Dispersion of Heavy Metals at Klein Letaba Gold Tailings Dam, Limpopo Province, South Africa

The accumulation of heavy metals such as Cd, Mn and Ni was investigated in seven different vegetables, fruits and soil samples from Thohoyandou, Limpopo Province, South Africa. Heavy metals were quantified using graphite furnace atomic absorption spectrometry. Concentrations of heavy metals in fruits and vegetables were in the range of 0.23–2.94 mg∙kg-1 for Cd, 11.72–50.16 mg∙kg-1 for Mn and 5.73 – 44.11 mg∙kg-1 for Ni on a dry weight basis. Analysis of soils from where fruits and vegetables were sampled showed that Cd in the soil was in the range of 0.08–1.07 mg∙kg-1, Mn levels were 204.99–249.13 mg∙kg-1 and Ni levels were 48.47–88.23 mg∙kg-1. Cd was below the instrument detection limit for soils on which onions and bananas were grown. Vegetables showed different accumulation abilities, with leafy vegetables being the highest accumulators of heavy metals. The obtained results showed that concentrations of Cd in fruits, vegetables and soils exceeded the recommended maximum acceptable levels proposed by FAO/WHO and, hence, may pose a health risk to consumers. Ni concentrations in bananas, onion, beetroot, spinach and Chinese cabbage exceeded recommended standards by FAO/WHO.

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Defining an appropriate steady state line for Merriespruit gold tailings

Canadian Geotechnical Journal ◽

10.1139/t00-111 ◽

2001 ◽

Vol 38 (4) ◽

pp. 695-706 ◽

Cited By ~ 44

Author(s):

A B Fourie ◽

G Papageorgiou

Keyword(s):

South Africa ◽

Steady State ◽

Companion Paper ◽

Tailings Dam ◽

Test Results ◽

Failure Investigation ◽

Static Liquefaction ◽

Flow Failure ◽

Undrained Loading ◽

Gold Tailings

Failure of the Merriespruit gold tailings dam in 1994 in South Africa was unusual in that never before had a gold tailings dam in South Africa failed in such a catastrophic fashion. Conventional thinking was that gold tailings would always exhibit dilative characteristics upon loading, primarily because of the method of deposition which allows significant consolidation to occur due to sun-drying. This paper demonstrates that the concept of a steady state line, which separates dilative from contractive behaviour upon undrained loading, is applicable to Merriespruit tailings. Four particle-size distributions of Merriespruit tailings were tested to determine the influence of the percent finer than 75 µm on the position of the steady state line. The tailings with the greater percentage of fines gave a steady state line that plotted above all the others, which translated to the requirement that a greater relative density was necessary to produce noncontractive behaviour than for the low-fines tailings samples. The difficulty of defining a unique steady state line for a particular tailings, due to errors in measurement of initial sizes, is illustrated and it is recommended that error bands be assigned to any steady state line. In a companion paper, evidence from the post-failure investigation is combined with the test results in this paper to explore the likelihood of static liquefaction as the cause of the Merriespruit flow failure.Key words: static liquefaction, tailings, steady state, flow failure.

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Determination of Cd, Mn and Ni accumulated in fruits, vegetables and soil in the Thohoyandou town area, South Africa

Water SA ◽

10.17159/wsa/2020.v46.i2.8244 ◽

2020 ◽

Vol 46 (2 April) ◽

Author(s):

Babra Moyo ◽

Vhahangwele Matodzi ◽

Malebogo A Legodi ◽

Vusumzi E Pakade ◽

Nikita T Tavengwa

Keyword(s):

Heavy Metals ◽

South Africa ◽

Fruits And Vegetables ◽

Graphite Furnace ◽

Absorption Spectrometry ◽

Dry Weight ◽

Limpopo Province ◽

Leafy Vegetables ◽

Town Area

The accumulation of heavy metals such as Cd, Mn and Ni was investigated in seven different vegetables, fruits and soil samples from Thohoyandou, Limpopo Province, South Africa. Heavy metals were quantified using graphite furnace atomic absorption spectrometry. Concentrations of heavy metals in fruits and vegetables were in the range of 0.23–2.94 mg∙kg-1 for Cd, 11.72–50.16 mg∙kg-1 for Mn and 5.73 – 44.11 mg∙kg-1 for Ni on a dry weight basis. Analysis of soils from where fruits and vegetables were sampled showed that Cd in the soil was in the range of 0.08–1.07 mg∙kg-1, Mn levels were 204.99–249.13 mg∙kg-1 and Ni levels were 48.47–88.23 mg∙kg-1. Cd was below the instrument detection limit for soils on which onions and bananas were grown. Vegetables showed different accumulation abilities, with leafy vegetables being the highest accumulators of heavy metals. The obtained results showed that concentrations of Cd in fruits, vegetables and soils exceeded the recommended maximum acceptable levels proposed by FAO/WHO and, hence, may pose a health risk to consumers. Ni concentrations in bananas, onion, beetroot, spinach and Chinese cabbage exceeded recommended standards by FAO/WHO.

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