Geographic Information System-Based Source Estimation of Copper Pollution in Lake Itezhi-tezhi and Metal-Accumulation Profiles in Oreochromis spp. from Both … (original) (raw)

The Copperbelt region, upstream of the Kafue River, including Lake Itezhi-tezhi (ITT), in Zambia has extensive copper (Cu) mines. In our field study, geographic information system analysis in lake sediment indicated that the northern part of the lake, i.e., the Copperbelt region, could be the source of Cu pollution. Concentrations of Cu in stomach contents between fish species were not significantly different. However, Oreochromis spp. liver showed significantly greater Cu concentrations than those in other fish species. Log liver [Cu], standard length, and nitrogen stable isotope ratio were positively correlated only in Oreochromis spp. In the laboratory study, O. niloticus and O. latipes were exposed to Cu for 4 days, and recovery phases B28 days were examined. O. niloticus showed significantly greater concentrations of Cu compared with O. latipes at all sampling points. Significantly greater concentrations of Hg in Schilbe intermedius liver than for other fish species were observed, whereas O. macrochir showed significantly greater concentrations of cadmium. In conclusion, the northern part of the lake could be the source of Cu pollution in Lake ITT. Diet may not be the reason for high Cu accumulation in Oreochromis spp. Results from both field and laboratory studies imply that Oreochromis spp. contain high concentrations of Cu under normal physiological conditions. The Kafue River, including Lake Itezhi-tezhi (ITT), plays an important role in providing drinking water for humans, livestock, and wildlife in Zambia. The Copperbelt region, upstream of the Kafue River, is one of the core mining areas in Zambia. Previous studies have shown that water, sediment, and fish in the Kafue River, downstream of the Copperbelt region, contain greater concentrations of heavy metals, especially copper (Cu), compared with samples collected upstream of the mining site Shouta M. M. Nakayama and Yoshinori Ikenaka participated equally in this work.