The main objective of this study was to evaluate the degree of DDT contamination of the river and lake environments by surface sediment analyses, in order to ascertain whether such remote environments were still contaminated. Little is known (Saoke 2005) about the degree of pollution in these environments by pp’DDT (e.g. Melack 1981, 1988) or explanations for the deaths of large numbers of lesser flamingos (e.g. Wood and Talling 1988), biodiversity (e.g. Much of the knowledge of the African Rift Valley saline lakes has come from studies on their chemistry (e.g. 2004 Marco and Kishimba 2005, 2007).Īlthough there is no reason to expect a direct negative impact of DDT contamination in the most remote lakes of the Eastern Rift Valley, as these areas are sparsely populated and hundreds of kilometres distant from the recognised pesticide sources, an indirect influence of DDT cannot be excluded, due to long-range transport and local occasional IRS in tourist lodges. Moreover, “hot spot” pollution areas have been found in a coastal region of Tanzania where obsolete pesticides stocked in a disused farm have been accidentally released since 1990 (Elfvendahl et al.

At present, however, use is allowed only for Indoor Residual Spraying (IRS) for malaria vector control (Mandavilli 2006). In Tanzania, this compound has been restricted, banning it in agriculture since 1991 and in Kenya the last import was in 1985 (Wandiga 2001). In Africa, pesticides have been used for combating agricultural pests and controlling disease vectors for more than 50 years (Mansour 2009) and the most common organochlorine compound used for pest control has been the insecticide pp’DDT (Dichloro Diphenyl Trichloroethane). Landscape in Northern Tanzania, inside the Rift Valley (Photo: Roberta Bettinetti 2009) Despite the high ecological value of this environment, few studies of the Lake Natron basin and its eco-hydrology exist and no data are reported in the literature on the contamination levels of Persistent Organic Pollutants (POPs). Nakuru, Elmenteita and Bogoria in Kenya Manyara in Tanzania-are all used extensively by Phoeniconaias minor, only one regular breeding site exists in East Africa, on soda islands in the middle of Lake Natron in Northern Tanzania (Brown 1973 Harper et al. Lesser flamingos feed preferentially on Arthrospira fusiformis, a planktonic cyanobacterium that is particularly abundant in these lakes (Mlingwa and Baker 2006). 1 latitude from 4☃5′ N to 14☃0′ S and a N–S distance of around 2,100 km Spigel and Coulter 1996) have an outstanding biodiversity value, despite being hostile environments, because together they are home to approximately two million lesser flamingos ( Phoeniconaias minor) a species considered “near-threatened” by the International Union for Conservation of Nature. 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.Īlkaline–saline (“soda”) lakes in the East African Rift Valley (Fig. On the whole, the contamination of Lake Natron and Lake Bogoria basins seems to be quite moderate.

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. 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. At Lake Natron, around 1 km from the sediment collection sites, tree leaves of Acacia tortilis were also collected. 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. 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. Dichlorodiphenyltrichloroethane (DDT) is still used in Africa for the indoor control of malaria and it may represent a potential hazard for wildlife.

Lake natron deaths