Determination of mercury and its fractionation products in samples from legacy use of mercury amalgam in gold processing in Randfontein, South Africa.
Malehase, Tshia Daso, Adegbenro P. Okonkwo, Jonathan O.
Malehase, Tshia
Daso, Adegbenro P.
Okonkwo, Jonathan O.
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Abstract
This study aimed at determining the levels of total mercury (THg) in tailings dams, soil, sediments and water samples collected in the vicinity of legacy mercury amalgam gold mines. Acid digestion was employed in sample digestion followed by analysis using CVAAS. Tailings dams, community and garden soil, and stream sediments were further investigated for mercury fractions using a five step sequential extraction procedure. The concentrations of THg in tailings dams, community and gardens soil were 0.890e6.755 mg/g, 0.431e0.968 mg/g and 0.471e1.019 mg/g, respectively and the concentrations of THg in the sediments obtained from tailings dams, streams and wetlands were 0.649e1.998 mg/g, 0.604 e1.356 mg/g and 0.681e1.356 mg/g, respectively. The concentrations of THg, in aqueous samples obtained from tailings, streams and wetlands were 0.032e0.070 mg/l, 0.004e0.068 mg/l and 0.007e0.012 mg/l, respectively. The sequential extraction procedure showed that most Hg in the tailings dams was largely elemental Hg and Hg bound to sulphur. Soil and sediments were largely dominated by organic bound Hg. Moderate seasonal correlation was observed in tailings dams soil, but weak seasonal correlation in soils collected in the vicinity of tailings. However, a strong seasonal correlation was observed in sediments and water samples. The concentrations of Hg obtained largely existed in organic and sulphate bound Hg and
there is elevated potential to methylate Hg.
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Date
2016-07-06
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Elsevier
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Keywords
Mercury concentrations, Fractions, Gold mining, Legacy amalgam, Tailing dams, Soil, Sediment, Water, Speciation