Concentrations of heavy metals in raw effluents, surface waters, hydrophytes and fish in the Kizinga stream receiving effluents from the Karibu Textile Mill, Dar es Salaam, Tanzania.

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Date
2001
Journal Title
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Publisher
University of Dar es Salaam
Abstract
The levels of heavy metals, turbidity and pH in industrial effluents from Karibu Textile Mill (KTM) and the receiving surface waters of Kizinga stream were investigated. The turbidity of the textile effluents ranged between 3 FAU for treated effluents and >1100 FAU for the effluents collected from textile washing and printing processes. The turbidity of the receiving waters was 8 FAU upstream, 67 FAU at the Kizinga bridge, 111 FAU at the Mangrove stand and >1100 FAU for both the outfall point and quarter a kilometer north-east of the Kizinga bridge. The pH of raw effluents ranged between 9.1 for the effluents collected from both textile printing and washing processes and 11.9 for the treated effluents. For the receiving surface waters the pH ranged between 7.9 and 9.5. The mean concentrations (mg / I) of the heavy metals in raw effluents were 6.497 for Pb, 9.62 for Ni, 0.127 for Zn, and 0.01 for Cr, while Cu and Hg concentrations were below detectable levels (bdl). The mean concentrations (mg / I) of heavy metals in receiving surface waters ranged between 2.507 and 5.113 for Pb; 8.31 and 9.207 for Ni and between 0.127 and 0.133 for Zn. On the other hand, the concentrations of Cu in receiving surface waters ranged between bdl and 0.133 mg / I while the range for Cr was between bdl and 0.04 mg/1. Mercury levels were bdl at all sampling points. The hydrophytes analyzed for heavy metals were Typha capensis, Cyperus exaltatus and Acrostichum aureum. The mean concentrations (mg of heavy metal / g dry weight of plant tissue) in T. capensis ranged between 221.7 and 222.3 for Pb; 41 and 80.7 for Zn; 37.77 and 74.7 for Cu and 90.3 and 1041.3 for Ni. In C. exaltatus the concentrations (ug /g) ranged between 167.7 and 180 for Pb, 41.3 and 79.3 for Zn, 43 and 103.3 for Cu as well as 721.3 and 854.3 for Ni. In A. aureum the metal levels ranges (in ug /g) were between bdl and 418.3 for Pb, 39.3 and 39.7 for Zn, 50 and 120 for Cu and between bdl and160.3 for Ni. For both Cu and Hg the levels were bdl in all hydrophytes analyzed. The animals analysed for heavy metals were Tilapia sp., Glossgobius biocellalus, Acetes sp, and Penaeus sp. The mean levels (ug of heavy metal/g dry weight of animal tissue) in Tilapia sp. were 152.3 for Pb; 53.3 for Zn; 31.3 for Cu, and 97.3 for Ni, while in G. biocellalus the mean heavy metal concentrations (ug /g) were 55.8 for Zn; 17.3 for Cu and 216.7 for Ni. The mean levels for Cr and Hg were bdl in both Tilapia sp and G. biocellalus. The mean levels (ug /g) of heavy metals in Acetes sp. were 105.8 for Zn, 142.1 for Cu while the concentrations of all the other metals were bdl. On the other hand, for Penaeus sp. the concentrations (in ug /g) were 287.8 for Pb, 58.2 for Zn and 45.8 for Ni and the concentrations of the rest of the metals were bdl. The significance of these results from a human health stand point is discussed in the text.
Description
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QH541.15.M64K3)
Keywords
Industrial pollution, Environmental monitoring, Environmental pollution, Kizinga stream, Tanzania
Citation
Kalema, V. N. (2001). Concentrations of heavy metals in raw effluents, surface waters, hydrophytes and fish in the Kizinga stream receiving effluents from the Karibu Textile Mill, Dar es Salaam, Tanzania. Master dissertation, University of Dar es Salaam.