Levels of heavy metals in wastewater and soil samples from open drainage channels in Nairobi, Kenya: community health implication

Abstract

Levels of Mercury (Hg), Lead (Pb), Cadmium (Cd), Chromium (Cr), Nickel (Ni) & Thallium (Tl) were established in wastewater & soil samples obtained from 8 sites in open drainage channels at Nairobi industrial area, Kenya. Ultra-trace inductively coupled plasma mass spectroscopy (ICP-MS) was used for metal analysis. Temperature, pH & turbidity of wastewater ranged from 16.75 to 26.05 °C; 7.28 to 8.78; 160.33 to 544.69 ppm respectively and within World Health Organization (WHO) allowable limits. Wastewater conductivities in 4 sites ranged from 770 to 1074 µS/cm and above WHO limits at 25 °C. The mean concentrations of the metals in wastewater ranged from 0.0001 to 0.015 ppm in an ascending order of Tl <Cd <Hg <Ni <Cr <Pb. Levels of Cd, Cr & Ni in wastewater were within WHO, World Bank (WB), United States Environmental Protection Agency (US EPA), China, Kenya and India’s Central Pollution Control Board (CPCB) limits while Hg & Tl were above US EPA limits. The mean Pb levels in wastewater (5 sites) were above WHO, US EPA and Kenya allowable limits. Mean levels of the metals in soil samples ranged from 0.085 to 199.99 ppm, with those of Hg, Pb, Cr, Cd & Ni being above WHO limits for agricultural soils. Positive correlations (P < 0.05) for Cd & Hg in soils; and Tl (wastewater) & Cd (soil) were noted. In conclusion, wastewater in open waste channels at Nairobi industrial area had elevated levels of Pb and Hg, while the soil from the same channels had high levels of Hg, Pb, Ni, Cr, and Cd. Good management of Nairobi industrial area effluents is inevitable since it borders densely populated informal settlements which are likely to suffer exposure to toxic wastes. Effective wastewater treatment and reuse is highly recommended.

An Assessment of Treated Greywater Reuse in Irrigation on Growth and Protein Content of Prosopis and Albizia

“…When plant roots uptake those metals and accumulate them in the vegetative parts, they become readily available for grazers. Heavy metals (Cr, Cd, Hg, Pb, and Ni) are metallic elements, have relatively higher density (heavier) than water, and are highly soluble in the aquatic environments, and therefore, they can be absorbed by living organisms easily [38]. Those metals are readily transferred through food chains and cause potential toxic effects to animal and human health [39].…”

Metal Removal from Nickel-Containing Effluents Using Mineral–Organic Hybrid Adsorbent

“…According to literature data, nickel concentrations in the main part of industrial effluents usually do not exceed 10 mg/L [ 11 , 12 , 13 , 14 ], with some exceptions [ 14 , 15 ]. In the present study, four synthetic effluents, Ni(II), Ni(II)-Sr(II)-Cu(II)-Zn(II), Ni(II)-Cr(VI)-Fe(III), Ni(II)-Zn(II)-Mo(VI)-Cu(II), were prepared ( Table 1 ).…”

Treatment of Wastewaters with Zirconium Phosphate Based Materials: A Review on Efficient Systems for the Removal of Heavy Metal and Dye Water Pollutants

“…Some of them are present in the human body and are fundamental for several biological processes, but when their concentration exceeds upper limit values, they become dangerous for human health. Their harmful effects on humans depend on the dosage, rate of emission and period of exposure [ 2 , 4 ].…”

“…Table 1 reports the main harmful effect of some heavy metals, used in industrial activities, and their upper limit concentration in drinking water according to the the World Health Organization (WHO) [ 4 ].…”