A Preliminary Evaluation of the DDT Contamination of Sediments in Lakes Natron and Bogoria (Eastern Rift Valley, Africa)
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Dichlorodiphenyltrichloroethane (DDT) is still used in Africa for the indoor control of malaria and it may represent a potential hazard for wildlife. The littoral sediments of two alkaline-saline lakes, Natron (Tanzania) and Bogoria (Kenya), in the Eastern Rift Valley, supporting large populations of lesser flamingos (Phoeniconaias minor), were analysed for DDT residues. Physical–chemical analyses (temperature, conductivity, pH and dissolved oxygen) were also performed on the water of the two lakes and in the tributaries of Lake Natron, to evaluate the influence of the environmental variables on pollutant occurrence. At Lake Natron, around 1 km from the sediment collection sites, tree leaves of Acacia tortilis were also collected. The main metabolite found in all sediment samples was pp’DDE, whilst equal concentrations of pp’DDT and pp’DDE were measured in acacia leaves. The levels of DDTs measured in the sediments were within 5.9–30.9 ng g−1 d.w., reaching the maximum value in a tributary of Lake Natron. On the whole, the contamination of Lake Natron and Lake Bogoria basins seems to be quite moderate. Nevertheless, the pp’DDE/pp’DDT ratio equals 1 in the Acacia tortilis leaves, which makes one suppose that the input of the parent compound was rather recent and could have been from aerial transport or dust from relatively close-by old pesticides storage sites.
KeywordsObsolete contaminant pollution Soda lakes Sediments Acacia leaves Tanzania Kenya
This research was partially funded by the British Council DELPHE 291 ‘FIELD IT’ FOR EAST AFRICA Project (University of Nairobi, Kenya). It was conducted under research permits from the Tanzanian Wildlife Research Institute and the Kenyan National Council for Science & Technology to Dr David Harper. We thank the staff of his project ‘Rift Valley Lakes Exploration & Research’ (RiVLER) for maintaining the camp, food and accommodation. We would also like to thank AfriCover for providing some of the data used to make the maps.
- Brown, L.H. 1973. The mystery of the flamingos. London: Country Life Ltd.Google Scholar
- Dawson, J.B. 2008. The Gregory Rift Valley and Neogene—Recent volcanoes of Northern Tanzania. Geological Society Memoir No. 33.Google Scholar
- Dean Jr., W.E. 1974. Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks by loss on ignition: Comparison with other methods. Journal of Sedimentary Petrology 44: 242–248.Google Scholar
- Elfvendahl, S., M. Mihale, M.A. Kishimba, and H. Kylin. 2004. Pesticide pollution remains severe after cleanup of a stockpile of obsolete pesticides at Vikuge, Tanzania. AMBIO: A Journal of the Human Environment 33(8): 503–508.Google Scholar
- Harper, D., R.B. Childress, M.M. Harper, R.R. Boar, P. Hickley, S.C. Mills, N. Otieno, T. Drane, E. Vareschim, O. Nasirwa, W. Mwatha, J.P.E.C. Darlington, and X. Escutè-Gasulla. 2003. Aquatic biodiversity and saline lakes: Lake Bogoria National Reserve, Kenya. Hydrobiologia 500: 259–276.CrossRefGoogle Scholar
- Hughes, R.H., and J.S. Hughes. 1992. A directory of African wetlands, Gland, Switzerland, Nairobi, Kenya, and Cambridge UK. Huston: IUCN, UNEP and WCMC.Google Scholar
- Jones, B.E., W.D. Grant, N.C. Colins, and W.E. Mwatha. 1994. Alkaliphiles: Diversity and identification. In Bacterial diversity and systematics, ed. F.G. Priest, A. Ramos-Cormenzana, and B.J. Tindall, 195–229. New York: Plenum Press.Google Scholar
- Mavura, M.J., and P.T. Wangila. 2004. Distribution of pesticide residues in various lake matices: Water, sediment, fish, algae, the case of Lake Nakuru, Kenya. In Proceedings of the African Network for Chemical Analysis of Pesticides (ANCAP), Arusha, 8–11 August 2004.Google Scholar
- Mlingwa, C., and N. Baker. 2006. Lesser Flamingo Phoenicopterus minor counts in Tanzanian soda lakes: Implications for conservation. In Waterbirds around the World, ed. G.C. Boere, C.A. Galbraith, and D.A. Stroud, 230–233. Edinburgh, UK: The Stationery Office.Google Scholar
- Nyamweru, C.K. 1983. Rift and volcanoes: A study of the East African Rift system, 128. Nairobi: Thomas Nelson and Sons.Google Scholar
- Oaks, J.L., D. Bradway, M. Davis, and D.M. Harper. 2006. Septic arthritis and disseminated infections caused by Mycobacterium avium in Lesser Flamingos, Lake Bogoria, Kenya. Flamingo 14: 30–32.Google Scholar
- Saoke, P. 2005. Kenya POPs situation report: DDT, pesticides and Polychlorinated Biphenyls. The International POPs Elimination Project (IPEP). Physicians for social responsibility (PSR) - Kenya. http://www.ipen.org/ipepweb1/library/ipep_pdf_reports/1ken%20kenya%20country%20situation%20report.pdf.
- Spigel, R.H., and G.W. Coulter. 1996. Comparison of hydrology and physical limnology of the East African Great Lakes: Tanganyika, Malawi, Victoria, Kivu and Turkana (with reference to some North American Great Lakes). In The limnology, climatology and paleoclimatology of East African Lakes, ed. T.C. Johnson and E. Odada, 103–139. Toronto: Gordon and Breach.Google Scholar
- Wetlands International. 2002. Ramsar sites database: A directory of wetlands of international importance. www.wetlands.org/RDB/Ramsar_Dir/_COUNTRIES.htm.
- Yanda, P.Z., and N.F. Madulu. 2005. Water resource management and biodiversity conservation in the Eastern Rift Valley Lakes, Northern Tanzania. Physics and Chemistry of the Earth 30: 717–725.Google Scholar