Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya

ABSTRACT

Heavy metal pollution is among the leading health concerns all over the

world because of their long-term cumulative effects. Consumption of

food crops contaminated with heavy metals is a major food chain route

for human exposure. Khat (Catha edulis forsk), a plant used as a

stimulant is grown in certain areas of East Africa and the Arab Peninsula.

In Kenya, it is cultivated in Embu and Meru counties and distributed to

consumers in other counties who include young children. Due to

increased demand and value, many farmers have not only begun growing

it but have also adopted modern farming methods which include

application of fertilizers, pesticides, compost manure, and irrigation. Yet

some of these agricultural practices such as application of fertilizers and

pesticides are known to increase the concentration of heavy metals such

as Cd, Pb, Zn and Cu in the soil. Some of these heavy metals such as Pb

and Cd are toxic even at low concentrations while Zn, Cu, Fe and Cr

though essential in the body, are toxic at high levels. This call for

monitoring to make sure that the levels of heavy metals in khat do not

exceed the threshold limits recommended by WHO due to their adverse

health effects to man. This study therefore determined the levels of Zn,

Cu, Pb, Cd and Cr in khat and in the soils where the plant is grown. Soil

and khat samples were collected from the three main khat growing

regions namely Embu, Mbeere and Nyambene. Known weights of oven

dried khat and soil samples were digested using nitric and perchloric

acids. The digests were analysed for selected heavy metals using flame

atomic absorption spectrophotometer. The following concentration

ranges in dry weight (μg/g) were obtained in khat: Zn(25.15-73.95),

Cu(0.10-41.80), Cr(ND-39.50), Cd(ND-0.90) and Pb(0.50-13.00). Cd

was only detected in khat samples from Embu. In soil, the concentrations

of selected metals in dry weight (μg/g) were as follows: Zn(25.50-

440.30), Cu(0.65-54.40), Cr(7.50-170.50) Cd(0.05-1.40) and Pb(5.00-

119.00). Levels of these metals in soil were below the permissible limits

for agricultural land use set by FAO/WHO. Correlation study revealed

positive correlation between metals in soil and khat except for Zn, Cu

and Pb in Embu. The ANOVA results suggested that there was

significant different (p 0.05) in the levels of heavy ˂ metals between khat

from various regions. Levels of studied heavy metals in khat were below

the maximum limits recommended by WHO except for Pb and Cr.

Therefore children should be discouraged from chewing khat since they

are more susceptible to adverse effects of Pb than adults.

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APA

Ireri, S (2021). Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya. Afribary. Retrieved from https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya

MLA 8th

Ireri, Sailus "Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya" Afribary. Afribary, 01 Jun. 2021, https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya. Accessed 29 May. 2024.

MLA7

Ireri, Sailus . "Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya". Afribary, Afribary, 01 Jun. 2021. Web. 29 May. 2024. < https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya >.

Chicago

Ireri, Sailus . "Determination Of The Levels Of Selected Heavy Metals In Soil And In Khat (Catha Edulis Forsk) Grown In Kenya" Afribary (2021). Accessed May 29, 2024. https://afribary.com/works/determination-of-the-levels-of-selected-heavy-metals-in-soil-and-in-khat-catha-edulis-forsk-grown-in-kenya