Selected Heavy Metals in Water and Sediments and Their Bioconcentrations in Plant ( Polygonum pulchrum) in Sosiani River, Uasin Gishu County, Kenya

Judith K. Jepkoech, Gelas M. Simiyu, Musa Arusei

Department of Chemistry, School of Science, University of Eldoret, Eldoret, Kenya.
Department of Environmental Biology and Health, School of Environmental Studies, University of Eldoret, Eldoret, Kenya.

DOI: 10.4236/jep.2013.48093                

Abstract

Heavy metals’ availability and accumulation along the food chain pose public health risks. Water, sediment and plant samples were collected from selected sampling sites along Sosiani River, Uasin Gishu County, Kenya. The sediment and plant samples were dried in the oven at 50°C to constant weight and digested in a mixture of acids according to standard procedures. The water samples, sediments and plants digests were analyzed for selected heavy metals using Atomic Absorption Spectrophotometer (model AAS Variant 200). The site near the Moi Teaching and Referral Hospital (MTRH) had the highest total heavy metals concentration in water: Cu (0.18 ± 0.04 ppm); Pb (0.46 ± 0.09 ppm) and Zn (0.70 ± 0.22 ppm) and sediments: Cu (1.62 ± 0.14 ppm); Pb (1.27 ± 0.17 ppm) and Zn (6.73 ± 0.88 ppm) respectively. Fractionation of heavy metals in sediments showed low percentage solubility (Cu 9.3%; Pb 8.5%; Zn 4.2%). Concentration of zinc in studied plants was highest (3.60 ± 0.63 ppm), with a bioconcentration factor of 15.1 based on soluble zinc fraction. This indicates that conditions in the study area show preferential zinc metal uptake in plants and may lead to accumulation in exposed plants posing Zn exposure risks along the food chain. Suggestions are made for monitoring of heavy metals in food crops and aquatic organisms such as fish in the study area.

Keywords

Bioaccumulation; Bioconcentration Factor; Food Chain; Exposure Risks

Conflicts of Interest

The authors declare no conflicts of interest.

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