RESEARCH ARTICLE
COMPARATIVE STUDIES OF METAL (Pb, Cr, Hg, As AND Al) UPTAKE BY LEAFY VEGETABLES AND
FRUIT GROWN IN GARDENS AROUND THE KING TOM REFUSE DUMP IN FREETOWN
*
Foday Thullah, Anthony J. Kamara and Morlai Kamara
Fourah Bay College, University of Sierra Leone (USL), Freetown, Sierra Leone
ARTICLE INFO ABSTRACT
The King Tom refuse dump site is a repository of different kinds of wastes such as biodegradable
waste, recyclable materials, electrical and electronic waste, hazardous waste, toxic waste and inert
waste. Most substances in these wastes invariably contain heavy metals. The areas around the refuse
dump have long been utilized for vegetable gardening by poor residents in the King Tom community.
This study was aimed at assessing levels of toxic heavy metals (Pb, Cr, Hg, As and Al) in selected
vegetables and fruit grown in the gardens around the King Tom dump site to ascertain bioaccumulation
and possible HM toxicity. Two sampling sites were chosen for this research; gardens in the King Tom
dumpsite in the west end and controlled site (Congo Water) in the East end of Freetown. Two
commonly consumed leafy vegetables in Freetown, Manihot utilisimma (Cassava leaves), Ipomea
batatas (Potato leaves) and fruit Solanu m melongena (Garden egg) were chosen for research. After
sample preparation, the level of heavy metals in the soil and plant samples was determined
spectrophotometrically, using Spectrophotometer model (Niton XL3t GOLDD+handheld X-ray
fluorescence). Results indicate that metal levels in dump site soil are far higher than those in controlled
site soil and that Al recorded highest level followed by Pb, Cr and As for dump site soil. Hg was not
detected in both sample sites investigated. In the leafy vegetables and fruit, the metal levels were found
to be in the following order; Al>Cr>Pb>As. The order of bioaccumulation of the metals in the leafy
vegetables and fruit is; Pb:Solanum melongena (Garden egg)>Ipomea batatas (Potato leaves)>Manihot
utilisimma (Cassava leaves); Cr:Ipomea batatas (Potato root)>Manihot utilisimma (Cassava
leaves)>Solanum melongena (Garden egg);Al :Ipomea batatas (Potato root)>Ipomea batatas (Potato
leaves) Manihot utilisimma (Cassava leaves)>Solanum melongena (Garden egg); As :Ipomea batatas
(Potato leaves)>Ipomea batatas (Potato root)>Solanum melongena (Garden egg)for both sample sites
investigated. The Product moment correlation coefficients between soil and cassava leaves (rsc),
between soil and potato leaves (rsp), and between soil and garden eggs (rsg)were calculated to giversc=
0.994, rsp= 0.992 and rsg= 0.997; indicating very strong relationships between the soil and plant parts.
This implies that the dumpsite soil is the most likely source of the extra metal concentrated in the plant
parts.
Copyright © 2019, Foday Thullah et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original work is properly cited.
INTRODUCTION
The influx of people migrating from rural areas to cities in
African countries, has led to an astronomical increase in size
and population of cities. In sub-Saharan Africa, only 35% of
the population lives in urban areas, and urban population grew
by 150 % between 1970 and 1990(www.encapafrica.org.,
2009). In Serra Leone migrants arriving in the cities from other
areas of the country are mostly unskilled and have poor
educational background. They mainly engage in various
economic activities such as sand and stone mining, petty-
trading, bike riding and urban vegetable farming for their
livelihood. For those pursuing the vegetable growing option
access to land and water in the cities is a major challenge.
Thus Landfills and/or open refuse dumps and areas around
them have become very attractive places to vegetable growers.
Land fills and/or open refuse dumps have been common
municipal solid waste (MSW) disposal practices all over the
world (Nagendran et. al., 2006) and Sierra Leone is yet to
properly design and operate sanitary land fills in and around
urban towns. Refuse dumps in cities in Sierra Leone usually
hold all kinds of solid wastes including: biodegradablewaste,
recyclable materials, inert waste, electrical and electronic
waste, hazardous waste and toxic waste. This mixture of solid
wastes in refuse dumps is a reservoir of hazardous substances
that can increase the health risks emanating from the leachate
and gases (Erses et al., 2005). MSW can bleed toxic materials
and pathogenic organisms into dumps and landfill leachate
contaminating ground or surface water, depending on the
drainage system and the composition of the underlying soils
(www.encapafrica.org., 2009). Land fill leachate is one of the
main sources of groundwater and surface water pollution
ISSN: 0976-3376
Asian Journal of Science and Technology
Vol. 10, Issue, 06, pp.9751-9755, June, 2019
Available Online at http://www.journalajst.com
ASIAN JOURNAL OF
SCIENCE AND TECHNOLOGY
Article History:
Received 27
th
March, 2019
Received in revised form
06
th
April, 2019
Accepted 19
th
May, 2019
Published online 28
th
June, 2019
Key words:
Bioaccumulate, dumpsite,
Hazardous, leaching, toxic metals,
X-ray fluorescence.
*Corresponding author: Foday Thullah
Citation: Foday Thullah, Anthony J. Kamara and Morlai Kamara, 2019. “Comparative studies of metal (Pb, Cr, Hg, As and Al) uptake by leafy vegetables
and fruit grown in gardens around the king tom refuse dump in freetown”, Asian Journal of Science and Technology, 09, (6), 9751-9755.