title: Analysis of heavy metals in water and surface sediment in five Rift Valley lakes in Kenya for assessment of recent increase in anthropogenic activities.
abstract: The concentrations of heavy metals Ag, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sn and Zn were analysed in water and surface sediments of five Rift Valley lakes Nakuru, Elementaita, Naivasha, Bogoria and Baringo in Kenya. The dissolved mean concentration levels (mug/L) in water ranged within 13.0-185.0 (Ag), 2.0-43.0 (Cd), 5.0-316.0 (Co), 25.0-188.0 (Cr), 4.7-100.0 (Cu), 50.0-282.0 (Mn), 19.0-288.0 (Ni), 25.0-563.0 (Pb), 300.0-1050.0 (Sn) and 29.0-235.0 (Zn). The mean sediment concentrations (in mug/g (dry weight)) ranged within 0.1-0.35 (Ag), 0.05-1.18 (Cd), 0.17-1.38 (Co), 1.94-4.91 (Cr), 1.46-20.95 (Cu), 667.7-3946.8 (Mn), 11.69-39.72 (Ni), 10.92-38.98 (Pb), 17.21-56.52 (Sn) and 96.2-229.6 (Zn). The data indicate that some of the sites analysed, especially in Lake Nakuru, had relatively higher concentration levels of heavy metals Cd, Co, Cu, Pb, Ni, and Zn in the water which points to anthropogenic addition. However, potential influence of geochemical processes on the concentration levels in sediment is also shown in Co, Ni, and Cu which were more concentrated in the remote Lake Baringo sediment as well as in Pb and Mn which were more concentrated in the remote Lake Bogoria sediment. Data on some important limnological parameters including pH, salinity, electrical conductivity and temperature are also presented.
authors.affiliation: Department of Chemistry, College of Biological and Physical Sciences, University of Nairobi, P.O. Box 30197, Nairobi, Kenya.
authors.forename: E Z
authors.initials: EZ
authors.lastname: Ochieng
authors.forename: J O
authors.initials: JO
authors.lastname: Lalah
authors.forename: S O
authors.initials: SO
authors.lastname: Wandiga
mesh_terms: D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D006802:Human Activities; D006863:Hydrogen-Ion Concentration; D007630:Kenya; D019216:Metals, Heavy / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical