The activity concentrations of 238 U, 232 Th and 40 K were determined using gamma spectrometry (HPGe detector) and their radiological hazards are presented in this study for shore sediment samples from the North Dune beach of Henties Bay, Namibia. The activity concentrations were found to range from 25.32 ± 1.24 Bq.kg À1 to 232.33 ± 0.62 Bq.kg À1 with an average value of 175.59 ± 0.92 Bq.kg À1 for 238 U, BDL to 77.99 ± 45 Bq.kg À1 with an average value of 40.17 ± 27 Bq.kg À1 for 232 Th and 222.39 ± 8 Bq.kg À1 to 482.16 ± 10 Bq.kg-1 with an average value of 349.66 ± 8 Bq.kg À1 for 40 K. In order to assess the radiological hazard of the shore sediment samples, the radiological hazard indices such as absorbed dose rates (ADR), radium equivalent (R eq) annual effective dose equivalent (AEDE), the hazard indices (H ex and H in), and the excess lifetime cancer risk (ELCR) were calculated. The values obtained in the present study were compared with world acceptable limits and it was found that the average values of radium equivalent (Req) and external hazard index (Hex) were below the world allowable limits. However, the average values of absorbed dose rates (ADR), annual effective dose equivalent (AEDE) (outdoor and indoor), internal hazard index (H in) and excess lifetime cancer risk (ELCR) exceeded the world acceptable limits.
Abstract-Environmental effects of open wastes disposal continue to receive global attention. This study determined the heavy metals pollution status of pasture grass around Katima Mulilo municipal solid wastes dumpsite, Namibia. Samples of the pasture grass were collected from grassland around the wastes dumpsite and a control site and then analyzed for levels of the heavy metals: Pb, Cr, Cd, As, Ni, Co, Cu and Mn using standard analytical procedures. The results obtained revealed that Mn recorded the highest mean concentration of 102.50mg/kg while Co recorded the lowest level (0.13mg/kg). Generally, the present levels of the heavy metals were below their health regulatory limits. However, the degree of contamination of the pasture grass was significantly higher (paired sample mean t-test, p < 0.05) in the samples collected around the wastes dumpsite with an index of 0.3502. The loading values obtained from the principal component analysis of the heavy metals suggest that all the seven metals detected can be grouped under one main factor. Therefore, we recommend periodic monitoring of the levels of heavy metals in the pasture grass around the wastes dumpsite and advice precautionary measures in order to limit unintended exposures of livestock and hence, human beings to metals toxicities.
Abstract-The main objective of this study was to assess the concentrations of some heavy metals of human health importance in the roadside dusts across three major locations in Monte Christo, Windhoek and compare the values with regulatory maximum permissible limits. Eighteen (18) samples of the roadside dusts (consisting of 6 each) were collected from both sides of the road at Hereford street, Fuel service station, and Traffic junction. The samples were digested using EPA method 3050B and analyzed for the heavy metals' concentrations using Inductively Coupled Plasma-Optical Emission Spectrophotometer (ICP: Perkin Elmer Optima 7000 DV). The overall mean concentrations (mg/kg) of the heavy metals recorded across the sampling sites follow the order: Fe >Mn> Zn > Cu >Pb> Cr > Ni. Result of the analysis of variance between the mean concentrations of the heavy metals was statistically significant (Anova: single factor, p < 0.05). Although, the present concentrations of the heavy metals were generally lower than their health regulatory maximum permissible limits in soils, the enrichment factors revealed deficient to minimal (2 < EF < 5) and significant indices (5 < EF < 20). These are related to anthropogenically induced contaminations. There are strong positive correlations between the mean levels of the heavy metals which suggest common sources of anthropogenic inputs. It is therefore, recommended that the impact of the sources of metals emission on heavy metals' accumulations in the area should be established with a view to advising precautionary measures that could minimize unintended exposure of the populace.
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