Copper Pollution in Rwenzori National Park, Uganda

It is well known that high concentrations of some heavy metals are toxic to green plants and that in excessive quantities they are poisonous and cause death to most living organisms (Antonovics, Bradshaw & Turner 1971; Lin Wu & Bradshaw 1972). Otto (1893) observed a reduction in growth rates of garden crops grown in nutrient solution derived from a copper still. Sommer (1931) found that root development was inhibited in some species at a concentration of copper of 0 25 mg I1-. Accumulated copper from fertilizers and foliar sprays was found to cause chlorosis in Citrus and at 100-250 ppm caused stunting of seedlings (Reuter & Smith 1952). Struckmayer, Peterson & Hsi-Mei Tai (1969) observed similar inhibitory effects of high copper levels on tobacco. Bradshaw (1952), Wilkins (1957), Jowett (1958), Lin Wu & Bradshaw (1972) and Cole (1973) have described plant populations on abandoned heavy metal mine workings. Adaptation within plant populations to soils containing heavy metals was shown by Melchers (1939) and Snaydon & Bradshaw (1961, 1962). In Uganda the problem of high level copper exists in the natural vegetation of the Rwenzori National Park. Bare patches of ground surrounded by poor vegetation occur in the park (Fig. 1) caused by copper toxicity.There is no copper outcropping in the park, and nearest is the copper mine at Kilembe which is 11 km distant (Fig. 1). The copper contamination has entered the park from the pyrite dams at Kilembe through drainage channels and from three copper concentrate leakages discovered by Barrett (1972) along the Kilembe Roast leach pipe line. The leakage spills were washed down slope into the rivers which eventually drained into the park. The prevention of further pollution is a matter of vital urgency both for the area facing contamination and dereliction, and for the wildlife threatened by incurable and irreversible damage. To provide a sound basis for taking preventive measures an investigation was carried out. (a) To find out sites of copper concentrate spill from the copper Kilembe/Roast Leach Line, and other areas of suspected spillage, and to follow their routes into the park. (b) To estimate copper in the soil. (c) To estimate the copper contents in the plant shoots surrounding the bare patches. (d) To estimate the damage done to the distribution and abundance of plant populations. (e) To estimate the effect of the dereliction of the patches to the invertebrate populations in the contaminated area. (f) To germinate and follow the fate of grass seedlings. (g) To look for copper tolerance in the grass species present in the area.