CHAPTER
ONE
1.0 INTRODUCTION
1.1 Background
Information
Since agrarian and industrial
revolution, heavy metals are increasingly being introduced into water bodies
from various sources (Gebrekidan and Samuel, 2011). Their increase is
attributed to human activities such as burning of fossil fuels, mining and
smelting of metal ores, agricultural activities, industrial wastes and poor
disposal of compounds that contain heavy metals (Linnik, 2000). In the aquatic environment the levels of heavy
metals have been reported to be increasing above recommended levels (Kanmony,
2009; Al-saleh et al., 2010; Gathigi, 2012). This raises concern on the
effects attributed to heavy metal poisoning since they are not only persistent
but also have potential for bio-accumulation and bio-magnification (Sax and
Lewis, 2007). Heavy metals are toxic and can damage soft tissues easily even at
very low concentration (Johannes et al., 2006).
Furthermore it has been established
that at concentration above the set limits in the human body may causes cancer
(Abdollahim et al., 2000). Since water is a scarce resource, with an
increase in the human population, availability of drinking water is apparently
a point of concern in both developing and developed countries (TWAS, 2002). It
is reported that more than one billion people worldwide lack access to clean
drinking water and 5-10 million people die annually of water borne related
illnesses (TWAS, 2002; Walakira, 2011). Unfortunately, the largest percentages
of people affected are children (Ahuja, 2009).
Following universally and locally set
limits of heavy metals in water bodies by World Health Organization (WHO) and
Kenya Bureau of Standards (KEBS), a number of water bodies have been studied
for the levels of heavy metals (Hanaa et al., 2000). The recommended
limits set by WHO and KEBS are in table 1.1 (WHO, 2004; KEBS, 2007).
Table 1.1: Recommended heavy metals level in drinking water
Metal levels (mg/l)
Lead 0.10
Cadmium 0.03
Copper 0.05
Manganese 0.50
In
Eastern Africa region, it has been reported that River Nile contains heavy
metals above the set limits (Omwoma, 2011). This requires urgent
intervention to remedy the situation. Most of water bodies in Ishiagu have been
studied for their levels of heavy metals (Schutte et al., 2008). Before
now, groundwater had been considered as uncontaminated but, presently either
these water sources are under threat from pollution as a result of human life
style manifested by low level 0f hygiene practiced by the developing nations or
leaching from solid rocks, industrial and agricultural practices (Akujieze et
al., 2003, Ikem et al., 2002). The quality of groundwater may also
be affected by the characteristics of the media through which the water passes
on its way to groundwater zone of saturation (Raji and Alagbe, 1997).
Notably there have been variations of
levels of heavy metals in different matrices of water bodies including water,
sediment and aquatic plants and animals. This is attributed to different
solubility of metal salts and adsorption to the sediments (Ogayi et al.,
2011). The solubility of metal salts in water is influenced by pH value. Most
of the metal salts dissolve below the pH of 6.5 and precipitates at the range
of 6.5 to 8.5 (Skudi et al., 2011). The well water of focus in this
study is in Ishiagu which is among the major sources of water used for
irrigation, drinking and for domestic purposes. These water bodies are feared
to be contaminated by heavy metals due to the surrounding activities such as
effluents from factories, industries and agricultural activities (Omwoma, 2011).
Further statistics show that over 200
cases of cancer and hematological effects have been reported in Ishiagu Ebonyi
State which could be attributed to the presence of high levels of heavy metal
(Obed, 2008).
Ishiagu is a community were quarry
site and lead/zinc mines are located and every family has their wells for
source of portable water during dry season because the streams within the area
usually dry at this period. There are literatures on physiochemical studies on
polluted water sources (Akubugwo et al., 2007, Singh et al.,
2009, Abulude, 2007, Agbaire and Obi, 2009). But much work have not been done
on the quality of hand dug wells in Ishiagu. It is in light of the above levels
of heavy metals in wells water in Ishiagu were studied.
1.2 Statement
of the Problem
Heavy metals are very harmful because
of their non-biodegradable in nature, long biological half-lives and their
potential to accumulate in different body parts. Even at low concentration they
may cause damage to human body organs and other internal organs of animals
because of absence of good mechanisms for their elimination from the body. Heavy
metals enter in human body through food, air we inhales and drinking water.
1.3 Justification
of the study
Well water is a major source of
drinking water, although is at risk of heavy metals exposure. It is dug in a
densely populated residential area and there area number of activities that
could also aggravate the levels of heavy metals in its water that includes
industrial and agricultural activities. These together with statistics of more
than 200 cases of cancer in the region that may be attributed to heavy metals,
residents in this region are still feared for more cases of negative health
effects of heavy metals present in drinking water. To ascertain the levels of
heavy metals in the water bodies under study was to serve as the basis of
filling literature gaps. Therefore there is an urgent need to determine the
levels of heavy metals in wells water. Findings are projected to inform
government authorities that would move in to address the underlying problem and
salvage foreseen cases that would result from metal poisoning in the area.
1.4 Hypothesis
The levels of heavy metals in Ishiagu wells
are above limits set by WHO and KEBS
1.5 Objectives
of the study
1.5.1 General Objective of the study
Ø To
assess the levels of lead, manganese, copper and cadmium heavy metals in
Ishiagu wells water.
1.5.2 Specific Objectives of the
study
Ø To determine the level of copper,
lead, manganese and cadmium in Ishiagu wells water during the periods of
sampling.
1.6 Significance
of the Study
The findings in this study are
particularly important as they show the levels of heavy metals in four
different wells. There is literature of heavy metals in Ishiagu wells water but not adequate enough
and has formed the basis of a literature gap to be filled, considering that
water from this wells is used for drinking and other domestic uses. The
strength of the findings will call for urgent intervention strategies by the
government of Ishiagu to cease further pollution of these water bodies that may
result into loses of life of people and animals in this region.
1.7 Limitations
of the study
Residents in Ishiagu rely on water
from Ivo river, wells, boreholes and piped water. Water samples were obtained
from the wells. Four selected heavy metals that pose high risk to human life
were considered for study during the period of sampling. Parameters such as
temperature, pH and geological factors that would influence levels of heavy
metals were not within scope.