Research Journal of Environmental and Earth Sciences 4(4): 424-427, 2012
ISSN: 2041-0492
© Maxwell Scientific Organization, 2012
Submitted: December 20, 2011
Accepted: January 26, 2012
Published: April 15, 2012
Pollutional Status of Kubanni Lake Through Metal Concentrations in
Water and Sediment Columns, Zaria - Nigeria
J.A. Adakole and D.S. Abolude
Department of Biological Sciences, Ahmadu Bello University, Zaria, Nigeria
Abstract: The aim of this study is to evaluate the level of pollution of kubanni lake. Concentrations of some
metals in water and sediment columns of Kubanni lake were investigated for a 2 year period (2002-2004).
Samplings were done monthly at 5 different sites. The concentrations of the metals were determined using
atomic absorption spectrophotometer. The pH fluctuated between acidity (6.50) and alkalinity (9.0). The mean
temperature, electrical conductivity, dissolved oxygen and hardness are: 24.97±.29ºC, 69.20±0.72 :/cm,
07.25±0.05 mg/ and 124.77±8.11 mg/. CaO3, respectively. Mg, Ca, Pb, Co, Cd and Cr were detected in all the
water samples with means of 1.47±.08, 9.21±0.52, 1.220.05, 1.26±0.05, 0.02±0.01 and 0.86±0.04 mg/L
respectively. The dry season means of Mg, Ca and Pb were higher than the rainy season means while a reverse
trend was observed for Co and Cr. The sediment metal concentrations correlated positively with the water metal
concentrations. The detection of Pb and Cd in Kubanni lake indicates the contamination of the lake’s water by
human activity. The concentrations of Cr, Cd and Pb in both sediments and water were above WHO
recommended limits. Also, the Ca: Mg ratio obtained for Kubanni lake water is 6:1, indicating Mg deficiency
of the lake’s water. Consequently, the lake water is not suitable for irrigational purposes in terms of Ca: Mg
ratio.
Key words: Ca: Mg ratio, effluents, lake, metals, permissible-limit
industries, thermal power plants and also the
indiscriminate use of heavy metal containing-fertilizers
and pesticides in agriculture are some of the main causes
of metal pollution in the aquatic ecosystems.
Though some metals like Cu, Fe, Mn, Ni and Zn are
essential as micronutrients for life processes in plants and
microorganisms, other like Cd, Cr and Pb have no known
physiological activity and have been proved detrimental
beyond a certain limit (Marschner, 1995; Bruins et al.,
2000). At low levels in water, some elements like Cd
(0.01 mg/L), Pb (0.10 mg/L) (ISL, 1982) and Cu (0.05
mg/L) pose threats to humans (Nnaji and Okoye, 2006).
Deadly diseases like edema of eyelids, tumor, congestion
of nasal mucous membranes and pharynx, stuffiness of
the head and malfunctions in genetic makeup,
gastrointestinal cavity, muscular, reproductive and
neurological systems caused by some of these heavy
metals have been documented (Johnson, 1998; Abbasi
et al., 1998; Tsuji and Kargatzides, 2001). Various
geochemical and environmental factors influence metal
availability/toxicity to aquatic organisms (Luoma, 1983;
Amman et al., 2002). These include; solute metal
speciation, influence of other metals, temperature, pH
among others.
Therefore, monitoring metals in aquatic environment
is important for safety assessment of the environment and
human health in particular. Regarding this background,
INTRODUCTION
The rate of water pollution of all types has increased
much more as compared to other fields of pollution due to
the discharge of all sorts of obnoxious matter into it
(Akhtar et al., 2005). The global concern about heavy
metals in the environment stem from their persistence,
toxicity and bioaccumulation in the trophic chain
(Adakole, 2000; Nnaji and Okoye, 2006).When heavy
metals enter water bodies, they change water quality, bind
to sediments and accumulate in aquatic biota causing
anemia, disturbance of physiological functions and
mortalities of fish (Post, 1983). Specifically, aquatic
organisms experience histological and morphological
changes in tissues; physiological changes like suppression
of growth/development, poor swimming performance,
changes in blood composition and circulation, behavior
and reproduction (Adakole et al., 1998; Widianarko et al.,
2000), adversely affecting aquatic biodiversity. This
adversely affects fish farming through decrease in revenue
and profitability. Heavy metals also pose a serious threat
to humans through ingestion of metal enriched aquatic
organisms.
Anthropogenic activities like mining, final disposal
of treated and untreated waste effluents containing toxic
metals as well as metal chelates (Amman et al., 2002)
from different industries, e.g. tannery, steel plants, battery
Corresponding Author: J.A. Adakole, Department of Biological Sciences, Ahmadu Bello University, Zaria, Nigeria
424
Res. J. Environ. Earth. Sci., 4(4): 424-427, 2012
Fig. 1: Map of Nigeria and part of Zaria region showing Kubanni lake and location of sampling sites
this survey monitored the surface water of Kubanni dam;
considering environmental factors variables and metal
content. The status of the lake’s water quality was
evaluated with respect to drinking and
agricultural/irrigation purposes.
and seepages. Five sampling sties were chosen, each
about 22.00±2.00 m from the other (Fig. 1).
Sample collection and analysis: Water and sediment
samples were collected from each of the sampling stations
on Kubanni lake for a 2 year period (2002-2004). The
water temperature (oC) (1m below water surface) was
determined in the field using a mercury thermometer.
Electrical conductivity and hydrogen ion concentration
(pH) by using Jenway 4010 conductivity m and Kent Eil
7055 pH m models respectively. Total hardness and
dissolved oxygen were determined by burette titration
while metals were determined by using atomic absorption
spectrophotometer after digestion (APHA, 1992). The
metals analysed were Mg, Ca, Pb, Co, Cd and Cr,
respectively.
MATERIALS AND METHODS
Study area and sampling sites: Kubanni lake, also called
Ahmadu Bello University dam, is constructed on river
Kubanni in 1973. The lake’s major use is to supply water
to the University community. The lake (reservoir)
catchment’s area is 57 Km2 (22 square miles), its width is
122 m (400 feet), mean depth is 6 m (20 feet), water level
during wet season is 644.81 m and the corresponding
crest is 646.34 m. The lake is located approximately
within latitude 11º11!N and longitude 7º38!E in SamaruZaria, Kaduna state, Nigeria (Fig. 1). It is located within
the premises of Ahmadu Bello University, main campus.
The lake’s two tributaries are the Kampagi and Samaru
streams. Kampagi stream, which originates from a rural
settlement, has a seasonal flow whereas Samaru stream
that originates from a semi-urban settlement has an allyear-round flow due to its sustenance by urban runoffs
RESULTS AND DISCUSSION
The pH of the lake water fluctuated between acidity
(6.50) and alkalinity (9.0) with an overall mean of
7.45±0.03. Seasonal mean values of pH varied from 7.34
in rainy season to 7.51 during the dry season. Nnaji and
Okoye (2006) reported that as pH decreases, more
425
Res. J. Environ. Earth. Sci., 4(4): 424-427, 2012
Table 1: Mean concentrations (mg/L) of metals in water and sediment samples from Kubanni lake
Water
--------------------------------------------------------------------------------------------------------------------------Mg
Ca
Cr
Co
Cd
Pb
Mg
Ca
Cr
Site 1
1.35
7.85
0.73
1.15
0.02
1.18
1.36
8.05
0.75
Site 2
1.37
9.43
0.84
1.35
0.02
1.26
1.41
9.71
0.86
Site 3
1.28
8.89
0.78
1.21
0.04
1.26
1.31
9.24
0.8
Site 4
2.3
8.9
1
1.33
0.01
1.15
2.26
9.16
1.03
Site 5
1.07
10.87
0.96
1.27
0.01
1.22
1.1
11.19
0.96
Dry season
2.33
12.71
0.67
1.16
0.02
1.6
2.4
13.09
0.69
Rainy season
0.61
5.71
1.05
1.36
0.02
0.83
0.68
5.88
1.08
Mean±sd
1.47±0.47 9.20±1.09 0.86±0.11 1.26±0.08 0.02±0.01 1.21±0.04 1.51±0.48 9.47±1.13 0.88±0.11
Permissible limit* >270
0.05
0.05
0.05
(WHO, 1996)
Sediment
--------------Co
1.18
1.39
1.24
1.36
1.3
1.19
1.4
1.29±0.08
0.05
magnesium, causing a magnesium deficiency (Terry and
Ulrich, 1974; Marschner, 1995; Nelson, 1998).
Conversely, if the ratio is less than 3-5 Ca: 1 Mg, the high
proportion of magnesium can block the uptake of calcium,
causing a calcium deficiency (Terry and Ulrich, 1974).
From Table 1, the Ca: Mg ratio obtained for Kubanni lake
water is 6:1, indicating Mg deficiency of the lake’s water.
Consequently, the lake water is not suitable for
irrigational purposes.
The dry season water values of Mg, Ca and Pb were
significantly higher than during the rainy season. Cr and
Co were higher in the rainy season than in the dry season.
Mean monthly values of chromium varied between 0.05
to 2.99 mg/L with an over all mean of 0.80±0.04 mg/L.
The monthly mean of Co concentrations were consistently
above 1.00 mg/L among the sampling sites. The monthly
mean concentrations of the four heavy metals (Pb, Cr, Cd
and Co) in water samples were in the range 0.00-3.78,
0.05-2.99, 0.00-1.00 and 0.06-2.45 mg/L, respectively.
The relative concentrations of the heavy metals in
sediment are: Co>Pb>Cr>Cd. Similar trend had also been
reported by Kar et al. (2008). A non significant
correlation was observed between water Pb and water Cr.
The effect of heavy metals on man can be additive,
antagonistic or synergic. For instance, Zn and Cu are Cd
antagonists and so adverse effects of high Cd intake can
be reduced by above normal amounts of Zn and Cu in the
body (Nnaji and Okoye, 2006).
The means of all the metal concentrations in water
positively significantly correlated (p<0.05) with the
metals in sediment. The sediment mean concentrations of
each of the elements were higher than their respective
concentrations in water (Table 1). According to Biney
et al. (1994), heavy metals are portioned between water,
sediments, suspended solids and aquatic biota in water
bodies. Heavy metals accumulate more in sediments than
in aquatic organisms and water (Tariq et al., 1996;
Ravanelli et al., 1997; Nnaji and Okoye, 2006) and as
such sediments act as sinks and sources of supply of
heavy metals to overlying water columns.
In view of the fact that heavy metals such as Pb, Cd
and Zn are good markers of contamination from human
activity (Ravanelli et al., 1997), detection of these metals
in Kubanni lake indicates contamination of the lake’s
dissolved metal ions are produced. Ionic forms of heavy
metals could induce acute poisoning in aquatic animals
leading to kills while complex forms could cause chronic
poisoning and bioaccumulation in fish tissues (Baeyens
et al., 2005). The mean temperature of the lake during the
study period is 24.95±0.09ºC. There is a non significant
correlation (p<0.05) between temperature and pH.
Temperature correlated positively with all the sediment
and water metals. As temperature increases, rate of
biological processes increase and may result in increase in
metal uptake by fish (Adakole and Alabi, 2007). Mean
values of electrical conductivity and dissolved oxygen
were greater in the dry season than during the rainy
season. The DO of the lake ranged between 5.20 and 9.60
mg/L, with a mean of 7.25 mg/L. The least water hardness
(61.00 mg/L.CaCO3) was obtained in September at site 1
while the highest (206.85 mg/L.CaCO3) was obtained in
June at site 2. Depending on pH and alkalinity, hardness
of above about 200 mg/L can result in scale deposition,
particularly on heating [2]. Soft waters with a hardness of
less than about 100 mg/L have a low buffering capacity
and may be more corrosive to water pipes (WHO, 1996).
The variations of the metals in lake kubanni is as
presented on Table 1. The water and sediment alkaline
metals, Ca and Mg concentrations varied between seasons
and among sampling sites. Both metals were almost below
detection in the months of May, June, August and
September. This observation could be attributed to
dilution from rainfall while the sharp increase in October
could be due to anthropogenic sources. In a similarly
study, Kar et al. (2008) had attributed an observed
decrease in metal levels due to water dilution from
rainfall. The means of Ca and Mg in water were
9.21±0.52 and 1.47±0.01 mg/L, respectively. Calcium
usually is higher than magnesium in waters; as these
elements increase the tendency for sodium to be toxic
decreases (Adakole, 2000).
When water hardness is greater than 150.00 mg/L as
obtained in this investigation, it is important to check the
amount of calcium and magnesium dissolved in the water
and determine the Ca: Mg ratio. This ratio should be 3 to
5 mg/L calcium to 1 mg/L magnesium (Terry and Ulrich,
1974; Nelson, 1998). If there is more calcium than this
ratio, it can block the ability of the plant to take up
426
Res. J. Environ. Earth. Sci., 4(4): 424-427, 2012
Biney, C., 1994. Review of Heavy Metals. In: Calamari,
D. Review of Pollution in the African (Ed.),
Environment, CFA/FAO, Rome.
Bruins, M.R., S. Kapil and F. W. Oehme, 2000. Microbial
resistence to metals in the environment. Ecotoxicol.
Enviro. Safety, 45: 198-207.
ISL., 1982. Indian Standard Tolerance Limits for Island
Surface Water Subject to Pollution, 2nd Revision,
Indian Standard Institute, pp: 2296.
Johnson, F.M., 1998. The genetic effects of
environmental lead. Mutat. Res., 410: 123-140.
Kar, D., P. Sur, S.K. Mandal, T. Saha and K.R. Kole,
2008. Assessment of heavy metal pollution in surface
water. Int. J. Enviro. Sci. Technol., 5: 119-124.
Luoma, S.N., 1983. Bioavailability of trace metals to
acquatic organisms: A review. Sci. Total Enviro.,
28: 1-22.
Marschner, H., 1995. Mineral Nutrition of Higher Plants.
Academic Press, London.
Nelson, P.V., 1998. Greenhouse Operation and
Management. Prentice-Hall, Upper Saddle River, NJ,
ISBN: 0-13-37468.
Nnaji, J.C. and F.C. Okoye, 2006. Toxicity of heavy
metals to fish: An important consideration for
successful aquaculture. Proceedings of the 21st
Annual Conference of the Fisheries Society of
Nigeria. (FISON), Published by Fisheries, Society of
Nigeria, pp: 250-254.
Post, G., 1983. Textbook of Fish Health. T.F.H.
Publication Inc., New Jersey, pp: 45-56.
Ravanelli, M., O. Tubertini, S. Valcher and W. Martinotti,
1997. Heavy metal distribution in sediment cores
from western Ross sea (Antartica). Water Air Soil
Pollut., 99: 697-704.
Tariq, J M. Ashraf, M. Jaffar and M. Afzal, 1996.
Pollution status of the Indus River, through heavy
metal and macronutrient contents of fish, sediment
and water. Water Res., 30(6): 1337-1344.
Terry, N. and A. Ulrich, 1974. Effects of magnesium
deficiency on the photosynthesis and respiration of
leaves of sugar beet1. Plant Physiol., 54: 379-381.
Tsuji, L.J.S. and J.D. Karagatzides, 2001. Chronic lead
exposture, body condition and Testis mass in wild
Mallard Ducks. B. Environ. Contaminat. Toxicol.,
67: 489-495.
WHO., 1996. WHO guideline values for contaminants in
water: Guidelines for Drinking-Water Quality. 2nd
Edn., Health Criteria and Other Supporting
Information, 2: 971.
Widianarko, B., R.A. Verweig, C.A.M. Van Gestel and
N.M. Van Straalen, 2000. Spatial Distribution of
trace metals in sediments from urban streams of
Semarang, Central Java, Indonesia. Ecotoxicol.
Environ. Safety, 46: 95-100.
water by human activities. The water and sediment mean
concentrations of Cr, Cd and Pb were above the WHO
(1996) permissible levels for drinking water. The excess
heavy metal load observed during this investigation can
be attributed to the discharge of municipal wastes,
geology and catchment’s area of kubanni lake. These
results indicate that heavy metal pollution and toxicity
might pose some risks to the health of communities
residing around and using the lake water for domestic,
commercial and socio-cultural purposes.
CONCLUSION
The pollutional status of Kubanni lake water quality
was investigated over a 24 month period. Human activity
is implicated for the lake’s water low quality. Continued
prohibition of farming activities on the lake’s immediate
borderline and renovation and reactivation of the sewage
treatment plants are suggested to avoid further
deterioration of the lake’s water quality.
REFERENCES
APHA, 1992. Standard Methods for the Examination of
Water and Wastewater. 18th Edn., American Public
Health Association, Washington, D.C., pp: 1365.
Abbasi, S.A., N. Abbasi and R. Soni, 1998. Heavy Metals
in the Environment.1st Edn., Mital Publication, New
Delhi, India.
Adakole, J.A., 2000. The effects of domestic, agricultural
and industrial effluents on the water quality and biota
of Bindare stream, Zaria-Nigeria. Ph.D. Thesis,
Department of Biological Sciences, Ahmadu Bello
University, Zaria, pp: 256.
Adakole, J.A. and E.E. Alabi, 2007. Effects of sublethal
concentrations of a vegetable oil effluent on growth
of Clarias gariepinus. Nigerian J. Fisheries, 4:
182-189.
Adakole, J.A., J.K. Balogun and F.A. Lawal, 1998. The
effects of pollution on benthic fauna in Bindare
Stream, Zaria, Nigeria. Nigerian J. Chem. Res., 3:
13-16.
Akhtar, N., T. Ahmad, M. Gulfraz and R. Khanum, 2005.
Adverse effects of metal ions pollution on aquatic
biota and seasonal variations. Pak. J. Biol. Sci., 8(8):
1089-1089.
Amman, A.A., B. Michalke and P. Schramel, 2002.
Speciation of heavy metals in environemtal water by
ion chromatography coupled to ICP-MS.
Biochemistry, 372: 448-452.
Baeyens,W., M. Leermakers, M.D. Geiter, H.L. Nguyen,
K. Parmentier, S. Pamutrakal and M. Elskens, 2005.
Over view of trace metal contamination in the
Scheldt Estuary and effect of regulatory measures.
Hydrobiologia, 540: 141-154.
427