Determination Of Chemical And Microbiological Contaminants In Soils, Water And Kales (Brassica Oleracea) From Selected Sites In Eastern Nairobi Metropolitan
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Date
2019Author
Ambuso, Beatrice A
Type
ThesisLanguage
enMetadata
Show full item recordAbstract
This study investigated the extent of pesticides residues, heavy metals and microbial
contaminants in Kales, water and soils from Nairobi metropolitan. Samples were collected from
six sites within Nairobi Metropolitan area namely, Kitengela, Mlolongo and Athi River farms
and open air markets, covering the wet and dry months between July 2015 and February 2016.
Pesticide residues were extracted using organic solvents and analyzed using Gas
Chromatography equipped with electron capture detector, whereas heavy metals were analyzed
using Atomic Absorption spectrometer. The microbial contaminants were analyzed using 3M kit.
Percentage recoveries for pesticides ranged from 70.00-114.83%, whereas the detection limits
ranged between 1.12 ng/L to 3.6 ng/L. The pesticides concentration in kales ranged from BDL to
322.55±9.64 μg/kg. p,p’-DDD was the highest detected pesticide during the month of February
2016 from Kitengela market. Soil pesticides concentration ranged from 0.001 to 170.53±3.03
μg/kg, with α-endosulphan recording the highest concentration in soil from Mavoko market.
Pesticides residues in water ranged from 0.001 to 3.53±0.02 μg/L, with aldrin recording the
highest concentration in February, 2016 from Mlolongo farm irrigation water.
Heavy metals concentrations in kales ranged from <0.01 to 0.74±0.00 mg/kg. Lead was the
highest heavy metal detected in vegetables from Mlolongo farm. Concentrations of heavy metals
in water ranged from <0.01 to 0.16±0.01 mg/L. Copper was the highest heavy metal detected in
Kitengela farm water. Heavy metal in soil ranged from <0.01 to 1.03±0.08 mg/kg, zinc was the
highest heavy metal detected in Kitengela market soil samples.
E-coli concentration ranged from 0 to 13±2 cfu/L. The highest levels in kales were measured
in samples from Mlolongo market during the month of December 2015. Soil E-coli
concentrations ranged from 0 to 145±8 cfu/g detected in soils from Kitengela farm. The
concentrations in water ranged from 4 to 89 cfu/ml, with the highest levels measured in water
samples from Mlolongo farm irrigation water.
Coliform concentrations in vegetables ranged from 8±2 to 353±19 cfu/g, with the highest
detected in samples from Mlolongo market in the month of December 2015. For soil, the
coliform concentration ranged from 1±0 to 3,214±284cfu/g and the highest detected was from
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Mlolongo market during the month of February 2016. For water, the concentration ranged
from 81±3 to 3,797±119 cfu/ml, with the highest detected in water from Mlolongo farm in the
month of February 2016.
The results showed that organochlorine pesticides such as aldrin, dieldrin, endrin, heptachlor,
DDT and its metabolites are still present in samples from Nairobi metropolitan. The presence of
high levels of lead, E. coli and total coliform in vegetables should be taken seriously by public
health sector, and also the kales should not be consumed raw since they expose people to dangers
caused by the contaminants.
Publisher
University of Nairobi
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Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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