Journal of Water Resource and Protection, 2012, 4, 622-633
http://dx.doi.org/10.4236/jwarp.2012.48072 Published Online August 2012 (http://www.SciRP.org/journal/jwarp)
Environmental Implications of the Discharge of
Municipal Landfill Leachate into the Densu River
and Surrounding Ramsar Wetland in the
Accra Metropol is, Ghana
Frank K. Nyame1*, Jacob Tigme2, Jacob M. Kutu1, Thomas K. Armah1
1Department of Earth Science, University of Ghana, Legon, Ghana
2SMD Lefa Gold Mine, Kankan, Guinea
Received May 24, 2012; revised June 27, 2012; accepted July 5, 2012
ABSTRACT
Investigations were conducted over a six-month period on leachate which continuously egresses from a “natural at-
tenuation” landfill site into a fragile ecosystem in the Accra Metropolis, Ghana. Most physico-chemical, oxygen de-
mand parameters and nutrient contents were within permissible limits but Total Dissolved Solids (1124 - 13200 mg/l),
conductivity (7960 - 24890 µS/cm), Mn (0.12 - 0.94 mg/l), Ca2+ (160 - 356 mg/l) and, more especially chloride contents
(1030 - 2967 mg/l) far exceeded respective World Health Organisation (WHO) limits for effluent discharge into the
natural environment. Multivariate statistics using Principal Component Analysis (PCA) and Cluster Analysis (CA)
suggest significant concentrations of Ca2+, , and to a lesser extent Zn, Cd, Mn and relative to the river water
samples. Because the landfill was abandoned recently (in 2009), degradation and other breakdown processes of waste
material may only have just began, suggesting that the uncontrolled and continuous discharge of chloride and some
heavy metal-laden leachate could, in the long-term, substantially impact negatively on the Ramsar Densu wetland and
surrounding water bodies, soil and nearby marine ecosystem.
Cl2
4
PO 
Keywords: Densu Wetland; Ghana; Landfill; Leachate
1. Introduction
Municipal solid waste landfills and the many harzardous
materials or contaminant types they contain could re-
portedly have various adverse effects on environmental
compartments including surface and groundwater re-
sources, soils, fauna and flora as well as human health
[1-7]. Such landfills often produce leachate, i.e. the liq-
uid that usually drains from landfills due to infiltration by
water and/or biogeochemical decomposition processes,
which serves as an important point source of pollution in
many environmental media around the world [8,9]. The
constituents in leachate, some of which may be toxic,
have often posed serious challenges in terms of cost of
treatment, accumulation of metal or species, remediation
and, in particular, possible eco-toxicological implications
resulting from both short- and long-term exposure or bio-
accumulation of leachate constituents.
In Ghana, municipal solid waste from households,
commercial establishments and industries in the city with
varied composition is commonly disposed of at open
mainly un-engineered dump sites or, more frequently,
abandoned quarry sites located in the city [10,11]. In the
Accra metropolis, for example, such landfill sites receive
the over 55% of all solid waste generated that the Met-
ropolitan Assembly (AMA) collects [12]. The Oblogo
landfill, one of many in the Accra Metropolis, is situated
within an abandoned quarry hosted in well bedded rocks
of the Togo Formation [13]. As a result of decomposition
of waste, streams of untreated leachate continuously flow
from the landfill into the surrounding environment [14].
In spite of the possible hazards presented by the appar-
ently uncontrolled seepage and migration of leachate
from many such un-engineered landfills throughout the
country, very few studies have been undertaken, neither
have effective mechanisms been put in place for leachate
control or management. This paper presents data on
leachate from the Oblogo landfill which continuously
seeps and discharges into soils, river (Densu River),
ecologically important Ramsar wetland and nearby ma-
rine environment in the Accra Metropolis, Ghana. The
*Corresponding author.
C
opyright © 2012 SciRes. JWARP

F. K. NYAME ET AL. 623
implications of the uncontrolled discharge of some con-
stituents in the leachate are also briefly discussed.
2. Study Area
2.1. Location and Geographic Elements
The study area is located on approximately latitudes
5˚33'26''N and 5˚33'40''N and longitudes 0˚18'45''W and
0˚18'55''W in the Ga District in south-western Accra,
Ghana (Figure 1). The landfill is situated in an area un-
derlain by the Togo series of rocks which consist of bed-
ded and interbedded sequences of quartzite, phyllite and
schist [15]. The site covers an area of approximately
20,000 m2 on the edge of a ridge about 200 m by road
from Oblogo Township and approximately 1 km off the
major Accra-Takoradi-Half Assini (Accra-Abidjan) high-
way.
The site lies in the coastal savannah zone and has
mean annual rainfall of 800 mm [16]. The rainfall is sea-
sonal with two peaks in June and September. According
to Ghana Meteorological Agency, rainfall up to a maxi-
mum of about 200 mm can occur in one day and much of
that could fall in about one or two hours. The highest
mean monthly temperatures occur between March and
April. Minimum and maximum daily temperatures range
from 22.8˚C to 33.0˚C, respectively. The minimum
yearly average is 24.2˚C with maximum yearly average
of 31.0˚C. The highest monthly mean temperatures occur
in April and the lowest in July. Mean relative humidity is
high within a 24-hr period with relative humidity occur-
ring in January and the highest in August.
The dominant vegetation is shrub and grassland. Thin
grass and occasional patches of shrub characterise the
landfill area. The vegetation grades gradually towards the
Densu River into the surrounding wetland close to the
coast. The wetland, a designated Ramsar site, is rich in
various fish species and rare flora and fauna [17]. Resi-
dential buildings occur quite close to the landfill. Stone
quarrying, fishing and subsistence farming are some
economic activities undertaken by many people in the
area. Others also undertake recycling and scavenging
activities at or close to the landfill. Leachate from the
landfill mainly flows into naturally created sumps where
it is stored temporarily before flowing downslope through
Wast
High Te
Buildin
e M aterial
nsion Line
g
Leachate Sump
Sampling Point
L E G E N D
From Weija
X
Road
0 50 100 150 me tres
To Accra Central
Stormwater Drain
Stormwater Drain
Stormwater Drain
OBLOGO TOWNSHIP
O BL O GO L A N DF IL L S IT E
X
Recycling Activity
G H A N A
INSET
STUDY AREA
Accra
Pro
Leachat
posed wall fence
e flow
Figure 1. Study are a with sampling locations.

F. K. NYAME ET AL. 624
Oblogo Township and parts of the wetland to join the
Densu River about 250 m from the landfill. The river
then flows less than a kilometre through the wetland into
the Atlantic Ocean.
3. Methodology
3.1. Field Work
The study involved sampling and analysing leachate and
river water along approximately 250 m from the landfill
at an interval of about 100 m for six months. The loca-
tion and description of sampling sites are given in Table
1. Sampling was done between January and June, 2004.
A hand-held Global Positioning System (GPS) was used
to locate sampling points. Samples were taken at varying
but designated locations from the landfill site up to where
leachate entered the Densu River through the wetland
system (Figure 1). Samples were collected in the dry
(January to March) and rainy (April to June) seasons
once every month from six sampling points in accor-
dance with protocols on sampling by APHA [18]. Most
samples were collected in plastic bottles and labelled
appropriately. Three samples were taken at each sample
point, one in a 1.5-litre plastic bottle for physico-chemi-
cal analysis, another in a 100 ml plastic bottle acidified
with nitric acid for mainly heavy metal contents and the
third in a standard “ox top” bottle for oxygen demand
parameters. Sample bottles were first rinsed with leachate
or water before carefully dipping individual bottles in
flowing leachate and water at the respective sampling
points. These precautions were taken to reduce contami-
nation. The collected samples were then kept in an ice
chest in the field and later transferred into a refrigerator
until analysis was done.
3.2. Analysis of Leachate and Water Samples
Analytical methods used for leachate and water samples
varied depending on the parameters of interest. All field
and laboratory determinations were done according to
standard methods for the examination of waste and waste
water [19]. For every sample, physico-chemical, nutri-
ents and oxygen demand parameters were determined.
Measurements of physical parameters were taken in situ
by the use of a Water Quality Check U-10 instrument.
Values of measured parameters were read from the digi-
tal display when the Checker U-10 was immersed in the
respective samples.
Physico-chemical parameters were determined at the
Water Research Institute (WRI) of the Council for Scien-
tific and Industrial Research (CSIR, Ghana). Trace met-
als Fe, Mn, Zn and Cd were determined with Unicom
Atomic Absorption Spectrometer (AAS). Samples were
first treated with a mixture of concentrated nitric, sul-
phuric and perchloric acid in a digest and each sample
solution aspirated into a flame and atomized. A light
beam was then directed through the flame into a mono-
chromator and onto a detector that measured the amount
of light absorbed by the element in the flame. A blank
sample (acidified) was also aspirated to set the automatic
zero control. At least six standards were used for each
element. Various samples were then aspirated individu-
ally and the respective concentrations obtained from the
digital display. Concentration of sulphate in the samples
was determined by the sulphate-turbidimetric method. To
100 ml of the sample, 5 ml of conditioning reagent (bar-
ium chloride) was added and stirred for about 60 seconds.
The absorbance was read at 420 nm on a spectrometer.
Concentration of sulphate was then calculated from
standard calibration formula. Phosphate 4

2
PO

was
also determined using the stannous chloride acid method
(APHA, 2005).
Biochemical Oxygen Demand (BOD) was determined
by diluting portions of the sample and incubating for 5
days at 20˚C. The BOD exerted over the 5 days deter-
Table 1. Location and description of leachate and stream or river water samples relative to landfill site, Accra, Ghana.
Sample No.* Description of Sample Point Sample Type** GPS Location~Distance (m) from landfill (Reference Pt.)
OS1 Naturally-created leachate sump Landfill leachate0˚18'44.8''W
5˚33'33.8''N 5
OS2 Artificial (dug) sump Landfill leachate0˚18'49.6''W
5˚33'32.6''N 100
OS3 Natural leachate sump Landfill leachate0˚18'52.8''W
5˚33'31.1''N 200
OS4 Leachate confluence with Densu River River water 0˚18'52.3''W
5˚33'25.8''N 220
OS5 Slightly upstream of leachate
confluence with Densu River River water 0˚18'54.8''W 5˚33'25.1''N 230
OS6 Downstream of leachate confluence
with Densu River River water 0˚18'55.1''W 5˚33'28.1''N 250
*OS1 represents the first leachate sampling point at a sump topographically just below landfill; OS2 sample point along leachate flow path downslope or down
gradient of OS1; OS3 is located along leachate flow path close to a major road linking Oblogo and Weija; OS4 is located in an area where the leachate empties
into the Densu River; OS5 and OS6 are located downstream and upstream of OS4, respectively (Figure 1). **River water = sample taken from Densu River.

F. K. NYAME ET AL. 625
mined as follows:
Calculations
BOD5 = BOD × S1 × S2
where
BOD5 = BOD recorded on the fifth day from the Oxi-
top.
S1 = Dilution factor.
S2 = Factor dependent on total volume of diluted sam-
ple put in Oxitop bottle.
In determining the Chemical Oxygen Demand (COD),
the sample was refluxed in concentrated sulphuric acid
with a known excess of potassium dichromate (K2Cr2O7)
for two hours. After digestion, the remaining reduced
K2Cr2O7 was titrated with ferrous ammonium sulphate to
determine the amount of K2Cr2O7 consumed and the oxidi-
zable matter calculated in terms of the oxygen equivalent.
Microsoft Excel (version 2007) was used to obtain
correlation coefficients between measured physical-che-
mical and nutrient parameters for leachate and river wa-
ter. In addition, the data were subjected to multivariate
statistical analyses [20,21] involving Principal Compo-
nent Analysis (PCA) and Cluster Analysis (CA) using
SPSS (version 12.0).
4. Results
4.1. Physicochemical Data for Landfill Leachate
Data on parameters from leachate samples taken during
the study are presented in Table 2(a). pH values of
leachate range from 6.6 close to the landfill (~5 m) in
January to 7.9 (mean 7.4) in Aprilat a distance of 200 m
from the landfill. Throughout the sampling period as well
as outwards from the landfill, the pH of leachate thus
remained fairly uniform. Temperature values also range
from a minimum of 27.8˚C in April at distance 5 m to a
maximum of 35.3˚C in January at the same sampling site,
i.e. 5 m from the landfill. Even though minor differences
occur up to about 100 m from the landfill, the values in
general suggest not much change in temperature of
leachate with respect to sampling period or distance from
the landfill site. The lowest and highest conductivity
values of 7960 and 24,890 µS/cm were obtained in
leachate taken respectively in March (distance 5 m) and
June (distance 100 m) from the landfill. Range of values
for total dissolved solids (TDS), salinity and turbidity of
leachate were as follows; TDS 1124 mg/l in April at
about 100 m from the landfill to 13,200 mg/l also in
April at about 100 m from the landfill; salinity 0.18% in
June at 200 m from landfill to 2.02% in April at 5 m
from landfill; turbidity 3.1 NTU in June at 200 m to 60.1
NTU in April at 100 m (Table 2(a)).
Fe concentrations in leachate ranged from 2.05 - 18.0
mg/l at 200 m and 5 m, respectively, from the landfill,
the lowest value in April and the highest in January (Ta-
ble 2(a)). Cadmium, Zinc and manganese also varied
from 0 - 2.45 mg/l (distance 100 m and 5 m both in Janu-
ary), 0.02 - 0.28 mg/l (distance 100 m in February and 5
m in January) and 0.12 - 0.94 mg/l, respectively.
Both the minimum (0.12 mg/l) and maximum (0.94
mg/l) Mn values were obtained at more than one site
(Table 2(a)). Calcium and chloride contents ranged from
160 - 356 mg/l (mean 276.7 mg/l) and 1030 - 2967 mg/l
(mean 2291 mg/l), respectively, whilst total hardness also
ranged from 104 to 1300 mg/l (mean 889.7 mg/l). The
highest Ca2+ value was obtained in March in leachate
sample taken about 5 m from the landfill and the lowest
in January about 200 m from the landfill. Chloride in
leachate (Table 2(a)), on the other hand, registered the
highest and lowest values in June, the former nearer the
landfill (distance 5 m) and the latter farther away (dis-
tance 200 m).
The nutrient contents of leachate, as given by concen-
trations of 4, 4
2
PO -P
2
SO

and 3 (Table 2(a)),
also showed variations with respect to distance from the
landfill and sampling period. 4 contents ranged
from 8.23 mg/l in April at about 200m from the landfill
to 30 mg/l in January about 100 m from the landfill. The
highest concentrations of SO4
2− (68.3 mg/l) and
3 (41.52 mg/l) were both obtained in January at
site 5 m from the landfill whilst the lowest (i.e. 4
NO -N

2
PO -P

NO -N

2
SO

28.6 mg/l and 1.03 mg/l) were also obtained in
June with the 4
3
NO -N

2
SO

at 200 m and 3 at 100 m
from the landfill. The oxygen demand parameters DO,
BOD and COD also exhibited variations with respect to
sampling site and period but were generally characterised
by low values (Table 2(a)).
NO -N

2
PO -P
2
SO
4.2. Physicochemical Data for River (Densu)
Water
Table 2(b) gives data from water samples taken from the
Densu River into which leachate egresses (see Figure 1).
Except for Cd and Zn that were generally below detec-
tion, the data show perceptible variations with respect to
site and period of sampling. pH ranged from 6.6 - 8.1
(mean 7.5), temperature 27.8˚C - 31.2˚C (mean 29.4),
conductivity 610 - 1903 µS/cm, TDS 102 - 450 mg/l,
salinity 0.01% - 0.13% and turbidity 2.0 - 45.1 NTU. Fe
and Mn ranged from 0.12 - 1.23 mg/l and 0.12 - 0.92
mg/l, respectively. Calcium, chloride and total hardness
also ranged from 23 - 70 mg/l (mean 36.1 mg/l), 59 - 105
mg/l (mean 81.8 mg/l) and 60 - 140 mg/l (mean 104.7
mg/l), respectively. Other variations were as follows;
4 0.15 - 10 mg/l (mean 2.23 mg/l), 4

16.1 -
33.8 mg/l (mean 25 mg/l), 3 (0.23 - 21.02 mg/l
(mean 5.6 mg/l), DO 0.26 - 1.64 mg/l (mean 0.94 mg/l),
BOD 0.03 - 1.04 mg/l (mean 0.20 mg/l) and COD 0.12 -
.93 mg/l (mean 0.93 mg/l).
NO -N

1

F. K. NYAME ET AL. 626
Table 2. (a) Physico-chemical data from landfill leachate from January to June, 2004, Accra, Ghana; (b) Physico-chemical
data from River water from January to June, 2004, Accra, Ghana.
(a)
Month Spl. Pt pH Temp
(˚C)
Cond.
×103
(μS/cm)
TDS
×103
(mg/l)
Salinity
(%)
Turb.
(NTU)
Fe
(mg/l)
Cd
(mg/l)
Zn
(mg/l)
Mn
(mg/l)
Ca2+
(mg/l)
Cl

(mg/l)
Total
Hard
(mg/l)
2
4
PO -P

(mg/l)
SO2
4

3
NO -N

(mg/l) (mg/l)
DO
(mg/l)
BOD
(mg/l)
COD
(mg/l)
OS1 6.61 35.3 21.61 10.80 1.31 41.0 18.002.450.280.122412730100022.8068.30 41.52 0.630.811.28
OS2 7.59 28.3 24.82 7.58 0.88 36.2 14.000.000.180.15168193680030.0063.20 33.03 0.990.361.23
Jan
OS3 7.68 28.3 23.13 9.01 0.95 31.2 9.780.050.120.14160198660017.0043.10 26.01 0.420.762.01
OS1 7.57 32.3 24.28 12.46 1.52 55.0 10.201.230.070.193482878120018.6063.70 15.23 0.510.231.32
OS2 7.61 29.4 15.12 8.97 1.12 48.1 10.100.010.020.35326235690017.3058.50 14.76 0.480.311.41
Feb
OS3 7.54 28.7 16.83 9.66 0.98 21.1 5.870.080.090.12189178211011.3048.90 12.53 0.470.121.23
OS1 7.63 32.7 7.96 10.79 1.51 56.1 8.780.980.050.233562913110018.9065.10 5.02 0.130.211.04
OS2 7.65 29.5 8.23 8.62 1.01 43.0 5.890.210.060.323422798100014.9056.30 4.89 0.520.420.43Mar
OS3 7.58 28.8 18.34 4.22 0.54 23.1 4.980.030.030.28289118990011.8044.00 2.43 0.390.811.03
OS1 7.75 27.8 24.43 13.20 2.02 54.9 6.320.780.040.342872889120016.0059.90 4.25 0.180.121.06
OS2 6.98 28.7 20.03 1.12 1.68 60.1 4.320.520.030.942912098100017.0049.40 9.03 0.380.250.96 Apr
OS3 7.87 29.6 18.34 9.08 0.64 56.1 2.050.430.020.1232112348008.2342.30 8.05 0.090.210.86
OS1 7.65 29.8 24.28 11.22 1.98 48.9 5.320.460.030.723422798130016.5052.20 3.23 1.021.031.89
OS2 7.36 27.8 21.74 11.88 1.23 50.9 4.820.620.020.453292869100020.0049.00 9.23 0.480.931.07May
OS3 6.79 29.4 20.04 11.24 0.56 35.7 3.480.640.030.2316226911049.4632.80 8.24 0.280.960.89
OS1 7.21 32.2 23.87 10.90 2.01 52.9 6.980.380.040.233212967110012.1040.80 3.02 0.920.781.74
OS2 7.13 30.1 24.89 12.45 1.02 56.8 6.050.640.050.943402106100010.2032.70 1.03 1.020.341.29 Jun
OS3 7.77 28.8 20.65 1.26 0.18 3.1 5.890.840.070.6716910309009.3428.60 9.01 1.030.560.89
WHO
limit 6.5 - 8.5 - -
1000 - 5 3 0.0033 0.50200250500- 400 10 - -
(b)
Month Spl. Pt pH Temp
(˚C)
Cond.
×103
(μS/cm)
TDS
(mg/l)
Salinity
(%)
Turb.
(NTU)
Fe
(mg/l)
Cd
(mg/l)
Zn
(mg/l)
Mn
(mg/l)
Ca2+
(mg/l)
Cl

(mg/l)
Total
Hard
(mg/l)
2
4
PO -P

(mg/l)
SO2
4

3
NO -N

(mg/l) (mg/l)
DO
(mg/l)
BOD
(mg/l)
COD
(mg/l)
OS4 6.56 29.7 610 402 0.02 2.6 0.860.010.010.472575 12010.0028.80 10.89 1.640.081.68
OS5 7.69 29.9 870 450 0.04 3.0 0.780.030.020.462678 1308.5830.10 20.78 1.580.051.32
Jan
OS6 7.84 30.1 790 305 0.03 2.7 0.870.020.030.512873 1405.0229.30 10.41 1.610.061.93
OS4 8.13 27.9 830 308 0.13 4.3 0.45BDBD0.152887 1090.6433.80 0.35 0.750.141.49
OS5 7.89 28.8 740 360 0.09 3.7 0.41BDBD0.132579 1080.3427.00 0.41 0.690.151.85
Feb
OS6 7.97 29.5 630 415 0.08 4.1 0.32BDBD0.182585 1080.1527.00 0.95 0.730.111.34
OS4 8.02 28.6 670 424 0.05 3.2 0.14BDBD0.182459 1090.1823.70 0.56 0.480.121.06
OS5 7.98 29.1 710 209 0.08 3.0 0.12BDBD0.162376 1070.1628.40 0.82 0.670.090.98Mar
OS6 6.99 28.4 740 322 0.07 2.3 0.13BDBD0.122474 1080.1929.70 0.68 0.630.071.06
OS4 7.94 30.4 850 428 0.01 45.1 0.21BDBD0.3432971202.0425.50 1.08 1.030.091.23
OS5 6.89 29.8 980 354 0.03 7.0 0.19BDBD0.182487 1103.7830.60 1.05 1.120.030.84
Apr
OS6 7.58 28.5 780 352 0.02 7.1 0.19BDBD0.922859 1001.7829.40 0.96 0.940.060.67
OS4 6.97 27.8 1080 122 0.08 4.0 0.12BDBD0.466289 1001.0518.90 0.23 0.260.030.21
OS5 7.02 30.4 690 328 0.02 4.7 0.17BDBD0.285997 1021.8919.10 0.34 0.961.040.12May
OS6 7.12 31.2 790 425 0.04 2.7 0.23BDBD0.617076 1041.2917.90 1.23 0.850.380.14
OS4 6.69 28.4 1903 102 0.05 2.9 1.23BDBD0.2134 105 800.6916.10 21.02 1.050.340.28
OS5 7.56 29.6 1480 403 0.03 2.0 1.02BDBD0.1642 100 701.0517.20 20.03 1.010.450.31
Jun
OS6 8.12 31.2 1263 324 0.04 2.7 0.23BDBD0.617076601.2918.20 8.56 0.850.380.14
WHO
limit 6.5 - 8.5 - -
1000 - 5 3 0.0033 0.50200250500- 400 10 - -
B
D: below detection. Distances of sample sites from landfill: OS4: 220 m; OS5: 230 m; OS6: 250 m.

F. K. NYAME ET AL. 627
4.3. Comparison of Data with WHO and UNEP
Values
Compared to WHO [22] and WHO/UNEP [23] values,
leachate and river water in the present study appear to
have fairly high conductivity and, to some extent, high
Mn, Ca and Cl contents. Leachate, however, registered
total hardness values above WHO guideline values
whereas corresponding river water values were below
WHO values (see Table 2). Comparatively low values in
river water than leachate probably reflect the extent of
dilution in the river water compared to the narrower, low
volume and channelized leachate.
4.4. Correlation Coefficients
Table 3 gives the correlation coefficients between meas-
ured parameters determined in leachate and river water
samples. In leachate samples, strong to moderate positive
correlations appear to exist mainly between 3
and Zn (0.96), 3 and Fe (0.85), 3 and
4 (0.67), Zn and Fe (0.86), Cl and each of
TDS (0.69), salinity (0.74) and turbidity (0.60) and
4 and Fe (0.75). Ca2+ also correlates positively
with turbidity (0.73) as are Cd and temperature (0.75)
and turbidity and salinity (0.69). Similar positive correla-
tions also exist between 4 and each of Fe (0.64) and
4 (0.78). Other relationships vary from weak to
only slightly positive or negative (Table 3). The river
water samples also show positive relationships between
and DO (0.61), 4
SO and COD (0.79),
and DO (0.85), total hardness and each of
4
NO -N

NO -N
NO -N 
2
PO -P

2
PO -P

2
SO 
2
PO -P

3
NO -N
2
2
4
PO -P

2
SO

(0.69) and COD (0.74), Fe and (0.89),
Fe and DO (0.64) and conductivity and 3 (0.65).
Negative correlations are also shown by the pairs
3
NO -N

NO -N

2
4
PO -P
2
4
SO 
3-N

Table 3. Correlation coefficients between measured parameters in landfill leachate (above) and river water samples (below),
Accra, Ghana.
pH Temp. (˚C)
Cond.
(mS/cm)
TDS
(mg/l)
Salinity
(%)
Turb.
(NTU)
Fe
(mg/l)
Cd
(mg/l)
Zn
(mg/l)
Mn
(mg/l)
Ca2+
(mg/l)
Cl-
(mg/l)
Total
Hard
(mg/l)
(mg/l) (mg/l)
NO
(mg/l)
DO
(mg/l)
BOD
(mg/l)
COD
(mg/l)
pH –0.45 –0.20 –0.09 –0.11 –0.16 –0.25–0.52–0.35–0.150.13–0.320.19–0.080.05 –0.28 –0.10–0.360.00
Temp.
(˚C) 0.07 –0.11 0.30 0.29 0.26 0.550.750.46–0.240.290.400.290.160.39 0.30 0.07 0.080.15
Cond.
(mS/cm) –0.24 –0.08 0.17 0.20 0.04 0.130.130.190.20–0.25–0.020.120.12–0.21 0.22 0.47 0.280.54
TDS
(mg/l) 0.30 0.50 –0.50 0.44 0.49 0.160.240.03–0.320.320.690.090.120.29 –0.01 –0.110.050.29
Salinity
(%) 0.32 –0.61 –0.09 –0.34 0.69 0.13 0.20–0.080.14 0.530.74 0.58 0.310.49 –0.13 0.01 –0.070.41
Turb.
(NTU) 0.20 0.21 –0.07 0.23 –0.33 –0.050.17–0.260.170.730.6 0.510.200.37 –0.20 –0.26–0.240.07
Fe (mg/l) –0.22 –0.01 0.56 –0.10 –0.16 –0.21 0.470.86 –0.37 –0.200.240.160.75 0.64 0.85 0.25 0.000.32
Cd (mg/l) – - - - - - - 0.52–0.040.090.350.300.190.33 0.37 –0.010.10–0.08
Zn (mg/l) - - - - - - - - –0.37–0.460.02–0.080.580.43 0.90 0.26 0.080.17
Mn (mg/l) –0.05 0.32 –0.06 0.10 –0.48 0.03 –0.06- - 0.26–0.080.35–0.20–0.38 –0.45 0.41 0.03–0.03
Ca2+(mg/l) –0.16 0.45 0.28 –0.16 –0.17 –0.08 –0.19- - 0.39 0.420.71 –0.040.29 –0.51 –0.12–0.17–0.07
Cl–(mg/l) –0.28 0.06 0.59 –0.32 0.00 0.28 0.37- –
–0.430.23 0.340.370.50 –0.02 –0.060.150.18
Total.
Hard
(mg/l)
0.04 –0.03 –0.67 0.29 –0.02 0.21 –0.04- - 0.01–0.53–0.30 0.300.39 –0.17 0.23 –0.030.12
2
4
PO -P

2
4
SO 
3
NO -N

(mg/l) –0.31 0.30 –0.18 0.32 –0.46 –0.02 0.43- -
0.34–0.19–0.130.50 0.78 0.67 0.14 –0.010.19
(mg/l) 0.26 –0.27 –0.61 0.27 0.27 0.07 –0.14- -
–0.09 –0.76 –0.43 0.69 0.33 0.46 –0.23–0.300.02
(mg/l) –0.18 0.14 0.65 –0.05 –0.31 –0.21 0.89- -
0.06–0.030.32–0.200.46–0.27 0.11 0.070.24
DO
(mg/l) –0.19 0.46 0.02 0.32 –0.57 0.05 0.64 - -
0.29 –0.24 0.040.400.85 0.26 0.61 0.310.37
BOD
(mg/l) –0.18 0.40 0.20 –0.02 –0.26 –0.13 0.04- -
–0.050.59 0.43 –0.44–0.19–0.62 0.09 –0.02 0.34
COD
(mg/l) 0.33 –0.18 –0.53 0.32 0.24 0.11 0.17- -
–0.22–0.8 –0.32 0.74 0.370.79 –0.07 0.36 –0.58
B
oldface = significance at 0.01 level; Italics = significance at 0.05 level.

F. K. NYAME ET AL. 628
Ca2+ and 4 (–0.76), Ca2+ and COD (–0.76), conduc-
tivity and total hardness (–0.67), conductivity and 4
2
SO 
2
SO

(–0.61), temperature and salinity (–0.61) and 4
2
SO

and
BOD (–0.62). Other pairs of parameters seem to show
little or no correlations with one another (Tabl e 3).
4.5. Multivariate Principal Component (PCA)
and Cluster Analyses (CA)
4.5.1. PC A and CA for Leachate
The dendrogram for leachate samples (Figure 2) sug-
gests three distinct clusters. Cluster 1 consists of pH, Mn,
BOD, DO, COD and electrical conductivity (EC). Clus-
ter 2 comprises TDS, Cl, Salinity, total hardness, Ca,
turbidity and Cd whilst cluster 3 is made up of tempera-
ture, , , Fe, and Zn.
2
4
POSO 3
4

3
NO
Cl
Varimax rotation of the landfill leachate data is pro-
vided in Table 4 and the scree plot in Figure 3. Principal
component 1 (PC1), which explains ~23% of the vari-
ance, consists of TDS, salinity, turbidity, Ca,
controlled by TDS, DO, BOD and COD whilst PC4 con-
sists of pH, temperature and Cd. There is a negative
loading of pH as compared to a positive loading of Cd.
PC5 loading is made up of Mn, total hardness and DO.
4.5.2. PCA and CA for River (Densu) Water

, total
hardness & . High loading on Ca and total hard-
ness suggests that calcium probably contributes mostly to
the hardness of the leachate whereas 4 and
2
4
SO 
2ClSO

also suggest increased significance of agricultural and/or
organically derived inputs. PC2 loading comprises Fe, Zn,
, and . There is strong correlation
between cluster 3 and PC2 suggesting that the presence
of the metals Fe and Zn in leachate could have come
from a common source in the landfill waste or material.
, and 3 are all likely sourced from ag-
ricultural or organic wastes in the landfill pile. PC3 is
3
4
PO 
3
4
PO 
2
4
SO
2
4
SO

3
NO
NO
2
SO
The interrelationships between the various parameters
measured for the river water samples are given by the
dendrogram (Figure 4) three different clusters. Cluster 1
consists of mainly 4

, COD, total hardness, TDS, pH,
turbidity and salinity. Cluster 2 comprises 4
2
PO

, DO,
temperature and Mn whilst cluster 3 is made up of Fe,
3

, electrical conductivity, Cl, Ca, and BOD. NO
Table 5 and scree plot (Figure 5) suggest that up to
~89% of the original mean logs of the dataset is gathered
in the first six components with Eigen values > 1. Prin-
cipal Component 1 (PC1) gives ~27% of the variance
and the parameters that are loaded in this component
include electrical conductivity, Ca, total hardness, 4
2
SO

and BOD. High loading of sulphate to water chemistry
suggests contribution from agricultural activities such as
use of fertilizers. PC2 consists of mainly electrical con-
ductivity, Fe, 3
NO

and DO. High loadings of Fe may
suggest dissolution of Fe-bearing bedrock in river water
since the Densu River is known to drain iron-rich Biri-
mianmetasedimentary and metavolcanic rocks in the
eastern region of Ghana. Again, anthropogenic activities
may not also be ignored as suggested by the high loading
on nitrate. PC3 is loaded with temperature, TDS, salinity
and DO whilst PC4, PC5 and PC6 are loaded with Cl

,
pH and turbidity, respectively.
Rescaled Linkage Distance
0 5 10 15 20 25
Zn
N
O
3
-N
Fe
PO
4
-P
SO
4
Temp
Cd
Turb
Ca
Total Hard
Salinity
Cl
TDS×10
3
Cond
COD
DO
BOD
Mn
p
H
Dendrogram of landfill leachate parameters. Figure 2.

F. K. NYAME ET AL. 629
able 4. Rotated component mat
Component
Trix for landfill leachate
data.
1 2 3 4 5
pH 0. 0. –
–0.
T
Salinity
Total Hard
N-NO
Eigenvalues
% ce
02000.22 0.83 05
emp 0.32 0.34 –0.09 0.73 –0.02
Cond 0.01 0.08 0.80 0.02 0.15
TDS 0.62 0.03 0.23 0.15 –0.55
0.87 0.12 0.21 0.02 0.06
Turb 0.86 –0.07 –0.10 0.08 0.01
Fe 0.03
0.92 0.13 0.27 –0.03
Cd 0.19 0.32 –0.09 0.81 0.09
Zn –0.27 0.82 0.14 0.39 –0.06
Mn 0.10 –0.42 0.17 0.04 0.78
Ca2+ 0.81 –0.23 –0.29 0.01 0.27
Cl– 0.78 0.11 0.12 0.31 –0.26
0.67 0.17 –0.02 –0.010.62
PO4-P 0.25
0.85 0.09 –0.07 0.05
SO42– 0.51 0.75 –0.31 –0.02 –0.11
3– –0.28
0.86 0.16 0.22 –0.18
DO –0.14 0.15 0.62 0.06 0.56
BOD –0.13 –0.16
0.60 0.35 –0.07
COD 0.23 0.21 0.79 –0.14 -0.10
4.296 4.159 2.471 2.429 1.832
of Total varian22.61 21.89 13.00 12.789.64
Cumulative % 22.61 44.50 57.51 70.29 79.93
5. Discussion and Environmental
Implications
e eight ionic specThies dominant in leachate, i.e. Ca, Cl,
, SO4 and NO3 are the most sig-
SO4 (PC1), Fe, Zn, PO4, SO4, NO3 (PC2), Cd (PC4) and
Mn (PC5) (Table 4) suggest decomposition of landfill
materials through a combination of physico-chemical
(inorganic) and biological (organic) processes and sub-
sequent release into the effluent discharge or leachate.
The seasonally wet and dry climate, together with the
generally heterogeneous, unsorted or mixed nature of
refuse dumped at the landfill site, may have enhanced
leaching of both organic and inorganic constituents of
decomposing waste by percolating rain water. Tigme [14]
characterized waste at the Oblogo landfill site into
dominantly organic components (70%) followed succes-
sively by inert material (13%), plastics (9%), metal
scraps (4%), paper (3%) and textile products (1%). The
Togo host rocks [15] within which the landfill is situated
is dominantly composed of quartzite and sandstone and
may, hence, not contain significant amounts of ionic spe-
cies such as observed in leachate, suggesting that most of
these species were derived from refuse at the landfill.
Though the proportion metals in the waste stream is low
[14], the fairly significant presence of some metals in
leachate may be an indication of the extent of decompo-
sition of the metallic constitutents of the waste. The rela-
tively high Ca, Cl and nutrient contents are likely remi-
niscent of decomposition from the high agricultural or
organic inputs of waste.
In river water, Fe, Mn
Scree Plot
6
5
4
3
2
1
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Component Number
Eigenvalue
Figure 3. Scree plot of eigenvalues for landfill leachate.

F. K. NYAME ET AL. 630
Rescaled Linkage Distance
0 5 10 15 20 25
Fe
N
O
3
-N
Cond
Cl
Ca
BOD
PO
4
-P
DO
Temp
Mn
SO
4
COD
Total Hard
TDS
p
H
Turb
Salinity
Figure 4. Dendrogram for river water data.
Table 5. Rotated component matrix for river water data.
Component
nificant species. Because the Densu River drains a sig-
nFe Mt Ban rocks
[1wo elements could have been sourced from
oted chloride concentrations of
10
achate collection systems in place, continuous
di
ificant portio
5], these t
n of and n-con ainingirimi
1 2 5 6 3 4
p
the dominant underlying geological formation. Again,
increased human activities such as use of fertilizers in
subsistence agriculture in the Densu River catchment
area may have contributed significant SO4 and NO3 con-
tents to the river water.
Farquhar [1] who provided data on expected contami-
nant types and ranges of concentrations in leachate as
function of refuse age n
H 0 – 0. 0. 0. 0.
p
y
ard
4
2
4
SO 
3
NO
DO
alue
27.43 18.76 15.41 10.31 9.167.79
e
% 27.43 46.19 61.60 71.91 81.07 88.86
.17 0.14120092 06
Tem–0.29 0.07 0.85 0.14 0.01 0.15
Cond –0.58 0.66 –0.38 –0.08 0.010.17
TDS 0.29 –0.09 0.77 0.06 0.28 0.03
Salinit0.18 –0.25 –0.57 –0.39 0.34 –0.37
Turb 0.11 –0.15 0.17 –0.03 0.090.95
Fe 0.06 0.95 0.00 –0.13 –0.11–0.09
Mn –0.16 0.02 0.20
0.91 –0.10 0.04
Ca2+ –0.85 –0.16 0.19 0.18 –0.12–0.04
Cl– –0.38 0.34 –0.07
–0.65 –0.24 0.41
Tot H0.83 –0.15 0.22 0.04 –0.24 0.09
PO-P 0.45 0.45 0.43 0.32 –0.44–0.05
0.91 –0.15 –0.02 0.05 0.08–0.05
-N –0.12 0.96 0.08 0.03 –0.04–0.07
0.36 0.65 0.53 0.18 –0.29 0.05
BOD –0.69 –0.03 0.43 –0.37 –0.19–0.15
COD 0.92 0.08 0.09 –0.11 0.19–0.03
Eigenv4.664 3.188 2.619 1.753 1.558 1.324
% of Total
Variance
Cumulativ
00 - 3000 mg/l for landfills in age category 0 - 5 years.
Because chloride contents obtained in leachate in this
study agrees fairly well or falls within this range, it could
reasonably be predicted that various physico-chemical
and biological decomposition processes within the land-
fill may result in increased pollutant levels in leachate
which would, in turn, be shed into the surrounding media
for well some time before decreases in concentrations
could be expected as the landfill ages [1]. As observed by
Mizumura [24], chloride ion is non-reactive, non-sorp-
tive and has no redox or precipitation. This suggests that
much of the chloride in the leachate plume will find its
way into the surrounding river and groundwater as well
as soils.
Because the rocks in which the landfill is situated are
highly bedded [15], the landfill not engineered [11]
andno le
scharge of leachate may pose serious threats to the
surrounding soils, water bodies, the Densu Ramsar wet-
land area and also possibly on the health of people who

F. K. NYAME ET AL. 631
Scre e Plot
5
4
3
2
1
0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
Component Number
Eigenvalue
Figure 5. Scree plot of eigenvalues for river water.
depend a lot on the environmental
5]. Furthermore, local communities and especially the
have pointed
ou
y from pollutants in leachate or
through bioaccumulation of leachate constituents in liv-
ave been documented by
w
Metropolis and throughout the
co
resources of the area some resulting directl
[2
urban poor who live around the landfill utilize water
(from rivers, streams, shallow wells and boreholes) and
soils for domestic and subsistence agriculture. Others
also undertake fishing activities as a means of livelihood
[26]. Food crops grown and the fish obtained from these
areas mainly go to feed the urban population. Leachate
also egresses through many low-income residential areas,
presenting potential threats to the health of people espe-
cially children who constantly attend school in or play
around such leachate contaminated areas.
Authors including Combs Jr. [27], Nordberg & Che-
rian [28], Frew [29] and Kurniawan [30]
t adverse health effects of substances such as cadmium,
chloride and zinc all of which occur in the leachate sam-
ples studied. As noted by Oteng-Yeboah [17], the wet-
land is known to be very rich in various species of fauna
and flora and therefore deserves maximum protection,
not the least from contamination through landfill leachate
which could be controlled or managed. Loss of biodiver-
sity in the internationally recognized Densu Wetland as a
result of pollution from the landfill leachate could also
not be entirely ruled out. Assessment techniques to pro-
vide information on early warning indicators of pollution
in the wetland, as suggested by Van Dam et al. [31],
could provide an important first step towards sustainable
management of this ecologically important wetland and
surrounding environment. Kao et al. [32] also suggested
using network Geographic Information System (GIS) for
the siting of landfills in order to reduce the potential for
spread of infection through run off during rain as well as
groundwater contamination.
Effects of landfill leachate on surrounding media,
ing organisms over time, h
orkers such as Schrab et al. [6], Stephens et al. [33],
Kjeldsen et al. [4]. Kurniawan et al. [34-36] have worked
extensively on recalcitrant contaminants in landfill
leachate especially those that pose serious hazards not
only to living organisms but also to public health in the
long term. In Uganda, Nigeria and many other countries
[8,9,37], the potential effect of leachate on surface and
groundwater resources could be very significant. Rocks
within which the landfill is located have a well bedded
structure [38,39] and, in addition, typically weather into
permeable sandy to silty soils. In addition, absence of
bottom liners and artificially constructed drains to trap
and channel leachate into channelized flow, respectively,
likely promote increased infiltration of leachate into the
surrounding environment.
Research to investigate the distribution and possible
attenuation of hazardous substances in uncontrolled
leachate from landfills [40], especially if done at many
such landfills in the Accra
untry, could help provide invaluable data for remedia-
tion efforts. In addition, assessment of the spatial vari-
ability in leachate migration from landfills along the lines
done by Kjeldsen [4] in Denmark could help identify
plumes of pollution that may be contaminating various
media around landfills. Finally, because chloride is non-
reactive, non-sorptive and has no redox or precipitation,
it is often used as a tracer element in leaching studies in
soils [24,41,42]. Mizumura [24], in particular, investi-
gated the influence of leachate plumes from sanitary
landfills on groundwater by determining the concentra-
tion of chloride ion in the groundwater, soil water and

F. K. NYAME ET AL. 632
river and observed that most of the leachate plume was
discharged into a river whilst the remainder infiltrated
into the ground through the weathered geological layer
near the landfills. Such investigations may also be rele-
vant in the present situation given that untreated leachate
not only directly drains into the Densu River and adjoin-
ing Ramsar wetland (at a distance less than 0.3 km from
the point or landfill source) but also egresses continu-
ously through households, soils and possibly into the
groundwater system in the area.
6. Conclusion
The current study has revealed fairly high levels of ionic
constituents including Cl, SO,
4PO4, NO3 and moderate
Ca, Cd and Zn in leachate discharge
from the Oblogo landfill site in Accra
rsity of Ghana in
uirements for the award of
ental Science De-
za-
16,
No. 3, 1989, pp.
d to high contents of
without treatment
into the immediately surrounding environment, a situa-
tion which makes the area very vulnerable to pollution.
The significantly high concentrations of chloride and, to
some extent, other chemical species, present formidable
challenges that may need to be addressed in order to
minimize possible short- and long-term stresses on the
immediate environment. It is suggested that simple but
cost-effective techniques such as construction of manu-
ally excavated holes or ponds (“dug-outs”) in the vicinity
of the landfill to impound leachate for considerable pe-
riod of time could provide a necessary first step towards
facilitating natural breakdown or settling of some con-
stituents in leachate. The “environmental cost” of any
such initiative could, under the circumstances, be a much
better option than the present indiscriminate and uncon-
trolled discharge of leachate into the immediate ecologi-
cally important Ramsar environment. Ultimately, the
risks posed by possible organic contaminants, pathogenic
microorganisms and other toxic substances that may ad-
ditionally be present in leachate would have to be ana-
lyzed and/or monitored to also prevent or minimize their
impact on the environment. In addition, it may be neces-
sary to study the leachate migration patterns in tandem
with leachate composition to gather information for fu-
ture planning and remediation efforts.
7. Acknowledgements
Data used in the study was part of the M.Phil. Thesis
work submitted by J. T. to the Unive
partial fulfillment of the req
the Master of Philosophy in Environm
gree for which we are very grateful. The Environmental
Protection Agency of Ghana (EPA Ghana), Accra Met-
ropolitan Assembly (AMA), the Water Research Institute
(WRI) of the Council for Scientific and Industrial Re-
search (CSIR), many other organizations and people who
contributed in diverse ways towards data collection,
analysis, and interpretation as well as during preparation
of the manuscript are all gratefully acknowledged. Fi-
nally, constructive criticisms by anonymous reviewers
helped improve the quality of the paper considerably.
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