Journal of Environmental Science and Water Resources
Vol. 3(5), pp.104 - 109, June 2014
ISSN 2277 0704
2014 Wudpecker Journals
Pollution assessment of sediment metals from the
middle region of the Ogun River, Nigeria
Diayi, M.A, Gbadebo, A.M.
Department of Environmental Management & Toxicology, University of Agriculture, P.M.B. 2240, Abeokuta, Ogun-State,
Nigeria.
*Corresponding author E-mail: [email protected], +2348063517259
Accepted 15 April 2014
Metal concentrations were determined for sediment samples obtained from depths of 0 to 5cm, 5 to
10cm and 10 to 15cm at Lafenwa, Arakanga Old Scheme, Arakanga New Scheme and Oyan. Samples
were obtained using Van Veen sediment grab after which they were stored in well labeled polythene
bags. pH and conductivity, were determined in-situ using standard methods by American Public Health
Association while Wakley and Black Method was used to determine organic carbon. Induced Couple
Plasma Mass Spectrometry (ICP/MS) was used to determine the metal concentrations. Sediment metal
concentrations from Lafenwa 0 to 5 cm (201 ppm), Arakanga 10 to 15 (263 ppm), Arakanga New Scheme
5 to 10 cm (135 ppm) and Arakanga New Scheme 10-15 cm (249 ppm) exceeded the Environment
Canada Sediment Quality Guideline standard (123.00 ppm). Cr values from Lafenwa (81.00 ppm), Oyan 0
to 5 cm (44.00ppm), Oyan 5 to 10cm (45.00 ppm) and Oyan 10 to 15 cm (60.00 ppm) exceeded the
standard limit (37.50ppm). Igeo result obtained showed very highly polluted status for Pb from Lafenwa
0-5cm (24.60). Similarly, contamination factor analysis also showed very highly polluted status for Pb
(121.8) and Cu (9.2) from Lafenwa 0 to 5cm and Pb (5.5) from Lafenwa 5 to 10cm. Sediments from
Lafenwa 0 to 5cm and Lafenwa 5 to 10 cm should be monitored frequently.
Key words: Sediment, metal concentration, geochemical, Ogun River, pollution.
INTRODUCTION
Bottom sediments consist of particles that have been
transported by water, air or glaciers from the sites of their
origin in a terrestrial environment and have been
deposited on the floor of a river, lake or ocean (Pravin et
al., 2011). The continuous growth in human population
and attendant sophistication in the commodities and
materials consumed have led to the generation of
substantial wastes of unprecedented quantities. The
nature of wastes had moved from mere nuisance to being
toxic and hazardous (Olatunji and Abimbola, 2010).
According to Lin et al. (2003), Sediment plays an
important role both as sink where heavy metals can be
stored and as a source of heavy metals to the overlying
water. Most heavy metals discharged into rivers are
found to deposit in bottom sediments via the complex
physical, chemical and biological processes.
However, the accumulated heavy metals may be
remobilized from sediments by natural and man-made
processes, which can pose a risk to the aquatic
ecosystem. Heavy metals have a great ecological
consideration due to their toxicity and accumulation
behavior (Purves, 1985). Metals in rivers, lakes or any
aquatic environment can change both aquatic species
diversity and ecosystem due to their toxicity and
accumulative behavior. Sediments have recently been
considered as diffuse sources of environmental
contaminants (Baudo et al., 1990).
Aquatic organisms such as fish are capable of
accumulating heavy metals in their living cells to
concentrations much higher than those present in water,
sediment and microflora in their environment (Forstner
and Wittmann, 1981). Heavy metals in fishes increase
with the increment of metal levels in water, sediment and
fish food organisms (Arvind, 2002).
Heavy metals like Cu, Co, Zn, Fe and Mn at low
concentrations are essential metals for enzymatic activity
and many biological processes. Other metals like Cd, Pb,
and Hg have no known essential role in the body of living
organisms, and are toxic even at low concentrations.
Copper is used as an algaecide to control algal growth.
Since algae are at the base of the food chain, the
amount of algal biomass present in an aquatic ecosystem
will affect the amount of food available for aquatic
animals including zooplankton, insects, fish and aquatic
105
J. Environ. Sci. Water Resources
mammals. Copper affects olfaction (sense of smell) in
fish by competing with natural odorants for binding sites,
thereby affecting activation of the olfactory receptor
neurons or by affecting intracellular signaling in the
neurons (Baldwin et al., 2003). This reduces the ability of
fish to detect predators which makes them vulnerable to
predation.
DWAF (1996) stated that Lead is bioaccumulated by
bacteria, fresh water plants, invertebrates and fish. In the
hematopoietic system, lead poisoning may result from;
the impairment of heme (a precursor of haemoglobin)
synthesis, an increased rate of red blood cell destruction
and an inability of red blood cells to transport basic cell
nutrients (sodium and potassium ions) into and out of the
cells (Hasan et al., 1967).
Cr is a human and animal carcinogenic agent; its
biological effects depend on chemical form, solubility, and
valence. Low concentrations of hexavalent chromium
cause sublethal toxic effects in aquatic plants and
animals (Frances, 2009).
Health effects like mouth ulcer, nose bleeding, kidney
disease, low white blood cell count, cancers and
miscarriages were reported by Bradl (2005) as effects of
hexavalent Chromium. Long-term arsenic concentration
leads to thickening and discoloration of the skin, nausea
and diarrhoea, decreased production of blood cells,
abnormal heart rhythm and blood vessel damage
(ATSDR, 1993).
Domestic and human wastes are deposited into the
river because of inadequate waste disposal systems.
Vehicular movements are high especially around the
Lafenwa area while fishing activities take place in all
sampling locations.
This research was carried out from January to March,
2012 along the middle region of Ogun River basin. The
Ogun-River, located in Ogun-State, South West of
Nigeria lies between latitude 6o35' and 8o58' North with
Longitude 2o40' and 4o10' East. It rises from Iganran Hills,
east of Shaki, Oyo state, South West, Nigeria (latitude
07o40' N and Longitude 03o20' E) (Jaji, et al., 2007). The
entire river basin (Ogun River) occupies an area of
approximately 23,700 sq.km (OORBDA, 1982).
middle region of the Ogun River course between January
and March, 2012. Five samples were collected per
location/layer after which they were composited for each
location/layer.
High vehicular movements and indiscriminate dumping
of municipal and human wastes as well as commercial
activities and fishing were observed at the Lafenwa area.
While Arakanga Old/New schemes and Oyan were
located in serene environments with low domestic
activities. Predominantly, fishing was observed as the
major activity at those sites. Dams were also observed at
the three locations (Arakanga Old Scheme, Arakanga Old
Scheme and Oyan).
Sediment samples which were collected with the aid of
a Van Veen sediment grab. The sediments collected
were transferred into polythene bags and placed in an ice
chested cooler for onward transportation to the
laboratory. pH and conductivity were determine using
standard methods by APHA (1992). 10g of dried/2mm
sieved sediment samples were place in a 50ml beaker
containing 20ml of distilled water. The mixture was
allowed to stand for 30 minutes after which the pH meter
was inserted into the partly settled suspension for the pH
values to be taken. The conductivity meter was also
inserted for conductivity readings. Organic carbon was
determined by Wakley’s and Black Method.
At the laboratory, sediment samples were air dried and
sieved using a 2mm sieve to remove coarse particles.
The finer sediments (ie < 2mm) were taken subjected to
the Induced Couple Plasma Mass Spectrometry
(ICP/MS) for the determination of metal concentrations
while the geochemical pollution indices were determined
using the mathematical equation Igeo = log 2 (Cn/1.5Bn)
introduced by Muller (1979).
Sampling area
RESULTS AND DISCUSSION
Four sampling sites along the Middle Region of OgunRiver course namely; Lafenwa, Oyan, Arakanga Old
Scheme and Arakanga New Scheme were surveyed.
All sediment pH values obtained were alkaline with the
highest pH observed at Arakanga New Scheme 0 to 5 cm
(12.7) while the least was observed at Oyan 0-5 cm
(8.12) as seen in Table 1. pH is critical to the release of
metals because low pH can accelerate the release of
metals like Pb, Cu, Hg, Mn and Cd. The highest
conductivity value of 2273 µS/cm (Table 1) was recorded
from Arakanga Old Scheme 10-15 cm while the least was
obtained at Oyan 5-10 cm (68 µS/cm ) (Table 1). All
sediment values obtained were sandy when subjected to
particle size analysis (Table 1). From the sediment metal
MATERIALS AND METHODS
Experimental methods
Sediments of depths 0 to 5cm, 5 to 10 cm, 10 to 15cm
respectively were collected from different sections of the
Quality assurance
Three replicates were taken for every sample that was
analyzed. A series of standard reference materials were
used at the Acme Laboratory for and sediment samples.
They include; STD OREAS45CA, STD DS9 and BLK.
Diayi and Gbadebo.
106
Figure 1. Map of the Ogun River.
Table 1. Levels (Mean) of physicochemical parameters of sediment samples obtained from the study area.
Location
pH
µs/cm
EC
(%)
Organic
Carbon (%)
Sand (%)
Clay (%)
Silt
(%)
Texture
Lafenwa 0-5 cm
Lafenwa 5-10 cm
Lafenwa 10-15 cm
Arakanga Old Scheme 0-5 cm
Arakanga Old Scheme 5-10cm
Arakanga Old Scheme 10-15 cm
Arakanga New Scheme 0-5 cm
Arakanga New Scheme 5-10 cm
Arakanga Old Scheme 10-15 cm
Oyan 0-5 cm
Oyan 5-10cm
yan 10-15cm
10.90
8.55
8.90
11.90
12.60
9.09
12.70
8.63
8.90
8.12
8.69
8.52
267.00
303.00
324.00
404.00
654.00
2273.00
476.00
573.00
150.00
79.00
68.00
73.00
0.60
2.59
4.59
1.00
0.80
0.80
0.80
2.19
2.79
1.00
1.20
2.99
96.40
98.20
98.20
98.20
98.20
98.20
98.20
100.00
91.00
100.00
100.00
98.20
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
1.80
0.00
0.00
0.00
3.60
1.80
1.80
1.80
1.80
1.80
1.80
0.00
7.20
0.00
0.00
0.00
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
Sand
analyses done using Induced Couple Plasma Mass
Spectrometry (ICP/MS), all Cu values (Table 1) were
lower than the Environment Canada Sediment Quality
Guideline Standard (35.70 ppm) except that of Lafenwa 0
to 5 cm (413.50 ppm).
All Hg values obtained were lower than the ECSQG
standard (0.17 ppm). Zinc values from Lafenwa 0-5 cm
(201 pppm) Arakanga 10-15 cm Old Scheme (263 ppm),
Arakanga 5 to 10 cm New Scheme (135 ppm) and
Arakanga New Scheme 10 to 15 cm (249ppm) were
higher than the ECSQG standard (123 ppm). High
conductivity values observed in those locations could
have resulted in the accumulation of Zinc in the
sediments sampled.
107
J. Environ. Sci. Water Resources
Table 2. Trace metal values of sediments obtained from the study area.
Location
Lafenwa 0-5 cm
Lafenwa 5-10cm
Lafenwa 10-15 cm
Arakanga Old Scheme 0-5 cm
Arakanga Old Scheme 5-10 cm
Arakanga Old Scheme 10-15 cm
Arakanga New Scheme 0-5 cm
Arakanga New Scheme 5-10 cm
Arakanga New Scheme 10-15 cm
Oyan 0-5 cm
Oyan 5-10 cm
Oyan 10-15 cm
ECSQG
Cu
413.50
17.70
8.50
4.90
2.60
33.60
2.30
14.70
33.20
7.10
7.20
7.60
35.70
Cd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.60
Zn
201.00
68.00
42.00
41.00
8.00
263.00
9.00
135.00
249.00
12.00
12.00
13.00
123.00
Hg
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.17
Ni
9.90
4.60
4.30
3.40
2.30
11.90
1.80
7.60
11.10
7.30
7.80
8.30
NS
Pb
2435.30
109.90
21.40
11.60
6.70
77.40
5.50
39.00
75.40
20.90
21.00
25.80
35.00
As
6.50
1.20
0.70
0.00
0.00
1.10
0.00
0.60
1.00
0.00
0.60
1.00
5.90
Pb
24.60
1.10
0.20
0.80
0.10
0.75
0.10
0.40
0.75
0.20
0.20
0.30
20.00
As
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
13.00
Cr
81.00
22.00
18.00
18.00
9.00
29.00
8.00
29.00
29.00
44.00
45.00
60.00
37.5
Mn
311.00
247.00
270.00
122.00
143.00
408.00
136.00
228.00
404.00
253.00
246.00
264.00
NS
Note: ECSQG: Environment Canada Sediment Quality Guideline, NS: No Standard
Table 3. Igeo values of sediments metal obtained from the study area
Location
Lafenwa 0-5 cm
Lafenwa 5-10cm
Lafenwa 10-15 cm
Arakanga Old Scheme 0-5 cm
Arakanga Old Scheme 5-10 cm
Arakanga Old Scheme 10-15 cm
Arakanga New Scheme 0-5 cm
Arakanga New Scheme 5-10 cm
Arakanga New Scheme 10-15 cm
Oyan 0-5 cm
Oyan 5-10 cm
Oyan 10-15 cm
Average Shale Value
Cu
1.80
0.10
0.00
0.00
0.00
0.15
0.00
0.10
0.15
0.00
0.00
0.00
45.00
Cd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.30
Zn
0.40
0.10
0.10
0.10
0.10
0.50
0.00
0.30
0.60
0.00
0.00
0.00
95.00
Hg
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.18
Ni
0.00
0.00
0.00
0.00
0.00
0.05
0.00
0.00
0.05
0.00
0.00
0.00
50.00
Cr
0.20
0.50
0.00
0.00
0.00
0.10
0.00
0.10
0.10
0.10
0.10
0.10
90.00
Mn
0.10
0.10
0.10
0.00
0.00
0.10
0.00
0.05
0.10
0.10
0.10
0.10
850.00
Note: ECSQG: Environment Canada Sediment Quality Guideline, NS: No Standard
Table 4. Contamination Factor values of Sediments Obtained from the Study Area
Location
Lafenwa 0-5 cm
Lafenwa 5-10cm
Lafenwa 10-15 cm
Arakanga Old Scheme 0-5 cm
Arakanga Old Scheme 5-10 cm
Arakanga Old Scheme 10-15 cm
Arakanga New Scheme 0-5 cm
Arakanga New Scheme 5-10 cm
Arakanga New Scheme 10-15 cm
Oyan 0-5 cm
Oyan 5-10 cm
Oyan 10-15 cm
Cu
9.20
0.40
0.30
0.10
0.10
0.75
0.05
0.30
0.70
1.60
0.20
0.20
Cd
0.00
0.00
0.20
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Zn
2.10
0.70
0.00
0.40
0.10
2.80
2.80
1.40
2.60
0.10
0.10
1.30
Similarly, high Pb values were observed at Lafenwa 0-5
cm (2435.3 ppm), Lafenwa 5 to 10 cm (109.9 ppm),
Hg
0.00
0.00
0.40
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Ni
0.20
0.10
0.00
0.10
0.05
0.20
0.00
0.150
0.20
0.15
0.20
0.20
Pb
121.80
5.50
0.10
0.60
0.30
3.90
0.30
1.90
3.80
1.05
1.05
1.30
As
0.50
0.10
1.10
0.00
0.00
0.10
0.00
0.05
0.10
0.00
0.50
0.10
Cr
0.90
0.20
0.05
0.20
0.10
0.30
0.10
0.30
0.30
0.50
0.50
0.10
Mn
0.40
0.30
0.20
0.10
0.2
0.50
0.20
0.30
0.50
0.30
0.30
0.30
Arakanga Old Scheme 10-15 cm (77.4 ppm), Arakanga
New Scheme (39.00 ppm) and Arakanga NS (75.4 ppm)
Diayi and Gbadebo.
as seen in table 2. According to Jaji et al. (2007) water
from the Oyan section of the Ogun River had a Pb value
of 0.134 mg dm-3 which was higher than the WHO
standard of 0.05 mg dm-3. Elsewhere from River Yauri,
North- West Nigeria it was reported by Yahaya et al.
(2012) that sediment Pb values were higher during the
dry season with sampling point 3 (P3) having the highest
value of 45.02 ± 1.04 µg/g. This high value observed was
attributed to anthropogenic inputs like fertilizers and
pesticides used in agricultural activities.
All Arsenic values were lower than the ECSQG of
5.9ppm except that of Lafenwa 0-5cm (6.5ppm) (table 2).
Chromium values from Lafenwa 0-5cm (81 ppm), Oyan
0-5 cm (44 ppm), Oyan 5 to 10 cm (45 ppm) and Oyan 10
to 15 cm (60 ppm), all exceeded the ECSQG standard of
37.50ppm as seen in Table 2.
The order of metal concentration in the sediment was
Mn>Pb> Zn> Cu> Cr >Ni >As > Hg =Cd. The highest
concentration of metals from the locations was from Mn
(3032 ppm) while Hg and Cd both accounted for the least
concentrations of 0.00ppm.
The mathematical equation Igeo = log 2 (Cn/1.5Bn)
introduced by Muller (1979) was used to determine the
geochemical pollution intensities for samples analysed.
This index is classified into various classes for easy
identification of sediment pollution status. Values
between 0 to 1, are termed unpolluted while 1 to 2 can be
classified as moderately to unpolluted, 2-3 is moderately
polluted, 3 to 4 is classified as moderately to highly
polluted, 4-5 is termed highly polluted while 5 and above
is known as very highly polluted. From the result
obtained in Table 3, all values for Cu, Cd, Zn, Hg, Ni, As,
Cr an Mn fell into the ‘unpolluted’ category except for
Lafenwa 0 to 5cm lead index (24.60) which rated ‘very
highly polluted’. This result reveals that Lead is at a high
risk to biota in the sediment of Lafenwa 0 to 5 cm. Since
fishing is a common activity in this area, man could be
affected when fishes containing high Pb values are
consumed.
From the Contamination Factor analysis, it was
observed that Zn was moderately polluted at Lafenwa 0
to 5cm being 2.1 while Cu (9.2) and Pb (121.8) had very
strong pollution status in that sediment layer.
Similarly, Pb contamination factor value of 5.5 from
Lafenwa 5 to 10cm sediment also showed very strong
pollution status. Elsewhere, moderate to strong pollution
status was observed for Pb (3.8) from Arakanga 10 to 15
cm while moderately polluted status were observed for
Zn (2.8) and Pb (3.8) from Arakanga Old Scheme 10 to
15 cm, Zn (2.8) from Arakanga New Scheme 0 to 5 cm,
and Zn (2.6) from Arakanga 10 to 15 cm.
Medium pollution status were shown for Pb (1.1) from
Lafenwa 10 to 15cm, Zn (1.4) from Arakanga New
Scheme (5 to 10 cm), Pb (1.9) from Aarakanga New
Scheme 10 to 15 cm, Cu (1.6), Pb (1.05) from Oyan 0 to
5 cm respectively, Pb (1.05) from Oyan 5-10 cm and Pb
(1.30) from Oyan 10 to 15.
108
Conclusion
Sediment from Lafenwa 0 to 5cm accounted for the
highest metal concentrations for Pb, Cr, As, and Cu. This
shows that there is high accumulation of toxic metals in
this sediment. Since fishing is carried out in the Lafenwa
area, it is important to carry out a proper assessment of
the lead value in the fishes that are harvested for public
consumption.
Man can be affected when fish with high Pb content is
consumed. Other sediments from Arkanga Old Scheme
10 to 15cm, Arkanga New Scheme 5 to 10cm, Arkanga
New Scheme 10 to 15cm and Lafenwa 5 to 10 cm should
be closely monitored as well owing to the high
concentrations showed for Zn and Pb respectively.
Chromium levels from Oyan should also be monitored.
Since fishing is a common activity in this area, man could
be affected when fishes containing high Pb values are
consumed.
Acknowledgement
I would like to appreciate My parents, Mr and Mrs E.O.
Diayi for all round support in life. My supervisor Dr A.M.
Gbadebo for the time, efforts and patience invested in
this project and my lovely wife Vivian Ndidi Diayi for the
extra mile encouragements.
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