In the Blesbokspruit area of Ekuhurleni, South Africa, previous gold mining activities resulted in many tailings dump sites. 20 representative soil samples were used in describing the distribution of metals. The soils were very strongly acidic ranging from 3.86 to 4.34 with a low cation exchange capacity (CEC). Based on X-ray fluorescence (XRF) analysis, elemental composition of the soils revealed average values of major elements such as Na2O (0.18%), MgO (0.63%), Al2O3 (6.51%), SiO2 (81.83%), P2O5 (0.04%), SO3 (3.40%), K2O (1.98%), CaO (0.45%), TiO2 (0.51%), Cr2O3 (0.17%), MnO (0.04%), Fe2O3 (3.59%), NiO (0.04%), As2O3 (0.02%), with Rb2O and SrO falling below 0.01%. Trace metals (TM) contamination levels in the soils were evaluated using various pollution indices which revealed that over 60% of the soils were between the high degree and the ultra-high degree of contamination classes. The concentration of various trace metals varies from 860.3-862.6 mg/kg for Cr; 324.9-328.4 mg/kg for Al; 200.9-203.4 mg/kg for As; 130.1-136.2 mg/kg for Fe; 121.9-125.8 mg/kg for Pb; 27.3-30.2 mg/kg for Co; 23.8-26.8 mg/kg for Ni; 7.2-9.2 mg/kg for Ti; 7.1-9.2 mg/kg for Cd; 4.0-5.6 mg/kg for Zn and 0.1-0.6 mg/kg for Cu.

The mining of gold is associated with several environmental challenges such as acid mine drainage, release of toxic metals which are associated to tailing sediments and have adversely impacted human health and the ecosystem. With increasing global population that is faced with limited land resources for agricultural activities, there is need for land restoration through effective rehabilitation of contaminated soils. The introduction of Hyparrhenia hirta, an indigenous grass specie as a phytoremediation technique for in situ rehabilitation of degraded soil is not only an economically viable approach but also environmentally friendly. Hyparrhenia hirta being a tufted and wiry perennial grass that is invasive with deep root system often aid in stabilizing the ecosystem owing to their self-fertile and drought resistant potentials that support that prevalence in harsh conditions at mine dump sites. In this study, mine tailings at Gold One Mine, Ekuhurleni, South Africa were assessed for heavy metal contents at the same time analysing the uptake of such heavy metals by Hyparrhenia hirta grass specie. The total metal mean concentrations was high (4023.67 mg/kg) for Hyparrhenia hirta which absorbed more of the following mean metal concentrations: 46.10 mg/kg for Cu; 40.08 mg/kg for Zn; 859.12 mg/kg for Pb; 618.26 mg/kg for Cr; 151.70 mg/kg for Co and 2308.41 mg/kg for Ni. The tailings were strongly acidic with a pH range of 3.86 – 4.34. These heavy metals despite the acidic environments were successfully absorbed by Hyparrhenia hirta grass specie. Along these lines Hyparrhenia hirta was discovered reasonable for re-vegetation of mine tailings dump as it has the capacity to hold together tailings sediments against wind and water erosion.

In this study, the selected streams within the Blesbokspruit located in South Africa were characterised in this study. Because of prolonged mining activities coupled with ineffective management practices, several mine tailing (MT) dumps are widely distributed in this area. Metals and metalloid contamination from these tailing facilities have been reported to be major contributors to environmental hazards such as acid mine drainage (AMD). With increased agricultural activities in this area, an assessment of the general quality of water being utilised for irrigation purposes and feeding of farm animals becomes inevitable. A procedural method was implemented in a bid to identify relations between tailing and stream water contamination. Representative gold tailing sediments and water samples were collected, respectively. With the aid of X-ray fluorescence (XRF) and X-ray diffraction (XRD), the mineralogical characterisation of the tailing sediments was successfully carried out, while acid digestion using inductively coupled plasma-optical emission spectrometry (ICP-OES) was utilised in the determination of trace metal contents. Samples of different water sources were also characterised. There was a clear description of the link between tailings, water contamination and possible implications to animals and humans in the long run.

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