The impact of alum discharges on a natural tropical wetland in Uganda

Alum sludge discharge effects on a natural wetland on the shores of Lake Vi ctoria at Gaba in Uganda has been investigated. The water quality in the sw amp, the sediment chemistry and plant growth and productivity were monitore d. The subsequent application of alum sludge discharges shows no immediate, noticeable. adverse overall effects on the water quality and sediment chem istry. A distinct effect on plant productivity was noted in Cyperus papyrus L. the dominant macrophyte in the Gaba swamp resulting in a low productivi ty rate of 5.1 g/m(2) d and the apparent phasing out of this macrophyte in the swamp. Phagmites mauritianus (Kunth) exhibited better tolerance to alum sludge. Clear indications are cited of the ecosystem degrading and cumulat ive effects being marked over a longer time Frame. (C) 2001 Elsevier Scienc e Ltd. All rights reserved.