In a semi-urbanized stretch of river Kubanni, Zaria, seasonal variations of some tree metals (copper, zinc and lead) in fish species (Clarias sp., Tilapia sp and Alestes sp) were investigated over a period of eight months. Water and fish were sampled monthly, pooled separately and seasonal analysis of each trace determined using atomic absorption method. The concentration of each of the elements in water higher in the dry season than during the rainy season. The dry and rainy season concentrations of copper, zinc and lead were 6.85~c10.66 mu gg super(-1)&1.45~c1.10 mu gg super(-1); 2.13~c1.68 mu gg super(-1)&0.1 5~c0.05 mu gg super(-1); and 0.52~c0.50 mu gg super(-1) & 0.31~c0.14 mu gg super(-1) respectively. Similarly, all the three accumulated more zinc and lead in the dry season than during the rainy season. Tilapia species and to some extent, Alestes species being pelagic had a higher concentration of trace metals than Clarias species which is a bottom dwelling fish Tilapia species may therefore be a better indicator species than Clarias species for monitoring trace metals in water bodies. Reasons for the observed variations in the trace metals were discusse

Adakole, J.A.

Mbah, C.E.

English

Aquatic Commons

SEASONAL VARIATIONS OF SOME TRACE METAL CONCENTRATIONS IN SOIVIE FISH
SPECIES ON A SRETCH OF RIVER KUBANNI, ZARIA.
BY
J.A. ADAKOLE* AND MBAH. C.E
drjaadakole@yahoo.com
Department of Biological Sciences, Ahmadu Befo University, Zaria, Nigeria.
"Author for correspondence
ABSRACTS
In a semi-urbanized stretch of river Kubanni, Zar/a, seasonal variations of some trace metals
(copper zinc and lead ) in fish species (Clones sp, Tilapia sp and Alestes sp) were investigated
over a period of eight months. Water and fish were sampled monthly, pooled separately and
seasonal analysis of each trace metals determined using atomic absorption method. The
concentration of each of the elements in water was higher in the dry season than during the-rainy
season. The dry and rainy season concentrations of copper, zinc and lead were 6.85 :t 10.66
iigg'1 & 1.45 .± 1.10 pgg'1; 2.13 ± 1.68 & 0.15 .-± 0.05 ,iigg4; and 0.52 .± 0,50 figg-1 & 0,31 ±
0,14 iugg-7 respective/y. Similarly. all the three fishes aCcumulated more zinc and lead in the dry
season than during the rainy season. Tilapia species and to some extent, Alestes species being
pelagic had a higher concentration of trace metals than Glades species which is a bottom
dwelling fieh. specie.s may therefore be a better indicator species than Glades species for
monitoring frac;-) metals in water bodies, Reasons for the observed variations in the trace metals
were discussed.
iNTRODUCTION
During the recent years, serious concern has been voiced about the rapidly deteriorating state of
freshwater bodies with respect to trace metal pollution. It is recognized that in freshwater
systems, trace neeials have high pollution potentials (IVIartin et ai.,1976; Tang et ai.,1996) that
could be measured throUgh the use of fish(Noris and Lake, 1984; James, 1985; Adakole, 2000).
in addition, the trace metas in such waters may wridergo rapid changes affecting the rate of
uptake or release by sediments (Boudou, 1981) thus influencing living organisms via the water-
sediment chain. Relationships between the consumption of fish containing trace metals, and
human exposure to trace metals (WHO, 1990. Paradis et al., 1997) through fish consumption has
been documented by various researchers. Over the years metal contamination of fish has
caused serious public hazards (James, 1985; WHO, 1996). Lawani and Alawode (1996) reported
objectionable levels of lead and Mercury in the tissues of the African Mudfish, Clarias gariepinus
from River Niger in Nigeria.
Nigeria, like other developing countries of the world, the level of metal pollution of
freshwater bodies, especially the rivers is no longer within safe limits for human consumption.
Earlier In base-line studies have identified elevated levels of certain trace metals in local
freshwater systems, especially rivers (Omoregie et al., 2002) arising mainly from agricultural and
industrial processes (Adakole, 2000). The assessment of metal pollution is an important aspect of
most water quality assessment programmes. The Global Environment Monitoring System
774
(GEMS) programme GEMS/WATER includes ten metals: Al, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn,
Arsenic and Se (which are not strictly metals) are also included (WHO, 2003). The United States
Environmental Protection Agency (US EPA, 1985) considers eight trace elements as high priority:
As, Cd, Cu, Cr, Pb, Hg, Ni and Zn. Most other countries include the same metals in their priority
lists. The ability of a water body to supPort aquatic life, as well as its suitability for other uses,
depends on many trace elements. Some metals, such as Mn, Zn and Cu, at increased
concentrations in sewage, industrial effluents or from mining operations can
- have severe
toxicological effects on humans when present in trace concentrations are important for the
physiological functions of living tissue and regu-late many biochemical processes (WHO, 2003).
The same metals, however, discharged into natural waters and the aquati'c ecosystem (UNESCO
UNEP - WHO, 1996). Thus, the present study was aimed at evaluating the seasonal
concentration levels of Cu, Pb and Zn in the tissues of Clarias spp, Tilapia spp and Alestes spp in
a stretch of river Kubanni.
MATERIALS AND METHODS
Study Area JK
Zaria, situated in the Northern guinea Savanna zone, possesses a tropical climate with
distinct wet and dry seasons. The nature of Kubanni river channel varies noticeably both froin
station to station and from season to season. A dam is situated 017 the river's upstream WhiCil is
used by the Ahmed,/ Bello University, Zaria for its water-supply (Figure 1). Three sampling
stations were chosen on a stretch of the river for the study. Station I in Tuclun-Jukun is located
upstream of station 2. Station 2 is in Sabon-gari/Tudun-wada is 20 meters downstream after river
Kubanni had received effluents from Kamacha streani. Station 3 is dose to the outskirts of the
town. The distance
;
.1
.21- -
-- \
,-.1/ -
.,
A
775
t
.1r,s ot .t11.,.}711
between the stations ranged from 1.30km to 1.50km.
Sampling
temperatures (oc) of the air (2m above water level), surface water (1cm below water
surface) and water depth (1m below water surface) were determined in the field using a mercury
thermometer. Water velocity was calculated using a floating plant material placed on the water
surface and allowed to flow over a measured distance. Transparency was measuered using a
Secchi disc pH and electrical conductivity by using Pye Unlearn model 292 pH meter at 25 °C
and conductivity meter EBA/10 model respectively. Total dissolved matter and dissolved oxygen
were analyzed as described (Lind, 1979). Total hardness and total alkalinity were
determined by titration methods (APHA, 1985).
From each station, for each season, water samples were collected monthly, preserved by
adding 1m! conc. HNO3 to about 150m! of the sample and then pooled. From the pool, 50m!
water sample taken was filtered and concentrated to about 30m! and 5.0m1 HNO3 was added. It
was then rnade up to (he 50m! mark in a 50m! volumetric flask with distilled water followed by
analysis with Unlearn 919 atomic absorption spectrophotometer Similarly, during each season of
the study period, fish samples caught from Kubarini River were bought from local fishermen,
identified, weighed and -grouped according to species. Each sample was then dried to a constant
weight in an oven set at 60 °C. 4.0g of each fish was then ashed in a muffle furnace at a
temperature of 52,5.0 °C. The ash obtained was then cooled and dissolved in 5.0m1 cone, HNO3
and made tip to 50.0m1 with de-ionized water. This solution was filtered and analyzed for metals
using Llnicam 919 atomic absorption spectophotometer
6
RESULTS
Mean seasonal values of water physicochemical characteristics are presented in Table
1.Except for the values of electrical conductivity, total dissolved matter, dissolved oxygen, total
hardness and total alkalinity, values of other parameters were all not significant (P > 0.05)
betvveen the two seasons. Similarly, variation in total hardness, pH, transparency, velocity, and
water depth temperature within the sampling stations were not significant (P > 0.05). The
concentrations in water of each of the elements were. higher in the dry season than in the rainy
season (Figure 2). Copper is predominant at station 1 while lead predominates in station 2.
Correlation analysis between the elements in water and fish tissue revealed a significant positive
< 0.05) correlation coefficient for lead. However, the correlation coefficient between copper in
water and copper in fish tissues was not significant (P > 0.05).
The accumulation of zinc and lead by all the three fishes were higher in the dry season
than during the rainy season (Figure 3). Copper concentration in Alestes spp followed a similar
trend However Clarias spp and Tilapia spp accumulated more copper in the rainy season than in
the dry season. Zinc was the most (82.20agg) accumulated while lead was the least (2.45pgg1).
There was a seasonal high significant difference (P < 0.05) in the metals accumulated by the
three fishes.
DISCUSSION
Using the criteria proposed by Federal Environmental Protection Agency (FEPA, 1991),
the mean values of most of the parameters are within the range of values accepted as safe for
aquatic life and for domestic water suppiy
776
Seasonal mean values (± S.D) of water physicochemical characteristics recorded from
three sampling stations along a stretch of river Kubanni
67.01
Dry season 147.50 ± 25.00 211.25 ± 40.90 235.00 ± 31.09
Total dissolved matter (mg-1) Rainy season 230.00 ±82.86 515.00 ± 77.24' 435.00 ± 42.03
Dry season 99.00 ± 16.45 137.50 ± 26.29 152.50 ± 22.17
777
Parameter
1 2 3
19.00 ± 4.32
24.25 ± 0.95
20.00 ± 2.70
24.25 ± 0.50
21.00 ± 3.82
24.62 ± 0.75
0.02 ± 0.02
0.14 ± 0.08
0.16 ± 0.05
0.13 ± 0.12
7.50 ± 0.85
7.36 ± 0.80
56.50 ± 11.74
46.0 ± 7.61
158.65 + 40.59
83.50 ± 10.37
351.25 ± 87.79
sampling stations
±
22.25 ± 2.62 23.00 ± 2.82
23.75 ± 1.25 23.50 ± 2.51
22.75 ± 3.86 22.75 ± 2.21
0.13 ± 0.24 0.17 ± 0.32
0.36 -± 0.14 0.33 ± 0.11
7.25 ± 0.31 7.66 ± 0.90
174.75 ± 122.82 179.87
258.50 ± 134.02 182.50
795.00 ± 120.41 667.50
Atmospheric temperature (°C): Rainy season
Dry season 22.00 ± 0.01 23.50 ± 1.73
Water surface temperature (°C) Rainy season
Dry season 22.30 ± 0.80 23.13 ± 0.63
Water depth temperature (°C) Rainy season
Dry season 25.12 ± 0.08 24.38 ± 1.10
Velocity (m/sec.) Rainy season
Dry season 0.15 ± 0.04 0.13 ± 0.06
Transparency (m) Rainy season
Dry season 0.12 ± 0.04 0.14 ± 0.14
pH Rainy season
Dry season 7.30 ± 0.52 7.08 ± 0.86
Total alkalinity (mg-'.CaCO3) Rainy season
38.79
Dry season 34.25 ± 7.59 42.87 ± 8.12
Total hardness (mg-1.CaCO3) Rainy season
65.53
Dry season 55.00 ± 12.48 72.00 ± 17.81
Electrical conductivity (pS/cm) Rainy season
24
C C C CO 0C'4 O 0 CO01 lb otitio c
o o .CO C
co0 o '3 o 4.)U) u) u) u) ra u)
a.. 2 >, s.. . .
....
s..(I) C C C'0 45 '8
,
w ._
'2 E EFigure 2: Mean seasonal variation in copper, lead and zinc along stations
on a stretch of river Kuhanni.
778
Ocopper
0 lead
O zinc
o
t15
20
18
16
14
_
o
12
*fa'L.
o
o
o
10
Ti3
The occurrence of metals in the stretch of river kubanni. can be attributed to
anthropogenic sources., Okoye et al., (1991) made similar conclusion on the heavy metal
enrichment of Lagos lagoon_ Metals in natural waters can exist in truly dissolved, colloidal and
suspended forms (US EPA, 1985). The proportion of these forms varies for different metals and
for different water bodies (Adakole, 2000). Consequently, the toxicity and sedimentation potential
of metals change, depending On their forms. This probably partially accounts in for the differ-Ea-It
concentration /eveis of Copper, /ead and zinc within the three stations and between the seasons
The comparatively high copper concentration in station 1 during the dry season may be due to
leaching from nearby garbage while the higher lead concentration at station 2 may be attribeted
to its closeness to a high way and battery effluents. Lead is widely used as an adciitive
petroleum for automobiles and is emitted to the atmosphere in their exhaust gases, thereby
entering the hydrological cycie (WHO, 1990, Paradis et al., 1997). Water pollution by heavy
metals as a result of human activities cou/d cause serious. ecological problems. ThiS situaticn
aggravated by the lack of natural eliniination processes for metals (Bertram and Balance, 1996).
As a result. metals shift from one compartment within the aquatic environment to another.
including the bio ta, often with detrimental effects. There is also an increasing toxicological risk for
humans (WHO, 2003).
Many organisms have been found to accumulate certain contaminants in their tissues
during their lifetime,without detectable effects on normal physiological functions in a phenomenon
known as bioaccumulation (MEP - WHO, 1996). The contaminants are effectively detoxified
and/or tolerated within the organism, often as -a result of binding into particular tissues in tne
body. The bioaccumulation of copper, lead and zinc in both seasons (except for Zinc where in the
dry season, Clarias spp had a higher zinc concentration than Tilapia spp) by Tilapia spp is higher
than for Clarias spp, Tilapia spp may therefore be a better indicator species for monitoring trace
metals concentration in fish communities than Glades sop. If the correlation between the
concentration of a contaminant in a water body and the concentration in the tissues of an aquatie
organisin is good, the organism may be used for chemical Monitoring of the contaminant in the
water body as an alternative-monitoring medium to water or particulate matter (Chapman, 199'3l.
Biological tissues sometimes have the advantage that the contaminant concentrations being
analysed are much higher than in water or particulate matter, thus requiring lower detection limits
and, possibly, less sophisticated analytical techniques. In addition, biological tissues can be
bulked together to give a greater total concentration.
REFERENCES
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, Dept. of
Biological Sciences, Ahmadu Bello University, Zaria, 256pp.
A P.H.A.(1985). Standard methods for the examination of water and wastewater, 16th edition.
Arnerican public health association, Washington, D.C. 1268 pp.
Bertram, J. and Ballance, R.(1996). Water Quality Monitoring: A Practical Guide to the Design
of Freshwater Quality Studies and Monitoring Programmes. Chapman & Hall.
London.158pp
Boudu, A(1981). Recherche en ecotoxicologie experimentale sur les processus de
bioaccumulation et de transfert des derives du murcure dans les systemes
aquatiques continentaux. Thesis d' tat, Universite de Bordeaux, 300pp.
Chapman, D(1996). Water Quality Assessments. A Guide to the Use of Biota, Sediments
and Water in Environmental Monitoring. Second edition. Chapman & Hall,
779
London. de Zwart, D. 1995 Monitoring Water Quality in the Future. Volume 3,Biomonitoring.
Ministry of Housing, Spatial Planning and the Environment (VROM), The Hague.523pp.
James, M.C(1985), ACcumulation of lead in fish from Missouri streams impactyed by
*Lead mining. Bull, EnvirOn. Contam. Toxicol. 34: 736 746.
Lawani, S.A and Alawode, J.A(1996). Concentrations of lead and mercury in river Niger
and its fish at Jebba,.Nigeria. Bioscience Research communication, 8: 47 49»
Lind, 0.1-.(1979). A handbook of common methods of water analysis for limnology.
C.V.Moshy publishers, St.Loiiis. U.S.A. 69pp.
Martin, J.H., Bruland, K.W and Broenkow, W(1976). Cadmium transport in the California
current. Marine Pollution.Transfer. pp 159 184. D.C. Health, LexingtoM. 145pp.
Noris R.N. and Lake. P. S(1984). Trace metal concentrations in fish from south ESK .
River, northeastern Tasmania. Aust.Bull. Environ. Contam. Toxicol. 33,.384 354
Okoye, B.C., Afolabi, A.0 and Ajao, C(1991). nternationalJoumalof Environmental
Studies. 37: 35 39
Omoregie, E., Okorankwo, M.O., Eziashi, A.0 and Zoakah, A.I(2002). Metal concentrations in
water column, benthic macro invertebrates and Tilapia from
Delimi riVer, Nigeria. Journal of Aquatic Sciences. 17(1): 55 59.
Paradis,S., Wheatley, B., Boswell-Purdy, J., Belisle, D.. Co/e., Lekers, H., Hayton, A. .and
Davies.K(1997).
Mercury contamination through fish consumption: A model for predicting and preventing
hazardous behaviour On a community level. Water, Air and Soil Polltion. 97: 147 185.
Taridt J., Ashraf, M., Jaffar, M and Afizal, M(1996). Pollution status of the Indus river,
through heavy metal and macronutrient contents of fish: sediment and water.
Wat. Res. 30(6): 1337 1344.
LINEP WHO(1996). United Nations Educational Program World Health Organization. Water
Quality Monitoring. A gractical guide to the design and implementation of freshvvater
quality studies and monitoring programtnes. 400 pp.
UNESCO - UNEP WHO (1996). United Nations Educational, Scientific and Cultural
Orgnanization United Nations Environmental Program World Health Organization.
Water Quality. Assessments. A guide to use of biota, sediments and water in
environmental monitoring (2nd edition). UNESCO - UNEP - WHO, 1996, 651 pp.
U.S.EPA (U.S. Environmental Protection Agency)(1985). Short-term Methods for
Estimating the.Chronic Toxicity of Effluents and Receiving Water to Freshwater
Organisms. EP.A/600/4-85/01.4. 57pp.
W.H.O(World health Organization)(1990). Environmental Health Criteria 101, Methyt-mercury.
International Programme on Chemical Safety. 42 pp.
WHO(1996). World Health Organization. Guidelines for Drinking-Water Quality 2nd ED.
- Vol. 2 Health Criteria and Other Supporting Information. 971 pp.
W.H.O(World health Organization)(2003). Water, Sanitation and Health Electronic
Libraiy. A compendium of WHO information on water, sanitation and health.13.000 pp.
10
780


Seasonal variation of some trace metal concentrations in some fish species on stretch of River Kubanni, Zaria

Abstract

Similar works

Full text

Available Versions

Aquatic Commons