Determination of heavy metals in Water, Plant Effluents Dam tailings, Fluorspar Ores, Soils and Rocks: A Case Study of Kerio River.

Abstract

The study showed that rocks had the highest contents of heavy metals, with nickel and iron ranging from: 26.5 - 103750 and 174.5 - 4985 mg/kg respectively. Lead and copper in rocks also ranged from: 2.1 - 4000 and 0.1 - 137.50 mg/kg respectively. Soils had also high heavy metal levels with lead ranging between, 20 - 255 mg/kg and cadmium between, 2.8 - 370.3 mg/kg. Iron concentrations was the highest in soils with levels falling between, 300 - 1284.2 mg/kg. The fluorspar ores, plant effluents, and the dam tailings also contained meaningful amount of heavy metals. The fluorspar ores containediron ranging from: 556.6 - 685.7 mg/kg and nickel ranging from: 734.2 - 84~.0 mg/kg. With respect to the heavy metals in the plant effluents, the iron concentrations. was the highest with values being between, 159.5 - 192.6 mg/l. These high levels of lead, iron,nickel, and copper could be attributed to the association of these metals with fluoride deposits. Analysis for heavy metals in water during the dry season showed iron concentration being the highest with levels being between, 0.1 - 38.6 mg/l while lead was found to range from, 0.00 - 0.43 mg/I. The wet season indicated heavy metal content of iron to range from, 0.44 - 3.71 mg/l. These levels are above the threshold values especially at sites after the convergence of the effluents with the river(s). The copper and zinc levels fall within the standard limits whereas lead, cadmium, iron, chromium, and nickel levels are above the threshold limits especially at sites of convergence between the effluents and Kimwarer River. Statistical analysis showed no significant differences in the heavy metal in the river waters during the wet and the dry season.