THE USE OF INDIGENOUS GRASS SPECIES AS PART OF REHABILITATION OF MINE TAILINGS: A CASE STUDY OF NEW UNION GOLD MINE

摘要

Mining has enormous global impacts on both the environment and human health and most of these impacts are due from mine tailings. Using local indigenous grass species for in situ mine dump rehabilitation is both environmentally friendly and cheaper. It is attractive to use local plants since these are adaptable to local climatic conditions and are able to strive under adverse conditions that are prevalent at mine tailings sites. In this study, mine tailings at New Union Gold Mine, Limpopo, South Africa, five grass species were analysed for their uptake of heavy metals. The total metal mean concentrations were high (329.5 mg/kg for Cynodon dactylon, 318.0 mg/kg Cyperus esculentus; 307.0 mg/kg Hyparrhenia tamba; 294.5 mg/kg Hyparrhenia hirta and 290.7 mg/kg Paspalum dilatum). C. dactylon was widespread and absorbed more of the following mean metal concentrations: 232.5 mg/kg for Mn; 39.8 mg/kg for Zn; 48.5 mg/kg for Cu; 5.7 mg/kg for Pb; 1.0 mg/kg for Cd and 1.9 mg/kg for Co. P. dilatum absorbed the least of the heavy metals (290.7 mg/kg). The tailings were highly acidic with a pH range of 3.28-3.64 and 3.78-4.84. C. dactylon species absorbed these heavy metals and was able to grow under the acidic conditions. Thus C. dactylon was found suitable for re-vegetation of mine tailings and was able to hold together the soil and stabilized the tailings against wind and water erosion.