Journal of Water Resource and Protection, 2012, 4, 605-615 Published Online August 2012 (
Assessment of the Impact of Solid Waste Dumpsites on
Some Surface Water Systems in the Accra
Metropolitan Area, Ghana
Vincent Kodzo Nartey1, Ebenezer Kofi Hayford2, Smile Kwami Ametsi3
1Department of Chemistry, University of Ghana, Legon, Ghana
2Department of Earth Science, Faculty of Science, University of Ghana, Legon, Ghana
3Environmental Science Programme, Faculty of Science, University of Ghana, Legon, Ghana
Received April 25, 2012; revised May 28, 2012; accepted June 7, 2012
Water samples from four water bodies that flow through some solid waste dump sites in the Accra metropolitan area of
Ghana were analysed over a period of six months for Cd, Pb, Cu, Zn and Mn contents; coliform bacteria and helminth
eggs. Other water quality parameters such as BOD, DO, suspended solids and turbidity were also assessed. Cd, Pb, Zn,
Mn, and Cu were determined using flame atomic absorption spectrometry (FAAS). Faecal coliforms, total coliforms
and helminth eggs were determined by the membrane filtration (MF) method. The water samples contain various levels
of Cd, Pb and Mn; Zn and Cu levels were low and found to be below the detection levels of the instrument in most
cases. Helminth egg counts in water samples were high; an indication that the water bodies were polluted with patho-
gens. It has been observed that the major sources of pollutants into the water bodies were organic waste as well as coli-
form bacteria derived from these waste dumps. The elevated levels of bacteria make the water bodies unsafe for both
primary and secondary contacts.
Keywords: Landfills; Solid Waste; Dumpsite; Water Bodies
1. Introduction
Solid Waste Management (SWM) is a complex issue
throughout the world. In developed countries the issues
of SWM (collection, transportation and disposal) are well
understood, accepted and workable. However, solid
waste management is one of the many problems con-
fronting many developing countries and recent events in
major urban centres have shown that the problem of
waste management has become too complex to handle
and has seen dwindling efforts of city authorities, federal
governments, state and professionals alike in addressing
the issue [1].
N’dow, (1996) [2] pointed out that by the year 2000,
half of humanity will be living in urban areas where most
economic activities will take place and where most pol-
lutants will be generated and natural resources con-
sumed. The problem of waste in urban cities of Africa
can be better understood in the light of rapid urbanization
and for the first time in the history of mankind, we are
witnessing an unprecedented phenomenon in the devel-
opment of places of habitat making the balance of human
settlement patterns shift from more people inhabiting
rural areas to more people living in cities [3,4]. This is
especially so in developing countries such as Ghana, Ni-
geria, Kenya and Mauritania. Whilst urbanization is not a
new phenomenon in Africa, the current rate of uncon-
trolled and unplanned urbanization in Africa has given
rise to a huge amount of liquid and solid waste being
produced. So much is generated that these wastes have
long outstripped the capacity of city authorities to collect
and dispose of them safely and efficiently.
Based on an estimated population of 23 million and an
average daily waste generation of 0.4 kg per person,
Ghana generates annually about 3.0 million tons of solid
waste [5]. The high population and its associated increase
in urbanization and economic activities within the Accra
Metropolis have made the impact of the society’s solid
waste very noticeable. The urban areas of the metropolis
produce about 760,000 tons of Municipal Solid Waste
(MSW) per year or approximately 2000 metric tonnes
per day [5]. According to the Environmental Protection
Agency (EPA) report, by 2025, this figure is expected to
increase to 1.8 million tons per year or 4000 metric tons
per day. The Accra Metropolitan Assembly (AMA) is
solely responsible for municipal solid waste management
in Accra and is able to collect through its private partners
opyright © 2012 SciRes. JWARP
1500 metric tons of municipal solid waste daily repre-
senting about 75% of solid waste generated. The re-
mainder ends up at community dumps in open spaces, in
water bodies, beaches and storm drainage channels. Only
a small fraction of solid waste generated in the Accra
metropolis is recycled mostly by the informal sector
without any support from the authorities. This indicates
an overwhelming dependence on landfillng as waste
disposal option, the least preferred waste management
option on the waste management hierarchy [6].
The design and optimization of solid waste manage-
ment technologies and practices that aim at maximizing
the yield of valuable products from waste as well as
minimizing the environmental effects have little or no
consideration in the African region. In the major cities of
Ghana (Accra, Kumasi, Takoradi and Tamale) open
dumps were the means of solid waste disposal. It was
under the World Bank’s Urban Environmental Sanitation
Project that Ghana developed plans to build her first
sanitary landfills in these four major cities [7]. The prob-
lem of solid waste management in the Accra metropolis
has been characterized by single and ad hoc solutions
such as mobilizing people to collect waste and de-silt
choked gutters after a flood disaster or for an occasion,
temporal allocation of waste contracts and dumping or
building a central solid waste composting site.
It is a common site seeing water bodies flowing
through most of these solid waste dump sites. Four
prominent water bodies which are found flowing through
some of these solid waste dump sites have been studied
in order to ascertain the effects of the dump sites on wa-
ter quality of these river sources. It is a known fact that
virtually all water pollutants are hazardous to humans as
well as lesser species. For example, sodium is known to
cause cardiovascular disease while nitrates are involved
in blood disorders. Mercury and lead are also widely
known to cause nervous disorders. Some other contami-
nants are carcinogens while others for example, DDT is
known to be toxic to humans and can also alter chromo-
somes. Others such as, PCBs cause liver and nerve dam-
age, skin eruptions, vomiting, fever, diarrhea, and fetal
abnormalities. These known effects therefore support the
need to assess the effects of these dumpsites on the water
quality of these water resources which are widely in use
by the communities leaving around them.
2. Materials and Methods
2.1. Profile of the Study Area
Accra, the capital city of Ghana, is located at the south-
eastern part of Ghana, and stretches between longitudes
5˚33' to 5˚55' north and latitudes 0˚15' to 0˚25' west. Ac-
cra ranges about 20 m above sea level on the average.
The landscape is low-lying with few short irregular hills
and depressions in some parts of the city. The map of the
study area is presented in Figure 1.
Figure 1. Map of the study area showing the sampling points.
Copyright © 2012 SciRes. JWARP
Accra has four major drainage catchment systems. The
Densu River and Sakumo Lagoon catchment drains set-
tlements like, Dansoman, Kwashieman, McCarthy Hill
and Awoshie areas. The Korle-Chemu catchment basin
covers an area of 250 km2. The Odaw River is the main
stream in this system with Nima, Onyasia, Dakobi and
Ado as tributaries. The Kpeshie catchment drainage ba-
sin covers an area of 110 km2 and drains settlements like
Cantonments, Osu, Labadi and Burma camp. The Songo-
Mokwe catchment covers about 50 km2, and drains
2.2. Vegetation and Soils
The vegetation consists mainly of coastal-savanna grass-
lands, shrubs and some few mangroves in isolated areas.
Market gardening is practiced in few places particularly
along major waterways where irrigation is possible to
support all-year round farming. Vegetables like pepper,
okra, cabbage, lettuce, onion and cereals like maize are
the main crops cultivated [8].
The geological formations consist mainly of the Pre-
cambrian Dahomeyan schist, granodiorites, granites gneiss
and amphibolites and the Precambrian Togo series. The
underground water table ranges between 4.80 metres to
70 metres. The main soil types include; Drift materials
from wind-blown erosion, alluvial and marine mottled
clays, residual clays and gravels from weathered quartz-
ite, gneiss and schist rocks and lateritic sandy clay soils.
2.3. Collection of Water Samples
Sampling of water from the study area was done over a
period of six months (June-November, 2009). Wet sea-
son samples were obtained in June, July and August
while dry season samples were collected in September,
October and November. The locations of the sampling
sites were established using a Garmin 45 Ground Posi-
tioning System (GPS). The geographical locations, site
elevations and types of samples collected from each
sampling site are presented on Table 1.
At each sampling point, two sets of water samples
were collected into separate pre-cleaned 1 L polyethylene
bottles. 2.0 mL of concentrated HNO3 was added to one
Table 1. Surface water bodies sampled and their locations.
Surface Water Bodies Sample Site Locations
Lafa 05º35.821N; 00º16.301W
Bale 05º34.372N; 00º17.338W
Densu (Oblogo) 05º33.493N; 00º18.813W
Gbegbe Lagoon (Glefe) 05º40.355N; 00º09.594W
Source: field survey, 2009.
of the bottles. The acidified sample was used for ele-
mental analysis [9]. The non-acidified sample was ana-
lyzed for biological characteristics. Collected samples
were stored in a cooler containing ice cubes, and later
transported to the laboratory at the Department of Chem-
istry, University of Ghana, Legon, for analysis. At the
laboratory, samples were stored in refrigerators at 4˚C
until analysis.
2.4. Apparatus and AAS Measurement
An atomic absorption spectrometer (Analyst 400, Perkin
Elmer) was used for the determination of the concentra-
tions of Cd, Pb, Zn, Mn and Cu. Boosted Cd, Pb, Zn, Mn
and Cu hollow cathode Superlamps (Photron, Australia)
were employed as radiation sources. The operating con-
ditions of the spectrometer for the determination of Cd,
Pb, Zn, Mn and Cu are presented in Table 2.
2.5. Chemicals, Reagents, and Standards
HNO3 (Merck, Germany); H2O2 (30%, Merck, Germany),
were used for mineralization of the samples. Standard
stock metal solutions were prepared from Cd stock stan-
dard solution (1000 mg/L in 2.0% HNO3, TraceCERT®,
Fluka, Switzerland), Pb stock standard solution (1000
mg/L in 2.0% HNO3, TraceCERT®, Fluka, Switzerland),
Mn stock standard solution (1000 mg/L in 2.0% HNO3,
TraceCERT®, Fluka, Switzerland), Cu stock standard
solution (1000 mg/L in 2.0% HNO3, TraceCERT®, Fluka,
Switzerland), and Zn stock standard solution (999 mg/L
in 1.4% HNO3, Teknolab AB, Sweden) respectively.
For all dilutions, demineralized redistilled water was
utilized. Calibration curves were developed by using cali-
brants prepared by appropriate dilution of the 1.0 g·L–1
Table 2. The AAS operating parameters for the five ele-
ments determined.
Element Operating conditions
Wavelength slit width
lamp current Flame
(nm)(nm)(mA)Fuel Oxidant
(Flow rate: 2 L·min–1) (Flow rate: 13.5 L·min–1)
Cd228.80.54 Acetylene Air
Pb 217.0 1.05 Acetylene Air
Zn 213.91.0 5 Acetylene Air
Mn279.50.25 Acetylene Air
Cu324.80.54 Acetylene Air
Detection limits for the five elements: Cd: 2.0 µg/l; Pb: 3.0 µg/l; Zn: 2.0
µg/l; Mn: 3.0 µg/l; Cu: 4.0 µg/l.
Copyright © 2012 SciRes. JWARP
stock solutions to the required concentration with 2.0%
HNO3. The working standard metal solutions were pre-
pared daily.
2.6. Cd, Pb, Zn, Mn, and Cu Measurements by
Determination of metals in the acidified filtered (0.45 µm
Millipore filter) water samples were carried out in ac-
cordance with standard methods [10,11]. The concentra-
tions of Cd, Pb, Zn, Mn and Cu in the samples were re-
spectively estimated by comparison with either the re-
spective calibration curve or by the standard addition
2.7. Physical and Chemical Measurements
Temperature, pH and dissolved oxygen were measured
in-situ and recorded at the sampling sites. Nitrates,
phosphates and physical parameters such as Biochemical
Oxygen Demand (BOD5), turbidity and suspended solids
were also determined using standard methods [12].
2.8. Determination of Biological Characteristics
Total coliforms and Faecal coliforms were determined by
membrane filtration method using M-Endo-Agar at 37˚C
and on MFC Agar at 44˚C ± 0.5˚C for 48 hours, respec-
All species of helminth eggs in water samples were
quantified using the concentration method [13]. The
identities of the specific helminth eggs were established
using the World Health Organization (WHO) bench aid
for the diagnosis of intestinal parasites [14].
3. Results and Discussions
3.1. Physical Parameters
The physical parameters of water quality can be broken
down into many topics and one needs to take into con-
sideration the nature of the physical parameters of the
ecosystem surrounding a water source to be able to un-
derstand the physical appearance of water. Physical pa-
rameters which usually determine water quality are con
sidered below.
3.1.1. Te mperature of Water
Temperature affects sediment and microbial growth
among other characteristics of water and it is also a
known fact that the rate at which chemical reactions oc-
cur increase with increasing temperature and the rate of
biochemical reactions usually double for every 10.0˚C
rise in temperature. Physically, less oxygen can dissolve
in warm water than in cold water. This is because in-
creased temperature decreases the solubility of gases in
water. Increased temperature increases respiration lead-
ing to increased oxygen consumption and increased de-
composition of organic matter [15]. It is for these reasons
that the temperatures of the water samples were deter-
mined for the river systems. The mean seasonal water
temperature ranged from 27.4˚C at Glefe to 31.1˚C at
Lafa in the wet season, Table 3 and 27.4˚C at Bale to
28.7˚C at Glefe in the dry season, Table 3.
Since water temperature affects the concentration of
biological, physical, and chemical constituents of water,
the relatively high temperatures recorded would speed up
the decomposition of organic matter in the water. Hence,
population of bacteria and phytoplankton would double
in warm weather in a very short time [16].
3.1.2. p H of Water
pH is important in water quality assessment as it influ-
ences many biological and chemical processes within a
water body [16]. The pH values recorded were slightly
alkaline with little variations among the study sites. The
seasonal mean values ranged from 7.64 at Lafa to 8.06 at
Glefe in the wet season, Table 2 and 7.60 at Lafa to 7.74
at Bale in the dry season, Table 4.
The mean values fell within the WHO acceptable lim-
its of 6.5 - 8.5 except at Glefe. The high pH value at
Glefe is probably due to the direct disposal of refuse into
the lagoon and also to sea water intrusion. However,
most of the sampled sites had pH values slightly higher
than natural background level of 7 for tropical surface
It is a known fact that variations in pH affect chemical
and biological processes in water and low pH increases
the availability of metals and other toxins for intake by
aquatic life. On the other hand, the slightly high alkaline
pH values recorded at the study sites would tend to de-
crease the availability of metals and other toxins for in-
Table 3. Physico-chemical characteristics of water samples
for rainy season.
Sampling sites/Mean levels of parameters
Parameters Bale Densu LafaGlefe
Temp. (˚C) 27.4 27.7 28.228.7
pH 7.7 7.8 7.67.6
Dissolved Oxygen (mg/l) 6.0 5.5 4.84.2
Biological Oxygen Demand (mg/l) 3.6 4.3 3.43.1
Suspended Solids (mg/l) 50.0 47.3 48.351.7
Turbidity (n.t.u) 33.6 39.9 32.043.4
Nitrate (mg/l) 2.1 2.2 2.22.0
Phosphate (mg/l) 0.4 0.2 0.20.3
Copyright © 2012 SciRes. JWARP
Table 4. Physico-chemical characteristics of water samples
for dry season.
Sampling sites/Mean levels of parameters
Parameters Bale Densu Lafa Glefe
Temperature (˚C) 28.2 31.1 28.427.4
pH 7.8 7.7 7.68.1
Dissolved oxygen (mg/l) 5.8 5.8 4.84.2
Biological oxygen demand (mg/l) 4.0 4.5 3.73.5
Suspended solids (mg/l) 43.7 42.3 33.346.0
Turbidity (NTU) 27.9 39.0 40.248.4
Nitrate (mg/l) 2.1 1.9 2.01.8
Phosphate (mg/l) 0.2 0.2 0.20.3
Source: field survey (2009).
take by aquatic life as well as plants. The high pH may
be due to the presence of other pollutants introduced into
the water. As most of the study sites are located near
3.1.3. Turbidity
Turbidity (a term that refers to the optical property that
causes light to be scattered and absorbed rather than
transmitted in a straight line through water) in water is
caused by suspended and colloidal matter such as clay,
silt, finely divided organic matter, plankton and other
microscopic organisms.
The mean seasonal values for this parameter ranged
from 27.9 NTU at Bale to 49.0 NTU at Glefe in the wet
season as can be seen in Table 2 and 32.0 NTU at Lafa
to 43.4 NTU at Glefe in the dry season, Table 3. All the
values recorded were higher than the WHO value of 5
NTU. The high turbidity value could be due to the siting
of the landfills/dumpsites close to the water bodies. It
could also be due to indiscriminate disposal of waste into
the water bodies. Figure 2 shows heaps of refuse dis-
posed off into the water body at Glefe.
Another possible cause of high turbidity values may be
the siltation of the Densu, the Lafa, Bale Rivers and the
Gbegbe lagoon. Siltation of these rivers and the lagoon is
one of the problems arising from the cultivation along the
banks of the rivers and the lagoon. Most of the farms are
situated very close to the banks of these water bodies and
cultivation of the banks is intense especially during the
dry season, when there is water scarcity. This therefore
results in erosion. According to the EPA, (2002) [6], tur-
bidity values between 0.0 - 5.0 NTU show no visible tur-
bidity, no adverse aesthetic effects and no significant risk
of infectious disease transmission. Values ˃ 10 NTU
have severe aesthetic effects and the water carries an
associated risk of diseases due to infectious agents and
chemicals absorbed onto particulate matter [6].
3.1.4. S u s p ended Sol i d s
Suspended solids consist of materials originating from
the surface of the catchment area, eroded from river
banks or lake shores and suspended from the bed of the
water body [16]. Suspended solids include tiny particles
of silts and clays, living organisms (zooplankton, phyto
plankton and bacterioplankton) and dead particulate or-
ganic matter [17]. The seasonal mean values for sus-
pended solids ranged from 33.3 mg/l at Lafa to 4.60 mg/l
at Glefe in the wet season, Table 3 and 47.3 mg/l at
Densu to 51.7 mg/l at Glefe in the dry season, Table 3.
The suspended solids values recorded were generally
high. The extremely high values recorded at all the sam-
pling locations could be due to the large quantity of de-
composing matter as all the sites have landfills/dumpsites
located near them. At Glefe, as evidenced in Figure 2,
aquatic microphytes are threatening to take over the la-
According to Lester and Birkett, (1999) [18], sus-
pended solid values of less than 25 mg/l have no harmful
effect on fisheries as indicated in Table 5.
One direct effect of suspended solids is the influence
on the turbidity of the receiving water body. This in turn
reduces the amount of light that can penetrate the water
and therefore will tend to reduce photosynthesis. More-
over, this could affect the recreational use of the water
body. Suspended solids may also exhibit an effect if they
settle out of suspension. Deposition of solids can change
the characteristics of the riverbed, which will in turn af-
fect plant and animal growth and fish breeding. Sus-
pended solids generally cause damage to fish gills af-
fecting their oxygen consumption and ultimately causing
death at high concentrations. There was a defined trend
in seasonal variations as dry season values were higher
than the wet season values.
3.2. Chemical Parameters
Chemical characteristics of water can affect aesthetic
qualities such as how water looks, smells, and tastes.
This can also affect its toxicity and whether or not the
water is safe to use. Since the chemical quality of water
is important to the health of humans as well as the plants
and animals that live in and around streams, it is neces-
Table 5. The effects of suspended solids on fisheries.
Suspended Solids (mg/l) Effects
˂25 No harmful effect
25-80 Some possible reduction in yield
80-400 Good fisheries unlikely
˃40 Very poor or non-existent
Source: lester and Birkett (1999).
Copyright © 2012 SciRes. JWARP
sary to assess the chemical attributes of water. It is in
light of these facts that the following chemical parame-
ters have been determined for the water systems.
3.2.1. Di ssolved O xygen
The amount of oxygen dissolved in water depends on the
rate of aeration from the atmosphere, temperature, air
pressure and salinity. While the actual amount of oxygen
that can be dissolved in water depends on the relative
rates of respiration by all organisms and of photosynthe-
sis by plants, oxygen levels are actually low where or-
ganic matter accumulates because aerobic decomposers
require and consume oxygen. The mean seasonal values
dissolved oxygen values of the river systems ranged from
4.7 mg/l at Glefe to 5.8 mg/l at Bale and Densu in the
wet season, Table 3 but ranged from 4.2 mg/l at Glefe to
6.0 mg/l at Bale and Lafa during the dry season as is ob-
served in Table 4. The DO values recorded at the loca-
tions compared with the natural background level of 7.0
mg/l were generally low. This low values give an indica-
tion of pollution at all the sampling sites especially at
Glefe and Lafa. The major possible causes of the pollu-
tion would include contamination by leachates from the
landfill sites and indiscriminate defaecation and dumping
of refuse along the banks and into the water bodies. The
influence of other human activities such as farming at the
river banks, fishing, washing and bathing in the river
cannot be ruled out.
According to Cunningham and Saigo, (1997) [19], the
addition of certain organic materials to water stimulates
oxygen consumption by decomposers. The dissolved
oxygen falls as decomposers metabolize waste materials.
Water with less than 2.0 mg/l will only support detritus
feeders, decomposers and worms. The optimal DO con-
centration for growth of fisheries is 5.00 - 8.00 mg/l. The
sites that fell within this range are Bale and Densu where
some kind of fishing is done. All the other sites except
Glefe which fell in the range lethal for tilapia had con-
centration for which growth of tilapia will be impaired
3.2.2. Biochemical Oxygen Demand (BOD)
Biochemical Oxygen Demand (BOD) is used as an index
for determining the amount of decomposing organic ma-
terials as well as the rate of biological activities in water.
This is because oxygen is required for respiration by mi-
cro-organisms involved in the decomposition of organic
materials. Thus high concentration of BOD indicates the
presence of organic effluent and hence oxygen-requiring
micro-organisms. Mean seasonal BOD for the water sys-
tems ranged from a minimum of 3.1 mg/l at Glefe to a
maximum of 4.3 mg/l at Densu in the wet season as in
Table 2 and 3.5 mg/l at Glefe to 4.5 mg/l at Densu dur-
ing the dry season, Table 4.
Indiscriminate defaecation and refuse disposal was
observed at all the sampling sites. The slightly high BOD
values may be attributed to the discharge of organic
waste into water bodies resulting in the uptake of DO in
the oxidative breakdown of these wastes [20]. The near-
ness of the sampling locations to landfill/dumpsites is a
factor promoting the loading of the water bodies with
organic matter hence, the high BOD values.
The implication of high BOD in surface water could
also mean that the oxygen present in the water will be
used for decomposition of the pollutants, and thus, is not
available for aquatic life anymore. The natural back-
ground level for freshwater ranges from 1.0 to 3.0 mg/l.
The BOD of a river must generally not exceed 4.0 mg/l.
This would reduce DO from saturating to 5.0 - 6.0 mg/l
which is still capable of supporting aquatic life.
3.3. Nutrients
Nutrients mainly refer to inorganic matter from runoffs,
landfills, livestock operation and crop lands, etc. The two
primary nutrients of concern are usually phosphorus and
3.3.1. Nitrate
Nitrogen which usually exists in water bodies as nitrate is
a key ingredient in fertilizers. It generally becomes a
pollutant in saltwater or brackish estuarine systems
where nitrogen is a limiting nutrient. Excess amounts of
bioavailable nitrogen in marine systems lead to eutro-
phication and algae blooms.
It is with regards to the key role nitrates play in water
quality determination that its assessment has been under-
taken in this study. As can be seen from Table 3, the
mean seasonal values for the compound ranged from 2.0
mg/l at Glefe to 2.2 mg/l at Densu and Bale in the wet
season and 1.8 mg/l at Glefe to 2.1 mg/l at Bale in the
dry season, Table 4. All the sites registered nitrate values
higher than the natural background level of 0.23 mg/l.
The nitrate concentrations were however lower than the
WHO limit of 10.0 mg/l. The presence of nitrate may be
the result of waste being disposed off at the land-
fills/dumpsites. Thus, contamination of the water bodies
with chemicals from the landfills/dumpsites is very likely
to occur. This is because wastes from agro-based Indus-
tries which may contain nitrates are not segregated be-
fore disposal and are likely to find their way into the
river systems in runoffs or leachate emanating from the
landfills. It could also be attributed to run-offs from
farms along the banks of the rivers which may contain
organic fertilizers. There was a slight seasonal variation
as the wet season values were higher than the dry season
Nitrates are the most common form of nitrogen found
Copyright © 2012 SciRes. JWARP
in natural waters with enough dissolved oxygen. The
natural background levels of nitrate may come from
rocks, land drainage and plant and animal matter. Ex-
tremely high concentration of nitrate is toxic. However,
the values recorded for all the sampling sites do not ex-
ceed the WHO limit value of 10.0 mg/l [21].
Invariably, nitrate is seldom abundant in natural sur-
face water because it is incorporated into cells and
chemically reduced by microbes and converted into at-
mospheric nitrogen [16]. This phenomenon may account
for the low concentration of nitrate in surface waters.
3.3.2. Phosphate
Phosphorus is a nutrient that occurs in many forms that
are bioavailable and phosphate is one such form of its
existence. It is a main ingredient in many fertilizers used
for agriculture as well as on residential and commercial
properties, and may become a limiting nutrient in fresh-
water systems. Phosphorus is most often transported to
water bodies via soil erosion because many forms of
phosphorus tend to be adsorbed to soil particles. Excess
amounts of the element in aquatic systems (particularly
freshwater lakes, reservoirs, and ponds) leads to prolif-
eration of microscopic algae called phytoplankton.
Mean seasonal values of the element in this study
ranged from 0.2 mg/l at Lafa and Densu to 0.4 mg/l at
Bale in the wet season as can be seen in Table 3 . The dry
season mean values range from 0.2 mg/l at Bale, Lafa
and Densu to 0.3 mg/l at Glefe in the dry season, Table 4.
The phosphate concentrations were relatively high com-
pared with the natural background level of 0.02 mg/l.
With the exception of Bale, all the remaining sites Regis-
tered values not above the WHO limit of 0.3 mg/l. The
high concentration may be due to the effect of seepage
from the landfill/dumpsites into the water bodies. It can
also be attributed to domestic waste water and agricul-
tural run-offs. A high phosphate concentration is an in-
dication of pollution. There was only minimal variation
in the seasonal trend in this study.
Phosphorus is also an essential nutrient and can exist
in water in both dissolved and particulate forms. It is
vital to the production of living organisms in the aquatic
environment. High phosphate concentration is response-
ble for the eutrophication of a water body as phosphorus
is a limiting nutrient for algae growth. All polyphos-
phates are eventually hydrolysed to produce the ortho
form and the rate of hydrolysis is increased by tempera-
ture, decreased pH and bacterial enzyme action [22].
3.4. Heavy Metals
Compounds including heavy metals like lead, mer c u r y,
zinc, and cadmium, and organics like polychlorinated
biphenyls (PCBs) and polycyclic aromatic hydrocarbons
(PAHs), fire retardants, and other substances are resistant
to breakdown. These contaminants can come from a va-
riety of sources including mining operations, vehicle
emissions, fossil fuel combustion, urban runoff, Indus-
trial operations and landfills.
These compounds can threaten the health of both hu-
mans and aquatic species while being resistant to envi-
ronmental breakdown, thus allowing them to persist in
the environment. These toxic chemicals could come from
croplands, nurseries, orchards, building sites, gardens,
lawns and landfills.
3.4.1. Lead (Pb)
Lead in the environment is mainly particulate bound with
relatively low mobility and bioavailability. Lead does, in
general, not bioaccumulate and there is no increase in
concentration of the metal in food chains [23]. Lead is
also not essential for plant and animal life. The mean
values of the metal ranged from 32.0 µg/l at Densu to
44.0 µg/l at Bale in the wet season, Table 6. The dry
season values range from 35.0 µg/l at Densu to 72.0 µg/l
at Bale as seen in Table 7.
The presence of lead in the water may be due to the
discharge of industrial effluents from petroleum produc-
tion [15]. Lead may also come from lead-acid batteries,
Table 6. Levels of Zn, Cu, Pb Cd and Mn in surface water
bodies for rainy season.
Sampling sites/Mean levels of metals (µg/l)
Parameters Bale Densu Lafa Glefe
Zinc bdl bdl bdl bdl
Copper bdl bdl bdl bdl
Lead 44.0 32.0 35.0 40.0
Cadmium 4.0 5.0 10.3 9.0
Manganese 186.0 130.0 240.0 139.0
Source: field survey (2009); (bdl = below detection limit).
Table 7. Levels of Zn, Cu, Pb Cd and Mn in surface water
bodies for dry season.
Sampling sites/Mean levels of metals (µg/l)
Parameters Bale Densu Lafa Glefe
Zinc bdl bdl bdl bdl
Copper bdl 5.0 bdl 6.0
Lead 72.0 35.0 41.0 43.0
Cadmium 8.0 7.0 17.0 11.2
Manganese 26.0 310.0 452.0 44.0
Source: field survey (2009); (bdl = below detection limit).
Copyright © 2012 SciRes. JWARP
plastics and rubber remnants, lead foils such as bottle
closures, used motor oils and discarded electronic gadg-
ets including televisions, electronic calculators and ste-
reos [22] where leachates from the waste dumpsites may
find their way into the rivers. All lead values fell between
32.0 µg/l to 72.0 µg/l. There are no adverse effects of
exposure to water at these concentrations. The recom-
mended range for livestock is 0.0 - 100.0 µg/l. All the
sites had concentrations below 100.0 µg/l and therefore
there are no health risk concerns. However, all the sites
were above the general upper limit of 30.0 µg/l for con-
tinuous exposure for fish.
3.4.2. C op per (Cu)
The mean seasonal values of copper in water systems
during the study period were below detection limit of 4.0
µg/l at all the study sites during the wet season, Table 6.
The dry season values ranged from below detection limit
to 6.0 µg/l as captured in Table 7.
Water quality range for copper for which there is no
health or aesthetic effect is 0.0 µg/l to 10.0 µg/l and all
the sites fell within this range. All the sites where the
water is used for irrigation also fell below the level for
which copper is toxic to plants, 100.0 µg/l to 1000.0 µg/l.
For fisheries, the level for which there are no adverse
effects on early life stages of some species ranges from
2.0 µg/l to 60.0 µg/l, and all the sites fell below this
range hence, copper levels in the river systems pose no
threat to the environment and health.
3.4.3. Manga nese (Mn)
Manganese occurs in surface waters that are low in oxy-
gen and often does so with iron. When oxidized in aero-
bic waters, the oxide builds up in distribution causing
severe discolouration at concentrations above 50.0 µg/l
[21]. The mean seasonal concentrations ranged from
130.0 µg/l at Densu to 240. 0 µg/l at Lafa in the wet sea-
son, Table 6. The dry season values ranged from 26.0
µg/l at Bale to 452.0 µg/l at Lafa, Table 7.
The presence of manganese may be due to discharge
from industrial facilities or as leachate from landfills [10].
The very high values of manganese may be as a result of
pollution from manganese dioxide cells for which the
nation has no controlled methods of disposal. The metal
may also come from other sources such as domestic
wastewater and sewage sludge disposal. There was no
clearly defined trend in seasonal variations. All the sites
registered mean values above the WHO limit of 10.0
3.4.4. Cadmium (Cd)
Cadmium is readily accumulated by many organisms,
particularly by micro-organisms and mollusc where bio-
concentration factors are in the order of thousands. Soil
invertebrates also concentrate Cd markedly [24]. Chronic
exposure to the metal produces a wide variety of acute
and chronic effects in mammals similar to those seen in
humans. Kidney damage and lung emphysema are the
primary effects of high Cadmium in the body.
Mean values of the metal in this study ranged from 4.0
µg/l at Bale to a maximum of 10.3 µg/l at Lafa in the wet
season, Table 6. The dry season values recorded ranged
from 7.0 µg/l at Densu to 17.0 µg/l at Lafa, Table 7.
There was a defined trend as the dry season values ob-
tained were higher than the wet season values. Even
though the values obtained are low, cadmium is known
to be one of the most toxic elements with reported car-
cinogenic effects to humans [25]. High concentration of
cadmium has been found to lead to chronic kidney dys
function. Cadmium may bioaccumulate at all levels of
aquatic and terrestrial food chains. Cadmium contamina-
tions in surface water bodies could be attributed to the
discharge of contaminants including nickel-cadmium
batteries. Some other activities which may introduce
cadmium into these environments include electroplating
and plastic manufacture.
3.4.5. Zinc (Zn)
Zinc levels were below the detection limits in all the wa-
ters sampled at the various sites. It is not clear why the
very low level of the metal in the rivers despite the re-
corded values of zinc in the leachates from the dumpsites
located close to the rivers [26]. This will need further
investigation to ascribe reasons to the very low values of
3.5. Bacteriological Parameters
Pathogens are bacteria and viruses that can be found in
water and cause diseases in humans. Typically, patho-
gens cause disease when they are present in public drink-
ing water supplies. Pathogens found in contaminated
runoff may also contain parasitic worms (helminths).
Coliform bacteria and faecal matter may also be detected
in runoffs. These bacteria are a commonly used indicator
of water pollution, but not an actual cause of disease.
3.5.1. Total Coliform (TC)
Total coliform gives a clear indication of the general
sanitary condition of water since this group includes
bacteria of faecal origin. However, many of the bacteria
in this group may originate from growth in the aquatic
environment. This is used to evaluate the general sanitary
quality of drinking and related water use [6]. The mean
total coliform population in this study varied between 6.0
× 104 cfu/100 ml at Densu and 94.0 × 104 cfu/100 ml at
Lafa in the wet season. The dry season recorded a value
of 2.3 ×104 cfu/100 ml at Densu to 118.0 × 104 cfu/100
Copyright © 2012 SciRes. JWARP
ml at Glefe. There was a defined trend in the seasonal
variations as the dry season values were generally higher
than the wet season values as indicated in Tables 8 and
The high concentration of TC could also be due to in-
discriminate defaecation, sewage, land and urban run-off
and domestic waste waters [16]. The presence of coli-
form group of organisms is an indication of faecal con-
tamination. The high TC counts observed at all the sam-
pled sites make the river systems unsuitable for both
primary contact, such as swimming and secondary con-
tact such as boating and fishing according to the World
Health Organization (WHO) limit [27].
Comparison of TC counts in the various sampled sites
with the natural background and WHO limit of 0.0
cfu/100 ml indicated gross contamination with bacteria at
all the sites making the water unsafe for drinking by hu-
mans and livestock. According to UNICEF, (1999) [28],
if water is found to contain faecal indicator bacteria, it is
considered unsafe for human consumption.
3.5.2. Faecal Coli form (FC)
Bacteriological examinations of water samples are done
to determine the sanitary quality and the degree of con-
tamination with waste [12].
Faecal coliforms are bacteria that live in the digestive
tract of warm-blooded animals. They are excreted in the
solid wastes of humans and other mammals. Where fae-
Table 8. Bacteriological parameters of water for the rainy
Sampling sites/Mean levels of metals (µg/l)
Parameters Bale Densu LafaGlefe
Feacal coliforms
(CFU/100 ml) 5.9 0.4 8.4 1.9
Total coliforms
(CFU/100 ml) 73.36.0 94.010.0
Helminth eggs/500 ml
of water 2.3 1.5 1.3 2.7
Source: Field survey (2009).
Table 9. Bacteriological parameters of water for the dry
Sampling sites/Mean levels of biological parameters
Parameters Bale Densu Lafa Glefe
Feacal coliforms
(CFU/100 ml) 11.1 0.6 9.6 9.8
Total coliforms
(CFU/100 ml) 94.7 2.3 38.0 118.0
Helminth eggs/500 ml
of water 0.6 0.5 3.3 0.0
Source: field survey (2009).
cal coliforms are present, disease-causing bacteria are
usually also present. Untreated faecal materials that con-
tain faecal coliforms add excess organic material to the
water. The decay of these materials depletes the water of
oxygen which may result in killing of fishes and other
aquatic life [29].
The mean values in our study ranged from 0.4 × 104
cfu/100 ml at Densu to 8.4 × 104 cfu/100 ml at Lafa in
the wet season and the dry season values ranged from 0.6
× 104 cfu/100 ml at Densu to 11.1 × 104 cfu/100 ml at
Bale as represented in Tables 7 and 8 respectively.
There was a clearly defined trend in the seasonal varia-
tions indicating higher values for the dry season than the
wet season. The high counts of faecal coliforms may be
due to run-offs from the municipal landfills and urban
solid waste disposal sites which contain domestic animal
and human faecal materials [16]. It may also be attrib-
uted to indiscriminate refuse disposal along the banks of
the water bodies.
The faecal coliform density was calculated using the
Colonies counted100 ml
Colonies100 mlsample volume (ml)
3.5.3. Helminths
Helminth eggs including Ascarislumbricoides and Strongy-
loidesster coralis were detected in the water samples. The
helminth egg population ranged from 1 to 4 egg(s) 500
ml–1 in the water samples. The mean seasonal values are
presented in Tables 8 and 9. The helminth egg in the
samples might be due to the disposal of waste containing
human and animal faecal materials at the disposal sites.
4. Conclusions
The study revealed that the major pollutants into the
Densu, Lafa, Bale Rivers and the Gbegbe lagoon (Glefe)
have been identified to be organic waste, total and faecal
coliforms. The sources of these pollutants into these wa-
ter bodies are through runoffs from the municipal land-
fills/dump sites and could also be attributed to indis-
criminate defaecation and refuse disposal which had
contributed to elevated levels of the pollutants. Also,
dumping and farming along the banks of these water
bodies had led to eroded materials accumulating in them.
This has resulted in the occurrence of large quantities of
suspended solids and ultimately high turbidities. The
discharge of organic waste including human excreta,
domestic and animal waste either directly or indirectly
through runoffs, into the water systems has resulted in
high BOD levels and subsequently, low levels of dis-
solved oxygen in the waters. The low level of dissolved
oxygen recorded for the entire study period is an indica-
tion that the waters in the study area could not support
Copyright © 2012 SciRes. JWARP
life sufficiently.
The presence of the coliform group of organisms is an
indication of faecal pollution. This is quite alarming con-
sidering the assertion by Pierce et al., (1998) [15], that
large numbers of coliforms in water is an indication of
recent pollution by wastes from warm-blooded animals
and therefore the water may contain pathogenic organ-
isms. Even though the people in the study area do not
depend solely on these water bodies as their sources of
water supply, the spate of water shortages could turn the
tide. The presence of these coliforms could be response-
ble for the transmission of infectious diseases which in-
clude typhoid fever, dysentery, salmonellosis, cholera
and gastroenteritis [6] which have been reported in the
Accra metropolis. Heavy metals such as Cd, Pb, Mn, Cu
and Zn analyzed in the water samples recorded varying
levels of the metals. Heavy metals of public concern like
Pb and Cd fell between 4.0 µg/l to 100 µg/l and were
below the WHO recommended levels. There is therefore
no threat to life in relation to the levels of these metals
detected in the water bodies.
Helminth eggs and especially those of the genus As-
caris and Strongyloides families are the most commonly
found in the water samples from the study area. However,
there is no evidence of significant pollution with hel-
minth ova that might pose a threat to humans especially
those who have direct contact with the water.
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