Browsing by Author "Ansah, Eugene"

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    Assessment of radionuclides activities and heavy metals contamination in sediments, water and fish in Lake Bosomtwi and Bui dam
    (2015-11-04) Ansah, Eugene
    Concentration of heavy metals and natural radioactivity were measured in water, sediment and fish samples from Lake Bosomtwi and Bui dam. The concentrations of the heavy metals in sediments were found to decrease in the sequence, Fe > Mn > Ni > Zn > Cr > Cu > Co > As > Hg for Lake Bosomtwi and Fe > Mn > Ni > As > Cr > Zn > Cd > Cu for Bui dam. Heavy metal concentration in water was in the order: Fe > Pb > Mn > Zn = As > Cd = Cr in Lake Bosomtwi and Fe > As > Pb > Mn > Cd = Zn > Cr for Bui dam whilst metal concentration in fish samples was in the order: Fe > Zn > Mn > Cu > Ni > Pb > Cr > Cd > Hg for Lake Bosomtwi and Fe > Mn > Zn > Cu > Ni > Pb > Cr > Cd > Hg for Bui dam. The study indicated a general absence of serious pollution in the two reservoirs with respect to heavy metals. The activity concentration due to 238U, 232Th and 40K determined with the - spectrometer indicated that the surface water radioactivity concentration of 238U, 232Th and 40K were ranging from 0.20±0.07 to 0.98±0.24, 0.03±0.08 to 0.82±0.13 and 0.02±0.67 to 3.32±0.77 Bq/L respectively for Lake Bosomtwi and from 0.13±0.08 to 0.42±0.01, 0.07±0.14 to 0.82±0.14 and 0.78±0.73 to 2.42±0.75 Bq/L respectively for Bui Dam. The average annual effective dose due to ingestion of radionuclide in water ranged from 20.5 to 156 and 26.5 to 162 μSv/year for Lake Bosomtwi and Bui Dam respectively. The average activity concentration of 238U, 232Th and 40K in the sediment from the two reservoirs was 7.90, 7.83 and 169.73 Bq/kg respectively for Lake Bosomtwi and 7.56, 8.11 and 49.0 Bq/kg respectively for Bui Dam which is lower than world averages. The determined absorbed dose rate and annual effective dose for the sediments ranged from 12.41 to 18.74 nGy/year and 15.2 to 23.0 S/year respectively for Lake Bosomtwi and 8.68 to 11.47 nGy/year and 10.6 to 14.1S/year respectively for Bui Dam which are within worldwide recommended average of 59 nGy/year and 100 S/year. None of the radioactivity is expected to cause significant health problems to human beings through ingestion of water, consumption of fish or use of sediments for building purposes. Keywords: Lake Bosomtwi; Bui dam; Heavy metals; Radioactivity; Hazard indices; Absorbed dose rate; Annual effective dose.
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    Characterization of Inhalation Exposure to Gaseous Elemental Mercury During Artisanal Gold
    (Environ. Sci.: Processes Impacts,, 2021) Snow, Melanie A.; Darko, Godfred; Gyamfi, Opoku; Ansah, Eugene; Breivik, Knut; Hoang, Christopher; Lei, Ying Duan; Wania, Frank; 0000-0001-7157-646X
    While occupational inhalation exposure to gaseous elemental mercury (GEM) has decreased in many workplaces as mercury is being removed from many products and processes, it continues to be a concern for those engaged in artisanal and small-scale gold mining or in recycling mercury-containing products. Recently, stationary and personal passive air samplers based on activated carbon sorbents and radial diffusive barriers have been shown to be suitable for measuring GEM concentrations across the range relevant for chronic health effects. Here, we used a combination of stationary and personal passive samplers to characterize the inhalation exposure to gaseous elemental mercury of individuals living and working in two Ghanaian gold mining communities and working at a Norwegian e-waste recycling facility. Exposure concentrations ranging from < 7 ng/m3 to >500 g/m3 were observed, with the higher end of the range occurring in one gold mining community. Large differences in the GEM exposure averaged over the length of a workday between individuals can be rationalized by their activity and proximity to mercury sources. In each of the three settings, the measured exposure of the highest exposed individuals exceeded the highest concentration recorded with a stationary sampler, presumably because those individuals were engaged in an activity that generated or involved GEM vapors. High day-to-day variability in exposure for those who participated on more than one day, suggest the need for sampling over multiple days for reliable exposure characterization. Overall, a combination of personal and stationary passive sampling is a cost- effective approach that cannot only provide information on exposure levels relative to regulatory thresholds, but also can identify emission hotspots and therefore guide mitigation measures.