Impact analysis of tannery effluent on the Nabajjuzi wetland

Nabajjuzi wetland is being polluted by tannery effluents, a serious threat likely to compromise its ecological functioning. In order to provide sufficient data for effective management of the wetland, this study assessed the impact of tannery effluent discharge on water quality and macroinvertebrates of Nabajjuzi wetland. Samples for macroinvertebrates and water quality were collected along Nabajjuzi wetland at one upstream site (R) and three downstream sites (X1, X2, X3) relative to tannery effluent discharge. Only 1 taxon of macroinvertebrates was collected at X2 whereas 4 taxa were collected at R. This distribution of macroinvertebrates can be associated with the very low DO at all study sites (1.32±0.09–1.67±0.20 mg/L) and increasing concentrations of BOD,5 (7.37±2.47– 199.75±44.01 mg/L), COD(44.15±10.35–1,192.30±220.60 mg/L), TSS(57.00±23.07–1699.9±578.32 mg/L), Cl- (56.17±50.37–1,454.60±331.94 mg/L), EC (47.42±2.14– 3087.10±612.89 μS/cm) and Cr3+ (0.30±0.06– 0.86±0.17 mg/L) from R to X3 respectively. All the identified physico-chemical parameters responsible for polluting water downstream were associated with tannery effluent discharge. This shows evidence that tannery effluent discharge has a direct impact on both the physico-chemical quality and macroinvertebrate characteristics along the Nabajjuzi wetland which is significant and needs to be reduced.