectively were detected at MP-2. At W1, 40K (max. 887.5 Bq/kg) recorded the highest mean level while 232Th (mean=16.7 Bq/kg) had the lowest level. For W2, 40K (max. 1535.7 Bq/kg) recorded highest level and 232Th (mean = 8.1 Bq/kg) recorded the lowest (10.7 Bq/kg). Results further show that mean activity levels of 226Ra, 232Th and 40K from mining area were 42.5, 35.5 and 652.4Bq/kg, respectively. In comparison, the respective average activity for 40K, 226Ra, and 232Th recoded 118.4, 14.5 and 9.7 Bq/kg, respectively in control area. For the sake of assessing the suitability of building materials, hazard indices were calculated and their results were less than unity indicating that, building materials are safe. The annual gonadal equivalent dose, representative gamma index, alpha index revealed values of 484.8 µSv/y, 1.1 and 0.2, respectively. The average annual effective dose was 85.5 mSv which is about 8% greater than the world average. Results show that mining activities in Rwamagasa might be posing radiological hazard to people. Therefore, measures on radioactive materials to the miners and the surrounding community are recommended.