TITLE:
Selected Heavy Metals in Water and Sediments and Their Bioconcentrations in Plant ( Polygonum pulchrum) in Sosiani River, Uasin Gishu County, Kenya
AUTHORS:
Judith K. Jepkoech, Gelas M. Simiyu, Musa Arusei
KEYWORDS:
Bioaccumulation; Bioconcentration Factor; Food Chain; Exposure Risks
JOURNAL NAME:
Journal of Environmental Protection,
Vol.4 No.8,
August
5,
2013
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.