Studies on arsenic rich mine dumps .2. The heavy element uptake by vegetation

The effects of abandoned mine dumps on the vegetation is in the Eastern region of Zimbabwe was assessed. The bioaccumulation of As, Cu, Ni, Mn, Zn and Fe in Cynodon dactylon (Couch grass), Pinicum sativum (thatch grass) and Amaranthus hybridus (Amaranths or Mhowa) were investigated over a period of nine months. While Couch grass was analysed at three sites namely, mine dumps (MD), adjacent to mine dumps (AMD) and at a site about 400 m away from mine dumps near the river (NR). The other two species were found at AMD and NR only. High concentration of accumulated As was detected in the roots of Couch grass. Amaranths had high levels of As in the leaves. Elemental uptake varied with the plant species and depended on the concentrations of respective exchangeable cations. In all the species, the rate of uptake was rapid at the early stages of the plant growth.